haritha

NEET Biology Agricultural Chemical Pesticides Plant Pests

Agricultural:

Agricultural chemicals, including fertilizers, plant growth regulators, and insecticides, are employed to enhance the production potential of crops.

Fertilizers restore soil nutrients, growth regulators facilitate plant development, and insecticides safeguard plants against diseases and pests. c Pesticides encompass fungicides, herbicides, rodenticides, insecticides, nematicides, and algicides.

Major Groups Of Pesticides

NEET Biology Agricultural Chemical Pesticides Notes

As regards the mode of action pesticides attack the nervous systems and respiratory systems and herbicides damage the photosystem 2 of photosynthesis and translocation. Pesticides are capable of damaging the ecosystem and in the long run render agriculture non-sustainable.

• All pesticides are poisons. They upset the food web in nature.
• Some resistant pests survive even after pesticide application, thus higher doses are required to kill them.
• The major problem with the application of pesticides is bioconcentration in the bodies of animals.
• Due to the lack of safety measures in the use of pesticides, they pose adverse health effects on people.
• Owing to the lack of stringent measures in the manufacture of pesticides, there may be grave consequences such as the recent Bhopal gas tragedy. (1984)
• Integrated Pest Management (IPM) is a combination of techniques such as biological control, mechanical control and carefully timed application of pesticides along with sound cultural practices,

NEET Biology Agricultural Chemical Pesticides

Pesticides are capable of damaging the ecosystem and in the long run render agriculture non-sustainable.

All pesticides are poisonous; they are not specific to the target organism and they may kill useful organisms. They upset the food web in nature.

Examples of Classes of Pesticides

1. Organochlorides – DDT, BHC, Aldrin, Endosulphanc.
2. Organophosphate – Maiathion, Parathion and Fenitrothion.
3. Carbamates – Carbofuran, Aldicarboropoxus.
4. Triazincs – Simazines, Atrazinc
5. Pyrethroids – Pyrethrin

Agricultural Chemical Pesticides NEET Notes

Types Of Pesticides

Various Organic Compounds With Heavy Metals, Commonly Used As Fungicides Are:

1. Agrosan GN, Ceresan, and Tillex are compounds of mercury used in seed treatment.
2. Dithane M-45 and Dithane Z-79 control the tikka disease of groundnut.

Burgundy Mixture. It is an important copper fungicide. Its nature and function are the same as the Bordeaux mixture.

Biocides The pesticides that affect useful plants and animals including human beings.

Organochlorides are lipophilic in nature; hence, show a great affinity for fatty tissues. These decompose very slowly; therefore, get accumulate in the environment posing serious problems.

• Organophosphates are organic esters of phosphoric acid, thiophosphoric acid and other phosphoric acids. These are sold under the names-organic phosphates, phosphorus insecticides, nerve gas relatives, phosphates, and phosphate insecticides.
• These are the most toxic pesticides to vertebrates e.g., Parathion, Malathion, Fernethion, Trithion, TEPP and Ethion.
• Organophosphates act on the central nervous system, combining with the phosphorus molecule of the enzyme cholinesterase inhibiting its normal functioning. As a result, the breakdown of acetylcholine stops.
• The accumulation of acetylcholine leads to a barrage of extraneous nervous impulses. It causes acute toxicity resulting in convulsions, paralysis and death. The recognition of this property led to the development of nerve gas used in World War 2.

Carbamates are organic esters of hypothetical carbanic acid. Isolan, carbaryl, carbofuran, aldicarb, and propoxur are widely used.

Pyrethroids are synthetic derivatives of pyrethrin—a chemical extracted from an annual plant Chrysanthemum cinerarifolium, C. narshallii, and C. coccinium.

Triazines are a group of herbicides which are derived from urea, for example, Simazines and atrazine.

Agricultural Chemical Pesticides NEET Notes

NEET Biology Agricultural Chemical Pesticides Plant Diseases

When the favourable conditions of life are so seriously affected by any agency that the life of a part of a plant or whole plant is threatened, we call it plant disease. or

Plant disease can be defined as a condition in which the structure and function of a plant are disturbed and threaten the life of a plant.

• A diseased plant can be differentiated from a healthy plant because of a disturbed morphological and physiological state.
• Pathogens are the disease-causing organisms. There are numerous different types of pathogens. They are classified as animate, viral and inanimate pathogens.

1. Animate Pathogens. They are generally microbial in nature. Nematodes and insects are the other pathogens of animal origin. The fungus Puccinia graminis tritici causes black rust in wheat. A bacterium Xanthomonas ciiri causes citrus canker. Mites cause Mango malformation.
2. Viral Pathogens. Certain viruses act as pathogens. A few viral plant diseases arc mosaic, vein-clearing, chlorosis and leaf curl of potato.
3. Inanimate Pathogens. There are certain plant diseases whose causes cannot be attributed to any pathogens. Molybdenum deficiency in the soil causes whip tail of cauliflower. The black tip of mango and scabs are caused by gases released from chimneys and respiratory gaseous products in cold storage respectively.

Chemical Method To Control Plant Diseases

1. Bordeaux Mixture. It is a mixture of copper sulphate and lime in the ratio 4:4 dissolved in 50 gallons of water. It was first used in controlling many types of crop diseases by French Prof. Mallardet of the University of Bordeaux in 1878.
2. Burgandy Mixture. It is a mixture of copper sulphate 5 lbs, sodium carbonate 0.25 lbs and water 50 lbs
3. Ammonical Copper Carbonate (3 oz. copper carbonate, 5 pints ammonia and 50 gallons of water.
4. Sulphur Dust. Inorganic dust is one of the oldest and most widely used fungicides. It can be used as a powder or in the wettable form.
5. Antibiotics. Several antibiotics are used to control various plant diseases. Penicillin, streptomycin, cycloheximide, griseofulvin, viridin, blasticidin, agrimycin are the most common effective antibiotics.
6. Commonly Used Fungicides Are:
   1. Agrosan GN Ceresan Tillex are compounds of mercury used in seed treatment.
   2. Dithane M-45, Dithane Z-79 Control tikka disease of groundnut.
   3. Pyrethroids

NEET Agricultural Chemical Pesticides Chapter Notes

NEET Biology Agricultural Chemical Pesticides Plant Pests

Pests. Pests are animals or plant organisms which damage cultivated plants or plant products.

Types Of Pests. Pests are of the following types: Arthropods (invertebrates with jointed appendages)

1. Insects like grasshoppers, bugs, beetles, weevils, caterpillars and grain moth.
2. Non-insect arthropods, like crabs, ticks and mites,
3. Molluscs like snails and slugs.
4. Birds such as pigeons, parrots, sparrows and crows,
5. Mammals like rodents, monkeys and wild elephants.

1. Pests Of Maize.
   • Maize stems Borer (Chilo-Cornelius).
   • Pink Borer (Sesamia inferens).
2. Pests Of Millets.
   • Deccan wingless grasshopper (Calemania sphenarroides)
   • Greasy cutworm (Agrotis physilon).
3. Pests Of Sugarcane.
   • Top shoot Borer (Scirpophaga nivella)
   • Stem Borer (Diatoroea venosata).
4. Pests Of Cotton.
   • Spotted Bollworm (Earias fabla).
   • Pink bollworm (Pectinophora gossypiella.)

Various Stored Grain Pests

1. Rice Weevil (Calandra oryzae): A little bug, reddish-brown in color, measures approximately 2.5 mm in length.
2. Angoumois Grain Moth (Sitotroga cerealella):  It is a 12 mm long, lustrous buff-colored moth with pointed, slender wings featuring broad fringes.
3. Puke Beetle (Bruchus sp.)is a 3.00 mm:  Long insect characterized by elongated antennae and a chocolate-colored body, which inflicts significant damage to crops and stored grain.
4. Lesser Grain Borer (Rhizopertha dominica): The beetle measures approximately 1.5 mm in length, with a coloration ranging from black to brown, and possesses a globular head.
5. Red Grain Beetle (Tribolium castaneum): The adult measures 1.5 mm in length and exhibits a reddish-brown hue, but the larva is pale yellow.
6. Khapra Beetle (Trogoderma granarium): It is a brown-oval beetle that inflicts damage on wheat, as well as pulses, maize, and cereals. Only grubs inflict the injury.
7. Rice moth (Coreyra cephalonica).

NEET Agricultural Chemical Pesticides Chapter Notes

List Of Some Of The Insect Pests That Destroy Crops In The Fields

Agricultural Chemical Pesticides Class 12 Notes For NEET

NEET Biology Agricultural Chemical Pesticides Synopsis

Common Examples Of Organochlorides Are:

1. BHC
2. DDT
3. Heptachlor
4. DDE
5. Chlordane
6. Endosulfan
7. Aldrin
8. Dieldrin
9. Endrin.

Carbofuran is sold as furadan, propoxur as Baygon and aldicarb as Temik.

Agricultural Chemical Pesticides NEET Chapter Summary

Pesticide Treadmill Effect:

The usage of pesticides results in farmers allocating a greater amount of their income to these chemicals without achieving higher yields. This has occurred with cotton in India.

• A fish residing in water contaminated with DDT can accumulate a concentration of DDT that is 1,000,000 times greater than that present in the water.
• DDT disrupts the correct production of eggshells in birds, resulting in the destruction of deposited eggs prior to hatching.
• Peregrine falcons, Ospreys, and bald eagles have nearly become extinct due to DDT. Gambusia fish have been employed to manage mosquito populations within Integrated Pest Management (IPM).
• Algicides are insecticides that eliminate algal diseases and blooms, such as Copper Sulphate.
  The inaugural commercial bioinsecticide is Sporeine, which was developed in Germany.
  Organophosphates are biodegradable.

Dioxan is present as an impurity in 2,4,5 -T It is highly toxic and Carcinogen also causes kidney/ liver disorders.

Bioinsecticides of Plant Origin

• Rotenone from roots of Derris elliptica
• Cinerin and Pyrethrin from Chrysanthamum cinnarifolium
• Thurioside and Sporeine from Bacillus thringenesis
• Azadirachtin from Azadirachta indica
• Squill from Sea Onion
• Nicotine from Nicotiana species.

Phenylcarbamates and thiocarbamates are used as herbicides while Dithiocarbamates are used as fungicides.

Mental Health And Community Health For NEET Mental Health Growth Of Human Populations

Modern humans appeared around 50,000 years ago from the archaic Homo sapiens that existed between 1,00,000 and 2,00,000 years ago.

Population is defined as a group of organisms of the same species or other species within which individuals may change genetic information occupying a particular space.

Demography deals with the statistical study of the population.

• The population has characteristics which are a function of the whole group and not of the individuals; these are population density, birth rate, death rate, age distribution, biotic potential, rate of dispersion and growth form.
• In the beginning, the human population was sparsely distributed over the earth. Its growth was very slow in the beginning.
• About ten thousand years ago, the growth of the human population increased. Since then it is grown rapidly.
• Today in the world the population is not evenly distributed.
• Nearly 70 per cent of the world population lives in less developed countries
• In 1700 the human population was about 0.6 billion, it touched the one billion mark around 1850. It reached 6.1 billion by 2000.
• This dramatic increase is called a population explosion.

Maximum Carrying Capacity is the maximum size which can be supported in the environment. It has the first two components life-supporting capacity and waste assimilative capacity.

• The increased levels of environmental degradation arise from population explosion and population densities within different parts of the world.
• Population growth is determined by biotic potential and environmental resistance. The human population shows a T-shaped growth curve in the absence of environmental resistance. Enhanced longevity has also contributed towards the population explosion.

Mental Health Growth Of Human Populations NEET

Malthus, An Economist, Proposed A Theory Of Human Population Growth that states when unchecked population grows geometrically, whereas, the means of sustenance grows only arithmetically and this would cause imbalance. There are positive checks such as floods, wars, volcanic eruptions, earthquakes etc. which maintain population.

Fertility-Related Statistics. Fertility can be measured by a number of the following factors:

Birth Rate. The birth rate is the simplest indicator of fertility and is defined as “the number of live births per 1000 estimated mid-year population, in a given year. It is calculated by the formula

= \(\frac{\text { Number of live births during the year }}{\text { Estimated mid }- \text { year population }} \times 1000\)

The birth rate is an unsatisfactory measure of fertility because the total population is not exposed to childbearing. Therefore it does not give a true idea of the fertility of a population.

Rate Of Change In Population Size 

1. In the ‘S’ shaped growth curve, the rate of change in population size \(\left[\frac{d \mathrm{~N}}{d t}\right]=r \mathrm{~N}\left[\frac{\mathrm{K}-\mathrm{N}}{\mathrm{K}}\right]\)
2. In ‘J’ shaped growth curve, Rate of change in population size \(\left[\frac{d \mathrm{~N}}{d t}\right]=r \mathrm{~N}\) where \(\left[\frac{\mathrm{K}-\mathrm{N}}{\mathrm{K}}\right] \text { or }\left[1-\frac{\mathrm{N}}{\mathrm{K}}\right]\) = Environment resistance, r = Biotic potential, population size.

General Fertility Rate (GFR). It is the ‘number of live births per 1000 women in the reproductive age group (15-44 or 49 years) in a given year’.

GFR = \(\frac{\text { Number of live births in an area during the year }}{\text { Mid year female population of age } 15-44} \times 1000\)

The general fertility rate is a better measure of fertility than the crude birth rate because the denominator is restricted to the number of women of childbearing age, rather than the whole population. The major weakness of this rate is that not all women in the denominator are exposed to the risk of childbirth.

Total Fertility Rate (TFR) is the average number of children that would be bom to a woman during her lifetime assuming the age-specific birth rates at a given time. The total fertility rate is lower in developed countries as compared to underdeveloped countries. It is controlled by economics and human aspirations.

Doubling Time. The time required for a population to double itself is called doubling time.

Dobuiling Time = \(\left(\frac{70}{\text { Growth rate (in %age) }}\right)\)

With a 2% growth rate in India, the doubling time will be 70/2 = 35 years

The doubling time for the world population = 35 -10 years

Crude Birth And Crude Death Rates are the number of live births and deaths respectively per thousand people, on July 7 i.e. middle of the year.

Demographic transition. If birth and death rates are equal, it results in a zero population growth rate, it is termed demographic transition. It may occur in all countries as they become developed but it may take many decades in underdeveloped countries.

Immigration is the movement of individuals into a place or country.

Emigration refers to the movement of individuals out of a place or a country.

Population Explosion. If the growth of the population is continued either due to an increased birth rate or decreased death rate, it is called a population explosion. This is a great hazard to the development and prosperity of a nation.

Mental Health Growth Of Human Populations NEET

Reasons For Population Explosion

1. Management of Natural Disasters: Mitigation of floods, earthquakes, cyclones, and cold weather has lowered mortality rates, thereby leading to population growth.
2. Management of Epidemics: Control over plague, smallpox, diphtheria, cholera, diarrhea, and whooping cough has also reduced the death rate.
3. Augmented Food Production: The Green Revolution pertains to the enhancement of crops such as wheat and rice. The White Revolution for dairy and the Blue Revolution for aquaculture have augmented the quantity and accessibility of food for a broader segment of the population.
4. Modes of Transportation: The enhancement of rapid transportation services has facilitated the delivery of food to remote locations during emergencies. During a flood, food packets are delivered via helicopter or other rapid transportation methods.
5. Deficiency in Education: Individuals lack education and awareness on the detrimental effects of overpopulation.
6. Decrease in Infant Mortality Rate and Increase in Life Expectancy. Improvements in medical facilities have reduced the newborn mortality rate and raised the life expectancy of the population.

Annual Average Growth Rate:

It is a measure of the human population. It is calculated as follows:

Annual average growth rate in percent = \(\left[\frac{P_2-P_1}{P_1 \times N}\right] \times 100\)

Where P₁ = Population size in the previous census

P₂ = Population size in the present census.

N = Number of years between two censuses.

Dependency Ratio = \(\frac{\text { Person in dependent ages }}{\text { Persons in economically providing ages }}\)

Replacement Level (RL). It is the number of children a couple must produce to replace clientele, The actual RL, is always higher than 2.0 because children may the even better than the reproductive ape, In developed countries RL, is achieved at 2. 1 whereas in developing countries it is around 2.7 due to higher mortality rate and short life expectancy.

Three Components Of Environment

1. Productive System. Such as croplands, and orchards which provide food and fibres.
2. Protective System. It buffers the air and water cycle and extremes in temperature example, forests and ocean.
3. Waste Assimilative System. This part assimilates wastes produced by human activities, for example, waterways, and wetlands.

Maximum Carrying Capacity. It is defined as the “Feeding capacity of an environment of an ecosystem for a population of a species under a provided set of conditions.” It is also defined as the “Level beyond which no major increase can occur.” This limit is a constant and represented by K.

Maximum Carrying Capacity Depends Upon Following Components Of Environment:

1. Productive system and
2. Protective system.

The use of advances in science and technology for the productive system of the environment has increased the carrying capacity.

Sustainable Development encourages a process of change in which the exploitation of resources, the direction of investments, the orientation of technological development and institutional changes are all in harmony. Such development enhances both present and future potential to meet human needs and aspirations.

The concept of sustainable development, thus, aims at a framework to integrate developmental strategies and environmental policies at local, national and global levels. Development should not endanger the natural systems that support life.

Birth Control Measures

Mental Health and Community Health For NEET Amniocentesis

Amniocentesis Aim. It is a technique to determine:

1. Sex of the developing baby;
2. Genetically controlled congenital diseases;
3. Metabolic disorders in the foetus.

So amniocentesis is a pre-natal diagnostic technique.

Amniocentesis Procedure. It involves the following steps:

• The location of the foetus is determined by a technique called sonography (using high-frequency ultrasound waves) to prevent accidental damage to the foetus.
• A fine hollow needle is passed through the abdominal and uterine wall of a pregnant female (about the 14th or 15th week after conception) into the amniotic cavity.
• A small amount of amniotic fluid is withdrawn. It contains foetal skin cells and a number of proteins, especially enzymes. The cells can be cultured in vitro for further examination.

Demography Statistical Study Population NEET

Amniocentesis Significance:

To know the sex of the baby, congenital genetic diseases and metabolic disorders in the developing foetus, the technique known as amniocentesis is followed.

Thus amniocentesis is a pre-natal diagnostic technique. But the technique is being misused even to abort normal female foetuses. So it has been now banned. Karyotypic studies show that human females are homogametic while human males are heterogametic. It is the father who is biologically responsible for the sex of the child.

Test Tube Babies (In Vitro Fertilization)-IVF.

The Technique of in-vitro fertilization and in-vitro development followed by the embryo transfer in the uterus of the normal female to start the development and finally lead to normal birth is called test tube baby.

Test Tube Babies (In Vitro Fertilization)-IVF Procedure. It involves the following steps:

1. Removal of unfertilized ovum from the reproductive tract of a female.
2. Ovum is kept under aseptic conditions.
3. Fusion of sperm and ovum in a culture medium, outside the female body, to form the zygote.
4. The zygote is stimulated to develop in-vitro up to 32-celled stages.
5. The developing embryo is implanted in the endometrium of the uterus at the 32-celled stage. So the pregnancy in the woman starts and further development of the child continues in the womb till it is bom.

Such a baby is called a test tube baby.

Test Tube Babies (In Vitro Fertilization)-IVF Significance

1. It is a boon to infertile mothers.
2. It can be used for men with oligospermia (low sperm count).
3. Old superior cows can donate oocytes.

Embryos can be frozen and preserved in an embryo tank for 10 years for future use. In very rare cases, a surrogate mother may have to be used to bring up an in vitro fertilized ovum to maturity. Though the biological realization of a test tube baby is a remarkable achievement, it has raised several ethical and legal problems including the right over the child.

• The first test tube baby was bom to Lesley and Gilbert Brown on July 25, 1978, in Oldham, England. Mrs. Brown had obstructed Fallopian tubes. Dr. Patricke Steptoe and Dr. Robert Edwards both from England experienced Mrs. Brown successfully.
• The world’s first test tube baby (a baby girl) was named Louise Joy Brown. Later, test tube babies were also born in Australia, the United States and some other countries. India’s first test tube baby was bom on August 6, 1986, at K.E.M. Hospital, Mumbai. Her name is Kumari Harsha.
• Mental Health. Behaviour according to the accepted norms of society is termed mental health.
• Mental Illness. A person may be physically fit and not suffering from any disease but because of certain inhibitions, abnormal behaviour and abnormal reactions to normal situations of life.
• Mental Illness is mainly classified into psychosis, neurosis and other disorders such as mental retardation and epilepsy.

Differences Between Psychosis And Neurosis

Symptoms Of Mental Illness

1. Depression.
2. Insomnia or excessive sleeping.
3. Compulsive action.
4. The feeling of hopelessness.
5. Serious thoughts of suicide.
6. Unreasonable phobias.

Population Characteristics NEET Exam Preparation

List Of Common Problems Of Adolescence

1. Anxiety
2. Hypochondria
3. Loneliness
4. Neurasthenia
5. Phobias
6. Post-traumatic stress.

Drug Abuse. The constant use of certain drugs forms a habit and one becomes a drug dependent.

• This is called drug dependency or drug addiction or drug abuse. Such drugs act on the brain and change the behaviour, consciousness and power of perception of an individual, and are called mood-altering or psychotropic drugs.
• The drugs of abuse are often taken with alcohol or with common medicines such as aspirin. It increases sedation.
• Drug abuse is not found among well-adjusted, satisfied and happy people. It is more common among those who are under stress and feel insecure.

Anxiety Disorders. These may be

1. Neurotic anxiety or
2. Separation anxiety or
3. School phobia. These disorders are due to overreaction to stress conditions. The symptoms are palpitation, sweating, nausea, trembling, diarrhoea and muscular tension.

Schizophrenia.

It is characterized by the following:

1. Distorted thoughts
2. Laughing or crying at an inappropriate time disturbs emotion
3. Incoherent and bizarre behaviour lasting for a week or more
4. Auditory hallucination.
5. Delusion.
6. List Of Psychological Disorders
7. Anxiety disorders
8. Obsessive-compulsive disorders
9. Attention deficit disorders
10. Mood disorders
11. Schizophrenia
12. Borderline personality disorders
13. Addictive disorder

Obsessive-compulsive Disorders. These disorders cause total disability and affect a person’s working hours. Affected persons manifest overwhelming obsessions and compulsions.

• They are compelled to perform an action or an idea despite their own attempt to resist it (compulsion).
• The most common obsessions are violence, concern about infection by germs or dirt, and constant doubts (obsessions).

Population Characteristics NEET Exam Preparation

Mental Health And Community Health For NEET Drugs

Drugs are substances used to treat diseases or to replace a missing substance essential for growth or combat against genus-causing infection. Another category of dmg includes those substances which work on the nervous system and act either as stimulants or as depressants.

Drug Dependence Or Drug Addiction. It is defined as self-administration of damage for a long period which leads to dependence of the body on them and may cause various disorders.

Drugs are classified on the basis of their action as follows:

• Tranquillisers. They slow down the high centres of the brain and relieve worries. They influence only mental activity but do not affect working efficiency, for example, alcohol, compose, diazepam, Librium (chlordiazepoxide) and luminal.
• Depressant. Depressants are used to calm anxiety. They produce drowsiness and a feeling of confusion, for example, Barbiturates are used as depressants or sedatives.
• Stimulants (Antidepressants). These drugs temporarily increase mental alertness or self-confidence. They are also called Mood elevators or Superman drugs, for example. Amphetamines, cocaine, coffee and tea also contain small amounts of stimulants.
• Narcotic. It is a drug or chemical which depresses the activities of the central nervous system.

Antidepressants: They are essential for the treatment of severe cases of depression and are prescribed in most cases of clinical depression. Four types are in use as given

Mental Health and Community Health For NEET Psychedelic Or Producing Drugs

These drugs have a strong effect on the cerebrum and sense organs and take the user to a world of fantasy giving him false and temporary happiness. The individual may sense strong colours and strong sounds even though nothing is there. They include LSD (Lysergic acid Diethyl amide), Marijuana and Hashish.

Barbiturates. They are the synthetic drugs. They are sedatives and are the major components of sleeping pills. Its use produces drowsiness, feelings of confusion and sleep. Its withdrawal causes epilepsy.

Cannabis. It is the most ancient drug-yielding plant. Three kinds of drugs are obtained from these plants (Derivation of Cannabis indica).

1. Hashish or Cliaras is obtained from the flowering tops of female plants.
2. Bhang is obtained from dry leaves.
3. Ganja. It is obtained from small leaves and bracts of inflorescence.

Marijuana is another drug obtained from Cannabis sativa. The common reaction of these drugs is relaxation, euphoria, laughing tendency, and rise in blood sugar level.

Human Population Growth Historical Perspective

Kinds And Effects Of A Few Drugs

Classes Of Psychoactive Drugs

Mental Health and Community Health For NEET Tobacco Addiction

The tobacco plant is a native plant of tropical America.

WHO report states that in India, about one million people die every year (2,200 Indians die every day) due to tobacco-related diseases.

Tobacco smoke mutates and inactivates the P-53 gene which checks cancer growth.

Benzpyrene. Carcinogen present in tobacco. About 33 per cent of all cancers are caused by tobacco.

In India, about 19 per cent of women workers engaged in beedi making, have one of four miscarriages at three to four months of pregnancy.

Byssinosis. Acute bronchitis is associated with generalized airflow obstruction.

No Tobacco Day: 31st May. Tobacco is commonly called killer weed.

1996- The Olympics held in Atlanta (USA) had been declared smoke-free.

Health Care Foundation of India (HCFI) has suggested that tobacco should be treated like any other narcotic as regular nicotine use may also lead to addiction.

In India, the graph of smokers skyrocketed by 400 per cent during the 1970-80 period alone. Meanwhile, a six-fold increase in mortality from bronchitis and emphysema was also noted in India.

An “ Anti-tobacco Bill” has been long pending before Parliament.

• One out of 20 children are tempted by cigarette advertisements.
• India is one of the top consumers of cigarettes. Over 142 million men and 37 million women above 15 years of age are regular smokers.

Lung Cancer mortality risk for a heavy smoker is 20-30 times greater than that of a non-smoker.

• China has the biggest cigarette market.
• According to WHO, by 2025 AD only 15 per cent of the world’s smokers will be in the rich countries compared to the present 28 per cent, while in the Third World, the percentage of smokers will rise from 72 to 85 per cent.

Central Tobacco Research Institute is located at Rajahmundry (A.P.)

Mental Health and Community Health For NEET Alcoholism

Alcoholism. The habit of drinking alcohol is called alcoholism. Alcoholism as a disease was declared by WHO in 1964.

Sedative. Which depresses functional efficiency.

Depressant. Lowers the activities of CNS.

Beer, Wine And Whisky contain 3%, 10% and 40% alcohol.

Malthus Theory Human Population Growth NEET

Anaesthetic. Causes loss of sensation.

Hangover. Mild effects of alcohol even after a long period of its consumption.

Polyneuropathy. A degenerative disease of the nervous system associated with chronic alcoholism.

The most common form of cirrhosis is known as Lenmec’s cirrhosis.

Alcoholism also causes a reduction in life span of 10 to 12 years.

Treatment Of Alcoholism: Abstaining from alcohol; general psychological rehabilitative treatments; use of drugs like Antabuse (disulfiram) and Temposil (Citrated calcium cyanide); aversion therapy; etc.

Mental Health and Community Health For NEET Community Health

The sum total of all the activities that contribute to the improvement of the health of the community.

Vaccination. The introduction of antigens into the body induces the production of specific antibodies, either to confer immunity against subsequent infection by the same antigen or, less commonly, to treat a disease.

Sanitary. Free from dirt and germs that might cause disease.

Sanitation. All the arrangements provide sanitary conditions.

Sterilization. A process which makes things free from germs.

National Programmes: The Government of India has launched various national programmes to eradicate and control some of the major communicable diseases. These are

1. National Malaria Eradication Programme (N.M.E.P)
2. National Filaria Control Programme (N. F. C. P.)
3. National Leprosy Control Programme (N.L.C.P.)
4. National Smallpox Eradication Programme
5. National Cholera Control Programme (N.C.C.P.)
6. Tuberculosis Programme
7. Other diseases—Trachoma, Cancer, V.D, T.B.

AIDS etc. are also covered under various National Programmes

Universal /National Immunisation Programme:

The success of the smallpox eradication program has catalyzed efforts to eliminate six avoidable illnesses via the universal immunization initiative. The six diseases are diphtheria, pertussis (whooping cough), poliomyelitis, tetanus, TB, and measles.

• The program was initiated by the World Health Organization in May 1974 and aims to reach every kid by the year 2000 A.D.
• It was launched in India in 1985 and reached every child by 1992. India has designated the year 2000 A.D. as the year for universal health. The immunization timetable for six selected diseases and two supplementary ones
  1. Cholera and
  2. Typhoid

Malthus Theory Human Population Growth NEET

The Human Population Increased To An Unmanageable Proportion In Recent Times Due To The Following Reasons:

1. Enhanced longevity has contributed to the population explosion.
2. Advances in medicines and surgery have made it possible to save thousands of lives.

Human Population Growth Curve Assumes T Shape And Sigmoid Or ‘S’ Shape: When the food supply becomes insufficient in comparison with population, mass starvation death results. The graph of population growth will become T -shaped. When there is no increase in population and the environment can sustain a limited population, the growth curve will become ‘S’-shaped.

Reasons For Depletion Of Environment:

1. Excessive deforestation,
2. Indiscriminate mining operations,
3. Excessive use of fossil fuels.

Limiting Factors Which Prevent The Earth From Supporting a Human Population Of Indefinite Size:

The following are the limiting factors which prevent the Earth from supporting a human population of limited size

1. Adequate food supply.
2. The habitable area on the land is limited. If a man tries to create more habitable areas by cutting down trees in forests, it would lead to imbalances in the nature.
3. Limited natural resources.
4. The adaptability of an organism for growth to the conditions.
5. Famine, floods and epidemic diseases.
6. Adolescence is the period of rapid growth, and physical and mental development period between childhood and adulthood.
7. Acne resulting from clogged pores of the skin is a common problem of adolescence in both sexes.
8. Neurasthenia is characterized by the inability to concentrate on enjoying things. It may lead to irritability, fatigue, insomnia, depression and headache.
9. Phobias are common in adolescents.
10. Mental Illness is characterized by abnormal behaviour and talk resulting in social and vocational dysfunction.

Important Psychological Disorders Are:

Anxiety disorders, obsessive-compulsive disorders, attention deficit disorder, mood disorder, Schizophrenia, Borderline personality disorder (BPD) Youths are tempted to go for drugs for non-clinical use.

Psychotropic Drugs or mood-altering drugs are also addictive:

• The substances are classified as sedatives and tranquilizers, opiate narcotics, stimulants, and hallucinogens.
• Drugs can be administered via inhalation or oral ingestion. They may also be administered by injections.
• All pharmaceuticals influence the central nervous system. Prolonged usage is exceedingly harmful to health.
• Nonetheless, some of these medications are given by physicians in appropriate dosages for certain conditions.
• Alcohol is swiftly absorbed and enters the circulatory system. A multitude of metabolic diseases is linked to persistent and excessive alcohol consumption.
• These encompass fatty liver disease, cirrhosis, hypertension, cardiovascular disorders, gastric ulcers, and vitamin shortages.
• Overcoming addiction is feasible with medical supervision and social assistance.
• The concurrent use of drugs and alcohol

Malthus Theory Human Population Growth NEET

Major Groups Of Psychotropic Drugs, Examples And Effects

Interaction Of Alcohol With Some Common Drugs

Mental Health and Community Health For NEET Synopsis

WHO (World Health Organization) is a specialized, non-political health agency of the United Nations with its headquarters in Geneva. The constitution came into force on 7th April, 1948. Which is celebrated every year as ‘World Health Day’.

Alcohol is by far the number one foetal teratogen. Maternal alcohol intake and characteristic pattern of malformation in the foetus has recently been recognized called FAS, Foetal alcohol syndrome.

Symptoms of FAS include slow growth before and after birth, small head, facial irregularities like narrow eye slits, defective heart and other organs, malformed arms and legs, genital abnormalities and damage of the central nervous system and many, behavioural problems like hyperactivity and nervousness.

Cigarette smoke may be teratogenic and cause cardiac abnormalities and anencephaly (absence of cerebrum). Maternal smoking is also a significant factor in the development of cleft tip, palate and gastrointestinal disturbances. It is linked with sudden infant death syndrome (SIDS).

Anabolic Steroids misused by players are mainly Nandrolone, stanozolol, oxymetholone and methandie- nonc.

Age Distribution Pyramids. For constructing age pyramids, 3-age groups are taken into consideration.

1. Pre-reproductive age (0-14 years).
2. Reproductive age (15-60 years).
3. Post Reproductive age (> 60 years).

There are 3-types of pyramids, i.e. Triangular, Bell-shaped and Urn-shaped

1. Triangular Pyramid. It indicates an expanding population with a high growth rate.
2. Bell-shaped Pyramid. It indicates a stable population with a zero growth rate.
3. Urn-Shaped Pyramid. It indicates a declining population with a growth rate of minus.

P₁ = Pre-reproductive age, P₂ = Reproductive age. P₃ = Post-reproductive age

Projected Growth Rates. Year 1999 = 1.4%, Year 2010 = 1.8%, Year 2030 = 0.5%

GIFT. Gamete intrafallopian transfer (GIFT), a modified form of IVF, was developed in 1984 and is used when at least one fallopian tube is open.

• The sperms (gametes) are injected into the oviduct (fallopian tube) when the ovulation occurs.
• The difference between IVF and GIFT is that in GIFT fertilization occurs naturally within the body of a female partner, instead of in the laboratory in IVF.

ZIFT. Zygote intrafallopian transfer is another variation of IVF, and is also called ‘tubal embryo transfer’. In this case, after in vitro fertilization (in a Petri dish or test tube) the zygote is transferred into the fallopian tube. The difference between ZIFT and GIFT is that in ZIFT fertilization is observed/assured, whereas in GIFT it is not.

• The success of IVF/GIFT/ZIFT declines with the advancement of the age of the woman, perhaps due to poor quality of eggs; and if the success rate is improved, the chances of multiple births are increased.
• The present rate of growth of the human population is about 2 per cent per annum and in developing countries, it is 2.5% per annum.
• Sigmoid (S-shaped) and J-shaped growth curves are the two main kinds of growth curves.
• In a recent cyclone in Bangladesh over 50,000 people were killed but with a birth rate of 3.3 per cent per year, the number was replaced in 40 days.
• At the current rate of growth human population is doubling every 35 years.

If the 4.5 billion people in the world today continue to increase at the present rate, their combined mass will exceed the mass of the earth which is about 6.5 billion trillion tonnes in a period of 1550 years.

• Japan is the most densely populated country in the world.
• Australia is the most thinly populated country.
• Kerala is the most densely populated state of India. The complete count of individuals in an area is called a census.

Population Characteristics NEET Exam Preparation

The sex ratio in India is 929 females per 1,000 males. About 56% of the world’s population lives in Asia alone

• Harsha is the name of the first test tube baby bom in India (Kolkata)
• Laparoscopy involves tubular ligation (blocking fallopian tubes)
• Biologically females are superior to men because they nurse the foetus in the womb for about 280 days.
• The Red Cross was established in 1864
• There is a proposal to bring legislation to discourage the use of tobacco products including a ban on the use/consumption of tobacco in public places and on tobacco advertisements.
• Blood transfusion was first practised by James BledclI.
• The mechanism to preserve vaccines is called the cold chain.
• Amnesia. Loss of memory is associated with excessive alcohol intake.
• International Day against Drug Abuse and Illicit Trafficking is celebrated on June 27.
• IV-Drug: Any drug which is taken intravenously and includes addictive narcotic drugs like heroin.
• Drug phencyclidine is useful in controlling “rogue elephants.”
• “The Narcotics, Drugs and Psychotropic Substances Act 1985” in India is one of the most powerful laws in the world to combat drug trafficking.

Teratogens. The drugs which cause foetal abnormalities when given to a pregnant mother are termed ter¬atogens. The placenta does not act as a barrier. Thalidomide is a well-known teratogen and causes phocomelia. Such drugs affect the foetus in three stages

1. Fertilization and implantation
2. Organogenesis
3. Growth and development.

Other Known Teratogens Are LSD, morphine, methotrexate, stilboestrol, corticosteroids, warfarin, antithyroid drugs, tetracycline etc.

World Breastfeeding Week is celebrated every year from 1-7 August.

• WHO = World Health Organisation
• NICD = National Institute of Communicable Diseases
• ICMR = Indian Council of Medical Research
• ESI= Employees State Insurance

Human Health And Common Human Diseases For NEET

Disease. It is defined as a condition of the body or a part of it in which functions are disturbed. The word disease means lack of ease and comfort.

Health. It is a state of complete physical, mental and social well-being. Health is also linked with social environment and cultural background.

Koch’s Postulate. Robert Koch (1876) studied diseases and pathogens of anthrax caused by Bacillus anthracite, later on, tuberculosis caused by Mycobacterium tuberculosis (1882) and cholera caused due to infection of Virbrio cholera (1883). He proposed the following four criteria for establishing an agent of infectious diseases.

The organism must be regularly found in the body of animals that have the disease.

1. It must be possible to isolate the organism and grow it in pure culture on artificial media.
2. A healthy animal must contract the disease and show its characteristic symptoms when it is inoculated with the culture of the organism.
3. It must be possible to recover the same organism from the body of an inoculated animal.

Human Health And Diseases NEET Notes Pdf Download

Kinds Of Diseases

Read and Learn More NEET Biology Notes

1. Congenital Diseases. (Inborn diseases). Diseases contracted before birth due to defective heredity (chromosomal abnormalities and gene mutations), physiological disturbance or transplacental transmission for example, Haemophilia, Down’s syndrome, colour blindness, hare lip, and transplacental syphilis.
2. Acquired Diseases. Diseases contracted after birth due to infection, defective diet, hypersensitivity, injury, addition, degeneration, depression, etc.
3. Infectious Diseases. They are diseases due to pathogens that can be transferred from one individual to another for example, tetanus, measles, flu, malaria, typhoid, cholera, and tuberculosis.
4. Deficiency Diseases. Diseases caused by absence or deficiency of an essential element, for example, anaemia, goitre.
5. Degenerative Diseases. Diseases caused by ageing, result in malfunctioning or decreased efficiency.

Human Health And Common Human Diseases For NEET Disease Agents

Any substance which causes a disease by its excess deficiency or absence is called a disease agent.

Types of Disease Agents. Disease agents are of the following types:

1. Biological Agents. These are also called pathogens (Gr. path means disease; genes means producing). These are those micro-organisms which when successfully infect the human body, multiply and produce toxins in the incubation period which interfere with the normal functioning of the body and cause a disease.
   • These include viruses (mumps, chicken pox, smallpox),
     • Mycoplasma, (for example bronchitis, acute leukaemia),
     • Chlamydia (for example. trachoma)
     • Bacteria (for example, cholera, tetanus),
     • Fungi (ringworm, thrush, moniliasis, pulmonary aspergillosis),
     • Protozoa (for example, giardiasis, sleeping sickness),
     • Helminths (for example, filariasis, ascariasis, taeniasis), and
     • Other organisms (for example, scabies).
2. Chemical Agents. Some chemical compounds are also causative agents of certain diseases. These are of two types on the basis of their source.
   • Endogenous Chemical Agents. These are formed inside the body. These include urea, uric acid, hormones, enzymes etc.
   • Exogenous Chemical Agents. These enter the human body from outside by ingestion, inhalation or inoculation. These include pollutants like gases, dust, metals etc. and allergens like spores, pollens etc.
3. Nutritive Agents. These include minerals, carbohydrates, proteins, fats, vitamins and water.
4. Physical Agents. These include heat (stroke), cold (frostbite), humidity, pressure, radiation, electricity, sound (impaired hearing) etc.
5. Mechanical Agent. These include injuries, fractures, sprains, dislocations etc.
6. Genetic Agents. Some diseases are caused by genetic causes and include haemophilia, sickle cell anaemia, etc.
7. Degeneration. Due to old age.
8. Social Agents. These may cause mental disorders.
9. Unknown Reasons. The agents for certain diseases like peptic ulcers, hypertension and coronary heart diseases are yet to be identified.

Human Health And Common Human Diseases For NEET Modes Of Transmission

Communicable diseases are those diseases which can be transmitted from the reservoir of infection or an infected person to healthy but susceptible persons.

There are two modes of transmission:

1. Immediate Transmission Or Direct Transmission:

The pathogens are transmitted straight from an infected individual to a healthy individual without an intermediary agent. It manifests in the following manners:

1. Through direct contact with an infected individual: Contagious diseases such as chickenpox, smallpox, athlete’s foot, measles, leprosy, ringworm, gonorrhoea, and syphilis are transmitted through direct contact between an infected individual and a healthy individual. Entamoeba gingivalis, the oral amoeba, is transferred through direct mouth-to-mouth contact, such as kissing.
2. Droplet Transmission: Diseases such as diphtheria, influenza, the common cold, measles, TB, pneumonia, mumps, and whooping cough are transmitted through droplet infection, which involves pathogens contained in minute mucus droplets expelled during sneezing, coughing, spitting, or conversing with infected individuals.
3. Animal Bites: Rabies viruses are transmitted to humans by the bites of rabid animals such as dogs, monkeys, and cats.
4. Transplacental Transmission: The viruses responsible for German measles and the bacteria causing syphilis can be transferred from maternal blood to fetal blood via the placenta.

2. Indirect Transmission:

When infections are transmitted from the infection reservoir to a healthy individual via intermediary agents.

It manifests in the following manners:

1. Vector-borne: Vector-borne diseases include, for instance, the tsetse fly (African sleeping sickness) and sandflies (kala-azar and oriental sores). Female Anopheles mosquito (malaria), rat flea (bubonic plague), Aedes mosquito (yellow fever), Culex mosquito (filariasis), and housefly (typhoid, cholera, dysentery, etc.)
2. Pediculus humanus capitis (typhus) – Vehicle-borne: Pathogens responsible for cholera, dysentery, and typhoid are disseminated by vectors such as food and water. AIDS is transmitted through the blood of infected individuals.
3. Airborne: Pathogens are disseminated through wind currents, aerosol sprays, and dust, as exemplified by epidemic typhus.
4. Formite Borne: Pathogens are disseminated by contaminated items such as handkerchiefs, towels, dinnerware, toys, soap, cutlery, and surgical tools.
5. Imperfect Hands: The pathogens responsible for disorders such as Ascariasis (Ascaris lumbricoides) and Enterobiasis (Enterobius vermicularis) are transmitted by contaminated hands; therefore, thorough handwashing is essential before to meals.

Human Health And Common Human Diseases For NEET Defence Mechanism Of Body

External Defence/ First, Line Of Defence/Physical And Chemical Barrier. It consists of physical barriers of skin, membranes, friendly microorganisms and chemical barriers.

1. Skin. Keratinised dead outer epidermal cells do not allow entry to pathogens. Oil and sweat are inhibitory to the growth of most pathogens.
2. Nostril Hair. They Filter out dust and microorganisms from inhaled air.
3. External Friendly Microorganisms/Friendly Bacteria. Many friendly bacteria live on the skin and secrete chemicals harmful to pathogens.
4. Mucous Membranes. They line digestive, respiratory and urinogenital tracts so as to prevent the entry of germs into body parts.
5. Mucus And Cilia. The mucous membrane of the nasal tract possesses cilia for pushing back dust and germs. It also secretes mucus for trapping and killing them.
6. Internal Friendly Microorganisms. They occur in the intestine and vagina.
7. Chemical Barriers
   • Sweat, oil and secretions of extremely friendly bacteria are acidic to prevent the growth of many pathogens.
   • Lysozyme or bacteriolytic enzyme is present in sweat, tears, saliva and mucus.
   • Hl of the gastric juice has germicidal properties.
   • Bile does not allow the growth of microorganisms.

Non-Specific Internal Defence/Second Line Of Defence: A pathogen having entered body tissues/fluid is confronted with the second line of defence consisting of phagocytosis and inflammatory response.

1. Phagocytosis. Phagocytes present in the blood come out of the capillaries through diapedesis. Phagocytes of blood and macrophages present in tissues attack germs and engulf them. Pus may collect. Pus is a thick liquid formed in the region of the wound and is composed of tissue fluid, damaged body cells, dead phagocytes, some leucocytes and microorganisms.
2. Inflammatory Response. It is the reaction of living tissues to injury, irritation or infection which is characterised by pain, swelling, redness and heat. Inflammatory’ response can be localised (area of injury or infection) or systemic (whole body). It is caused by the release of an amine called histamine (C₅H₉N₃) from body tissues and lymphocytes.
   • Histamine dilates blood capillaries, makes them more permeable, lowers blood pressure, and allows greater leakage of phagocytes and plasma so that tissue fluid accumulates (histamine also stimulates gastric secretions and uterine contractions).
   • Toxins released by pathogens, and endogens pyrogens (Substances capable of producing fever/pyrexia) produced by leucocytes raise body temperature to stimulate phagocytes and inhibit microorganisms.
   • Pyrogens reset the thermoregulatory centres of the hypothalamus. However, body temperature may rise too high when it is brought down by the administration of antipyretic drugs (for example, paracetamol, and aspirin) and cold packs. Phagocytes attack vigorously when body temperature is high.

Specific Internal Defence Immune System/Third Line of Defence:

A constituent of a pathogen behaves as an antigen. Antigen (antibody generating) is any foreign substance like protein or polysaccharide present on the external coating of the pathogen, the toxin of the pathogen, white of egg, feathers, a constituent of a vegetable, fruit, meat, drug, chemical, tissue or organ transplant which induces the immune system to produce antibodies.

Human Health And Diseases Neet Notes Pdf Download

Antibodies. Chemical substances are produced for the destruction of disease-producing external factors. Antibodies are made of complex proteins called immunoglobulins (Ig). They are of 5 types (IgM, IgG, IgA, IgD and IgE). Some important antibodies are tetanus antitoxin, agglutinins, bacteriolysis, oposonins etc.

Types Of Antibodies

Structure Of Antibody And Its Specificity: An antibody is a globular protein consisting of four polypeptide chains; two identical heavy chains, with more than 400 amino acids each, and two Identical light chains, with about 200 ammo acids each.

Along half the molecule, carbohydrate groups are attached and the two heavy chains are held closely together by a series of disulphide bonds. Along the other half, the chains are aligned in two pairs, with one heavy and one light chain in each pair. The entire molecule is shaped like a Y. Each antibody molecule has two functions:

1. An effector function or type of action taken to eliminate the antigen, and
2. A specific antigen-binding function.

There are five groups of mammalian antibodies, which are classified according to their effector function IgG, IgM, IgA, IgD, and IgE. (Ig stands for immunoglobin, the term for all proteins with antibody function.) IgG antibodies are the gamma globulins that circulate in the blood and attack both bacteria and viruses.

• Other groups attach to the plasma membranes of B cells, activate complement, enhance phagocytic activity, and play various other roles in fighting disease-causing microbes.
• The five groups are distinguished from one another by the amino acid sequences in their constant (C) regions, with all molecules in a group having the same sequence. Additionally, the attached carbohydrate groups help determine the particular effector function of the antibody.

There must be millions of different kinds of antibodies with regard to specific-binding capacity since one kind exists for almost every kind of foreign macromolecule. The specificity of an antibody for an antigen lies in its sequence of amino acids within the two “arms” of the molecule.

• These so-called variable (V) regions form the active sites, where the molecule binds to specific antigens. Both arms have the same amino acid sequence and so bind the same kind of antigen.
• Thus, each antibody can join two antigens, and many antibodies working together can clump, or agglutinate, more antigens for many efficient elimination by die different effectors.

Antimicrobial Substances. Antimicrobial biochemicals are also part of the non-specific immune response. Certain animal cells infected with viruses produce polypeptides called cytokines.

One type of cytokine, an interferon, diffuses to healthy neighbouring cells and stimulates them to produce biochemicals that block viral replication. When these cells become infected, the viruses are unable to take over the protein synthetic machinery to manufacture more of themselves. The spread of the infection halts.

Interferon. It is a protein produced by virus-infected cells. Interferon binds to receptors of non-infected cells, causing the cells to prepare for a possible attack by producing substances that interfere with viral replication. Interferon is specific to the species, therefore, only human interferon can be used in humans.

Human Health And Common Human Diseases For NEET Types Of Immune System

The immune system is of two types:

1. Humoral Or Antibody-Mediated Immune System (Amis). It is formed of proteinaceous defensive chemicals, called antibodies which are produced by B-Iymphocytes and circulate in the plasma of blood and lymph (humour = body fluids) and protect the body from bacteria and viruses that enter the blood and lymph. There are about 10²⁰(100 million trillion) antibody molecules.
2. Cell-Mcdialcd Immune System (CMIS). It is formed of highly specialized cells called T-Iymphocytcs which directly attack the pathogenic micro-organisms (like protozoans and fungi) that have entered the host’s body or grafts such as transplanted kidney or skin grafts taken from another person (allografts). It also protects the body from its own cells which have become cancerous.

How Do The Different Kinds Of T Cells Develop: The source of all blood cells, including white cells, is Lhc bone marrow. However, this tissue produces only stem cells —primitive, immature lymphocytes that migrate to other parts of the body for development into mature, functional cells. Most immature lymphocytes are formed during foetal life (prior to birth).

• About half the lymphocytes that leave the bone marrow pass through the thymus a mass of tissue located within the chest cavity just below the neck. The thymus is quite large during infancy but shrinks to a very small size in early childhood and remains small throughout life.
• Cells that pass through this organ before entering the circulatory system develop into T cells. They are especially effective in detecting and destroying eukaryotic cells with foreign antigens on their surfaces, such as those that have become cancerous and infected with viruses.
• The plasma membrane of a T cell contains receptor proteins that recognize one particular antigen. When the cells contact with this antigen, they differentiate into one of three types of T cells—cytotoxic, helper, or suppressor.
• Cytotoxic (or killer) T cells destroy their target cells by releasing a substance that dissolves holes in their plasma membrane, causing the target cell to lyse. Helper T cells stimulate B cells to make antibodies and facilitate the action of other T cells.
• Some helper cells secrete lymphokines or interleukins, which are messenger molecules that recruit other white blood cells to the battle site. Suppressor T cells cause both B cells and other T cells to become less active.

Action Of T Cells: When triggered off by antigens, T-cells also produce a clone of T-cells such as

1. Killer T-cells or KT Cells—Directly attack and destroy antigens.
2. Helper T-cells or HT cells—Stimulate B-cells to produce more antibodies.
3. Suppressor T-cells or ST-cells—Check on entire immune system to attack the own body cells. Some of these cells become memory cells.

Memory T-cells. They are sensitised T-cells which retain the memory of antigen-specificity for the future, sometimes lifelong. Killer, helper and suppressor T-cells are also called effector cells.

Action Of B-Cells: The antigen-specific helper T-cells stimulate specific B-lymphocytes to multiply rapidly forming clones of plasma cells. In the presence of antigens, the plasma cells form antibodies at the rate of 2000 molecules per cell per second, a total of some 20 trillion per day.

Distribution Of B-And T-Cells In Human Body

Antibody Action (Effector Mechanism),

1. Neutralisation. Some antibodies function as antitoxins and neutralise the toxins produced by pathogens/foreign chemicals.
2. Agglutination. Antibodies called Agglutinins cause immobilisation and clumping of antigens (precipitation) and antigen-containing pathogens.
3. Opsonisation/Adherence. Antibodies called opsonins (for example, IgG) attach themselves to the surface of antigen-containing cells so as to be recognised by phagocytes,
4. Complement Mediated Cell Lysis. Antigen-containing cells are perforated by enzymes produced with the help of lysin antibodies (IgM IgG).
5. Phagocytosis. The lysed immobilised clumped pathogens are engulfed by killer T-cells and other phagocytes.

Principles Cells Of The Immune System

Immunity: After being stimulated B-cells and T-cells produce numerous effector cells and memory cells. Effector cells help in killing effective antigens and they live for a few days. The memory cells kill the antigens of the second infection and they live for much longer time and some may live even for the whole life.

These memory cells are stored in the spleen and lymph nodes. This explains the reason why some childhood diseases are not contracted for a second time. This is called acquired or active immunity. Immunity is of two types.

1. Innate immunity—Inborn.
2. Acquired immunity—Acquired after birth.
   1. Active acquired immunity
   2. Passive acquired immunity

Role Of Lymphoid Organs: The organs where lymphocytes are formed and mature, termed lymphoid organs. They are of two types i.e. Primary lymphoid organs and secondary lymphoid organs. Primary lymphoid organs such as hone marrow and thymus are the sites where B and T-cells can be produced.

• Secondary lymphoid organs such as lymph nodes, spleen, and mucosa-associated lymphoid tissue such as tonsils are the sites where lymphocytes are stored. They multiply and undergo differentiation at these sites.
• They acquire an immune response to antigens develop in their organs.

Human Health And Diseases Neet Notes Pdf Download

Innate Or Inborn or- Non-specific or Natural Immunity:

It is present from birth and is inherited from the mother to offspring through the placenta. It is not acquired from the previous attack of disease, for example, innate immunity against distemper (a fatal disease of dogs) and cholera. It is the first line of defence. It consists of four types of barriers

1. Anatomical
2. Physiological
3. Phagocytic and
4. Inflammatory barriers.

Besides that phagocytes kill bacterial cells, virus-infected cells and some foreign cells of the body by creating perforin-lined pores in the plasma membrane of target cells. These pores allow entry of water into the target cell which then swells and bursts.

Acquired Immunity. The immunity acquired during a lifetime is called acquired immunity. It is specific and also known as adaptive immunity.lt requires many days to be activated. It has four unique properties

1. Specificity
2. Diversity
3. Memory and
4. Discrimination between self and non-self.

Specific Immunity employs two major groups of cells

1. Lymphocytes and
2. The antigen-presenting cells.

Properties Of Acquired Immunity

1. Specificity. It is able to recognize various foreign molecules.
2. Diversity. It can recognize a vast variety of foreign (non-self) molecules.
3. Memory. The immune system responds to first encountered by forming antibodies. It retains the memory and if there is a second attack by the same antigen, (microbe/foreign molecules) evokes a heightened immune response.
4. Distinguish Between Self And Non-Self Molecules. It can recognise and respond to molecules that are foreign or non-self

Activation Of Adaptive Immunity:

Every antigen is scanned by antigen-presenting cells like macrophages, B lymphocytes, etc. The processed antigen is present on the surface of these cells. A subgroup of T- T-cells, called T helper cells, specifically interacts with the present antigen and becomes activated.

The activated T helper cells then activate B cells and a subgroup of T cells called T cytotoxic cells in a specific manner. The activated B and T cytotoxic cells divide repeatedly to produce clones (similar cells). All the cells of a clone recognize the same antigen and fight it, neutralize the action or eliminate it.

Vaccination: Originally the term vaccination (alter the Latin word vacca = cow) is described as the process of inoculating persons with discharge from cowpox to protect them from smallpox.

But now it is applied to the inoculation of any antigenic material for the purpose of producing active artificial immunity. The first successful polio vaccine (the Salk vaccine) was composed of viruses that had been inactivated by treatment will) formaldehyde.

Kinds Of Vaccine

1. Killed Vaccine.
   1. The organisms are killed by phenol, alcohol, heat and UV rays, for example, Typhoid.
   2. Vaccine is prepared by killing organisms with the use of formalin, for example, whooping cough, and poliomyelitis (discovered by Salk).
2. Toxoid. They have lost their toxic property but retained antigenic properties, for example, antitetanus, and diphtheria toxoids.
3. Attenuated Living Vaccine. Oral ‘Live’ Sabine vaccine (OPV), Antipoliomyelitis (Salk); Antimeasles, B.C.G., yellow fever.
4. Antigens Isolated From Infectious Agents, for example, polysaccharides of pneumococci.
5. Antiserum/Serum. It is fibrinogen-free serum or blood plasma of an animal which has antibodies or antitoxins against a particular pathogen/toxin because the animal has been injected with a safe dose of the pathogen at regular intervals, for example, diphtheria, tetanus, or snake bite.
6. Monoclonal Antibodies (Magic Bullets). They are identical antibody molecules, specific for a particular antigen, which have developed from a single source like hybridoma.

They were devised by Cesar Milstein and George Kohler (1975). Hybrid cell culture formed of antigen-sensitised cells, fused with myeloma/cancerous bone marrow cells for indefinite production of monoclonal antibodies.

Passive Immunity: Passive immunity is short-lived. Passive immunity occurs when an individual is given prepared antibodies and immunoglobulins to combat a disease. Since these antibodies are not produced by the individual’s B cells, passive immunity is short-lived.

• For example, newborn infants are passively immune to diseases because antibodies have crossed the placenta from the mother’s blood.
• These antibodies soon disappear, however, so that within a few months, infants become more susceptible to infections. Breastfeeding prolongs the natural passive immunity an infant receives from the mother because antibodies are present in the mother’s milk.
• Even though passive immunity does not last, it sometimes is used to prevent illness in a patient who has been unexpectedly exposed to an infectious disease.
• Usually, the patient receives a gamma globulin injection (serum that contains antibodies), perhaps taken from individuals who have recovered from the illness.
• In the past, horses were immunized, and serum was taken from them to provide the needed antibodies against such diseases as diphtheria, botulism and tetanus.

Interferon: Interferon was first identified in 1957. These are proteins released by cells in response to a viral infection which they help to combat. They do not inactivate the virus but make the healthy cells less susceptible to the viral attack and prevent the viruses from taking over the machinery of the cells. Interferons have proved to be effective in treating influenza and hepatitis.

Common Human Diseases Important Questions For NEET

Antisera

• Prior to the development of vaccinations, serum with preformed antibodies was utilized.
• This serum is referred to as Antiserum or hyperimmune serum.
• When utilized for protection, it is referred to as prophylactic serum.
• When utilized for therapeutic purposes, it is referred to as therapeutic serum, generally known as Gammaglobulin.
• It is derived from human blood sera provided by donors and contains antibodies.
• In certain instances, the body identifies these serum antibodies and antigens, subsequently generating antibodies against them in an allergic response. This condition is referred to as serum sickness.
• It leads to rash, respiratory distress, and joint swelling.

Human Health And Common Human Diseases For NEET Autoimmunity

The immunity developed against one’s own structure is known as autoimmunity. It has been observed that sometimes the immune system of the body goes off track and starts working against the own body and this in turn leads towards disease for example immunity developed against RBCs causes Anaemia and autoimmunity against the muscular system causes severe wsafeness (myasthenia gravis).

Human Health And Common Human Diseases For NEET Immunodeficiency

It is a disorder of the immune system where one or both components are unable to work properly due to congenital or acquired disease.

• SCID (Severe Combined Immunodeficiency): It is a congenital immunodeficiency disorder in which both B—and T—lymphocytes are not formed and the patient dies of even minor infection (Such children can survive only in germ-free isolation chambers).
• Acquired Immuno-Deficiencv Syndrome (AIDS) Cause. AIDS is a severe viral disease which has been able to overcome all the defensive mechanisms of the human body and generally leads to death.

It is caused by a retrovirus-HIV (Human immunodeficiency virus), earlier called LAV (Lymphadenopathy-associated virus) or HTLV (Human T-lymphotropic virus). It was first reported in African green monkeys but was first isolated in man by Moulagnier et al. (1983) and Gallo et.al. (1984). Its genetic material is RNA so it multiplies through the process of reverse transcription. Another peculiar feature of HIV is its mutability.

HIV– Human Immunodeficiency Virus

Subgroup- Lentivirus

Family– Retroviridae

Incubation Period, It ranges between 15-57 months. The average incubation period is 8 months.

Sites From Which HIV Can Be Isolated.

1. Blood
2. Semen
3. Cervical fluid
4. Saliva
5. Breastmilk
6. CSF
7. Tears
8. Skin
9. Lungs
10. Glial cells, Microglia of CNS.

AIDS Is a Pandemic Disease Symptoms. HIV attacks Helper T- lymphocytes. The reduction in number of Helper T-lymphocytes causes severe cellular immunodeficiency. The number of T-cells drops to even below 200 in comparison to 500-1500 in a normal person.

So it is a disorder of the cell-mediated immune system of the body. These clinically unhealthy persons are called opportunistic. AIDS is characterized by one of the following symptoms:

1. Pneumocystis Carinii Pneumonia (PCP) is a lung disease. Idiopathic multiple-a skin cancer (Kaposi’s sarcoma) These forms 70% of AIDS cases.
2. Psychosis Or Chronic Encephalitis– severe brain damage.
3. Thrombocytopenic Purpura– decreased count of blood platelets causing haemorrhage.
4. Lymphoma – cancer of lymphatics.
5. Lymphadenopathy- swelling of lymph nodes.
6. Another peculiar symptom of AIDS is severe wasting syndrome (substantial weight loss and general decline in health).
7. AIDS patients also become more susceptible to infections of any system of the body.
8. When the brain is damaged, then it may cause loss of memory, and the ability to speak and even think.

A full-blown AIDS patient dies within three years and mortality is 100%. The most serious form of AIDS is AIDS-related complex ARC which is characterized by swollen lymph nodes, night sweats and loss of weight.

New Anti-Retrovirus Drugs Against HIV

1. Protease Inhibitors in combination with AZT blocks the enzyme essential for multiplication of HIV-virus.
2. Sustiva, also called Efavienz, was developed by Food and Drug Administration (FDA) of USA in September, 1998.
3. XQ- 9302, a Chinese herbal medicine.
4. Interleukins (a class of proteins secreted by immune cells) when given in combination with AZT and protease inhibitors can remove the virus even from CD- 4 cells where the virus hides and rests.
5. Nono Xynol- 9, a spermicide in gel form and claimed to be anti- HIV is found to be ineffective in protecting women from HIV- Infection.
6. Nevirapine pervents HIV transmission from mother to child.

Two Serological Tests For Anti-HTV Antibodies

1. Screening Test.
2. Confirmatory Test.

1. Screening Test. These tests are not highly specific. The most widely used screening test is the ELISA test.
2. Confirmatory Test. A commonly employed confirmatory test is the Western Blot test. It is carried out after the screening test shows a positive result.

Immunosuppressants: They are chemicals which suppress the immune reaction of the body towards transplanted organs (for example, kidney, parts of the intestine, heart) for example, cyclosporin.

Infectious Diseases—some of them fatal, have newly emerged and were not previously known:

1. HIV infection which causes AIDS
2. Hepatitis C, B and E
3. A new form of Cholera
4. A highly fatal respiratory disease caused by a virus called Sin Nombre
5. A variant of Creutzfedt-Jakob disease—a disease of the central nervous system
6. Ebola haemorrhagic fever
7. A haemolytic uraemia syndrome

Reemerging Infectious Diseases: Some of the infectious diseases which were earlier controlled are now reappearing in epidemic forms. They are

1. Tuberculosis
2. Cholera
3. Dengue
4. Malaria
5. Plague
6. Meningococcal meningitis
7. Diphtheria
8. Japanese encephalitis

Diseases Caused By Bacteria

Other Bacterial Diseases Are diarrhoeal diseases (Shigella, Escherichia coli, Campylobacter, Salmonella etc.), botulism (food poisoning – Clostridium botulinum); anthrax (Bacillus anthracis); meningitis (Neisseria meningitis) etc.

Common Human Diseases Important Questions For NEET

Diseases Caused By Viruses

Dengue Fever. It is a viral fever whose vector is a daytime-biting Aetles aepypti mosquito. Its incubation period is of seven days.

• It is characterized by high fever (above 102° F), severe frontal headache, pain behind the eyes, muscular and joint pain, loss of appetite, measles-like rash on the chest and upper limbs, nausea, vomiting etc.
• Dengue haemorrhagic fever is also associated with bleeding from the nose, mouth, and gums and vomiting. In October 1996, Dengue fever was declared as an epidemic.
• Adult Aetles mosquitoes can be killed by spraying malathion. Aedes mosquito has small, black and white strips on its legs and back. It bites during the daytime in the early hours of the morning and late hours of the afternoon.

The hepatitis -B Virus causes so many deaths in only one day as by AIDS virus in one year. In India, about 4.30 crore people suffer from hepatitis- B. The vaccine against hepa- titis-B is available and is given to the 6th, 10th and 14th years age group of children.

Revac-B vaccine is a genetically engineered vaccine against hepatitis-B disease. It has been developed by Bharat Biotech International Ltd. (Hyderabad).

SARS (Severe Agile Respiratory Syndrome): Typical pneumonia is an infection of lung tissue caused by organisms other than pneu¬monia causing organisms, maybe a virus, metapneumo virus another virus called corona vims has also been identified.

• Symptoms And Signs Of SARS
  • High fever
  • One or more respiratory symptoms (Cough, breathlessness or hypoxia.)
  • Headache, muscular stiffness, loss of appetite vague feeling of discomfort, confusion, rash and diarrhoea
  • Close contact with a person having SARS for the previous 10 days.
• Countries Which reported SARS cases: China. Hongkong, Taiwan province, Singapur, Vietnam and Canada In India only 12 cases of SARS were reported.
• Modes Of Transmission Droplet infection spread through respiratory surface Diagnostic Test. Rapid molecular Genetic Test ( PCR Test) 2. Serological Test. Treatment. Combination of Antiviral drugs and cortical steroids plus other intensive supportive treatment.

Protozoanal Diseases: Malaria, amoebiasis, sleeping sickness etc are the main protozoan diseases caused by Plasmodium, Entamoeba and Trypanosoma respectively. Malaria is spread by the female Anopheles mosquitoes, amoebiasis is spread by contaminated food and water, and sleeping sickness is spread by Glossina (Tse-tse fly).

Helminth Diseases: Tueniasis, ascariasis and filariasis are common helminth diseases of man. These are caused by Taenia solium, Ascaris lumbricoides and Wuchereria bancrofii respectively. Human infection of Taenia occurs by taking undercooked measly pork while that of Ascaris occurs through contaminated food. Filariasis is spread through Culcx and Aedes mosquitoes.

Important STDs And Common Techniques For Their Detection

Heart Diseases: These are the most common cause of death in human beings in the present century. Rheumatic heart diseases result from the repeated attacks of rheumatic fever in childhood.

• The toxins cause inefficiency of the valves between the auricle and the anti-ventricle. Arteriosclerosis is another common cardiovascular disease caused by the deposition of calcium or cholesterol in the walls of the arteries. Hypertension is characterized by persistent high blood pressure.
• Coronary thrombosis, also called myocardial infarction, involves the formation of a thrombus in the coronary artery. High sperm cholesterol, cigarette smoking, hypertension, diabetes and obesity are other risk factors for coronary heart disease.

Diabetes Mellitus

Diabetes Mellitus Causes

• Deficiency of insulin hormone due to hypoactivity of p—p-cells of Islets of Langerhans of the pancreas.
• Obesity and overweightness.
• Mental shocks.
• Heredity (diabetes controlled by a recessive gene present on the short arm of chromosome 11).

Diabetes Mellitus Symptoms. Due to a deficiency of insulin hormone, the person can neither store glucose as glycogen nor use glucose as respiratory fuel, so diabetes mellitus is characterized by:

Human Health And Diseases Neet Previous Year Questions With Answers

Hyperglycemia (blood glucose many times greater than normal), polyuria or diuresis (excessive urination, about 10 litres per day), polydipsia (excessive thirst), polyphagia (increased hunger), glycosuria (sugar in urine, about 100 g/24 hrs), loss of weight, decreased glycogen level in liver, blurred vision, reduced healing capacity etc. Due to incomplete oxidation of fats, ketonic bodies are formed, so secondary symptoms of diabetes mellitus are:

Ketonemia (ketones in the blood), Ketonuria (ketones in urine), acidosis (pH of blood decreased from 7.4 to 6.8), diabetic coma and death.

• A person suffering from diabetes is called a diabetic. It is reported in about 1-3% of Indian population. China now has 20 million diabetics and their number is swelling each year by 750,000. About 5.3 per cent of the inhabitants of Beijing city suffer from diabetes.
• So Beijing is becoming the city of diabetics. There are over 15 million known diabetics in India with Delhi alone accounting for over 3 lakhs. Increasing urbanization and a changing lifestyle with less physical exercise and overeating are responsible for the increase.

27th June is called Diabetes Day: Diabetes occurs in two forms

1. Insulin-dependant Diabetes (IDDM—Type-1 diabetes). It occurs due to a deficiency of insulin from (β cells of Islets of Langerhans. It is more severe and generally occurs in young.
2. Non-insulin-Dependent Diabetes (NIDDM—Type-2). It occurs due to the failure of the target cells to take up insulin from the blood. It generally affects after 40 years of age. Patients are mostly overweight so should reduce their weight by a low-calorie diet and exercise.

Diagnosis. Diabetes mellitus can be diagnosed by testing blood and urine sugar levels.

Diabetes Insipidus

Diabetes Insipidus Cause. The main cause of diabetes insipidus is decreased secretion of ADH (anti-diuretic hormone), also called vasopressin, from the neurosecretory cells of the hypothalamus and released from the posterior lobe of the pituitary gland.

Diabetes Insipidus Symptoms. Deficiency of ADH causes decreased permeability of the wall of collecting tubules and decreased reabsorption of water from the urine, so diabetes insipidus is characterized by:

Diuresis, polydipsia, loss of weight, weakness etc. but urine is sugar free.

Arthritis: It is a disease more of advanced age characterised by the abnormality of joints. The common three types of arthritis are :

1. Degenerative Arthritis (Osteoarthritis). It first attacks the cartilage of the joint. The lumps are formed which make the movement impossible. It causes joint fixation or ankylosis.
2. Rheumatoid Arthritis. It first attacks the synovial membrane (membrane which lines the joints) and causes inflammation which leads to stiffness of the joints.
3. Gout. It is a type of arthritis in which the accumulation of uric acid crystals occurs at the joints. These crystals make movement difficult and also cause severe pain.

Human Health And Common Human Diseases For NEET Allergies

Allergies Definition. An allergy is the hypersensitivity of a person to some foreign substance, called an allergen, which either comes in contact with or enters the body. About 15% of the Indian population suffers from one or other type of allergic disorder.

• Allergy, also known as hypersensitivity, is an inappropriate overreaction of the immune system.
• An allergy is a non-infectious, unnatural and unusual reaction to a substance called an allergen which is generally a weak antigen.
• Common allergies are anaphylaxis, urticaria, hay fever, asthma, eczema, etc.
• Antibodies belonging to the class IgE trigger allergy by combining with the antigen and surface of mast cells in the connective tissue.
• Mast cells release a large amount of histamine into the bloodstream.
• The symptoms of an allergy reaction develop in response to histamine which stimulates capillary dilation, increased permeability, closure of bronchial tubes, mucus secretion, pain and swelling.
• A severe allergic reaction called anaphylactic shock occurs when a large amount of histamine is suddenly) released by the mast cells.
• All the peripheral arteries dilate at once causing a very low blood pressure or shock. It is fatal if not immediately treated.
• Allergies are treated with drugs that cause vasoconstriction: antihistamines in the case of normal allergic reaction and epinephrine in the case of anaphylactic shock.

Human Health And Common Human Diseases For NEET Inflammation

Inflammation Definition. Damage to the body’s tissues triggers a defensive response called inflammation.

• Inflammation can be caused by microbial infection, or physical agents (heat, radiant energy, electricity or sharp objects).
• Inflammation is usually characterized by four symptoms.
  1. Redness
  2. Swelling.
  3. Heat
  4. Pain
• Sometimes a fifth symptom, loss of function, is present,
• Inflammation has the following functions:
• To destroy the injurious agent to limit the effects of the injurious agent on the body by confining or walling off
• To repair or replace tissue damaged by the injurious agent
• Any substance or agent that tends to cause a rise in the body temperature (fever) is called pyrogen.
• Pyrogens are released by WBCs that set the body’s thermostat at high temperatures.

Type Of Allergens. The common allergens are dust, pollens, spores, feathers, fur, venom food and drugs. Some physical agents also act as allergens.

Allergens Mechanism. It involves 3 steps:

1. Sensitisation. In this, allergen acts as a mild antigen so stimulates the formation of antibodies which bind to mast cells of connective fissure.
2. Second Stimulation. In this, allergens combine with antibody-bound mast cells which rupture and release histamine.
3. Histamine Action causes hypersensation.

Human Health And Diseases Neet Previous Year Questions With Answers

Symptoms Of Allergic Reactions. The following are the symptoms of allergies

• A person may suffer from high fever which affects the mucous membrane of the eyes, nose and upper respiratory tracts.
• The mucous membrane of the lower part of the respiratory tract leads to cough and asthma.
• Reddening of skin, the appearance of blisters on the skin.
• Accumulation of tissue fluid below the skin.
• Watering of eyes and inability to breathe.

Human Health And Common Human Diseases For NEET Cancer

Cancer is characterized by uncontrolled growth and division of certain body tissues, so forming a tumour. It is more common in people between 40 to 60 years of age. It is one of the chief killers today. Every year about 6 million people throughout the world are diagnosed as having cancer, being equally divided between developed and developing countries.

• In the world, about 4 million people die of cancer which accounts for about 10% of all deaths. In India, 80 per cent of cancer patients come from viral areas and are first diagnosed with cancer at an advanced stage.
• Neoplasm is a new abnormal tissue that is capable of continued growth, formation of tumours, crowding and disruption of normal cells. Tumours are of two types, benign and malignant. A benign tumour is a large localised mass of abnormal tissue which presses other tissues but does not infiltrate adjacent tissues because it is encapsulated in connective tissue.
• A Malignant Tumour is a large mass of abnormal tissue which is not encapsulated, is capable of invading adjacent tissue and distant sites. Metastasis is the spread of cancerous cells from one part of the body to other parts through blood, lymph or the formation of secondaries from a malignant tumour.

Cancers Are Of the Following Types:

1. Carcinoma:

It is a carcinoma of epithelial or epidermal tissues and its derivatives, including skin, mucous membranes, glands, lungs, breasts, pancreas, and stomach.

2. Sarcoma:

It is a malignancy of primordial mesodermal tissue, including connective tissue, bone, muscle, and lymph nodes.

3. Kaposi:

Kaposi sarcoma is a secondary condition linked to AIDS. Leukemia (= Leukemia). It is a malignancy characterized by an excessive and uncontrolled proliferation of white blood cells (200,000—1,000,000/mm³) and immature myeloid stem cells.

In a prevalent form of leukaemia, white blood cells invade the bone marrow, spleen, liver, lymph nodes, and other organs, resulting in damage and enlargement.

In myelocytic leukaemia, the 9th and 22nd chromosomes amalgamate their transposable elements, resulting in the degeneration of erythroblastic tissue in the bone marrow.

Hemorrhaging is occurring at several locations. Tonsils and cervical lymph nodes hypertrophy. The predominant cancers in India are oral-pharyngeal cancer in males and cervical-uterine cancer in females.

4. Adenoma: Glandular carcinoma

5. Lymphoma:

It is a malignancy of the lymphatic system and spleen, characterized by the overproduction of lymphocytes.

Carcinogenic Factors (Factors inducing Cancer).

Carcinogens/Chemical Carcinogens. They are substances/often environmental pollutants which cause cancer, for example, soot (skin, lungs). coal tar (3, 4, benzopyrene—skin and lungs), cigarette smoke (N-nitroso- dimethyl—lungs), cadmium oxide (prostate gland), aflatoxin (liver), 2-naphthyl amine and 4-aminobiphenyI (urinary bladder), mustard gas (lungs), nickel and chromium compounds (lungs), asbestos (lungs, pleural membrane), diethylstilbestrol (DES—vagina), vinyl chloride (liver).

• Radiations. Both UV and ionising radiation increase the incidence of cancer. For example, Leukaemia incidence is 10 times higher in radiologists than other medical workers.
• Heat. Reverse smoking causes mouth cancer. Kangri (heating device) increases the incidence of cancer in Kashmiris.
• Tobacco. Tobacco chewing produces mouth cancer. Smoking increases the chances of throat and lung cancers.

Biological Agents. Some viruses and other parasites, excessive secretion of certain hormones are believed to produce cancers.

Mechanical Agents. Friction, trauma or continuous irritation seem to produce cancer.

Mechanical Agents Symptoms. A lump or hard area, swelling or sore that does not heal, unexplained loss of weight, difficulty in swallowing, persistent cough or hoarseness, change in colour of a mole/wart, a change in digestive/bowel habits, loss of blood through a natural orifice or excess out of date loss of blood in women.

Therapy: Cancer can be controlled in early stages and control depends upon the location and spread of the cancer

1. Radiation Therapy. In this, the cancerous parts of the body are exposed to ionising radiation like X-rays which kill the cancerous cells. It gives good results in skin, lip, mouth and cervix cancers.

It is used in almost 80% of cancer patients for treatment Brachytherapy is a special radiotherapeutic technique in which a very high doze of radiation in a short period to a small volume of body tissue by small radioactive sources like Radium, Cobalt 60, Iridium-192, etc. arranged in a geometrical fashion in and around the tumour.

2. Hormonal Therapy. In this, a hormone-caused cancer is treated by another hormone which neutralizes carcinogenic hormones for example, breast cancer can be controlled by testosterone.

3. Surgery. It involves the removal of cancerous parts by operative methods.

4. Chemotherapy. A number of chemicals like mercaptopurine, 6-aminopterin etc. are known to kill cancerous cells or inhibit DNA synthesis and cell division in cancer cells. Catharantlius roseus, commonly called sadabahar, provides two anti-cancerous drugs; Vincristin and Vinblastin which are used against leukaemia.

A new drug called Photoferin has been discovered in the U.S.A. to cure throat cancer. It is a modified porfimer sodium extracted from cow’s blood.

Drugs Used In Chemotherapy Of Cancer

5. New Anti-Cancer Drugs. The new drug, Doxil, contains an antitumour ingredient called Doxorubicin.

• Recently Israeli researchers have developed a new technique of new dmg delivery in which liposomes (a group of ball-like biomaterials) infiltrate the malignant tumours through the gaps in the blood vessels of cancerous tissue and release the anticancerous doxil to kill the cancerous cells.
• These liposomes cannot penetrate into healthy tissue as no such gaps exist in their blood vessels.

6. Gene Therapy For Skin Cancer. A revolutionary form of gene therapy for skin cancer has been developed by Mary Collins of the Institute of Cancer Research (London). In this, tumour cells are genetically engineered to carry a protein—Interleukin-2.

Then the tumour cells are injected into the skin of the patient where they begin to release Interleukin- 2 which stimulates the white blood cells to attack cancer cells in the skin, hopefully preventing cancer from spreading.

Therapy Mechanism: Carcinogenic factors activate certain genes called oncogenes. Jumping genes or transposons are also involved. The activated oncogenes result in uncontrolled cell proliferation or cancer.

Cancer cells have irregular, hypertrophied nuclei, abundant nuclear granules, an increased number of lysosomes, reduced cristae in mitochondria, melanin, mucus, fat droplets and debris in cells.

ABO Blood Group:

Whether a person has type A, type B, type AB or type O blood depends on the presence or absence of specific substances on the red blood cells. There are two of these substances- antigens A and B.

• Thus a person with antigen A is considered to be with blood group A, a person who is in blood group O has neither of the antigens and a person with antigen B, blood group is called B. If both the antigens A and B are present the blood group is called AB. The blood group character is controlled by a set of three alleles.
• During injury or disease blood is lost and is generally replaced by transfusion. The blood is obtained from a donor and must be compatible with that of the person receiving, i. e.. recipient.
• In case the blood is not compatible then the antibodies present in them cause clumping of blood in the capillaries and may result in death. The plasma of B-group blood contains antibodies A. The formation of clumps occurs in case B group blood is mixed with blood group A.

Human Health And Diseases Neet Previous Year Questions With Answers

Rh Factor. The Rh-blood types were first discovered in the Rhesus monkey. It was found that RH (rhesus) antigens were causing many of the transfusion failures that were unexplained by the A-B-O system. There are at least eight different Rh antigens discovered so far. A person is called Rh- Rh-Rh-positive if he has any one of these antigens and Rh-negative if the antigens are absent.

• A complication arises if the blood of an Rh-negative is transferred to Rh- a positive individual or vice-versa.
• When the red blood cells of an Rh-positive person is transfused into a person with Rh-negative blood an agglutination of red cells occurs. The antibodies against the Rh antigen are present in the Rh- Rh-negative person. The agglutinated cells clog up capillaries and the white cells of the recipient attack and break up the red blood cells (hemolysis).
• Repeated exposure to transfusion increases the speed and seriousness of the antibody-antigens response. In such cases, serious complications arise which lead to death.

NEET Biology Strategies For Enhancement In Food Production Animal Sources

Animal Husbandry. It is a branch of science that deals with the improvement of domesticated animals, with regard to race, reproduction, and feeding.

Livestock. The animals like cattle, sheep, goats, camels, horses, pigs, and poultry form the livestock.

Apiculture. Rearing and management of honey bees for obtaining honey and wax is called apiculture.

Poultry Fanning deals with the rearing of game birds such as domestic fowls, ducks, turkeys, and pheasants which yield eggs and meat, rich in protein and other nutrients.

Aquaculture is the production of aquatic plants along with animals like prawns, fishes, oysters, etc.

Piscicultural Practices (production of fishes) differ depending on whether the fishes belong to freshwater or marine water.

Marine Fishery practices include trapping and collecting by using trawlers, nets, baits, electronic locators, etc. The most important edible freshwater fish in India is the rohu. catla and Singhara: marine ones arc Bombay duck, hilsa, and pomphret.

Strategies For Enhancement In Food Production Class 12 NEET Solutions

Strategies For Enhancement In Food Production NEET Notes

Animal Husbandry

Animal husbandry is the agricultural practice of breeding and rearing livestock. Consequently, it is an essential skill for farmers, embodying both scientific and artistic elements.

• Animal husbandry pertains to the management and breeding of livestock such as buffaloes, cows, pigs, horses, cattle, sheep, camels, and goats that are beneficial to people.
  It encompasses poultry farming and aquaculture.
• Fisheries encompass the cultivation, capture, and sale of fish, mollusks, and crustaceans.
• Since ancient times, humans have utilized creatures such as bees, silkworms, prawns, crabs, fish, birds, pigs, cattle, sheep, and camels for products like milk, eggs, meat, wool, silk, and honey.
• It is believed that over 70 percent of the global livestock population resides in India and China.
• It is noteworthy that the contribution to global agricultural output is about 25 percent, indicating a low productivity per unit.
• Therefore, with traditional methods of animal breeding and care, it is essential to implement advanced technology to enhance quality and output.

NEET Biology Strategies For Enhancement In Food Production Dairy Farm Management

Dairying is the management of animals for milk and its products for human consumption.

• In dairy farm management, we deal with processes and systems that increase yield, and improve the quality of milk,
• Milk yield is primarily dependent on the quality of breeds on the farm. Selection of good breeds having high yielding potential (under the climatic conditions of the area), combined with resistance to diseases is very important.
• For the yield potential to be realized the cattle have to be well looked after – they have to be housed well, should have adequate water, and be maintained disease-free.
• The feeding of cattle should be carried out in a scientific manner – with special emphasis on the quality and quantity of fodder.
• Besides, stringent cleanliness and hygiene (both of the cattle and the handlers; are of paramount importance while milking, storing, and transporting the milk and its products.
• Nowadays, of course, many of these processes have become mechanized, which reduces the chance of direct contact of the product with the handler.
• Ensuring this stringent measurement would, of course, require regular inspections, with proper record keeping. It could also help to identify and rectify the problems as early as possible. Regular visits by a veterinary doctor should be mandatory.

Strategies For Enhancement In Food Production Class 12 NEET Solutions

Improvement Of Livestock:

1. Four Essential Methods For Livestock Improvement: breeding, weeding, feeding, and heeding.
   1. Both the male and female animals selected for breeding should be of superior quality.
   2. Weeding aims that uneconomic animals must be prevented from reproducing.
   3. Feeding is also very important for animals. Each animal should be fed on a balanced ration.
   4. Heeding implies good animal management and general supervision including housing care and maintenance of proper cleanliness and hygiene.
2. Proper health care.
3. Suitable environmental conditions for housing accommodation.
4. Resistance to disease.
5. Regular inspections by veterinary doctors. Three Principle Factors For Productive Potentialities Of Livestock;
   • Genetic make up
   • Nutrition and
   • Environment including the climatic conditions.

Breeds Of Cattle – 26 Indian breeds. The cattle breeds are classified into three groups:

1. Milch Breeds: The cows are good milk-producing bullocks and are of poor quality.
2. Drought Breeds: Bullocks are good for working, and cows are poor milk producers.
3. General Utility Breeds (Dual-Purpose Breeds): Crows are good milk producers, and bullocks are good draught animals.

Some Breeds Of Indian Cattle:

1. Milch Breeds: Gir, Sahiwal, Red Sindhi, Deoni.
2. Drought Breeds: Malvi, Nageri, Hallikar, Kangayam
3. General Utility Breeds: Haryana, Ongole, Kankrej, Tharparkar

New Breeds

1. Karan Swiss: Evolved at the.NDRI, Kamal
   • Breeding between Sahiwal cows with the semen of Brown Swiss bulls imported from the U.S.A.
2. Sunandini: Originated in NDRL Kerala.
   • Cross between the local non-descript cattle with Jersy, Brown Swiss, and Holestein-Friesian breeds.
3. Karan Fries: Evolved at the NDRI, Kamal.
   • Cross between Tharparkar and Holstein Friesian.

Some Exotic Breeds Of Cattle Are Jersy, Holstein-Friesian, Ayrshire, and Brown Swiss

Feeding Cattle: The feed consists of two main components roughage and concentrates.

1. Roughages: Contain high fiber content and include fodder, hay, straw, and silage.
2. Concentrates: Include broken grams, cereals and millets, rice polish, cotton seeds, forage crops, oil cake, oil seeds, and animal by-products.

Strategies For Enhancement In Food Production NEET Important Questions

Indian Buffaloes; Bubalns Bubalis.

• Breeds Of Indian Buffaloes: 7 breeds of buffaloes in India.
  • Good, well-defined milk breeds – Punjab, Rajasthan and Gujrat.
  • Drought breeds – Central and – South India.
• Some Breeds Of Indian Buffaloes: are Murrah, Bhadawari, Jaffrabadi, Surti, Mehsana, Nagpuri, or Ellichpuri, Nili Ravi.

Strategies For Enhancement In Food Production NEET Important Questions

Difference Between Cow And Buffaloes

• Heat period is weaker in buffalo than cows (silent heat).
• Sexual maturity in buffalo bull is later than an ox.
• High calf mortality in buffaloes.
• More annual milk yield.
• Mineral content (Ca, P) is higher in buffaloes.
• Better adaptability, disease resistance, and life span than cows.
• Milk is free from carotenoids.

Uses Of Cows And Buffaloes: Milk, agricultural operations, manure and fuel, leather, meat, hair (for making brushes), bone meal, glue, and gelatin, horns, and hybridization.

Strategies For Enhancement In Food Production NEET Important Questions

Cow And Buffaloes Memory Points

Cow:

• Domesticated animals are used for
  1. Agricultural operations
  2. Milk
  3. Transport
  4. Manure and Fuel
  5. Leather
  6. Glue and Gelatin
  7. Meat.
• The most important breeds of milk cows in the United States are Holstein, Friesian, Jersey, Guernsey, Ayrshire, Brown Swiss, etc.
• There Are 26 Breeds Of Cattle, Classified Into:
• A balanced diet for a cow is rich in carbohydrates, fats, proteins, minerals, vitamins, and water.
• Feeds are divided into roughages and concentrates.
• Roughages contain fibre including hay, fodder, and silage.
• The concentrate mixture is made up of grains and seed by-products.
• The most Common And Nutritious Feed For cats is grasses.
• The Two Breeds – The Karanswiss and Sunandini are developed through cross-breeding at the National Dairy Research Institute, Kamal (Haryana), and in Kerala respectively.

Strategies For Enhancement In Food Production NEET Mcqs With Answers

Buffaloes

• Number of breeds of buffalo in India.
• Indian buffaloes – Bubalis bubalis.
• The average yield of buffalo is 495 kgs. with 6.5 – 7.5 percent fat.
• The average yield of Zebu Cow is 186 kgs. with 4.5 – 5.0 percent fat.
• Sex Vigour in buffalo increases in the colder season.
• The uterine and ovarian cycle of buffalo is 21 days (subject to great variations)
• The duration of heat is 1 to 1 1/2 days.
• On average, the length of gestation is 307 days or 10 months for a buffalo.
• The length of gestation of a cow is 284 days or 9 months.
• Breeding season for buffaloes: September to February.
• Calving season – July to November.
• In buffaloes, the period of lactation is 281 days, the dry period is 139 days, calving interval is 420 days.
• Gastroenteritis is the second highest cause of buffalo calf mortality.
• India possesses the largest number of buffaloes.
• Some important disease-resistant varieties are Zebu Cattle or Bos indicus. They are resistant to Rinderpest, Foot and mouth disease, Anthrax, Black quarter, and Haemorrhagic septicemia.

NEET Biology Strategies For Enhancement In Food Production Animal Breeding

Animal Breeding Aims At:

1. Increasing the quantity of yield.
2. Improving the quality of the produce.

Breeding is of two types Natural breeding and artificial breeding

Inbreeding

• The breeding strategy includes the identification of superior males and females of the same breed and mating them in pairs.
• The progeny of such matings are evaluated and superior males and females are identified for further mating.
• Inbreeding increases homozygosity and thus inbreeding is necessary for evolving a pure line in any animal.
• Inbreeding exposes the harmful recessive alleles, which become eliminated by selection.
• Inbreeding also helps in the accumulation of superior genes and the elimination of less desirable genes.
• However continued inbreeding causes inbreeding depression, which reduces fertility and even productivity.
• Under such a situation the selected animals of the breeding population are mated with unrelated superior animals of the same breed to restore fertility and yield.

Outbreeding: Outbreeding refers to the breeding of unrelated animals either of the same breed or of different breeds or even different species.

Outbreeding is of the following types

1. Outcrossing
   1. Outcrossing is the practice of mating animals of the same breed, but that have no common ancestors on either side of their pedigree up to 4-6 generations.
   2. A single outcross helps to overcome inbreeding depression.
   3. It is the best breeding method for animals that are below average in productivity and growth rate.
   4. Growth rate.
2. Cross-breeding
   1. It is a method of outbreeding in which superior males of one breed are mated with the superior females of another breed of the same species.
   2. This helps in combining the desirable qualities of the two different breeds into the progeny.
   3. The hybrid progeny may be directly used for commercial production or they may be subjected to some form of inbreeding and selection, to develop new stable breeds.
   4. One example of cross-breeding is discardable, a new breed of sheep developed by crossing Bikaneri ewes Marino rams.
3. Interspecific Hybridisation: It is a method of outbreeding in which male and female animals of two different species are crossed to combine the desirable features of both parents into one. for example, the male is produced by a cross between a male donkey and a female horse.

Artificial Insenunalion: It is the process in which the semen collected from a superior male is inserted into the reproductive tract of the selected female by the breeder.

• The advantages of this practice are:
  1. Semen can. be used immediately or stored/frozen and used at a later date when the female is in the right reproductive phase.
  2. Semen can be transported in the frozen form to a distant place where the selected female animals are present.
  3. Semen from one selected male animal can be used on a number of female animals.
• The disadvantage is that the success rate is fairly low.

Strategies For Enhancement In Food Production NEET Revision Notes

Multiple Ovulation Embryo Transfer (MOET): It is a method to improve the herds.

• The steps in the method are as follows:
• A cow is administered hormones (like FSH) to induce follicular maturation and superovulation, i.e., the production of 6-8 ova in one cycle.
• The cow is mated with the selected bull or artificially inseminated.
• The fertilized eggs at 8-32-celled stages are recovered and transferred to surrogate mothers.
• This technology has been used for cattle, rabbits, mares, etc.
• High milk-yielding breeds of females and high-quality meat-yielding bulls have been bred successfully to increase the herd size in a short time.

Sheep

• Breeds of Indian Sheep which do not give any wool – Deccani and Nellore.
• Exotic breeds of sheep are – Dorset, Horn, Suffolk coereidale, or Merino.
• Sheep are most suitable as a class of livestock for utilizing waste lands or weeds from the fields.

Shearing

• Shearing means cutting wool in sheep with shears.
• Shearing is done after the winter or after the rainy season.
• Shearing is done mechanically either with clippers, a pair of scissors, or by a power-operated machine.

Camel-Camelus: There Are Two Types Of Camels

1. One humped – Arabian – Camelus dromidarius
2. Two humped – Bactrian – Camelus bactrianus

Camel found in India – Arabian Adaptations so as to be called the ship of the desert:

1. A thick skin to prevent water loss.
2. Thick foot pads to move on loose, hot sands.
3. Long eyelashes to protect the eye from sand.
4. Hard lips to prevent injury from thorny bushes they browse.
5. Hump – the storehouse of fat.

Indicator of good nutrition in camels – the size of the hump.

• Camels breed in winter (November to March).
• Camels suffer from diseases like – anthrax, pneumonia, camel pox, and surra, e Camels, Llamas, and alpacas are included in one family – camelidae.
• The wt. of camel at maturity is 500-700 kgs. The gestation period of the camels – is 300 days
• Lactation period – 18 months.
• Females produce a calf twice in three years.
• The camels are monooestrous under desert conditions.
• Females mate at the age of 4 years.

Strategies For Enhancement In Food Production NEET Revision Notes

Elephants – Elephas maximum. (Loxodonta Africans)

• Elephants are found in forests with tall trees where bamboos grow in profusion.
• Mean intake varies from 4.2 to 5.6% of the animal’s body weight.
• The daily water consumption of an elephant is 140 – 230 liters.
• Puberty occurs at the age of 8 -12 years.
• The gestation period is 21-22 months.
• The calving interval is 4 years

Pig – Sits Scrofa

• Pig droppings are a good source of nitrogen, phosphorus, and potassium.
• The dominant coat color in pigs is white.
• To feed a pig, maize can be replaced by millet to an extent of 50 percent, similarly, maize can also be replaced by wheat bran and tapioca meal to an extent of 50 percent.
• The marketable body wt. of pigs is 90-95 kgs.

Strategies For Enhancement In Food Production NEET Revision Notes

Domestic horse – Equus caballm

• No. of important Indian breeds is 6.
• Mineral specially added to the diet ofliorscs is a common salt. Donkeys – Eqitus asinu
• Two kinds of donkeys found in India are small grey and large white.
• A large white donkey is found in the Rann of Kutch.

NEET Biology Strategies For Enhancement In Food Production Poultry

It deals with the rearing of fowls, ducks, turkeys, and pheasants for their eggs and meat,

• The average production of an Indian breed is about 60 eggs per annum.
• High-yielding varieties can yield up to 240 eggs per annum.
• The best table bird with plenty of flavored flesh-Aseel.
• Exotic breeds – White leghorn, Rhode Island red, Plymouth rock. New Hampshire, Orpington, Anstrnlorp, Sussex. Minorca.

Poultry: Poultry farming deals with the rearing of fowls (chicken), ducks, turkeys, and pheasants for their eggs and meat. India and the neighboring countries are recognized as the original home of the red jungle fowl (Callus gallus).

• There is evidence that Aseel or Malay fowl were carried to Europe through the Middle East about 2,000 years ago and have given rise to the present-day European breeds.
• Poultry and poultry products are a rich source of animal protein and other nutrients such as fats vitamins and minerals, Consumption of eggs would pave the way for overcoming the protein malnutrition prevalent, especially among children in India.
• Poultry farming has definite advantages over livestock-rearing. Poultry birds are easy to raise, can be acclimatized to a wide range of climatic conditions, have short life spans, and are prolific breeders.
• Hens have an average yield of 60 eggs per year (up to 240 eggs in high-yielding varieties). Poultry farming requires less space is easier to manage and maintain and brings fast returns within a span of six months.
• In a poultry farm, comfortable, well-ventilated, and illuminated, dry houses are built. Birds of different ages the kept in separate houses. In regions with moderate climates, they are kept in cages (coops). The floor is littered with chopped straw, paddy husk, dry leaves, or groundnut hulls.
• It is made rat-proof and provided with water channels with proper drainage. Minerals that are important for poultry diets are calcium, phosphorous, sodium, copper, lo-zinc, iron manganese, and zinc. Vitamins required are vitamin A, D₃,E, and pyridoxine. riboflavin, pantothenic acid, niacin, folic acid B_12, and choline.
• The male breeder’s diet should contain extra calcium, manganese, and vitamin H to ensure proper fertility. Thus a balanced diet is required so that the utilization for building of tissues and egg production is maximised. Clean and fresh water is very much essential for birds.

Light Management:

Illumination is crucial for optimal egg yield. Optimal manufacturing necessitates 14 to 16 hours of light, including natural sunshine.

• When the pullets (young hens, particularly at the onset of egg production) commence laying, provide supplemental lighting if daylight is less than 12 hours.
• Incrementally augment the light duration by 20 minutes each week until a total of 10 hours is achieved.
• A single 40-watt tube light adequately illuminates a 30 sq.m area, whereas a 40-watt bulb is suitable for an 18 sq.m floor area. The illumination must distribute evenly. The illumination should not be sustained during the entire night.

Strategies For Enhancement In Food Production NEET Study Material

Methods For Improvement Of Poultry Farming

• Selection of disease-free suitable breeds.
• The most common egg type variety is single comb while leghorn.
• Meat type variety – Plymouth Rock, Cornish, New Hampshire.

Breeds Of Fowls

• Indigenous Breeds: Aseel, Karaknath, Basara, Briihma, and Cochin.
• Exotic Breeds: White Leghorn, Rhode Island Red, Plymouth Rock, New Hampshire.

Advantage Of Poultry

• Food: Eggs and meat are rich in proteins, minerals fats, and vitamins.
• Economic uplift and employment.
• Birds fecal matter as manure.
• Feathers
• Recreation.
• For food widely distributed as domestic animals, the most common species of jungle fowls are Gulins, gallus, G. Lafayette, and G.sonneratti.
• Poultry feed includes all the nutrients and is made of cereals and millets, oil cake, protein concentrates, fish and meat meal, minerals, and green vegetables.

The domestic fowl (Gallus domesticus) population of our country can be roughly classified into two types:

1. Indigenous (desi type),
2. Exotic (improved type)

Some of the indigenous breeds like Aseel, Karaknath, Ghagus, Brahma, and Busra are the best table birds, The Aseel fowls are used in cock-flighting. The exotic breeds are classified, according to their source of origin, into American class, English class, Mediterranean class, and Asiatic class.

• Some examples are White Leghorn, Rhode Island Red, Plymouth Rock, and New Hampshire. They are now completely acclimatized to Indian conditions. Some of them are excellent egg-layers, whereas others give good meat.
• The indigenous breeds are crossed with exotic breeds to improve egg production. Heterosis has been utilized for producing better egg layers and broilers (birds grown for meat) with high nutritive value.
• Some of the diseases like fowl pox ranikhet, coryza, fowl cholera, and aspergillosis take a heavy toll on poultry. But with better management, proper housing and nutrition, and timely vaccination of the chicks, these diseases can be controlled.
• Ducks comprise 6 percent of the total poultry population in India. They are abundant in the southern and eastern parts of India. There are 20 breeds of duck of which Muscorl, Pekin, Aylesbury, and Campbell are popular exotic breeds. Indigenous breeds include Indian Runner.
• Syhelt meta, etc. Brown and white geese are common in India. Turkeys which are in demand during Christmas time, belong to the breeds Narfold, British White, Broad Breasted Bronze, and Beltsville Small White.

Poultry Diseases

1. Encephalomalacla: The deficiency of vitamin E causes the softening of brain tissue in young poultry.
2. Coccidiosis: The protozoan Eimeria causes coccidiosis in fowls. It causes bloody diarrhea.

Bacterial Diseases

1. Pasteurella – Fowl cholera
2. Salmonella pullorum – Pullorum
3. Mycoplasma gallisepticum – Mycoplasmosis
4. Spirochaete – Spirochaetosis

Aquare: It involves the production of useful aquatic plants and animals such as fishes, prawns, shrimps, lobsters, crabs, and mollusks (edible and pearl oysters) by proper utilization of small and large bodies of water.

• Fisheries: Industry devoted to catching, processing, or selling fish.
  • Fisheries have an important place in the Indian economy. It provides income and employment to millions of fishermen and farmers, particularly in the coastal states. For many, it is the only source of their livelihood.
  • In order to meet the increasing demands on fisheries, different techniques have been employed to increase production. For example, through aquaculture and pisciculture, we have been able to increase the production of aquatic plants and animals, both fresh-water and marine.
  • This has led to the development and flourishing of the fishery industry, and it has brought a lot of income to the farmers in particular and the country in general.
• Aquaculture: Production of useful aquatic plants and animals such as fishes, prawns, shrimps lobster, crabs mollusks, etc.
• Pisciculture: Production of fishes. Fishes are reared in small rivers, ponds, lakes, and canals.

Fish Farming/Fisheries: There are 2 types of fisheries-Inland and Marine fisheries.

Inland Fisheries: Freshwater: Cultivation in rivers, canals, reservoirs lakes, ponds, and tanks.

Brackish Water: Estuaries, Lagoons, reservoirs.

Types Of Ponds: 3 types of ponds are required for Indian major carp.

Strategies For Enhancement In Food Production NEET Study Material

Nursery Ponds

• Receive tender hatching and spawn.
• Small and seasonal nurseries are preferred.
• Production of zooplankton to serve as food for the spawn.

Rearing Ponds: Fries (young fish) are collected from nursery ponds and released into rearing ponds to develop in fingerlings

Stocking Ponds: Fingerlings are transferred from rearing to stocking ponds, where they develop into adult fish and are kept for stocking.

Types Of Breeding

1. Natural Breeding/Bundh Breeding: Breading is done in natural bundhs, a special type of ponds formed by the accumulation of large quantities of rainwater in a low-lying area, and natural conditions are provided with exits also.
2. Artificial Breeding: Sperm from males and ova from females are collected and fertilization is done in in-vitro conditions.
   • Hormone gonadotrophins are also used. FSH and LH secreted by the pituitary, influence the maturation of gonads and spawning in fish.

Composite Farming: Selected species of fish are stocked together in proper proportion to increase fish production many times.

Compatible species do not harm each other, example, Catla catla (surface feeder), Labeo-rohita (Column feeder), and Cirrhinus mrigtila (bottom feeder) are used for composite farming. Some edible freshwater fishes.

• Rohu – Labeo-rohita
• Calbasu – L. Calbasu
• Catla – Catla catla
• Mirgal – Cirrhinus mrigala
• Magur – Clarius
• Common carp

Marine Fisheries: Fishery aspect of seawater of the ocean. A recent survey revealed abundant resources of sardines and mackerel on the southwest coast. Fishing trawlers fitted with sophisticated electronic fish-locating equipment have also been introduced to give a fillip to deep-sea fishing.

Integrated Fisheries project located at Cochin engaged in the exploration and utilization of marine resources in S.W. India.

Strategies For Enhancement In Food Production NEET Study Material

Edible Marine Fishes

• Eel – Anguilla
• Hilsha – Hilsa
• Pomphret – Stromateus
• Salmon – Aluitheronema
• Bombay duct – Harpodon
• Sardine – Sardinella
• Mackeral

Marine Fishes Use/Importance

• Fish as food
• Fish for controlling disease: Larvivorous (gambusia).
• Scientific value: Lung fishes of importance.
• Aesthetic value: Aquarium fishes, Macropodus, Carassius (goldfish), pterophyllum (angel fish), and Betta (fighting fish).
• Fish product: Fish oil
• Fish glue: Sticky product obtained from the skin of cod.
• Isinglass: Gelatinous substance from the air bladder of perches, Indian salmon used in the preparation of special cement and in clarification of wine and beer.
• Shagreen: Skin of sharks and rays used in polishing wood and other materials as well as for covering jewelry boxes and swords.
• Leather and artificial pearls (from silver bony scales of cyprinids
• Employment.

Pisciculture production of fishes.

• Seed fish are produced by aquaculture techniques of induced breeding by administration of pituitary hormones.
• Fish is a valuable food source of proteins.
• India is among the six foremost seafood-producing nations in the world.
• Fresh water includes the country’s great river systems, an extensive network of irrigation canals, reservoirs, lakes, tanks, ponds, etc.
• Brackish water includes estuaries, lagoons, and mangrove swamps.
• An Integrated fishery project located at Cochin is engaged in the exploration and utilization of marine resources and is the biggest of its kind in Southeast Asia.
• Inland fisheries provide 40% of total fish production.

NEET Biology Strategies For Enhancement In Food Production Apiculture or Beekeeping

Beekeeping or apiculture is the maintenance of hives of honeybees for the production of honey. It has been an age-old cottage industry.

Common Species Of Honey Bee: Apis mellifera, Apis indica, Apis dorsata, Apis florea. Social Organisation: Good and well-developed honeycomb. 40-50 thousand individuals.

Social Organization (Castes) Of Honey Bee: The nest of the honey bee is known as the bee hive. The hive consists of 32 to 60 thousand individuals, showing a highly organized division of labor in the colony. Bees are polymorphic, consisting of three types of individuals (Castes) viz, QUEEN, DRONE, and WORKER. The characters are given in the following table.

Honey is a food of high nutritive value and also finds use in the indigenous system of medicine.

• It is composed of levulose, dextrose, maltose and other sugars, enzymes and pigments, ash, water, vitamins and minerals.
• Honey produced by the honey bee Apis species is probably the oldest sweetening agent in our civilization. Honey contains two sugars – dextrose and levulose – and a mixture of several other substances. It is tasty, health-giving, and also medicinally useful.

Honeybees also yield wax, which has multiple uses. A large quantity of honey is still collected from wild sources. However, bee-keeping (apiculture) using domesticated bees has been practiced in many parts of the world, including India (using A. dorsata, A. florea, and A. indica).

• From its mandibular gland, the developing queen secretes a queen substance. It inhibits the worker bees from building brood chambers for future queens. Honeybee also produces beeswax, which finds many uses in industry, such as in the preparation of cosmetics and polishes of various kinds.
• The increased demand for honey has led to large-scale beekeeping practices; it has become an established income-generating industry, whether practiced on a small or on a large scale.

Strategies For Enhancement In Food Production NEET Question Bank

Bee Diseases

• Pebrine – N.apis,
• Paralysis dysentery
• Acarine disease – Acarapis wood

Bee-keeping: It can be practiced in any area where there are sufficient bee pastures of some wild shrubs, fruit orchards, and cultivated crops. There are several species of honeybees that can be reared. Of these, the most common species is Apis indica. Beehives can be kept in one’s courtyard, on the verandah of the house of even on the roof. Beekeeping is not labor-intensive.

For Successful Bee-keeping

• Knowledge of nature and habits of honey bees.
• Selection of suitable locations for keeping bee hives.
• Catching and hiving of swarms.
• Management beehives during summers
• Handling and collection of honey and bee wax.

Bee Communication: Karl van Frisch (1946-69: Awarded Nobel prize for decoding the language of honey bees. Bee performs two types of dance

Round Dance: Food source is within 75 m.

Strategies For Enhancement In Food Production NEET Question Bank

Tail Wagging Dance/Waggle Dance: Food is more than 75 m away.

Bees are the pollinators of many of our crop species (see concerned chapter) such as sunflower, Brassica, apple, and pear. Keeping beehives in crop fields during the flowering period.

Apiculture: Science of rearing bees for economic value,

Strategies For Enhancement In Food Production NEET Question Bank

• Types Of Honey Bees;
  1. Apis indica (Indian bee)
  2. Apis mellifera (Italian bee)
  3. Apis dorsata (Rock bee)
  4. Apis florea (Little bee)
• Most Important And Useful Bee – Apis Mellifera
  • Worker bees are immature, sterile females.
  • The compartments of honeycomb are called cells and are divided by thin plates of wax.
  • The foundation to build honeycombs is provided by a comb foundation – a wax sheet.
  • Honeybees are reared in apiaries
  • Apis dorsata is the main source of bee wax.
  • Sugars in honey are glucose, fructose, and levulose.

Silkworms Sericulture: The science of rearing silkworms for producing silk.

Main cottage industry of silk – China, Japan, India, and some European countries.

Silkworms Life Cycle: Egg Larva → Pupa → Adult

Silk Extraction

• After one or two days of cocoon formation pupa are either killed by boiling or drying in the Sun.
• The raw silk fibers from the cocoon are then reeled into silk thread.
• Pupa are killed before they emerge into adulthood as the long silk fibers are broken and can thin and only be spun like cotton can not reel.
• Few cocoons or seeds are kept to develop into adults to continue generation.

Silk Extraction Important Points

• Composition of silk.
• Protein fibroin (75 – 80%) and Sericin (20 – 25%)
• The intestine of silkworm – Gut, used in fishing and some surgical work.
• Bombyrmori: China silk worm – Mulberry silk – Best silk.
• The disease of the silkworm is Pebrine caused by Nosema bombycis.
• Silkworm Bombyx mori is reared on mulberry leaves.
• Caterpillars are very active feeders.
• The hard covering of silk fibers around the worm is called a cocoon, A silkworm with a cocoon is known as a pupa.
• Pupae are killed to get silk thread because the emergence of an adult breaks the thread.

NEET Biology Strategies For Enhancement In Food Production Lac Culture

The zoological name of the lac insect is Laccifer lacca or Tachardia lacca.

• Lac insect belongs to the order Homoptera.
• Lac is a resinous substance secreted from the hypodermal glands of the body of the larval stage and females.
• Lac insects usually build lac houses for the protection of host plants like Butea monosperma (palas), Shorea robusta, (sal), Acacia nilotica (Babul), Mangifera indica (mango), etc.
• Male and female insects live separately in lac capsules
• After copulation male dies, female lays about 200-300 eggs.
• The larvae (nymphs) are red-colored and suck the plant sap by boring the tender twigs.
• The secretion of the lac glands covers the body of the insect, it joins the cover of the insect with a twig of tree.

Strategies For Enhancement In Food Production NEET Question Bank

Lac Culture Uses

1. Lac in the form of shellac is used as sealing material.
2. Lac is also used in the printing industry, preparation of gramophone records, electrical appliances, varnish, polish paints, toys, bangles, buttons cosmetics, etc.

Hybrid Breeds Of Livestock. Karanswiss was developed at NDRI Kamal while Sunandini was developed at NDRI Kerala.

Broiler. Chicken reared for meat.

Fish Gauno. Dried refuse after extraction of oil.

Honey is aromatic, viscid, and sweet-material. The color and flavor of honey depend upon the source of nectar.

The Honey consists of:

• Fish Liver Oil. It is extracted from the liver of fish. It is the main source of Vitamin-A though the liver oil of some fishes also contains vitamins C, D, and E. For example, the liver oil of certain fishes like Tuna, Halibut, etc. is rich in vitamin D.
  • Vitamin- E (a-tocopherol) acts as an anti-oxidant of vitamin A. Cod liver oil contains about 60-75% of oil contents but a low percentage of vitamin A, while Tuna and Halibut liver oil contain a lower (4 to 28%) percentage of oil Fut higher percentage of vitamin -A.
• Fish Protein. It is in the form of white powder extracted from fish wastes by removing the fat and contains 80 to 90% soluble proteins. It is used in the preparation of ice cream, pharmaceuticals, paints, varnishes, textiles, paper, and cosmetics.
  • Fish Protein Concentrate (FPC) has been defined as a stable product prepared from whole fish or parts thereof, by the removal of water and, in certain cases, oil, bones, and other materials.
• Milk Yield/Cow/Yr. 4250 kg in the U.S.A. and 220 kg in India. Tassar Silk. Besides Anthenea roylei, other species are A- paphia, A. perenyi, and A. mylitta.
• Arnadi Silk is obtained from the cocoon of the Eri silkworm—Altacus ricin
• Muga Silk is obtained from cocoons of muga silkworm Anthenea assama.
• Pashmina. Under the fur of Kashmiri goat
• Angoora Wool. From Angoora rabbit.
• An insecticide used to control external parasites, like lice on cattle is lindane.
• Yak – Lahaul Spiti, Leh, Ladhakh, Garhvval, Sikkim

NEET Biology Strategies For Enhancement In Food Production Synopsis

Animal Husbandry. Agricultural practice of breeding and raising livestock like buffaloes, cows, pigs, horses, cattle, sheep, camels, goats etc. It also includes poultry farming and fisheries.

Strategies For Enhancement In Food Production NEET Question Bank

Dairy Farm Management: Management of animals for milk and its products

• Selection of high-yielding breeds.
• Resistance to diseases
• Cleanliness and hygienic shelter
• Regular inspection
• Proper record
• Quality and quantity of fodder
• Water
• Milking, storage of milk and products.

Poultry Farm Management

• Management of domesticated fowls (birds) used for food and eggs.
• All facts about dairy farm management + Eradication dispersing of vims affected birds.

Apiculture (Beekeeping Maintenance of hives of honey bees for obtaining honey and wax.

• Successful bee-keeping
• Knowledge of nature and habits of bees
• Selection of suitable location for keeping beehives.
• Catching and hiving of swarms.
• Management of beehives during different seasons.
• Handling and collection of honey and of bees wax.

Fisheries. Catching, processing, selling of fish, and shellfish or other aquatic animals;

• Freshwater fishes
• Catla, Rohu and Carps
• Marine fishes
• Hilsa, Sardine, Mackerel Pomffet

NEET Biology Evolution Theory Of Evolution By Natural Selection

Recent study indicates that evolution refers to the alteration in the genetic makeup of a population resulting from the interplay of variations and natural selection.

• The notion of organic evolution was conceived by Darwin and Wallace.
• Aristotle posited that all living organisms can be systematically organized according to ascending complexity, with no gaps and no potential for positional alteration within the established hierarchy. The perspective on life is referred to as Scala Naturae.
• Evidence of evolution substantiates the occurrence of evolutionary processes. Notable proponents of organic evolution included Aristotle, Bacon, Kant, Buffon, and E. Darwin.
• The mutation hypothesis of evolution, proposed by de Vries, addresses certain limitations of Darwin’s theory.

NEET Biology Evolution Theories Of Evolution

The doctrines of organic evolution state that the world has evolved and not created as was believed earlier. Various theories have been put forward to explain organic evolution. Some of the important theories are as follows:

Read and Learn More NEET Biology Notes

1. Lamarck’s Theory of Inheritance of Acquired Characters (1744-1829): It is based on the following propositions.

1. Living organisms and their parts tend to increase in size continuously due to internal forces of life.
2. Production of a new organ in the body of organisms results from a new need for movement.
3. If an organ is used continuously and constantly, it tends to become highly developed, whereas its continuous disuse results in its disappearance.
4. Modifications produced or acquired during the lifetime of an individual are inherited.

• Lamarck’s Theory of Inheritance of Acquired Characters (1744-1829) Books written
  • Philosophic Zoologique
  • Organisation descerps vivont
  • Historic
  • Naturellecles Animax Sons Vertebrae.
• Lamarck’s Theory of Inheritance of Acquired Characters (1744-1829) Examples. Giraffes obtain their long necks by stretching them upwards to reach the available food in the form of leaves from tall trees. Eyes are reduced in moles because they live underground.
• Objections against Lamarckism. Lamarckism failed to meet the tests of observations. There is no evidence in support of the first proposition. The experiments conducted by Weismann in mice have discarded the law of inheritance of acquired characters.
• Neo-Lamarckism. A group of scientists Tower, Mendel, Morgan, Myar, and Smith have further studied Lamarckism and supported its modified form, which is known as Neo-Lamarckism.

2. Theory Of Catastrophism. Cuvier (1769-1832) is considered the father of modem palaeontology. Cuvier believed in the fixity of species. The occurrence of fossils of different rock strata was accounted on the basis of catastrophes. A succession of catastrophes have periodically destroyed all living things, followed each time by the successive creations of new and higher forms.

3. Theory Of Uniformitarianism. James Hutton (1878) and Charles Lyell (1932) established the concept of uniformitarianism which holds that slowly acting geological forces result in the formation of fossil-bearing rock strata.

4. Darwin’s Theory of Natural Selection ‘Descent of Man’ in 1871 – propounded by – Charles Darwin and Alfred Russel Wallace

Evolution Neet Notes

Summary Of The Theory Factors

Evolution Neet Notes

Objections To Darwinism

1. The type of variations that provide the raw material for natural selection are generally non-inheritable.
2. It does not explain the effect of use and disuse and the presence of vestigial organs.
3. Darwinism explains the survival of the fittest but not the arrival of the fittest. Darwin also put forward a hypothesis of pangenes in order to explain the possible mode of inheritance of these variations.
4. According to pangenesis theory each and every cell of the body produces minute primordia which are known as gemmules or pangenes. The gemmules from all parts of the body are carried by the bloodstream to the gonads where these accumulate in the germ cells.

5. Weismann’s Theory of Continuity of Germplasm. According to this theory, the cytoplasm of the animal body is differentiated into somatoplasm and germplasm. The germplasm produces gametes which transmit the characteristics of the parents to the offspring. The remaining body of the organism is formed of somatoplasm.

6. Recapitulation Theory of Haeckel. Haeckel (1811) proposed that “ontogeny repeats phytogeny ”, that is, the development of the individual repeats the evolutionary history of the race, condensing some stages and eliminating others.

7. Isolation Theory. The role of isolation in evolution was first emphasized by M. Wagner. He stated that any factor or mechanism which separates the individuals of a species into groups, so that these are unable to intermingle and interbreed, constitutes the isolating mechanism and is helpful in the progress of evolution.

8. DeVries’ Theory of Mutation. De Vries suggested that variations which are important for evolution are sudden and large; which he called mutations or saltation

Evolution Neet Notes

Salient Features Of The Mutation Theory: On the basis of his observations, Hugo de Vries (1901) put forward a theory of evolution, called mutation theory. The theory states that evolution is a jerky process where new varieties and species are formed by mutations (discontinuous variations) that function as the raw material of evolution. The salient features of mutation theory are

1. Mutations or discontinuous variations are the raw material of evolution.
2. Mutations appear all of a sudden. They become operational immediately.
3. Unlike Darwin’s continuous variations or fluctuations, mutations do not revolve around the mean or normal character of the species.
4. The same type of mutations can appear in a number of individuals of a species.
5. All mutations are inheritable.
6. Mutations appear in all conceivable directions.
7. Useful mutations are selected by nature. Lethal mutations are eliminated. However, useless and less harmful ones can persist in the progeny.
8. Accumulation of variations produces new species. Sometimes a new species is produced from a single mutation.
9. Evolution is a jerky and discontinuous process.

Evolution Neet Notes

Modern Synthetic Theory has evolved dm in; the last century through an accumulation of fuels and theoretical conclusions from a number of scientists, Dobzhansky (1937) emphasized the role of genetic changes in populations in the process of evolution. Julian Huxley and Ernst Mayr have explained the mechanism of origin of variations in higher animals,

1. Genetic Variations in n Population: Population is the unit of Involution
   • Mechanism Of Genetic Change
     • Gene mutation
     • Chromosomal aberrations
     • Recombination of genes
     • Hybridization
2. Natural Selection: It really means differential reproduction i.c. some members of a population reproduce at a higher rate and leave more surviving offspring in the next generation than others. The organisms that produce more offspring contribute a proportionately greater percentage of genes to the gene pool of the next generation.
   • What really matters in evolution is not how well or poorly the individuals can face the environment, but how many of their young ones survive to become parents of the next generation.
3. Speciation: Species are the group of actually or potentially interbreeding natural populations that are reproductive and isolated from other such groups. The formation of new species may be caused by the gradual drifting away of two or more populations of a single species until such time they cease to interbreed.

NEET Biology Evolution Factors Causing Genetic Divergence In The Populations

1. Mutations. These are the changes in the chemical constitution of the DNA in the chromosomes of an organism. Depending upon the mutation, selection will operate either for or against the mutated gene.
2. Recombination. Brings about new combinations of old genes present in the gene pool of a population as a result of interbreeding, crossing over at the time of meiosis, free assortment of genes at the time of gamete formation etc.
3. Genetic Drift Or Random Drift. In small populations, frequencies of particular alleles may change drastically by chance alone. Such changes in allele frequencies occur randomly, as if the frequencies were drifting, and are thus known as genetic drift. For this reason, a population must be large to be in Hardy-Weinberg equilibrium.
   • If the gametes of only a few individuals form the next generation, the alleles may by chance not be representative of die parent population from which they were drawn, for example when a small number of individuals are removed from a bottle containing many.
   • By chance, most of the individuals removed are blue, so the new population has a much higher population of blue individuals than the parent one had.

Mechanism Of Origin Of Species. There are two distinct ways in which new species arise from the pre-existing ones.

1. Speciation. Splitting of species into two or more species.
2. Transformation In Time. Transformation of the old species into new ones in due course of time.

• Geographical Speciation. The geographic isolation of a population of pre-existing species into sub-populations for a sufficiently long time produces genetic changes thus changing them into new species.
• Sympatric Speciation. It generally takes place due to a sudden new effective mutation occurring in a single individual.
• Role Of Hybridization And Polyploidy In Speciation: Generally the members of different species do not interbreed and produce fertile offspring. But sometimes, the individuals of two different but closely related species may interbreed to produce fertile young ones. This phenomenon is called hybridization.

Rapid Speciation Occurs By Polyploidy: Hybridization between even closely related species is prevented by a number of barriers. Examples. Polyploidy is uncommon in animals but about one-third of the plant species are polyploids example,

1. In wheat (2N=14), there are species with chromosome numbers 14, 28 and 42
2. In rose, there are species with 14, 28, 42 and 56 chromosomes.
3. Experimental formation of Raphanobrassica (Chromosome number = 36) by crossing radish (Raplianus, 2N=18) and cabbage (Brassica, 2N=18).

Isolation: It is the segregation of the population of a species into smaller units of individuals by certain mechanisms so as to prevent interbreeding among them.

Isolating Mechanism is the process of producing and maintaining reproductive isolation in a population. This can be brought about by mechanisms acting before or after fertilization.

Theodosius Dobzhansky suggested a classification of isolating mechanism

Theodosius Dobzhansky External Barriers: The premating mechanism prevents interspecific mating: Potential mates do not meet due to

1. Geographical isolation
2. Climatic isolation
3. Seasonal isolation
4. Habitat isolation
5. Isolation due to distance.
   • Potential mates meet but do not mate, it is ethological isolation
     • Copulation attempted by transfer of mates does not take place due to
     • Mechanical isolation
     • Physiological isolation

Theodosius Dobzhansky Internal Barriers: Post-mating mechanism. Reduce full success of interspecific isolation

1. Gametic Mortality. Sperms are transferred but eggs are not fertilized
2. Zygote. Eggs are fertilised but the zygote is inviable
3. Hybrid Inviability. Zygote produces F, a hybrid of reduced viability
4. Hybrid Sterility. Hybrid is produced but partially or completely sterile

Evolution NEET Important Questions

Kinds Of Isolation. They are given below:

1. Geographical Isolation. The various physical barriers, such as mountain ranges, rivers, deserts, water connections, etc; play an important role in the isolation of a population into units.
2. Isolation Due To Sheer Distance Apart. The members of a widely distributed species, which occupy a large extent of territory without natural barriers, may become isolated since they are unable to cover great distances. Thus the members of one part interbreed among themselves and do not reach other parts.
3. Climatic Isolation. The abrupt climatic differences in the range of distribution of species cause its separation into sub-units. The climatic factors may be temperature, moisture, mineral concentration and chemical composition of the surroundings.
4. Mechanical Isolation. Animals of different species are unable to interbreed due to the differences in size and structure.
5. Ecological Isolation. Due to different ecological habits, the organisms become isolated and interbreeding between them is prevented.
6. Physiological Isolation. Certain species are established only on the basis of some physiological differences developed between them. For example, in certain species of Drosophila mating is not possible among the members of different species. In Drosophila, the vaginal mucous membrane swells up after mating. This swelling lasts for a few hours if the mating is among the members of the same species, but continues for days if the mating is interspecific. This precludes the passage and eggs fail to come out.
7. Reproductive Isolation. In some species closely allied species are intersterile due to the differences in their copulatory organs. For example, in insects, the copulatory organs are developed on lock and key arrangement i.e., only one type of key fits into one definite pattern of lock.
8. Gametic Isolation. Interbreeding is prevented by gametic inviability. The sperms of one species are either unable to survive or poorly survive in the genital tract of the females of other species.
9. Hybrid Inviability. In other cases even if the gametes survive and bring about fertilization, the zygote is either unable to develop further or the embryo dies after developing for some time.
10. Hybrid Sterility. In some cases, the hybrid formed by the mating between different species is viable but is either sterile or produces fewer offspring, for example, Mules.
11. Changes In The Developmental Rhythm. Speed of development and length of life-cycle changes split up the species into groups and genera into species.
12. Psychic Isolation. Animals have a tendency to mate with like forms. They fail to copulate because of differences in mating behaviour and nest-building habits.

NEET Biology Evolution Neo Darwinism

Neo-Darwinism gains strength from a number of evidence like industrial melanism, the origin of DDT-resistant mosquitoes, geographical distribution of sickle cell anaemia etc.

Five Major Causes Of Evolutionary Changes Accepted By Neo-Darwinism

1. Gene mutation
2. Chromosomal mutations
3. Genetic recombination
4. Natural Selection
5. Reproductive isolation

G.L. Stebbins (1966—76) gave this theory in the present form as follows: Five factors have been identified as main bases

There are also accessory factors like gene migration and hybridization to increase genetic variability. Lastly, the chance factors (genetic drift) in a small population are also relevant in the evolution of the new species.

Evolution NEET Important Questions

Neo Darwinism Examples

1. Industrial Melanism. Before the industrial revolution, the dull grey forms of peppered moth – Bistort betuJaria were dominant; the carbonara form (black) was rare because it was susceptible to predation by birds. The reason was that it was conspicuously visible while resting on tree trunks.
   • The Industrial Revolution resulted in large-scale smoke which got deposited on tree trunks turning them black. Now grey varieties became susceptible and the black forms flourished.
   • Replacement of coal by oil and electricity, reduced soot production – the frequency of grey moths increased again.
2. Drug Resistance. The drugs which eliminate pathogens become ineffective in the course of time because those individuals of pathogenic species can tolerate them, survive, and flourish to produce tolerant populations.
3. Sickle Cell Anaemia And Malaria. Individuals homozygous for sickle cell anaemia die at an early age. In heterozygous individuals, the cells containing abnormal haemoglobin become sickle- shaped. In fact, when RBC becomes sickle-shaped, it kills malarial parasites effectively so that these individuals are able to cope with malaria infection much better than normal people.
4. Favism, Glucose 6 phosphate dehydrogenase deficiency is a common abnormality in Negroids. Haemoglobin gets denatured and is deposited on the cell membrane. If such persons eat beans, haemoglobin is destroyed.

J. Lederberg And E. Lederberg provided experimental evidence for ‘selection* in bacteria. By using the replica plating technique, they demonstrated the processes of ‘selection* of antibiotic-resistant strains of bacteria.

Genetic Basis Of Adaptation: Lederberg’s Replica Plating Experiment is a good example of the genetic basis of adaptation.

1. After introducing penicillin, in the culture plate, it was found that some colonies were resistant to it. Bacteria acquired this ability due to mutations (preadaptive) which occurred before exposure to penicillin.
2. The new environment only selects such mutations.
3. Lamarckian explanation of this could be that the penicillin induced changes in some bacteria enabling them to grow in this medium. Thus these bacteria became adapted to live in a penicillin medium.
4. The Darwinian interpretation could be that the colonies had two types of strains: Penicillin-sensitive and penicillin-resistant arising by mutation. Before the use of penicillin, the suitable condition was for sensitive strain, hence after using penicillin they were wiped out, but was favourable for resistant strain. Thus natural selection operates here as advantageous to the resistant strain.

Evolution NEET Important Questions

Gene Frequency. Suppose two alleles A and A of a gene exist in a population. Suppose X individuals have genotype AA. Y have Aa, Z have aa. N (Total no. of individuals) = X + Y+ Z.

The no. of alleles would be 2 x N.

The ratio of A alleles (p) in population = \(\frac{2 X + Y}{2N}\) = \(\frac{X + 0.5 Y}{N}\)

This is called the gene frequency of A. Gene frequency of ‘a’ would be q = \(\frac{Y + 2 Z}{2N}\) = \(\frac{0.5 Y + Z}{N}\)

Selection Change. Over a period of time, the criteria of natural selection also change. As a result, the genetic composition and the direction of evolution also change.

NEET Biology Evolution The Hardy Weinberg Equation

Hardy-Weinberg Equation developed independently by G.H. Hardy, an English mathematician, and G. Weinberg, a German physician, in 1908, describes the relationship between allelic frequencies and genotypic frequencies in successive generations of a population that is at equilibrium is not evolving.

The Hardy-Winberg equation is p² + 2pq + q² = 1

where p = frequency of one allele (for example, A) at a locus

q = frequency of the alternative allele (for example, a) at the same locus

p² = frequency of the genotype homozygous for the allele present in frequency p (for example, A/A)

2pq = frequency of the heterozygous genotype (for example, A/a)

q² = frequency of the genotype homozygous for the allele present in frequency q (for example, a/a)

• If the frequency of one of the alleles (for example, p) is known, then the frequency of the other allele (q = 1 -p) can be known and the frequencies of the homozygous genotypes (p and q²) as well as those ofthe heterozygous genotype (2pq) can be calculated.
• Or, if the frequency of homozygous recessive individuals in the population (a/a, or q²) is known, then the frequencies of the allele (q) and the A allele (p or 1 – q) can be calculated.
• It is then possible to predict genotypic frequencies in the present and future generations. The Hardy-Weinberg principle states that the frequencies of alleles and genotypes remain the same from generation to generation- are not altered by genetic recombinations-provided that the following conditions hold.

1. No mutations
2. An infinitely large population (no genetic drift)
3. No emigration out of or immigration into the population (no gene flow)
4. Random matings between individuals (no assortative matings)
5. Equal reproductive success among the genotypes (no natural selection)

Illustration: An investigator has determined by inspection that 16% of the human population has a recessive trait. Using this information, we can complete all the genotype and allele frequencies for the population, provided the conditions for Hardy-Weinberg equilibrium are met.

Given: q² = 16% = 0.16 are homozygous recessive individuals.

Therefore, q = √0.16 = 0.4 = frequency of recessive allele

p = 1.0 – 0.4 = 0.6 = frequency of dominant allele

p² = (0.6)(0.6 = 0.36 = 36% are homozygous dominant individuals) 84% have the dominant phenotype

2 pq = 2(0.6)(0.4) = 0.48 = 48% are heterozygous individuals = 1.00-0.52 = 0.48

Present-Day Concept Of Evolution: A modified form of Darwin’s theory, lienee is often called Neo-Darwinism.

Also called the synthetic theory of evolution (synthesis of Darwin’s and Hugo de Vries’ theories). According to this theory, only genetic variations are inherited. It includes the following factors.

1. Genetic Variations in a population occur by mutations, genetic drift (elimination of gene of certain traits due to migration or death of a section of a population), geneflow (addition or removal of alleles when individuals enter or leave a population), gene recombination, hybridization, etc.
2. Heredity, i.e., the transmission of characters from parents to offspring plays an important role in the mechanism of evolution.
3. Natural Selection selects those members which have traits that enable them to grow up and reproduce at a faster rate. It is of four types:
   • Stabilizing Selection: Keeps population genetically constant and favours normal phenotypes whereas eliminates extreme variants.
   • Directional Selection: Produces a regular change within a population in one direction and favours non-average phenotypes.
   • Disruptive Selection: Favours extreme or more adaptable phenotypes hence poplution is disrupted into two groups.
   • Cyclic Selection: Maintains genetic differences in a population and fixes all the alleles of a gene pool.
4. Speciation occurs which is die formation of new species from existing ones by evolutionary means. It is of four types:
   • Multiplicative: Splitting of a species into new species which may be gradual (occurring in many generations) or instant (occurring in a single generation).
   • Phyletic: Replacement of one species by another without an increase in number.
   • Speciation By Fusion: Here two species merge into one.
   • Quantum: Speciation by reproductive isolation due to chromosomal rearrangements.
5. Reproductive Isolation i.e., prevention of interbreeding between populations of two different species is accomplished by either premating methods that may be mechanical, ethological, seasonal and gametic isolation or post-mating methods like incompatibility, hybrid sterility, etc. (post-mating).

• Mutations. A mutation is a random inheritable change in the genetic material. It may be due to changes in the structure of chromosomes, number of chromosomes, and gene mutation (Change in sequence of nucleotides).
  • Mutation is a recurrent event because a given length can undergo only a limited number of chemical changes if given enough time, each of these will appear again and again. Thus, in a hypothetical population in which all individuals are homozygous AA, the allele A will be eventually introduced by mutation.
• Mutations Are Regarded As Fountainheads Of Evolution. Recombination. During meiosis, crossing over causes reshuffling of gene combinations which provides new combinations of existing genes and alleles.
  • This is the essence of recombination. It may bring together the alleles that arose at different times and places. Recombination can occur not only between genes but also within genes resulting in the formation of a new allele. As it adds new alleles and a combination of alleles to the gene pool it is an agent of evolution.
• Gene Migration. Because few populations are completely isolated from other populations of the same species, usually some migration between populations takes place.
  • Therefore, members of a population may enter a  new population due to migration.
  • If the migrating individuals breed within the new population, the immigrants will add new alleles to the local gene pool of the host population. This is called gene migration.
• Genetic Drift (Or Wright’s Effect). Random change occurring in the allele frequency by chance alone is called genetic drift.
  • It is the change in the number and frequency of genes (alleles) that occurs by chance – and plays an important role in evolution.
  • It operates in small isolated populations by persistent in-breeding. As a result, some alleles become permanently fixed. While some alleles undergo change in their frequency and some others disappear completely.
  • When a species is split into many isolated populations without migration or mixing, its genetic composition is mainly determined by genetic drift.
  • In the case of Biston betulciria even though the grey moth was easily visible it was not that dark to escape predation.
  • Rather sometimes in areas with a high population of grey moths, birds used to prey on more black moths due to sheer chance.
• Founder Effect. When a population gets separated from the existing population it becomes the founder of a new population. This is called the founder effect which is the result of genetic drift i.e., by chance.
• Genetic Bottleneck. Wien in a season the one population leaves a few individuals of the population which become the founder of the new population then it will produce only a few genes by selection i.e. by chance new population emerges and it is similar to a bottle in which only certain population is allowed to flow as in the neck of the bottle.
• Gene Flow: Gene flow is the movement of alleles from one population to another. It can be a powerful agent of change because members of different populations may exchange genetic material. Sometimes gene flow is obvious, as when an animal moves from one place to another.
  • If the characteristics of the newly arrived animal differ from those of the animals already dire, and if the newcomer is adapted well enough to the new area to survive and mate successfully, the genetic composition of the receiving population may be altered.
  • Other important kinds of gene flow are not as obvious. These subtler movements include the drifting of gametes or immature stages of plants or marine animals from one place to another.
• Male Gametes of flowering plants are often earned great distance by insects and other animals that visit their flowers.
• Seeds may also blow in the wind or be carried by animals or other agents to new populations far from their place of origin.
• Gene flow may also result from the mating of individuals belonging to adjacent populations.
• Gene flow can alter the genetic characteristics of populations and prevent them from maintaining Hardy- Weinberg equilibrium.

Evolution NEET Revision Notes

Kinds Of Selections

1. Stabilising selection
2. Directional selection
3. Disruptive selection

Even low levels of gene flow tend to homogenize allelic frequencies among populations and thus keep the populations from diverging genetically.

• In some situations, gene flow can counter the effect of natural selection by bringing an allele into a population at a rate greater than that at which the allele is removed by selection.
• Migration is the movement of individuals from one population to another population.
• Emigration is the migration of individuals out of an area.
• Immigration is the migration of individuals into an area. AHopatric speciation. The speciation by the geographical separation of two populations and the divergence of the population.
• Sympatric Speciation. When a sub-population becomes reproductively isolated in the midst of its parent population this is called sympatric speciation.
• Balancing Selection. A heterozygous condition in sickle cell anaemia (H^A/H^S) survived the malarial condition and balanced the loss by sickle cell anaemia is called balancing selection.
• Biological Species concept. A sexually interbreeding population which is separated from other species by reproductive isolations.
• Evolutionary Species Concepts. An evolutionary species is a lineage evolving separately from others with its own unitary evolutionary role and tendencies.
• Convergent Evolution (Adaptive Convergence). The development of similar adaptive functional structures in unrelated groups of organisms is called convergent evolution. Example: Wings of insect, bird and bat.
  • Thus analogous organs show convergent evolution (adaptive convergence). When adaptive convergence is found in closely related species. It is called “Parallel Evolution” Example: development of running habit in deer (2-toed) and horse (1-toed with two vestigial splint bones.)
• Stabilizing Selection
  1. Stabilizing selection operates in a constant or unchanging environment.
  2. Stabilizing selection introduces homogeneity in the populations.
  3. Stabilizing selection favours average or normal individuals and eliminates over-specialised as well as less-specialized or less adapted individuals.
  4. Stabilizing selection checks the accumulation of mutations that may lower the fitness of species in unchanging environments.
  5. Stabilizing selection tends to arrest variance and evolutionary change.
  6. Stabilizing selection operates rarely because the environment is rarely constant.
     • Stabilizing Selection Examples
       1. Stabilizing selection in sparrows observed by H.C. Bumpus in 1S99.
       2. Stabilizing selection in Land Snails was observed by W.F.R. Weldon in 1901.
       3. Mortality of babies
       4. Stabilizing selection in red checkered moths (Panaxiadominula) observed by E.B. Ford.

Evolution NEET Revision Notes

Directional Selection:

This selection process functions in reaction to incremental alterations in environmental variables.

• It functions within the spectrum of phenotypes present in the population and applies selection pressure that shifts the mean phenotype towards a phenotypic extreme.
• When the mean phenotype aligns with the new optimal environmental conditions, stabilizing selection will prevail.
• This type of selection induces evolutionary change by creating a selection pressure that promotes the proliferation of novel alleles within the population.
• Directional selection underpins artificial selection, whereby the selective breeding of phenotypes exhibiting desirable qualities enhances the prevalence of those phenotypes in the population.
• D.S. Falconer conducted a series of tests in which he picked the heaviest mice from a population at six weeks of age and allowed them to inbreed. He also chose the lightest mice and permitted them to inbreed.
• This selective breeding based on mass led to the emergence of two populations: one exhibiting an increase in bulk and the other a decrease
• Following the cessation of selective breeding, neither group reverted to the original population mass of around 22g. This indicated that the artificial selection of phenotypic traits resulted in certain genotypic selection and a reduction of alleles within each population.

Disruptive Selection. Fluctuating conditions within the environment may favour the presence of more than one phenotype in a population. It was studied in sunflowers.

NEET Biology Evolution Theory Of Evolution By Natural Selection Synopsis

The unit of evolution is the population. The unit of natural selection is individual (phenotype).

• An Isolating Mechanism is a means of producing and maintaining reproductive isolation within a population. This can be brought about by mechanisms acting before or after fertilisation. Theodosius Dobzhanskv suggested a classification of isolating mechanisms.
• Adaptive Radiations. Evolution of groups of animals in different directions.
• Of all the species that have ever lived more than 99% have gone extinct
• Danvin used the breeding of domestic animals, known as artificial selection as evidence of evolution. In artificial selection, humans are the selective agents, while in natural selection, the environment is the selective agent.
• Darwinism Fitness. In an individual it is a measure of its ability, relative to others in the population, to pass genes to the next generation.
• The branch of Biology that emerged from the synthesis of Darwinian Evolution and Mendelian genetics is called Population Genetics
• Parallelism is the adaptive convergence of closely related species in evolution.
• Genetic variation that parallels a gradient (for example, Rainfall) is called Cline.

Darwin regarded continuous variations to be more important since discontinuous variations being mostly harmful would not be selected again.

1. G6PD is an X-chromosome-linked trait. Clinical features
2. Drug-induced hemolytic anaemia, for example, sulphonamide, primaquine nitro furantin and phenacetin. Ingestion of the drug is followed by fever, malaise, prostration and passage of dark urine
3. Favism
4. Neo-natal jaundice Diagnosis is established by enzyme assay.

NEET Biology Evidence Of Evolution Relationship Among Organisms

Organic evolution is also stated as ‘Descent with modification’ (Darwin, 1859)

Empedocles (493—435 B.C.). Founder of the concept of Evolution.

Herbert Spencer (1820-1903). Coined the term evolution.

Biological evolution has given rise to a large number of different kinds of organisms.

NEET Biology Evidence Of Evolution Evidence In Support Of Evolution

The types of evidence which support organic evolution are, morphological, anatomical, embryological, palaeontological, biogeographical, physiological, and biochemical.

Read and Learn More NEET Biology Notes

NEET Biology Evidence Of Evolution From Taxonomy

Classification of animals both present and extinct is based upon their natural similarities and dissimilarities which establish their genealogical relationship and common ancestry.

Palaeobiological study helps in understanding and locating hydrocarbon sources.

Evidence Of Evolution NEET Notes

Palynofossils—the tiny microscopic spores, pollen, and other vegetal remains of the past—assist us in interpreting ancient environmental conditions favourable for organic matter accumulation and its conversion to fossil fuels by transformation and subsequent thermal alteration.

Genclogieal lice was first drawn by Lamarck (1809).

• The levels of classification are Phylum → Class → Order → Family → Genus → Species.
• All similar species are grouped together in one genus, all such genera in one family and so on.

Evolution Of Plants

• Diverse life processes, including energy transformation, macromolecule synthesis, genetic coding, and various biochemical reactions, exhibit similarities among diverse creatures.
• The parallels in biological processes reinforce the notion that every living being originated from a shared primordial ancestor and emerged through evolution.
• Evolutionary change is an essential trait of all living species.

NEET Biology Evidence Of Evolution Morphological And Anatomical Evidence

Body Organisation. Body of all multicellular animals: cell organelles → cells → tissues → organs → systems.

Vertebrate Organs. Certain organs (for example Heart) show gradual modifications.

• Fish’s Heart. 2 chambered (1 auricle + 1 ventricle)
• Amphibian’s Heart. 3 chambered (2 auricles + 1 ventricle)
• Reptilian Heart. Incompletely 4 chambered (2 auricles + partly divided ventricle).
• A crocodile is a reptile, but it has a 4 chambered heart with completely divided ventricles.
• Mammals And Aves. 4 chambered hearts (2 auricles + 2 ventricles).

Homologous And Analogous Organs NEET Biology

Homologous Organs. Organs which look different and perform different functions but have the same basic structure and origin are called homologous organs. They are evidence in support of divergent evolution Examples,

1. Forelimbs of vertebrates such as seal (flipper), bat (patagium), horse (forelimb), man (arm).
2. Thom of ‘glory of the garden’ ( Bougainvillea) and tendril of Passiflora. Both look different and help in climbing in a different manner. But both arise in the axillary position and are modified branches.
3. Insect Legs. They are used in squatting in mosquitoes, collection of pollen in bees, clinging in lice, grasping in praying mantis and digging in mole cricket. However, in each case, it has five parts – coxa, trochanter, femur, tibia and 1-5 jointed tarsus.
4. Insect Mouth Parts. They have a labrum, two mandibles and two pairs of maxillae. Mouth parts are specialised for chewing and biting in cockroaches, chewing and lapping in Honey bees, sponging in Housefly, piercing and sucking in Mosquito and siphoning in Butterfly.

Differences in homologous organs are examples of divergent evolution/adaptive radiation. The occurrence of similar types of biomolecules in various groups of organisms is called molecular homolog}’, for example, blood proteins in humans and apes, hormones in mammals, and Rubisco in plants.

Analogous Organs. Organs which have the same function and look superficially alike but are quite different in fundamental structure and embryonic origin are called analogous organs and support convergent evolution. Examples,

1. Wing of an insect and that of a bat.
2. Fins of fishes and flippers of whales have similar functions and are structurally quite different,
3. Stings of Honey bee and Scorpion have similar functions but are modifications of the ovipositor and last abdominal segment respectively,
4. Photosynthesis is performed by different structures in Wild peas (stipules). Australian acacia (petiole) and Ruscus (cladodes).

Connecting Links are the living animals which possess the characteristics of two different groups of animals known as the connecting links. Examples

1. Lung Fishes — connecting link between fishes and amphibians.
2. Resemblance With Fishes — paired fins, gills and dermal scales.
3. Resemblance With Amphibians — internal nares, 3 chambered heart single or double lung for breathing.
4. Egg Laying Mammals — spiny ant eater, duck-billed platypus. Link mammals with reptiles.

Mammalian Features — hair, mammary glands, diaphragm, single aortic arch.

Reptilian Features — lay large eggs, presence of cloaca, large coracoid in pectoral girdle.

Some Other Connecting Or Missing Links

Missing links are the extinct animals which possess characters of two different groups of animals.

Fossil Evidence Supporting Evolution NEET Study Material

Vestigial Organs. The organs which occur in reduced form and are useless to the possessor, but correspond to the fully developed functional organs of their ancestors called vestigial organs. For example, the Human body has about 90 organs which are vestigial.

1. Tail Bone (Coccyx)
2. Wisdom Tooth
3. Nictitating Membrane. (Plica semilunaris) also called the third eyelid. Used in cats, eels, pigeons and frogs for cleaning the cornea. In men, this function is carried out by the upper eyelid.
4. Auricular Muscles. Three in mammals such as dog, cow, rabbit etc. ( Anterior, superior and posterior).
5. Caecum And Vermiform Appendix

Examples In Other Animals

1. Whales. Whales possess vestigial pelvic girdle and vestigial ear pinna (reduced).
2. Pythons and Boas possess vestigial, greatly reduced pelvic girdles.
3. The splint bones of horses represent the vestigial second and fourth toe.
4. Eyes have become vestigial in deep sea-dwelling animals like crayfish, salamanders etc.

Examples Of Vestigial Organs Of Plants. Leaves are reduced to scales in Ruscus and Asparagus. Pistil is reduced in ray florets of sunflower.

Atavism (Reversion ). It is the reappearance of certain ancestral (not parental) structures which have either completely disappeared or greatly reduced.

NEET Biology Evidence Of Evolution Embryological Evidences

Embroyological Evidence includes similar early development; similar vertebrate embryos, temporary embryonic structures; recapitulation theory and development of certain organs.

• Development of all triploblastic animals starts from a zygote and undergoes similar processes to form gastrula having-3 primary germ layers (ectoderm, mesoderm and endoderm) which have the same fate in organogenesis.
• Early embryos of different vertebrates are similar in having similar structures like gill slits, notochord, tail etc. and are indistinguishable from one another. All these support organic evolution.
• It is also supported by recapitulation theory by Von Baer (modified into Biogenetic Law by Haeckel) which states “Ontogeny repeats phytogeny” example, a tadpole larva of the frog.

NEET Biology Evidence Of Evolution Palaeontological Evidence

Palaeontological evidence includes missing links; distribution of fossils in the rocks of different periods, ancestries of animals etc.

• Vinci (1452-1519) is regarded father of palaeontology. Palaeontological evidences are based on a comparative study of fossils of different animals. Fossils are the remains or impressions of harder parts of past animals preserved in sedimentary rocks or other media.
• The age of the fossil is determined either by C¹⁴ – dating technique or the amount of lead in a rock.

Radioactive Carbon Method: The radioactive carbon method was discovered by W.F. Libby.

• Half half-life of radioactive carbon is 5730 years which was found in very minute quantity i.e. 0.1 % in the atmosphere and continuously produced from cosmic ray bombardment on earth’s upper atmosphere.
• Living organisms absorb radioactive carbon (C¹⁴) throughout their life from the environment in the form of CO₂ and organic molecules which signal death.
• After the death of organism, C¹⁴ began to decay according to its half-life i.e., 573 x 10³ years. It means 100 grams C¹⁴ will remain 50 grams in 5.73 x 10³ years and 25 grams in another 5.73 x 10³ years.
• By measuring the amount of C¹⁴ in a fossil relate this amount with the amount of C¹⁴ in a living organism, the age of the fossil can be estimated.
• This method is useful only to determine the age of actual remains and useless for moulds, casts or impressions.
• The C¹⁴ Radioactive carbon method can be used to determine the age of younger fossils that are not older than 70,000 years.
• This method is used for dating not only fossils but also archaeological remains.

Fossil Evidence Supporting Evolution NEET Study Material

Radioactive Clock Method: This method was discovered by Boltwood (1907) and is based on the disintegrating property of radioactive elements. These elements disintegrate at a steady rate into a stable substance for example in the U²³⁸ – Pb²⁰⁶ method the following decay takes place.

Uranium²³⁸  → Radium²²⁶ →Polonium²¹⁸ → Lead²⁰⁶ → Polonium²¹⁰ → Astatine²¹⁸

• One-half of uranium238 atoms will convert into Lead206 after 4.5 billion years (4.5 x 10¹⁰ years).
• The age of the rock can be calculated by estimating the uranium and lead quantity.
• This method is used for igneous rocks containing minerals and is useless for determining the age of sedimentary rock and fossils directly.

It is based on the fact that the older rock is less radioactive.

Potassium-argon Method: The transformation of radioactive potassium K⁴⁰ to argon and rubidium to strontium has been used for dating fossil-bearing rocks of any age and any type. Due to the greater concentration of potassium in most rocks, it is a more accurate method of dating fossils than uranium, a relatively rare element.

• It is the latest method to estimate the age of fossils.
• The half-life of potassium is 1.3 x 10⁹ years.
• Ordinary potassium contains 0.01 % of radioactive isotopes which disintegrate into calcium and argon.
• The age of the earliest known fossil of hominids in East Africa has been estimated by this method recently.
• It is possible to date very old rocks i.e. over three billion years by this method. Electron spin resonance dating

Electron Spin Resonance (ESR) dating is a relatively new, more precise and most accurate method of dating. It is based on the fact that background radiation causes electrons to dislodge from their normal positions in atoms and become trapped in the crystalline lattice of the material.

• When odd numbers of electrons are separated, there is a measurable change in the magnetic field (or spin) of the atoms.
• Since the magnetic field progressively changes with time in a predictable way as a result of this process, it provides another atomic clock or calendar, that can be used for dating purposes. ESR is used mostly to date Calcium carbonate in limestone, coral, fossil teeth, molluscs and egg shells. This method can date quartz and flint.
• This method has been used by palaeontologists mostly to date samples from the last 300,000 years.

1. Missing Links. They are those extinct organisms which had the characteristics of two different groups of animals. These also show the path of evolution. Archaeopteryx (lizard-bird) is a missing link between the reptiles and the birds.
   • They are the transitional forms between two present-day groups of organisms, for example, Pteridosperms (Pteridophytes and gymnosperms).
   • Toothed birds Reptiles and birds.
   • Archaeopteryx (Wagner 1861)
   • Reptilian Characters—toothed jaws, non-pneumatic bones, keel-less sternum, free caudal vertebrae, free clawed fingers.
   • Avian Characters—Fore limbs forming wings, feathers, beak, rounded cranium, fused skull bones.
2. Geological Succession Of Fossils shows that fossils have become more in number and show gradually increased complexity from the earliest to recent rocks.
   • Dinosaurs were highly flourished, giant reptiles of the Jurassic period (Age of Reptiles) of the Mesozoic era. These became extinct probably due to the direct hitting of a comet or a meteorite having rich amounts of iridium and global cooling.
3. Geological Time Scale is the tabulated form showing the sequence and duration of different eras and periods with their dominant form of life. It was proposed by Giovanni Avaduina (1760). It has 5 principal eras: Archaeozoic; Proterozoic; Palaeozoic; Mesozoic and Coenozoic. Another era is Azoic 4200- 4600 million years ago in which no life existed.
4. Phylogeny is the evolutionary history of an organism. The Palaeontologists have traced the ancestries of horses, elephants, camels etc. The evolution of horses started in North America about 60 million years ago.
   • The original dawn horse (Eohippus) has passed through stages like an intermediate horse (Mesohippus), ruminating horse (Merychippus) and Pliocene horse (Pliohippus) to transform into a modern horse (Equus).
   • These stages confirm the occurrence of changes like an increase in height, a reduction in the number of functional digits and an increase in the size of the crown of the molars.

NEET Biology Evidence Of Evolution Type Of Fossils

1. Unaltered. Woolly mammoth buried in ice.
2. Petrified. Replacement of organic parts by mineral
3. Moulds and casts
4. Prints. Footprints, prints of leaves, stems etc.

Types Of Rocks

1. Igneous Rocks. Rocks which are formed by the solidification of the original molten earth are called igneous rocks.
2. Sedimentary Rocks. Rocks formed due to deposition and subsequent stratification of soil particles over a long period of time are sedimentary rocks.
3. Metamorphic Rocks. These rocks are sedimentary rocks that are changed by heat and pressure.

In passing from the earliest to recent rocks, the fossils become more numerous and also progress from simple to more complex types.

Geological Time Scale

NEET Biology Evidence Of Evolution Biogeographical Evidence

1. Biogeography. The study of the distribution of animals and plants in the world is called biogeography.
2. Pangaea. It is held that around the carboniferous period ( about 375 million years back) or slightly earlier, all the present-day continents formed a single large irregular-level mass called Pangaea.
3. Realms Of Life. Sclater ( 1858) divided the earth into six realms for the distribution of birds while Wallace (1923) divided the earth into six realms for the distribution of both plants and animals.
   1. Nearctic
   2. Palaearctic
   3. Neotropical
   4. Oriental
   5. Ethiopian
   6. Australian
4. Discontinuous Distribution. Descendants of a common ancestor in some cases inhabit different continents and also differ from each other.
   1. Even with the same climate and topography, different realms have different types of flora and fauna. Central Africa has lions, elephants, antelope, and giraffes while Brazil has tapir, sloths, opossums, and llamas. The deserts of the two realms also differ with cacti in America and euphorbias in Africa. It is believed that at one time the whole land mass was one piece of Pangaea.
   2. About 200 million years back, it broke up into northern Laurasia and southern Gondwanaland. Laurasia further split up to form Eurasia, Greenland, and North America. Gondwanaland formed South America, South Africa, Australia, New Zealand and India.
   3. Another reorientation occurred 135 million years back when India was pushed upwardly to rest against Eurasia, South Africa joined North Africa and South America came close to North America.
      • The degree and period of separation of an area from another correspond to species diversity.
   4. Double coconut occurs only on Seychelles Island. Egg-laying mammals are restricted to Australia, Tasmania, and New Guinea. Kangaroo and Koala are marsupials found in Australia while Opossum is found in S. America.
   5. The two sides of the isthmus of Panama separated only a few million years back. They possess different but related species of invertebrates.
   6. Galapagos Islands is a group of 14 islands situated 800-960 km off the west coast of South America. Darwin visited the islands and called them living laboratories of evolution. The islands have 23 different species of birds and 11 types of tortoises.
   7. Amongst the birds are 14 species of finches (named Darwin’s finches by David Lach, 1947), a group of small birds which resemble the mainland seed-eating ground finches in general body pattern but differ in food habits, types of beaks, and several other physical features to appear distinct species.
   8. The finches must have come from the mainland but different islands of the Galapagos provided different types of environmental conditions so that the common stock became diversified due to genetic drift and adaptation to different food habits. It is an example of adaptive radiation/divergent evolution. Example,
      1. Alligators – occur only in the S.E. U.S.A. and Eastern China.
      2. Restricted Distribution. The parts separated from the rest of the world long have unique fauna and flora example, Australia.

Comparative Embryology In Evolution NEET Exam Preparation

NEET Biology Evidence Of Evolution Biochemical Evidences

1. Enzymes
2. Hormones
3. Blood proteins– of various mammals are similar to a large extent but are sharply distinguishable from those of other vertebrates. Man is nearest to the great apes (Chimpanzees and gorillas) and next in order are the old-world monkeys, the new-world monkeys and the tarsiers.
4. Molecular Homology. Similarity among animals at the molecular level is called Molecular Homology.

NEET Biology Evidence Of Evolution Cytological Evidence

All the living organisms are similar in being:

1. Cellular in nature and are formed of one (protozoans) or more cells (metazoans).
2. Presence of similar organelles having similar ultrastructure and functions.
3. All, the cells are formed of similar material called protoplasm having similar physical, chemical, and biological properties.
4. Basic metabolic cellular functions are performed similarly.

This supports that all the organisms are interrelated and have a common ancestry.

NEET Biology Evidence Of Evolution Comparative Physiology

All living organisms exhibit similarities in their chemical structure and function i. e., the biochemical composition and physiological activities, for example, the blood as regards cell and plasma, is markedly similar in different groups.

NEET Biology Evidence Of Evolution Genetics

The selection and interbreeding of domestic animals by man has led to the establishment of new races. This has been possible because of the changes occurring in genes producing mutations and variations in changed environments.

The natural forces of isolation and natural selection operate on these variations and some of them become heritable, leading to the formation of new races. The same process of gene mutation, variations, selection and interbreeding might have occurred on a large scale in nature leading to the establishment of new species.

Great Chain Of Being Or Aristotle’s Ladder Of Nature:

To express ideas about evolution various naturalists explained their different views. About 2000 years before Darwin explained his theory others expressed their views. According to Plato (428-348 BC), each species was an unchanging ideal form. All earthly representatives are imperfect imitations of such true essence of an ideal unseen world.

• As God is perfect, everything that existed on earth was His ideas. Later on, Aristotle (384-322 B.C.) further explained Plato’s idealistic concept to chain like a series of forms, each form representing a link in the progression from most imperfect to perfect. He called this chain as Ladder of Nature or Scala Naturae. It is also known as the “Great Chain of Being”
• Plate Tectonics: The concept of plate tectonics supposes that the surface layers of the Earth fit together like a spherical zig-zaw puzzle, and the individual pieces are on the move about one another.
• Continental Drift is the process in which it is supposed (from recent geological and other evidence) that the continental land masses have not always occupied their present position on the globe and that, powered by processes within the Earth itself, they are slowly and continuously on the move.
• In this way new land masses are created and destroyed, split apart and joined, over geological time. This hypothesis was first proposed by Snider in 1858 but developed by Taylor in America and Wagner in Germany in the late 1800s.
  • Significance. Continental Drift is one of the processes that can lead to geographical isolation.
• K-T Boundary. The boundary between rocks of the cretaceous and tertiary periods, about 65 million years, often having iridium and marketing the extinction of dinosaurs.
• Magma. It is the molten rock material present in the earth’s interior from which igneous rocks have been formed. Lava is also magma that has reached the surface of the crater of a volcano.
• Aeon Or Eon. It is the geological age consisting of one or more eras, viz., archaean, Proterozoic, and phanerozoic. Phanerozoic eon has three eras-palaeozoic, Mesozoic, and economic.

Comparative Embryology In Evolution NEET Exam Preparation

Evolution Of Horse:

The primary tendencies observed in equine evolution pertained to movement and alimentation.

They signify adaptations to fluctuating environmental conditions and can be summarized as follows:

• Augmentation in dimensions
• Elongation of extremities and feet
• Reduction of lateral digits.
• Augmentation in length and girth of the third digit
• Alignment and rigidity of the spine
• Enhanced sensory organs
• Expansion in size and intricacy of the brain correlated with the evolution of sensory organs.
• Broadening of incisors, substitution of premolars with molars, elongation of teeth, elevation of molar crown height, augmented lateral support of teeth through cement, and expanded cusp surface areas due to enamel ridge exposure.

The Basic Timeline Of A 4.6 Billion-Year-Old Earth, With Approximate Dates:

• 2 billion years of complex cells (eukaryotes),
• 1 billion years of multicellular life,
• 1000 million years of simple animals,
• 570 million years of arthropods (ancestors of insects, arachnids and crustaceans),
• 550 million years of complex animals,
• 500 million years of fish and proto-amphibians,
• 475 million years of land plants,
• 400 million years of insects and seeds,
• 360 million years of amphibians,
• 300 million years of reptiles,
• 200 million years of mammals,
• 150 million years of birds,
• 130 million years of flowers,
• 65 million years since the dinosaurs died out,
• 2.5 million years since the appearance of the genus Homo,
• 200,000 years of anatomically modern humans,
• 25,000 years since the disappearance of Neanderthal traits from the fossil record.
• 13,000 years since the disappearance of Homo floresiensis from the fossil record.

NEET Biology Evidence Of Evolution Synopsis

Mammals among animals and angiosperms among plants are the most advanced forms. The earliest era in the geologic record is Precambrian.

Phylogenetics = Cladistics. Some workers in cladistics equate homology with synapomorphy. In molecular biology, the term indicates a significant degree of sequence similarity between D.N.A. or protein sequences.

• Evolved from common ancestor = Monophyletic origin
• Dundee. It is the famous city of fossils in Italy
• Unaltered fossils of 25, 000 yrs old elephant woolly mammoths were found in ice of Siberia (Russia)
• Evolution Is Irreversible. Also called Dollo’s law (Dollo, 1893).
• Cope’s Law. In the course of evolution, there is a tendency for animals to increase in size.
• Bergman’s Law. Warm-blooded animals are larger in size in the colder regions as compared to hotter parts.
• Allen’s Law. Extremities like tails and ears become smaller in colder areas.
• Gloger’s Rule. Warm-blooded animals have more melanin in hot wet areas but develop yellow-red pigment in hot dry areas.

Paleontological Evidence Of Evolution NEET Preparation

Ontogeny Repeats Phylogeny

Recapitulation theory – Karl Von Baer

Biogenetic Law – Ernst Haeckel

• Biogenetic Law can be illustrated even with an example amongst plants. Seedlings of Acacia tree initially develop simple leaves which later transform into compound leaves. Another example is that modern-day oaks of the southern U.S.A. retain their foliage throughout the year whereas the oaks of the northern United States are deciduous and shed their leaves during winter.
• Dinosaurs. Extinct reptiles were of two types, lizard-hipped (order Saurischia) and bird-hipped (order ornithischian), originated about 230 million years back, both carnivorous and herbivorous, using four or two legs, brain small as compared to body, often with a long tail, smallest, with size of chicken (Compsogncithus) and the largest Brachiosaurus reaching 12.6 m and weighing 80 tonnes (some workers believe that the largest dinosaur was Apatosaurus = Brontosaurus that reached a length of 21 m having a weight of 30 tonnes). The teeth of carnivorous Tyrannosaurus were 16 cm long. Plesiosaur and Pilosaur are marine reptiles of the Jurassic and Cretaceous period.

The main factor responsible for the mass extinction of dinosaurs is suggested to be the hitting of the earth by a comet or a meteorite with rich amounts of metal- iridium. Another hypothesis, suggested for this mass extinction, is ‘global cooling’

• Pterosaurs are extinct flying reptiles of the Mesozoic age. Some of them had a wing span of 12 m.
• Synapsids/Synapsida. Mammal-like reptiles of carboniferous to Triassic (315-195 million years). Some of them gave rise to mammals (for example, Pelycosaurs and Therapsids). Synapsids were eliminated by dinosaurs.
• Convergence. Development of similarities between animals or plants of different groups resulting from evolution to similar habitats
• Latimeria (Coelocanth) is a lobe-finned (Cross- opterygian) fish in which fins arise from limb-like stalks and not directly from the body. It is the oldest living fish and once was believed to have become extinct about 70,000,000 years ago.

It is regarded as a “living fossil” as it has lived till today without undergoing any change in it. Other living fossils are Antedon (Feather star – echinoderm); Limulus (king crab -an arachnid); Cycas, etc.

• George Cuvier (1769 – 1832). Proposed the theory of catastrophism. Founder/father of modern palaeontology.
• Leonardo de Vinci ( 1452-1519). Father of palaeontology.
• The fossil-like impressions formed on certain rocks due to the deposition of minerals in rock crevices are called pseudofossils.
• The large-scale extinction of plants and animals within a short period is called mass extinction.
• Triassic. An epoch between 181 -225 million years ago with dry climate. Sandstone rocks are common. First mammals appeared.
• Palaccology. It deals with the study of ancient organisms and their environment.
• Hoofed animals like horses originated in the Eocene epoch in North America.
• Igneous rocks are devoid of fossils.
• A thorn of Bougainvillea and tendril in Cucurbita: Homologous

NEET Biology Origin Of Life

Life– The inherent capacity of organisms to utilise outside materials for energy, growth and reproduction through chemical reactions. Life is regarded as a power that an organism possesses to maintain and produce itself.

Big Bang Theory – A single huge explosion

• The universe expanded → Temperature came down – Hydrogen and Helium formed later on.
• Gases condensed under gravitation and formed galaxies of the present-day universe.
• Earth formed almost 4.5 billion years ago.
• No atmosphere on early Earth.
• Water vapours, methane, CO₂, NH₃ released from molten mass covered the surface.

UV rays of the sun broke up.

Read and Learn More NEET Biology Notes

Oxygen is combined with ammonia, and methane to form water CO₂ and other simple molecules.  An ozone layer was formed.

Biopoiesis – the process by which life originated.

According to the Cosmozoic theory developed by Richter and supported by Thomson, Helmholtz and Arrhenius states that life (protoplasm) reached the earth in the form of spores or germs from outer space.

Origin Of Life NEET Notes

Theory of special creation—By Father Suarez.According, to it life was created by super supernatural power in 6 days.

• 1st day — he made heaven and earth
• 2nd day—separated sky from water
• 3rd day—dry land of plants
• 4th day—Sun, moon and stars
• 5th day—Birds and fishes
• 6th day—Land animals and human beings.

Theory of eternity of Life—By Richter (1865), Preyer (1880), Helmholtz (1884), Arrhenius (1908), Moyle (1950), Bonds (1952).

According to it, “Life is immortal”. Living matter has occurred in association with non-living matter from the beginning. Thus according to this theory, Life changes its form and it was never created.

• According to spontaneous generation theory, life originated from non-living things. It is estimated that life originated approximately 3,600 million years ago.
• Scientists supporting this theory— Aristotle, Van Helmont, William Harvey, Haeckel, Plato, Xanophanes, Thales, Anaximander, Empedocles
• Experimental support was provided by the Van Helmont experiment (1642).
• Abiogenesis was challenged on the basis of experiments by—Francisco Redi and Spallanzani. Finally disapproved by – Louis Pasteur.

Biogenesis. The fact that new life (nowadays) comes from any pre-existing life (Omne vivutn exvivo).

Theory Of Catastrophism. It states that there have been several creations each preceded by a catastrophe due to some geological disturbance. Each catastrophe completely destroyed life and each creation consisted of life quite different from that of the previous one. (George Cuvier and Orbigney)

Origin Of Life NEET Notes

Oparin-Haldane Theory (Naturalistic, Chemical or Heterotroph Theory)

A.I. Oparin and J.B.S. Haldane’s (1936)

The theory of the “Origin of Life” is widely acknowledged.

• Life emerged by chemical evolution, as the primordial Earth’s atmosphere was decreasing, characterized by elevated temperatures and the presence of gases like as nitrogen, hydrogen, methane, ammonia, and water vapor.
• As the temperature decreased, certain gasses condensed into liquids, while some liquids solidified. Free oxygen was nonexistent.
• Extensive polymers, including proteins, nucleic acids, and other molecules, were methodically synthesized by the influence of high-energy solar radiation, energy from alternative sources (likely isotopes on primordial Earth), and energy from electrical discharges.

The main steps of the theory are as follows:

• The first organisms were heterotrophs and anaerobic containing nucleoproteins which gave rise to autotrophs.
• Universe – 15-20 bya (Billion years ago.)
• Earth – 4.5/4.6 bya
• Life 4.0 bya (life appeared 500 mya after the formation of the earth)
• Non-cellular form of life may have originated 3 by (RNA + Protein + Polysaccharides)
• Cellular form of life 2000 mya(million years ago)
• Life was present on earth about 3.9 bya.
• Microfossils of cyanobacteria appeared 3.3 to 3.5 bya.
• Origin of Eukaryotic cell – 1.5 bya.

NEET Biology Origin Of Life Some Early Contributors To The Knowledge Of Evolution And Related Topics

Thales (624-548 B.C.): A Greek who proposed a theory that water (ocean) was the mother of all life.

Anaximander (611—547 B.C.): A Greek who thought that life arose from a mixture of water and earth and that landforms arose from aquatic types, particularly under the influence of the sun’s heat.

Heraclitus (510—450 B.C.): A Greek natural philosopher who stated that “struggle is life” and “all is flux”— thoughts that are basic to modem ideas in evolution.

Empedocles (495-435 B.C.): A Greek who theorized that living organisms were generated spontaneously from scattered materials, being attracted by love and hate.

“Founder of the concept of organic evolution”

Aristotle (384-322 B.C.): A Greek who theorized that in the living world, there was a gradual change from the simple and imperfect to the more complex and perfect, thus suggesting the idea of evolution.

Saint Augustine (353-439 A.D.): Saint Augustine interpreted the first chapter of Genesis, stating that in the beginning matter was created with the properties and potentialities to evolve into living and non-living worlds as we know them today.

Origin Of Life NEET Notes

Leonard de Vinci (1412-1529) “Father of Palaeontology”

Francisco Redi (1621-1697): An Italian who overthrew the theory of spontaneous generation, which stated that life arose from non-living materials spontaneously, by discovering that eggs and larvae of insects originated from previous living insects, rather than from non-living substances.

Carl Linnaeus: Father of taxonomy

Giovanni Avadeuna (1760) proposed Geological time scale

Thomas’ Robert Malthus (1766-1834): An English economist whose “Essay on Population,” published in 1798, inspired both Darwin and Wallace in their theories of evolution.

Charles Lyell (1797-1875): A Scottish geologist who laid the foundations for the science of earth structure in his Principles of Geology (1830-1832). He is considered an important contributor to the theory of organic evolution because of his influence on Charles Darwin and Alfred Russel Wallace.

Georges Cuvier (1769-1832): A Frenchman who supported the “Cataclysmic Theory,” in which he stated that there had been numerous creations, each of which was followed by a cataclysm (catastrophe) that destroyed it, and its place was taken by new forms. He is regarded as the founder/father of modern palaeontology

Georges de Buffon (1707-1788): A French naturalist who excluded the possibility that species have the ability to evolve (change). He probably was influenced by the ancient ideas revived during the Renaissance that discredited such a possibility.

Charles Bonnet (1720-1793): A Swiss naturalist and philosopher who first used the term “evolution” but not quite as we do today, and conceived that organisms could be arranged in a ladder-like, linear series.

Erasmus Darwin (1731-1802): An English evolutionist who was the grandfather of Charles Darwin. He believed that acquired traits could be transmitted to future generations and he may have influenced Lamarck, who had similar views.

Jean Baptiste Lamarck (1744-1829): A French biologist who was a student of organic evolution. He believed that environmental influences, and the effects of the use and disuse of body parts, were causes of evolutionary changes—a theory that laid the foundation for the “Theory of the Inheritance of Acquired Traits.”

Charles Darwin (1809-1882): Darwin, on a voyage around the world in the sailing ship HMS Beagle, indicated the descent of species by the development of varieties from common stocks. This process entailed a “struggle for existence,” which resulted in a “natural selection of species” and a “survival of the fittest.” He wrote The Origin of Species by Means of Natural Selection (1859).

Origin Of Life Class 12 NEET Solutions

Thomas Henry Huxley (1825-1895): An English surgeon who actively supported the views of Charles Darwin and assisted in promoting them extensively.

Alfred Russel Wallace (1823-1913): An Englishman who studied animal geography in the East Indies and concluded that the life of wild animals is a struggle for existence. He worked on the problem of the origin of species and arrived at conclusions concerning evolution that resembled those of Charles Darwin.

Louis Pasteur (1822-1895): A French microbiologist and chemist who proved that only living organisms such as bacteria and yeasts could cause fermentation. He proposed a method of preventing this process by heating to a temperature high enough to kill the germs. This method is known as pasteurization. Pasteur’s work ended the controversy regarding the possibility of the spontaneous generation of living organisms from non-living materials.

August Weismann (1834-1914): A German who distinguished between body cells and germ cells and proposed the “Theory of the Continuity of Germplasm from Generation to Generation” (1885). He opposed the idea that acquired traits might be transmitted.

Mendel’s work published (1866)—(Unknown to Darwin)

Henry Walter Bates (1825—1913). Proposed the concept of Batesian mimicry in 1862.

J Fritz Muller (1821—1897). Described in 1879 the Mullarian mimicry.

Scaler (1858) divided the earth into six realms for the distribution of birds,

Richard Leaky (1930). Modem Palaeontologist

Lewis and Leaky (1955) excavated fossil forms of Ramapithecus and Kenyapithecus

Origin Of Life Class 12 NEET Solutions

Lucy, C. Johanson (1981) American anthropologist discovered the complete skeleton of a 30-35 lakhs years female fossil hominid resembling Australopithecus

Eugene Dubois (1891) excavated a fossil of Homo erectus erectus

Laplace (1749—1827) proposed a nebular hypothesis to explain the origin of the solar system

Horowitz suggested that the earliest form of life was in the form of naked gene

Solar System. Sun along with orbiting planets and their satellites, the comets and asteroids constitute the solar system.

Origin Of The Solar System. The solar system originated from the gravitational contraction (condensation) of a solid cosmic cloud and dust called a nebula.

• During condensation, this cloud began to rotate due to the initial velocities of particles brought together. The condensation and spin continued. Thus most of the mass is concentrated near the centre. The flattened discs broke into a number of whirling masses of smaller clouds. The sun was formed from the central dense part.
• The sun started radiating energy. The other planets including the Earth were formed from the cooler, less dense outer regions almost in the same plane.

Cosmology. The study of heavenly bodies and the cosmos is called cosmology. The major theories of the origin of the universe are chemical origin and the Big Bang is the most accepted theory about the origin of the universe.

According to the Big Bang theory universe came into existence some 19 billion years ago by a thermonuclear explosion, called the Big Bang, or a dense entity will eventually contract again. Sun and its planets including Earth came into existence at the same time from a common source.

Origin Of Life Class 12 NEET Solutions

Two Major Events Of The History Of Life Are:

1. Origin of life (biopoiesis).
2. Evolution of life.

The Major Theories Of the Origin Of Life Are:

1. Special Creation (Proposed by Father Saurez). This theory of special creation attributes the origin of life to a supernatural or vitalistic event at a particular time in the past. In other words, this theory believes in the creation of life by God.
2. Spontaneous Generation. (Concept held by Thales, Anaximander, Empedocles, plants). This theory discards abiogenesis and believes in the biogenetic origin of life i.e. life originates from pre-existing life-biogenesis.
3. Extraterrestrial or Cosmic Origin (Richter). This theory believes that life on Earth came from some other planet.
4. Terrestrial Origin or Abiogenic Origin (Oparin and Haldane). This theory states that life originates on Earth from collections of organic molecules that were produced early in the history of Earth.

This theory of terrestrial origin has a scientific base.

Role Of Catalytic Rna In Origin Of Life

1. The precursor of RNA of ciliate protozoan, Tetralymena was found to contain a self-splicing intron-containing 413 nucleotides which act as enzymes,
2. The very first living molecule might have been an RNA replicase that catalysed its own replication without the help of a protein.
3. Catalytic RNA are now considered to be molecular fossils.

• Biogeny. Origin of first life.
• Chemogeny. Origin and evolution of organic chemicals.
• Cognogeny Is The Evolution of different forms of living species.
• Biopoiesis. Origin of life.
• Biogenesis. Origin of life from life.
• Continental Drift Theory. Proposed by Wagener (1912) that about 250-200 million years there was a single land mass or continent which subsequently got split into continents as are known today.

Plate Tectonics:

John Tujo Wilson (1965) posited that the Earth’s outer surface comprises a mosaic of thick plates, both large and small, with a thickness of 70-100 km, which move in relation to one another, perhaps due to convection currents in the semi-molten mantle underneath.

• This movement is thought to have commenced approximately 2000 million years ago at a velocity of 6 centimeters per year. As a result, the continents are gradually rotating around the Earth. They have previously accomplished this four times.
• Francisco Redi denied the spontaneous creation of flies from decaying flesh in 1668.
• The energy radiated by the sun originates from nuclear fusion events.
• The initial kind consists of seas created from atmospheric water.
• Clay is optimal for the concentration of monomers. cs Cells with extended metabolic pathways were favored as primitive cells depleted the directly usable organic compounds.
• The most ancient fossilized cells resemble heterotrophic bacteria.
• The primordial autotrophs were likely anaerobic chemoautotrophs.
• The initial creatures to emit oxygen were likely cyanobacteria.

NEET Biology Origin Of Life Synopsis

The study of the universe or cosmos is called cosmology.

• Exobiology. Investigation of life on heavenly bodies other than the earth.
• The first organisms were — Heterotrophs. (Chemo- heterotrophs).
• Age of the earth – 4600 million yrs.
• Earliest prokaryotes – 3600 million yrs.
• The first formed compounds were probably – proteins and nucleic acids.
• Aristotle – The first proponent of the theory of abiogenesis.
• Origin of life – somewhere between 4.5 x 10⁸ to 3.6 x 10⁸ years ago.
• Origin of life – in water (probably sea).
• Gas is absent in the primitive atmosphere – free oxygen.

Gases present in the primitive atmosphere – N₂, CH₄, H₂, NH₃, H₂O_(g)

• Spontaneous generation (Abiogenesis) theory was proposed by Van Helmont (1577—1644) and the concept was supported by – Thales, Xanophanes, Empedocles, Plato, and Anaximander.
• Empedocles is regarded as the father of evolutionary concepts.
• Spontaneous generation theory challenged by – Fran-cisco Redi, Spallanzani and Pasteur Tyndall
• No life on the moon as there is no atmosphere on the moon because of the low escape velocity on the moon in which gas molecules easily cross.
• A.I. Oparin wrote a book “Genesis and Evolutionary Development of Life” and “Origin of Life” on Earth.
• “Evolution from Space” was written by Fred Hoyle.
• F.H.C. Crick (1982) published a book with the title ‘Life itself’.
• Cosmozoic theory of the origin of life was proposed by Richter and supported by Arrhenius.

Sydney W. Fox. discovered aqueous suspension of polymers’ spherical aggregates. He called the coacervates a microsphere.

• S.W Fox demonstrated that if a nearly dry mixture of amino acids is heated, polypeptide molecules are formed.
• Melwin Calvin (1951) strongly irradiated CO₂ and H₂ in a cyclotron to form formic acid, succinic acid and oxalic acid.
• J.B.C. Haldane bom on 5 Dec. 1897 in England. He shifted to India in July 1957 and settled in Bhubnashwer. He died on 1st Dec. 1964. He was a biologist, biochemist and geneticist.
• Louis Pasteur gave “Germ Theory of Disease and Immunology.”
• Progenote is regarded as early single-celled common ancestors of archaebacteria, eubacteria and eukaryotes. Thus, no present-day bacterial type can be regarded as an ancestor of eukaryotes.

NEET Biology Origin Of Life Of Earth

The genesis of life is associated with the inception of Earth, the Cosmos, and the Universe, which emerged 10 to 20 billion years ago due to the Big Bang (a thermonuclear explosion). A galaxy, such as the Milky Way, consists of billions of stars, including our Sun, together with its respective planets and satellites.

• The solar system comprises the sun, its planets, and their satellites.
• Earth is the third planet, characterized by its rocks, water, and atmosphere. It commenced as gaseous clouds of metallic and non-metallic atoms, subsequently condensing to create surface rocks, a boiling fluid core, and a gaseous atmosphere.
• Cosmology. Investigation of the cosmos.
• The oldest extant rock is 4.3 billion years old and contains no evidence of life.
• 3.9 billion-year-old rocks contained carbonates indicative of biological activities.
• The most ancient microfossils of Cyanobacteria date back 3.3 to 3.5 billion years.
• Francis Crick and Leslie Orgel suggested the notion of guided panspermia, which was substantiated by genetic code and the function of the metal molybdenum.

NEET Biology Evolution Of Man

Male Primula is positioned to inquire about his origin.

• Male Is classified within the order Primates alongside monkeys and apes.
• The ancestors of humans and other comparable species developed approximately 24 million years ago.

NEET Biology Evolution Of Man Relationship Of Man With Other Primates

The older primate includes three sub-orders. Leinuroidac, Tarsioidac, and Anthropoidae. The Leminoidne and Tarsioidac are collectively called prosimians and Anthropoidae are called simians.

Read and Learn More NEET Biology Notes

• The first mammal was 210 million years old, the first primate 80 million years, the first anthropoid apes 36 million years, and the first hominids 24 million years ago.
• The three families of modern hominids are the Hominidae (the family of man), llylobatidae (Gibbous), and the Pongidne (chimpanzees, gorillas, and orangutans).
• The unique features of the man are erect posture, shorter arms, and a large brain, and can fabricate special tools, use spoken language, and practice prolonged parental care.

• The evolutionary history of man has been built up from the study of fossils and molecular homology.
• Human evolution took place in Africa and Asia.
• A common ancestry for great apes and man has been deduced from similarities in DNA contents, chromosome number, and banding pattern.

Human Evolution NEET Notes

NEET Biology Evolution Of Man Human Evolution

The evolution of man is associated with intelligence and bipedal locomotion

• TA. Huxley (1863)– Book ‘Man’s Place in Nature’ Charle’s Darwin (1971) – ‘Descent of Man’.
• Darwin suggested Man, Apes, and monkeys had a common ancestor.
• Mammals evolved in the early Jurassic period about 210 million years ago from Cynodont Reptiles.

Cotylosaurs → Cynodont → Mammals (Stem reptiles) (reptiles)

Early History

1. Dryopithecus (Proconsul, 18-24 million years)—Common ancestor of humans and apes that lived in Asia as well as Africa. Common species D. africanus. Semi-erect, with hind limbs and forelimbs of the same size.
2. Ramapithecus (Kenyapithecus, 8-15 million years)—It was the earliest man like Primate which probably walked on its legs and possessed dentition similar to humans.
3. Australopithecus (Southern ape, First ape-man, 2-5 million years)—A. africanus was lightly built and omnivorous while weight was 20-30 kg.
   • A. robustus was heavily built and vegetarian, height-120 cm, Cranial capacity-380-430 cm.
   • Face-Prognathous (Projecting Type)—Low forehead, prominent brow ridges, no chin, bipedal locomotion but with bent knees, used crude tools.
4. Homo Habilis (2 Million Years)—Bipedal Locomotion with 150 cm height, (40-50 kg) Cranial capacity 680 cm3, Prominent brow ridges and hominid teeth. He was the first toolmaker. Used chipped stone tools.
5. Homo erects (1.7 Million Years, Erect man)—It walked on erect long legs, 150 cm, cranial capacity 775-1225 cm³, prominent brow ridges, no chin, massive jaws, and longer teeth. Semi-erect posture made more elaborate tools, hunted big game birds, used lire, and primitive speech.
6. Java man (Homo Crectus Credits)—had a smaller cranial capacity (775-900 cm³)— first used fire for cooking and protection.
7. Peking Man (Homo Erectus Pekinesis)—(H. eredus Sinanthropus) had sharp and chisel-shaped tools. Large cranial capacity (915-1225 cm³) Neanderthal Man (Homo sapiens neanderthalcnsis)-30,000-50,000 years ago. 150 cm, Cranial capacity (1300-1600 cm³), sloping forehead, brow ridges, chin, and thick bones of the skull which protruded behind strong shoulders and arms, used tools, and animal hides. Lived in caves and probably built hut-like shelters-had religious feelings and burial customs.
8. Cro-Magnon Man (H. sapiens Fossilis) 20,000-50,000 years back, 180 cm, Cranial capacity-1600 cm³, Broad forehead but arched, brow ridges moderate, strong jaws with man-like dentition, and a well-developed chin. The face was perfectly orthognathous with an arrow and elevated nose. Cave dwellers, the hunter with the domesticated dog, used stone spears and arrowheads, paintings, etc.
9. Modern Man (H. sapiens Sapiens): evolved about 25,000 years ago and spread only about 10,000-11,000 years ago. Cranial capacity- (1400-1450 cm³). Four flexes in the vertebral column, a slight raising of the skull cap.

Time Scale Related To Human Evolution

NEET Biology Evolution Of Man Evolutionary Changes During Human Evolution

1. Skull And Brain. Increase in size, complexity, and intelligence.
2. Bipedal Locomotion. Due to bipedal locomotion forelimbs became free.
3. Forelimbs. Modified into organs of manipulation and lengthening of hindlimbs and shortening of forelimbs.
4. Thumb. Perfection of thumb opposability in forelimbs.
5. Toe. Loss of opposability of great toe in hind limbs.
6. Upright posture. Erect posture by the development of lumbar curve.
7. Jaw. Jaw power reduced.
8. Teeth. Due to omnivorous feed habits, the size of incisors and canines is reduced.
9. Chin. Development of chin.
10. Pelvic Girdle. Development and broadening of iliac bones of the pelvic girdle.
11. Social organization and cultural evolution.

NEET Biology Human Evolution Notes Pdf

Evolution Of Man

Early Human Evolution

NEET Biology Evolution Of Man Synopsis

Evolutionary History Of Man

1. The evolution of hominids occurred in Africa and Asia.
2. The evolution of man took place in Africa.
3. Dnvpiihecus and Ramapithccus lived about 15 million years ago; they were hairy and walked like apes.
4. 3-4 million years before man-like primates walked in Eastern Africa; they were about 4 feet tall and walked upright.
5. Rcmuipithecus and Sivapithecus lived in Africa and Asia and were the forerunners of hominids.
6. Genus Australopithecus appeared in Africa about 5 million years ago.
7. The genus Homo appeared about 2 million years ago.
8. Homo habilis lived in Africa about 2 million years ago and was characterized by a larger brain; could use tools.
9. Homo credits appeared about 1.7 million years ago and believed to have migrated to Asia and Europe.
10. As a result of the abrupt transition that occurred in Europe about 84000 years ago, Neanderthal man was wiped out and gave way to more efficient Cro-Magnon.
11. Homo sapiens evolved about 10000 years ago.

• Leaky (1930) excavated the first fossil ape Proconsul from early Miocene rocks around Lake Victoria of Kenya. It had 5 cusped molars.
• Leaky (1959) excavated fossils of Zijanthropus (15.5 lakhs year old rocks).
• Leaky (1960) excavated fossils of Homo habilis. (16 to 18 lakhs yrs old).
• Dryopithecus. This fossil ape is known from middle Miocene or early Pliocene rocks
• Sivapithecus was excavated from the middle and late Pliocene rocks of the Shivalik hills of India.
• Fossils Of Ramapithecus And Kenyapithccus were excavated by Lewis (1930) and Leaky (1955) from about 1.2 to 1.4 crore-year-old rocks from Kenya, China, and India.
• Raymond Dart 1924 excavated a fossil baby skull (Tuang baby) from the Pliocene rocks of Australopithecus near Tuang in Africa.
• Robert Brown (1936 onward) excavated fossils of Paranthropus (10-18 yrs old, Pleistocene rocks of Africa).

The most primitive and earliest ape during the Oligocene is called Parapithccus.

• Linnaeus was the first scientist who placed human beings along with monkeys and apes.
• The skull of Pithecanthropus was found in Java.
• Geological evidence for the most primitive numerals found in C. Africa.
• Apes are characterized by the absence of a tail.
• The most primitive ape is Gibbon while the most advanced is Gorilla.
• Old-world Monkeys (Ceboids). Long prehensile (grasping) tails and flat noses, ground dwellers example, Baboons, Rhesus monkeys

New World Monkeys (Ccrcopithecoids) have No such tails but have protruding noses example, spider monkeys, organ grinder’s monkeys (capuchin)

• The first evidence of Australopithecus was the skull of a child discovered by Raymond Dart. Later in 1974 a complete skeleton named Lucy was found by Donald Johanson and Timothy white
• Mitochondrial Eve—A member of archaic Homo sapiens
• The Efe pygmies of Zaicr’s Itwi Forest are among the world’s shortest people, with males reaching an average of 4. 8″ (1,42m) and females reaching 4′ 5″ (1.35 m)
• Piltdown man. It is hypothetical and developed on the basis of artifacts consisting of fragments of skull at Piltdown England

NEET Biology Chapter Evolution Of Humans

Cultural Evolution Is Divided Into Three Phases:

Paleolithic Era. The evolution of knowledge regarding rudimentary hunting implements and primitive language: the human species was Homo habilis.

• Mesolithic Period. Development of intricately designed implements for collective hunting, pyrotechnology, animal skin processing, lithic artistry, and ivory craftsmanship.
• The primary human kinds were Neanderthals and Cro-Magnons.
• Neolithic Period. Progressive development of agriculture, animal domestication, matrimonial practices, education, science, and technology.
• The Indian subcontinent and the Middle East are the initial locations of agriculture. This phase encompassed Homo sapiens.

Percents Of Bands Common Among Humans 

• Chimpanzees: 99 %
• Gorillas: 99%
• Orangutans: 99%
• African Green Monkeys: 95%
• Domestic Cats: 35%
• Mice: 7%

Cranial Capacities

• Chimpanzee (Ape): 400 cc
• Gorilla (Gorilla): 650 cc
• Australopithecus: 300-500 cc
• Java ape Man (Pithecanthropus): 800-1000 cc
• Peking Man (Sinanthropus): 1075 cc
• Neanderthal Man: 1400 cc
• Rhodesian Man: 1280 cc
• Cromagnon Man: 1600 cc
• Modern Man (Homo sapiens): 1900-1450 cc

Biotechnology And Its Applications For NEET

Biotechnology can be defined as the use of microorganisms, plain and animal cells for commercial-scale production of biopharmaceuticals and for human welfare.

The Applications Of Biotechnology Include:

1. Therapeutics
2. Diagnostics
3. Genetically modified crops for agriculture
4. Processed food
5. Bioremediation
6. Energy production and
7. Waste treatment

The Three Critical Research Areas Of Biotechnology Are:

1. Providing the best catalyst in the form of an improved organism, usually in the form of a microbe or pure enzyme.
2. Creating optimal conditions through engineering for a catalyst to function.
3. Downstream processing technologies to purify the protein/organic compound for marketing.

Read and Learn More NEET Biology Notes

Applications Of Biotechnology In Agriculture For NEET

The Three Options For Increased Food Production Are:

• Agrochemical-based agriculture.
• Organic agriculture and
• Genetically engineered crop-based agriculture.

The Green Revolution succeeded in increasing the yield of crops mainly due to

• Use of improved varieties of crops and
• Use of agrochemicals (fertilizers and pesticides).
• Further increases in the yield with the existing varieties of crops are not possible using conventional methods of breeding.
• Agrochemicals cause soil and water pollution and are too expensive for farmers.

Biotechnology And Its Applications NEET Notes

Genetically Modified Crops:

A transgenic crop incorporates and expresses a transgene. A prevalent designation for transgenic crops is genetically modified crops, or GM crops.

The methodologies employed in the cultivation of transgenic crops provide two distinct advantages:

1. Any gene, whether derived from an organism or manufactured chemically, can be utilized for transfer
2. The alteration in genotype can be meticulously regulated since only the transgenic is incorporated into the crop genome.

Genetically Modified Crops Contrasting Breeding Activities:

• Only genes existing in specific species can undergo hybridization within those species.
• Alterations arise in all qualities for which the parental organisms utilized in hybridization exhibit differences.
• Upon the introduction of a transgene into an organism’s genome, it may accomplish one of the following outcomes:
• Generates a protein that is the subject of our interest.
• Generates a protein that independently manifests the desired trait.
• Alters an established metabolic pathway to provide a novel end product.
• Inhibits the expression of a pre-existing native gene.

Hirudin is a protein that inhibits coagulation. The gene that encodes hirudin was produced chemically. The gene was subsequently introduced into Brassica napus, resulting in the accumulation of hirudin in the seeds. Hirudin is refined and utilized as a pharmaceutical agent. The transgene product is the primary focus of interest.

The ‘Flavr Savr’ tomato variety exemplifies the suppression of a native tomato gene’s expression. The expression of a native gene can be inhibited by many techniques.

The enzyme polygalacturonase facilitates fruit softening by degrading pectin.

• The transgenic tomato cultivar ‘Flavr Savr’ exhibited a cessation of polygalacturonase production.
• Consequently, the fruits of this tomato variety maintain freshness and preserve their flavor significantly longer than those of other tomato types.
• Furthermore, the fruits exhibit an enhanced flavor and elevated total soluble solids, which serve as an unforeseen advantage.

The final two elements are under investigation through various tests prior to arriving at a definitive conclusion.

Genetically Modified Food:

The food prepared from the produce of genetically modified (= transgenic) crops is called genetically modified food, or in short, GM food. GM food differs from the food prepared from the produce of conventionally developed varieties mainly in the following aspects.

• Genetically modified food contains the protein produced by the transgene in question, for example, Cry protein in the case of insect resistance varieties.
• Genetically modified food contains the enzyme produced by the antibiotic resistance gene that was used during gene transfer by genetic engineering.
• Genetically modified food contains the antibiotic resistance gene itself.
• Genetically modified food t has been argued that the above features of GM foods could lead to the following problems when they are consumed. Firstly, the transgene product may cause toxicity and/or produce allergies. Secondly, the enzyme produced by the antibiotic resistance gene could cause allergies, since it is a foreign protein.
• Finally, the bacteria in the alimentary canal of humans could take up the antibiotic resistance gene in GM food. These bacteria would then become resistant to the concerned antibiotic. As a result, these bacteria could become difficult to manage.

The scientists involved in the production of transgenic crops are addressing to these concerns. Efforts are being made to use other genes in place of antibiotic resistance genes. The toxic and allergenic actions of the transgene product can be adequately examined by detailed assays using suitable animal models.

Biotechnology For NEET GM Products Benefits And Controversies

GM Products Benefits And Controversies Benefits

1. Crops
   1. Enhance taste and quality
   2. Reduced maturation time
   3. Increased nutrients, yields, and stress tolerance
   4. Improved resistance to disease, pests, and herbicides
   5. New products and growing techniques.
2. Animals
   1. Increased resistance, productivity, hardiness, and feed efficiency
   2. Better yields of meat, eggs, and milk
   3. Improved animal health and diagnostic methods.
3. Environment
   1. “Friendly” bioherbicides and bioinsecticides
   2. Conservation of soil, water, and energy
   3. Bioprocessing for forestry products
   4. Better natural waste management
   5. More efficient processing.
4. Society: Increased food security for growing populations.

GM Products Benefits And Controversies Controversies Safety:

1. Potential human health impact
2. Allergens, transfer of antibiotic resistance markers, unknown effects
3. Potential environmental impact
4. Unintended transfer of transgenes through cross-pollination, unknown effects on other organisms (for example, soil microbes), and
5. Loss of flora and fauna biodiversity

Biotechnology And Its Applications NEET Important Questions

Biotechnology For NEET Applications Of Genetically Engineered Microbes

Nif genes, Found in Rliizobiuin leguminosarum may be transferred to major food crops to increase food production without using expensive fertilizers

Introduction Of Gene For Coding: Vitamins, antibiotics, and hormones from higher animals to bacteria—thus Bacteria will act as living factories.

Production Of Pest Resistant Plants Bt Cotton.

The soil bacteria Bacillus thuringiensis synthesizes crystal proteins known as Cry proteins, which are lethal to the larvae of insects such as tobacco budworms, armyworms, beetles, and mosquitoes.

• The Cry proteins are present as inactive protoxins and are transformed into active toxins upon ingestion by the insect, as the alkaline pH of the stomach solubilizes the crystals.
• The active toxin adheres to the epithelial cell surface of the midgut and forms pores.
• This induces cellular swelling and lysis, resulting in the insect’s (larva’s) demise.
• The cry genes that encode this protein are extracted from the bacterium and integrated into several crop plants like as cotton, tomato, corn, rice, and soybean.
• The proteins expressed by the specified cry genes regulate the corresponding pest resistance.
• Cry 1 Ac and Cry 2 Ab regulate cotton bollworm populations.
• Cry 1 Ab regulates the borer.
• Cry 3 Ab targets the Colorado potato beetle, while Cry 3 Bb targets the corn rootworm.

Protection Against Nematodes

• A nematode Meloidogyne incognita infects tobacco plants and reduces their yield.
• The specific genes (in the form of cDNA) from the parasite are introduced into the plant using Agrobacterium as the vector.
• The genes are introduced in such a way that both sense/coding RNA and antisense RNA (complementary to the sense/coding RNA) are produced,
• Since these two RNAs are complementary, they form a double-stranded RNA (ds RNA).
• This neutralizes the specific RNA of the nematode, by a process called RNA- interference.

As a result, the parasite cannot live in the transgenic host and the transgenic plant is protected from the pest.

• Tomato resistant to Homeworm larvae.
• Similarly Tobacco, Populus, etc. with the help of Agrobacterium tumefaciens
• Transgenic potato and tobacco plants that produce human serum albumin (USA)
• Transgenic potato plants, with increased levels of cyclodextrins.
• Transgenic tobacco plants with increased levels of mannitol
• Transgenic plant for hybrid seed production.

Genetically Modified Food:

A tomato called Flavr Savr has been created to have a better flavourful shelf-life. It is due to delayed ripening.

This has been achieved in reducing the contents of cells with a degrading enzyme called as polygalacturonase which leads to tomato fruit ripening. Another example of transgenic modified food is transgenic rice with higher vitamin A contents.

Transgenic Animals:

We can produce new animals and human beings, having traits tailored according to our own will.

Biotechnological Applications For NEET In Medicine

Therapeutic Agents: Proteins with potential as pharmaceutical agents are produced by using genetically engineered organisms. Enzymes have also been used for this purpose, for example, DNase 1 and alginate lyase have been used in aerosols. Some known examples are given below:

1. Human growth hormone obtained from E. coil is used for the treatment of dwarfs.
2. Chorionic gi nadotropin hormone produced by genetic engineering is used for the treatment of infertility.
3. Interferons produced by E. coli are commercially used for the treatment of viral infections and cancer. Interferons were first obtained through DNA recombinant technique by Charles Weisman in 1980. He inserted the gene for interferon production in E. coli.
4. Interleukins produced by E. coli are used to stimulate the immunity system.
5. Tissue Plasminogen Activator (TPA) – an enzyme is used for dissolving blood clots after a heart attack and stroke.
6. Antihemophilic human factor 8 is used by people with hemophilia to prevent and control bleeding or to prepare them for surgery.
7. Platelet-derived growth factor produced by recombinant DNA technology is useful for stimulating wound healing.
8. Penicillin G acylase is also produced by genetic engineering. This enzyme is used for converting penicillin into 6- 6-amino penicillin acid for the formation of new antibiotics.

Biotechnology And Its Applications NEET Previous Year Questions

Molecular Diagnosis: Recombinant DNA molecules and techniques like PCR (Polymerase Chain Reaction; are used for early diagnosis of disorders.

• Cloned genes when expressed to produce recombinant proteins, help in developing sensitive diagnostic techniques like ELISA.
• The cloned genes are also used as ’probes’ to detect the presence of complementary DNA strands.
• A probe is a piece of single-stranded DNA that is tagged with a radioactive molecule and it is used to find its complementary DNA by hybridisation.
• It is followed by the detection of radioactivity by autoradiography.
• The presence of a normal or mutant gene can be detected using such a method.
• PCR is used to detect HTV and to detect mutations in genes.

Biotechnology For NEET Genetically Engineered Insulin (Humulin)

Human insulin consists of so short polypeptide chains: chain A and chain B linked by disulfide bridges.

• Insulin is secreted as prohormone which has to be processed before it becomes a mature and functional hormone.
• The prohormone contains another polypeptide called C-peptide, which is removed during maturation.

Gene For Coding Insulin: From humans to bacteria is transferred and the insulin produced is called Humulin. In 1983. American Company Eli Lily produced genetically engineered Insulin called Humulin with the help of E. coli—Plasmid clone.

• In 1983, Eli Lilly, an American company, prepared two DNA sequences coding for chains A and B of human insulin and introduced them into the plasmids of Escherichia coli to produce insulin.
• The two chains produced were extracted and combined by creating disulfide bridges.

Biotechnology For NEET Gene For Preparing Interferon

Charles Weismann produced interferon through recombinants of E. coli. Production of transgenic plants for preparing recombinant products.

Many viral, bacterial, and protozoan vaccines are being synthesized through the technique of genetic engineering. These synthetically produced vaccines are the latest ones used in immunization. The gene coding for antigen protein is isolated from the pathogen and is cloned in bacterial host cells.

The social, economic, and environmental implications of genetic engineering techniques.

1. Generally prepared human insulin and edible vaccines will be readily available and also will be economical.
2. Transgenic crop plants for human consumption may cause concerns about safety due to unwanted properties they may have.
   • Hence the Indian Government has set up organizations that are authorized to make decisions regarding the validity of genetic modifications and the safety of introducing genetically modified organisms for public sendees.
   • One such organization is the Genetic Engineering Approval Committee (GEAC).
3. Some people believe that transgenic plants and animals can solve many human problems, especially of hunger and disease.

Biotechnology For NEET cDNA Library

The copy of DNA formed on mRNA is called cDNA. 1,000 – 30,000 types of various mRNA sequences can be obtained from a typical eukaryotic cell.

• cDNA library and cDNA clone bank are the populations of such viruses where each virus has at least one cDNA inserted plasmid is present.
• In a complete viral population, each member has from outside DNA sequence.
• It is easy to make a clone bank of those viruses that have DNA as genetic material, for example, the Influenza virus and Reovirus, etc.
• Prokaryotic gene has no introns, so cDNA is the continuous copy of mRNA while in Eukaryotes introns break the DNA molecules in small segments called exons.

Single Cell Proteins (SCP). Cells from different kinds of organisms such as bacteria, filamentous fungi, yeast, and algae are treated in different ways so that they are used as food or feed, and are called single cell protein.

The biomass is obtained from both mono and multicellular micro-organisms. The common substrate used for preparing such food containing SCP ranges from air, whey, sawdust, and paddy straw. SCA provides a valuable protein supplement in the human diet.

Advantages Of Introducing Transgene

1. Formation of a desired protein.
2. Produces a protein that on its own produces the desired phenotype.
3. Modifies an existing biosynthetic pathway so that a new end product is obtained.
4. Prevents the expression of an existing native gene.

For example, Hirudin is a protein that prevents blood clotting. The gene encoding for hirudin was chemically synthesized’’ This gene was then transferred into Brassica napus. where hirudin accumulates in seeds. The hirudin is purified and used as medicine. In this case, the transgene product itself is the product of interest.

Biofertilizers: These are organisms that can bring about soil nutrient (like nitrogen or phosphorus) enrichment. The main sources of biolertilizers are bacteria, cyanobacteria, and fungi. Rhizobin from root nodules in legumes and cyanobacteria from symbiotic association with the form Azolla. The fungus and plant root association is termed mycorrhiza.

• They Are The Following Advantages Thus Preferred To Chemical Fertilizers:
  1. They are safe and moreover do not pollute the atmosphere.
  2. The surface runoff does not pollute water.
  3. They do not disturb the naturally occurring food chains.
  4. They are of low cost as compared to chemical fertilizers and pesticides.
  5. They do not cause any danger to the natural resources.
  6. Pesticides are poisons and non-specific in their target. They also kill useful predators and upset the natural balance.

Biopesticide involves the biological control of weeds, insects, and pathogens by some living organisms. It involves the use of insects feeding on a specific weed or the use of certain microorganisms viruses, bacteria, fungi, protozoa, or mites which will cause disease in weeds.

• The first bioherbicide was developed in 1961 and it was a mycoherbicide derived from the fungus Phytophthora palmivora which controls the growth of milkweed vines in citrus orchards.
• Another fine example of biological control of weeds is the control of overgrowth of cacti by the introduction of a cochineal insect (Cactoblastis cactorum) in India and Australia.

Key Concepts Of Biotechnology And Its Applications For NEET

A few Examples Of Biopesticides Are: Biochemical active ingredients

1. Plant Volatile And Floral Attractants
   1. Lemon grass oil
   2. Eucalyptus oil
   3. Mustard oil (Allyl isothiocyanate)
   4. Geranium oil
   5. Citronella oil
2. Natural Insect Growth Regulators
   1. Dihydroazadirachtin
   2. Azadirachtin.
   3. Biological products Transgenic animals that produce useful biological products can be created by the introduction of the portion of DNA that codes for a particular product such as human proteins (α-antitrypsin) used to treat emphysema.
      • Similar attempts are being made for the treatment of phenylketonuria and cystic fibrosis. In 1997, the first transgenic cow, Rosie, produced human protein-enriched milk (2.4 g/L). The milk contained human alpha-lactalbumin and was nutritionally a more balanced product for human babies.
   4. Vaccine safety Transgenic mice are being developed for use in testing the safety of vaccines before they are used on humans. Transgenic mice are being used to test the safety of the polio vaccine.
   5. Chemical safety testing Transgenic animals are made that carry genes that make them more sensitive to toxic substances than non-transgenic animals. They are then exposed to the toxic substances and the effects studied. Toxicity testing in such animals will allow us to obtain results in less time.

Biopesticide Ethical Issues

• The manipulation of living organisms by the human race cannot go on any further, without regulation.
• Some ethical standards are required to evaluate the morality of all human activities that might help or harm living organisms.
• Going beyond the morality of such issues, the biological significance of such things is also important. Genetic modification of organisms can have unpredictable results when such organisms are introduced into the ecosystem.
• Therefore, the Indian Government has set up organizations such as GEAC (Genetic Engineering Approval Committee), which will make decisions regarding the validity of GM research and the safety of introducing GM organisms for public services.

The major bioethical concerns connected with exploits of biotechnology are

1. The use of animals in biotechnology causes great suffering to them.
2. When animals are used for the production of pharmaceutical proteins, they are virtually reduced to the status of a factory.
3. The introduction of a transgene from one species into another species violates the integrity of the species.
4. The transfer of human genes into animals (and vice-versa) dilutes the concept of humanness.
5. Biotechnology is disrespectful to living beings and only exploits them for the benefit of human beings.
6. Biotechnology may pose unforeseen risks to the environment, including risks to biodiversity.

Biological Resources Or Bioresources:

Biological Resources Or Bioresources include all those organisms that can be used to derive commercial benefits. Traditional knowledge related to bioresources is the knowledge developed by various communities over long periods of history, regarding the utilization of bioresources, for example, the use of herbs, etc. as drugs.

Often, this traditional knowledge can be exploited to develop modern commercial processes. The traditional knowledge suggests the direction to be followed and saves considerable time, effort, and expenditure for their commercialization. Institutions and companies of industrialized nations are collecting and exploiting the bioresources, as follows.

1. They are collecting and patenting the genetic resources themselves. For example, a patent granted in the U.S.A. covers the entire ‘basmati’ rice germplasm indigenous to our country.
2. The bioresources are being analyzed for the identification of valuable biomolecules. A biomolecule is a compound produced by a living organism. The biomolecules are then patented and used for commercial activities.
3. Useful genes are isolated from the bioresources and patented. These genes are then used to generate commercial products.
4. The traditional knowledge related to bioresources is utilized to achieve the above objectives. In some cases, the traditional knowledge itself may be the subject of a patent.

A west African plant, Pentadiplcmdra brazzeana produces a protein called brazzein, which is approximately 2,000 times as sweet as sugar. In addition, brazzein is a low-calorie sweetener. Local people have known and used the super-sweet berries of this plant for centuries.

• However, the protein brazzein was patented in the U.S.A. Subsequently, the gene encoding brazzein was also isolated, sequenced, and patented in the U.S.A. It is proposed to transfer the brazzein gene into maize and express it in maize kernels.
• These kernels with then be used for the extraction of brazzein. This development could have serious implications for countries exporting large quantities of sugar.

Biopatent:

A patent is a right granted by a Government to an inventor to prevent others from making commercial use of such an invention. At present patents are granted for biological entities and the various products obtained from these organisms, termed as biopatent. Biopatents are being granted for the following

1. Strains of micro-organisms
2. Cell lines
3. Genetically modified strains of living organisms
4. DNA sequences
5. The proteins prepared by DNA sequences
6. Biotechnological process
7. Production process
8. Products
9. Product application.

Biopiracy:

Exploitation of patent biological resources without proper permission is called biopiracy. The collection of such material without a benefit-sharing agreement is likely to find its way into the list of criminal violations in many countries.

• For thousands of years, neem has been used in India for killing pests and as medicine. One of the American companies patented neem. As a result, anybody using neem will have to pay for it. This was called as legalized theft. Biopiracy permits the piracy of gene resources and knowledge from non-western countries. Such piracy was claimed by them as an invention.
• Many biotechnology patents are very broad in their coverage. For example, one patent covers ‘all transgenic plants of Brassica family’. Such broad patents are considered morally unacceptable and fundamentally inequitable since these would enable financially powerful corporations to acquire monopoly control over biotechnological processes.
• They may, in the end, even come to control the direction of agricultural research, including plant breeding. Such a position would pose a threat to the global food security.
• Any organizations and multinational companies exploit and/or patent biological resources or bioresources of other nations without proper authorization from the countries concerned; this is known as biopiracy.
• The industrialized nations are rich in technology and financial resources but poor in biodiversity and traditional knowledge related to the utilization of bioresources. In contrast, developing nations ar poor in technology and financial resources, but are rich in biodiversity and traditional knowledge related to bioresources

Biowar:

The use of bioweapons originated in the 5th century. It is the use of biological weapons against humans and their crops and animals. A bioweapon is a device that carries and delivers pathological biological agents or toxins to a target. Recently Anthrax bacterium was sent by post after the attack. It causes anthracis.

Biotechnology Applications NEET Important Questions With Answers

Misconceptions About Biological Weapons

1. Technically difficult.
2. Will not be used because use is morally repugnant.
3. Rarely used, no chance of use of biological weapons in the near future.

Misconceptions About Biological Weapons Realities

1. Biological agents for biological warfare are not costly and can be produced with ease.
2. Detection or interdiction is almost impossible.
3. Use is likely to increase.
4. More dangerous than conventional weapons.

Misconceptions About Biological Weapons Real Threat

1. It is considered that by 1995, more than 18 countries had biological weapons.
2. Salmonella was used to contaminate salad bars in Oregan restaurants by members of a cult in 1984.
3. Two members of a Minnesota militia group were convicted for having ricin in 1995.
4. A lab. technician in Ohio placed orders for 3vials of Y. pestis by mail in 1995.

Potential Biological Weapon Agents. Biological Weapon agents can cause the following diseases

1. Anthrax
2. Smallpox (variala)
3. Botulism toxins
4. Plague
5. Q. (fever, chills, fatigue, etc.)
6. Tularemia (it can occur in humans in two forms; ulceroglandular and typhoidal).
7. Viral Encephalitis,
8. Viral hemorrhagic fevers.

Characteristics Of Biological Weapons That Make Them Attractive To Countries And Terrorists,

1. Cost efficiency. Biological weapons are low-cost weapons.
2. A large number of casualties. They cause far more casualties than chemical or conventional weapons.
3. Biological weapon agents are invisible, odorless, and tasteless once released.

Defence Against Biological Weapons

1. Respirator or gas mask;
2. Safer shelter;
3. Decontamination;
4. Vaccination
5. Antibiotics;
6. Detection mechanism.

Bioethics:

Bioethics are a framework of principles utilized to govern our actions concerning biological endeavors.

The principal bioethical issues are as follows:

1. The incorporation of transgenes from one species into another undermines species integrity.
2. The transfer of human genes to other animals and vice versa is unethical.
3. Creation of a clone.
4. May pose a threat to biodiversity.
5. The suffering of animals utilized in biotechnology will escalate.

Fermentation:

The anaerobic oxidation of food in the presence of micro-organisms which results in the production of alcohol and waste gas CO₂.

Immobilization Of Enzymes:

It is the process of fixing an enzyme or enclosing it in solid support so as to protect it from deactivation and attack of proteases, maintain enzyme purity, ability to recover it after reaction and perform the continuous reaction.

The methods which include covalently attaching the enzyme to a solid support, trapping it in a gel, crosslinking the enzyme molecules to one another, and encapsulating them in small artificial cells is called immobilization of enzymes.

NEET Biology Ecosystem

Ecosystem. The relationship between a living community (biotic) and its non-living environment (abiotic) is expressed by the term ecosystem. The term was introduced by Tansley (1937).

• Ecosystems are also called biocoenosis, geobiocoenosis, phytocoenosis, biosystem, exosome, and Holocene.
• Microecosystem. Very small-sized ecosystem.
• The Ecosystem is maintained by the flow of energy through it. This flow is unidirectional.
• Amount Of Energy Trapped. 2% of solar radiation by aquatic ecosystems.
• 1% of solar radiations by terrestrial ecosystems

Read and Learn More NEET Biology Notes

Ecosystem NEET Notes

Bioenergetics. The flow of energy into ecosystems and its transformations in living organisms.

• Sun utilizes about 4 million tonnes of H₂ per second.
• Solar energy travels in space in the form of electromagnetic waves. Only 47% of solar radiation reaches the surface of the earth.
• Biomass. The amount of living matter present in an organism is biomass.
• The amount of biomass can be calculated in terms of energy.

NEET Biology Ecosystem

Components Of Ecosystem

Food Chains. A food chain consists of a connected group of producers, consumers, and decomposers. It starts with energy from the sun and nutrients from the soil. They pass through plants and one or several consumers to a final consumer that is not fed upon by any other.

Producers. They use the radiant energy of the sun during photosynthesis whereby CO₂ is assimilated and the light energy is converted into chemical energy. Green plants are called producers transducers or converters.

Autotrophs. They are green plants that have the capacity to synthesize food in sunlight. They are also called primary producers because solar energy is locked up only in these plants.

Heterotrophs. These are those organisms that are non-green and hence can’t manufacture their own food. Hence they have to depend upon other plants and animals for their food requirement. Hence they are consumers.

Primary Consumers. These are herbivorous animals and depend upon green plants i.e. on producers for their food, for example, Cows and goats.

Secondary Consumers. These are carnivorous animals and eat the flesh of herbivorous animals, for example, dogs, and cats.

Tertiary Consumers are the carnivorous animals that eat other carnivores for example, snakes eat frogs, birds, eat fish.

Top Consumers are carnivores of an ecosystem that are not killed and eaten by other animals, for example, Lions, Vultures, bears, etc.

Microconsumer. Decomposers are termed microconsumers.

Grazing Food Chain: The grazing food chain is also known as the predator food chain.

• In grazing food chains, the size of an individual gradually increases in successive trophic levels.
• Ecosystems with grazing food chains are directly dependent on solar radiation.
• Most of the ecosystems in nature follow the grazing food chain.

Detritus Food Chain: It starts from dead organic matter into microbes and then to detritus-feeding organisms (detritivores) and their predators. A good example of a detritus food chain is given by Heald and Odum.

The chain is based on mangrove (Rhizophore wangle) leaves, which fall into shallow estuarine waters of south Florida, leaf fragments acted on by saprotrophs and colonized by algae are eaten and re-eaten by a group of small detritus consumers which in turn, provide the main food for game fish and fish (small carnivore) eaten by birds (top carnivores).

• Dead plant parts and animal remains are called detritus.
• Dried plant parts such as leaves, bark, flowers, etc., and dead remains of animals including fecal matter dropped over the soil constitute the above-ground detritus or litter fall while dead roots (root detritus) constitute the below-ground detritus.
• In the detritus food chain source of energy is detritus (dead organic matter) and not the Sun.
• The detritus food chain is composed of a long chain of detritus-eating organisms (detritivores).
• In some ecosystems such as tropical rain forests, more energy flows in the detritus food chain than the grazing food chain.

Decomposers. These include bacteria, fungi, and other organisms that break down the complex compounds present in dead producers and consumers into simpler compounds. These simple organic matters are again decomposed by bacteria into inorganic forms.

Ecosystem NEET Notes

Processes Of Decomposition

1. Fragmentation of detritus.
2. Leaching
3. Catabolism

1. Fragmentation. Due to fragmentation, the surface area of detritus particles is greatly increased.
2. Leaching. Water percolating through soil removes soluble substances (for example sugars, several nutrients) from the fragmented detritus due to leaching action.
3. Catabolism. The extracellular enzymes released by bacteria and fungi carry out catabolism i.e. enzymatic conversion of the decomposing detritus to simpler compounds and inorganic substances. It is important to know that all three decomposition processes operate simultaneously on the detritus.

Humification And Mineralization occur during decomposition in the soil. Humification leads to the accumulation of a dark-colored amorphous substance called humus. Humus is highly resistant to microbial action and undergoes extremely slow decomposition. It serves as a reservoir of nutrients. Mineralization results in the release of inorganic substances (for example CO₂, H₂O) and available nutrients (NH⁺₄, Ca⁺⁺, Mg⁺⁺, K^+, etc.) in the soil.

Factors Affecting The Rate Of Decomposition

1. The upper layer of soil is the main site of decomposition processes in the ecosystem.
2. The rate of decomposition of detritus is affected by climatic factors and the chemical quality of detritus.
3. Temperature and soil moisture affect the activities of root microbes.
4. The chemical quality of detritus is determined by the relative proportion of water-soluble substances, polyphenols, lignin, and nitrogen.

The amounts of energy and materials transferred from one trophic level to the next higher level become less and less and can be represented graphically as pyramids of energy and pyramids of biomass.

Abiotic Components. Abiotic components are non-living factors. It includes water, minerals, salts, humidity, light, temperature, pH, wind, topography, and background.

NEET Biology Ecosystem Food Web

Many food chains operate in a community. They are not independent but are interconnected to such an extent that disturbance in any food chain disturbs the whole community. The interrelationship among the various food chains of a community is called the food web.

When food chains are interconnected with each other forming a network of food transfer of energy flow. This network is called a food web.

The arrows in the figure indicate – the flow of energy which is always transferred but never exchanged.

Kinds Of Ecosystem

E. P. Odum classified ecosystem on the basis of photosynthesis-respiration ratio as under (P/R Ratio):

1. Stabilized Ecosystem: The P/R ratio is one.
2. Autotrophic Ecosystem: P/R is more than one.
3. Heterotrophic Ecosystem: The P/R ratio is less than one

NEET Biology Ecosystem General Pattern Of Energy Flow

Under favorable environmental conditions, only about 1-5% of the energy of incident radiation or 2-10% of PAR is actually captured by the photosynthetic process (gross primary productivity) and the remaining portion is dissipated.

Since the simultaneously occurring respiratory processes are energy-consuming and use up part of the photosynthetic gain, the net capture of energy (net primary productivity) is reduced to only 0-8—4% of the incident total radiation or 1-6-8% of PAR. Only the energy captured in the net productivity of producers can be used by other trophic levels.

NEET Biology Ecosystem Ecological Pyramids

Ecological Pyramids can be of three types:

1. Pyramid Of Number. It can be upright, inverted, or spindle-shaped.
   • Upright Pyramid. Grassland, Pond ecosystem
   • Spindle Pyramid. Forest ecosystem.
   • Inverted Pyramid. Parasitic ecosystem
2. Pyramid Of Biomass: It is upright for terrestrial habitats.
   • It is inverted or spindle-shaped for aquatic habitats where the biomass of a trophic level depends upon the reproductive potential and longevity of its members.
   • If the total biomass produced per unit of time is calculated, the pyramid of biomass shall always be upright.
   • Maximum biomass occurs in producers. About 10-20% of the biomass is transferred from one trophic level to another.
   • Upright-Pyramid. Grassland, Forest, and Parasitic ecosystems,
   • Inverted Pyramid. Pond ecosystem.
3. Pyramid Of Energy. Always upright, more accurate than the pyramid of biomass or the pyramid of numbers.

The energy content is expressed in kcal/ m²/ yr or kJ/ m²/yr.

Components Of Ecosystem NEET Biology

Energy Conserving Efficiency

• Grasslands: 1.15%
• Savannah: 0.9%
• Mixed Forests: 0.8%
• Modem Crops: 5%
• Sugarcane Field: 10-12%

1. Community Productivity. Rate of net synthesis of organic matter by a community per unit time and area.
2. Gross Primary Productivity. The total amount of food synthesized or biomass added by the organisms is called gross primary productivity.
3. Net Primary Productivity. The organism loses a part of this biomass during its metabolic activities. The net or balanced dry matter accumulated in the organism, after it has consumed a part of it in metabolism or respiration, is called Net Primary Productivity. It is also called assimilative photosynthesis.
   • Net primary productivity = Gross primary productivity – Biomass consumed in respiration.
4. Primary Productivity. The amount of energy accumulated through photosynthesis by producers is termed primary productivity.
5. Secondary Productivity. The rate of synthesis of organic matter by consumers is termed secondary productivity.
   • In one year one hectare of forest shall consume 30 tonnes of CO₂ and evolve 10 tonnes of O₂
   • The amount of carbon dioxide fixed annually through photosynthesis is 7 x 10¹³  kg.

NEET Biology Ecosystem NEET Biology EcosystemEcological Efficiency

It is the effectiveness with which it maintains its dynamic nature. It is expressed as the energy ratio, expressing the efficiency with which organisms exploit their food resources and convert the food into biomass.

• Such ratios are calculated by relating output to the input of energy, at various points along the pathway of energy flow.
• These ratios are multiplied by 100 to express in percentage

Photosynthetic Efficiency = Gross primary productivity/Total incident solar radiation x 100

Net Production Efficiency (NPE). The efficiency with which assimilated energy is incorporated into reproduction, growth, and storage, is called the net production efficiency. It may be shown as:

∴ NEP = Production (reproduction and growth)/Assimilation x 100

In plants, NPE is defined as the ratio of net to gross production. This varies, between 3085% depending on the habitat and growth pattern.

Gross Production Efficiency. The GPE is the product of the assimilation efficiency and net production efficiency.

∴ GPR = Assimilation efficiency x NPE = Production}/Ingestion

This represents the overall efficiency of biomass production within a trophic level.

Assimilation Efficiency. The entire food energy that is consumed is not assimilated. The assimilation efficiency is defined as the percentage expressing the proportion of ingested or consumed energy that is assimilated. It may be shown as:

∴ Assimilation Efficiency = \(\frac{\text{Assimilation}{Ingestion}}\) x 100

Herbivores assimilate about 60 to 70% of the energy in young vegetation and 80% of that in seeds.

Exploitation Efficiency. It is defined as the efficiency with which the biological production of an entire tropic level is consumed.

Components Of Ecosystem NEET Biology

∴ Exploitation efficiency = Ingestion of food/Prey production x 100,

Ecological Efficiency. The % of energy converted into biomass by a higher trophic level over the energy of food resources available at the lower trophic level is called ecological efficiency.

∴ Ecological Efficiency = Energy converted into biomass at tropic level/Energy present in biomass at lower trophic level x 100

Significance Of Ecological Efficiency:

The ratio is used to express the efficiency with which organisms exploit their food resources and convert the food into biomass. The ability of herbivores and carnivores to use the food energy ingested varies from one species to another.

NEET Biology Ecosystem Biomes

Biomes are large biogeographic areas characterized by the presence of distinct groups of climax vegetation, unique animals, and other forms of life.

Typical Climatic Conditions In Major Forest Types In India

• Temperate Deciduous Forests. The areas have warm summers and moderately cool winters. Rainfall is 75-150 cm. Dominant trees are Oak, Elm, Birch, Maple Ash, Chestnut, and chickory. Beech, Poplar, and Magnolia. Conifers occur at places. Shrubs, herbs, ferns, mosses, lichens, grasses, vines, and epiphytes are abundant.
  • Most trees shed their leaves during autumn or fall making the soil brown. A mixed coniferous broad-leaved forest occurs in Indian hills between 1500-3500 m. Tree height can reach 30-40 m. Fauna consists of Deer, Fox, and Beaver. Wild Cat. Racoon, Opossum, Squirrel, Rabbit, Hare, Snakes, Lizards, Salamanders. Thrushes, Owls, Sparrows, and songbirds.
• Taiga is the northern coniferous forest biome with long, severe winter and growing seasons limited largely to the few months of summer. Hardy conifers, Spruce in particular are the most representative of the flora and wolves and bears of the fauna.
• Grasslands Distribution. The temperate grasslands are present in North America (Canada and the USA), South America, Eastern Europe, Central Asia, South Africa, and Australia. These are called prairies in North America, pampas in South America, steppes in Europe and Asia, veldts in Africa, and tussocks in Australia.
  • Economic Importance. The grasslands are of tremendous economic importance, for they are the prime farming (grain-growing and cattle-raising). Overfarming and loss of topsoil are serious ecological problems that threaten food production.
  • Physical Conditions. The land is plain or gently rolling. The annual rainfall ranges between 25 to 75 cm and it rains intermittently. Moisture is not enough to support forest or woodland. The climate is cold in winter and hot in summer. Dry periods are long. The sunlight is bright and evaporation high.
• Life. Life is rich in the temperate grasslands.
  • Flora. The short and tall grasses, legumes, and composites form the dominant vegetation. Shrubs and trees may occur as scattered individuals.
  • Fauna. The animals of grasslands are grazing and burrowing mammals.
    • The grazing forms include bison, elk, prong-homed antelope, zebra, bighorn sheep, and deer. The burrowing forms are represented by rodents, such as jackrabbits, prairie dogs, gophers, and ground squirrels.
    • Carnivores, such as wolves, badger, coyotes, and many birds, such as lark, burrowing owl; and insects are also common. Some reptiles (lizards and snakes) also occur.

Characteristics Of Different Terrestrial Biome

Desert: It is a dry sandy or rocky area with sparse vegetation due to the occurrence of little rain. Rainfall is low less than 120 mm or extreme deserts less than 70 mm per year because the area lies in rain shadow.

This is due to being present either far away from cloud-seeding areas, adjacent to cold ocean currents, beyond a mountain range, or without cloud intercepting mountains. Common deserts are Tibet, Gobi (Mongolia), Thar (India, Pakistan), Arabia, and Sahara, Deserts may be cold deserts or hot deserts.

Hot Deserts: Fewer plants grow in deserts. They are of different ecological categories, ephemeral annuals, rain perennials, succulents, and non-succulent perennials. Succulent include Cacti and Euphorbias. In cold deserts, Sedum, Draba, and Saxifraga occur.

Non-succulent hot desert plants are Aerua, Alhagi, Capparis, Calotropis, Cyperus, Calligonum, Eragrostis, Acacia, Tamarix, Prosopis, and Phoenix. Desert animals live in burrows during the hot periods. Common animals are ants, wasps, locusts, scorpions, spiders, lizards, snakes, desert rats, rabbits, hares, foxes, jackals, cats, etc.

Components Of Ecosystem NEET Biology

NEET Biology Ecosystem Aquatic Biomes

Oceanic, Lakes And Ponds, Marshes, Streams And Rivers.

Oceanic Biome– 2/3 of earth’s surface, 3.5%-concentration of salts, productivity is 1000 kcal/m² yr (less than the most terrestrial biomes). Temperature of ocean surface-28°C in equatorial regions and 0°C near the poles.

Divided Into (Depending Upon The Availability Of Light):

1. Photic Or Euphotic Zone-upper 200 m layer of ocean.
2. Apliotic Zone-200-2000 m.
3. Abyssal Zone-dark zone, below 2000 m.
4. Oceanic Basin Is Differentiated Into Three Parts:
   • Continental– Shelf. Gradually sloping area of the seashore. Slope- 0.1° from coastline to 160 km in the sea.
   • Continental Slope. A slanting area connects the continental shelf to the oceanic floor. Slope 3-6°.
   • Ocean Floor. Horizontal bottom area of open sea. Normal depth-6000m to 10,000m.

Three Main Types Of Environmental Zones Of Oceanic Basin:

1. Littoral Zone-sea floor of continental shelf.
2. Benthonic Zone– sea floor along continental slope, aphotic and abyssal zone, further differentiated into
3. The Pelagic Zone, the water of the ocean, is further differentiated into Epipelagic, Mesopelagic, Bathypelagic, and Abyssopelagic.

Marine Organisms Are Classified According To The Region Of Their Activity.

1. Plankton. Passively drifted organisms in surface layers of water bodies (some workers restrict the term plankton for micro-organisms, they refer to other large-size planktons as Neuston)
2. Nekton, actively swim in surface and deep waters, phagotrophic.
3. Benthos. Organisms of the bottom.

The Oceanic Biome Is Divided Into Three Major Ecosystems:

1. Open Sea. the area beyond the continental shelf, divisible into photic, aphotic, and abyssal zones. Otherwise has 2 parts pelagic and benthoic.
2. Coastal Region. The area of the continental shelf is divisible into 3 parts-intertidal, littoral, and neritic. The intertidal region is exposed, neritic zone comprises the main water body of the area. Beaches belong to the intertidal zone. A highly productive part of the coastal region is the Coral Reef, formed by foraminiferans, calcareous algae, and calcareous skeletons of coelenterates (especially corals).
3. Estuary. The name of the coastal bay is formed by the tidal mouth of the river due to the mixing of fresh and seawater, there is a wide fluctuation of salinity 0.5-3.5%. Fluctuations of temperature also occur.

Lakes And Ponds. Stationary freshwater bodies that occur on land. Ponds are small, hollow size than one hectare, depth of less than 2 in. Lakes are larger and deeper. Actually, ponds arc natural or man-made depressions which get filled with rain or runoff water. Lakes develop due to:

1. As a result of glaciation,
2. Natural or man-made depressions get filled with H₂O.
3. Develop from main stream or river (oxbow lakes).

• Oligotrophic Lakes– deep, rocky sides, little circulation of nutrients, little biota, for example, Sambhar Lake of Rajasthan.
• Eutrophic Lakes are rich in biota, quick circulation of nutrients, and shallower, for example, Dal Lake of Kashmir.
• Marshes -wetlands possessing turbid water bodies of a few cm in depth. Water received from rains and drains. Typical flora consists of amphibians and emerged hydrophytes named heliophytes. Snails, mosquitoes, larvae, insects, frogs etc occur.
• Streams And Rivers – Lotic Ecosystems – flowing fresh water which differs in physical and climatic conditions, O₂ content, temperature, speed, and volume of H₂O.
• Agroecology-Study of interrelationships between agricultural crops and their surrounding animate as well as inanimate environments.

Ecosystems do not occur in isolation, are in contact with adjacent ecosystems, and a part of their area overlaps (the overlapping area is called a Transition zone). Polar bear shows hibernation during winter in caves.

• Microscopic Phytoplanktons-diatoms, Chlamydomonas, chlorella, spirogyra.
• Freely Floating Plants – Lemna, Azolla, Pistia, Eichhomia.
• Suspended Macrophytes – Utricularia, Hydrilla.
• Anchored Submerged Plants – Vallisneria.
• Floating Leaned Anchored Plants – Nelumbo, Nymphaea.
• Emerged Plants – rooted at the bottom but part of them comes out of water. Sagittaria, Typha, Sciipus, Phragmites.

[All of the above varieties of plants are present in ponds and lakes]

Energy Flow In Ecosystem NEET Study Material

Aquatic Biomes Memory Points

• The word “Biocoenosis” was introduced by Carl Mobius.
• The Earth Summit in Rio de Janeiro focused on the conservation of genetic resources of flora and fauna.
• The flora of Delhi is predominantly xerophytic.
• Resurrection plants – examples of drought evasion Selaginella lepidophylla.
• Fecundity refers to the potential ability of an organism to generate reproductive units, including eggs, sperm, or asexual structures.
• Association. A collection of species within a trophic level use a shared resource base in a comparable manner, such as nectar-feeding birds or grazing and browsing mammals.
• Herbivores are sometimes referred to as Key Industry Animals. (Elton, 1927) due to their ability to transform plant materials into animal matter.
• Chaparral vegetation comprises resilient, dense, broad-leaved evergreen plants, such as sage and oak, that exhibit fire resistance.
• Illumination is severely deficient in the tundra, with winter temperatures ranging from -30°C to -40°C. Summer lasts around 60 days at a temperature of 10°C.

NEET Biology Ecosystem Vegetation Of India

In India, there are two most common types of plant formations.

Forests. Indian forests are classified into four major types based on temperature such as tropical, mountain subtropical, temperate, and alpine.

1. Tropical forests. They are of two types moist and dry. Moist tropical forests. On the basis of the degree of wetness, they may be
   • Tropical Wet Evergreen Forests. Annual rainfall is over 250 cm. as in the West Coast, Assam, Bengal, and Andaman islands. The dominant trees arc Dipterocarpus, Hopea, Artocarpus, Emblica, Man gif era, Iscora, and some climbers (Lianas) and epiphytes.
   • Tropical Moist Semi-Evergreen Forests. They are found in North Assam, Bengal, parts of Orissa receiving heavy rainfall. Trees shed their leaves for a brief period. They include trees such as Terminalia; and Shorca.
   • Tropical Moist Deciduous Forests. They are common in moist areas of Kerala, Karnataka, South Madhya Pradesh, Northern Uttar Pradesh, and Bihar. Bengal and North Orissa. They include teak and Sal trees.
   • Dry Tropical Deciduous Forests. Trees remain leafless for several weeks in the dry season. Trees are moderate in size with sparse canopy. Thorny shrubs, grasses, and some bamboos are also present in some regions. In the north, such forests are found in Punjab, U.P. Bihar, and Orissa in regions that are neither wet nor too dry.
2. Temperate Forests. They occur above 5,300 ft altitude, chiefly in the mountains of the Himalayas and Nilgiri. In the Himalayas, Oaks and conifers are abundant.
3. Alpine Vegetation. They are extensive throughout the Himalayas above 11,000 ft. The tree’s height becomes lesser with increasing altitude. Alpine vegetation is characterized by Rhododendrons. It includes small plants like Sedum, Primula, Saxifraga, and lichens.
4. Grasslands. In India, natural grasslands are not found. Most Indian grasslands are being maintained in their present serai stage due to biotic interference.

NEET Biology Ecosystem Biosphere

Biosphere. The inhabited part of the earth and its atmosphere form the biosphere. It extends to about 22.5 km in thickness from the ocean bottom to the mountain tops.

• Maximum Density Of Organisms is found in coral reefs and tropical rain forests.
• Pedosphere. Consists of soil.
• The lithosphere is the dry crust of the earth (rocks and soil) 20 km in thickness.
• Hydrosphere. Oceans and sea (70% of the total earth’s surface).
• The atmosphere consists of 78% N₂, 20.9% 02, 0.94% Ar, and 0.03% CO₂.

The atmosphere is differentiated into the troposphere, stratosphere, ozonosphere, and ionosphere.

NEET Biology Ecosystem Ecological Succession

Biotic Succession. A biologically controlled modification in the composition of a community of a particular area is called biotic succession or ecological succession. Biotic succession is also known as the successive development of different communities in a particular area till a climax community is formed.

It was first studied by King (1685). The term succession was coined by Hult(1885). Clements defined it as a natural process by which the same locality becomes successively colonized by different groups of plants. Odum further described it.

Energy Flow In Ecosystem NEET Study Material

Kinds Of Succession

1. Primary Succession (Prisere). In any of the basic environments, primary succession starts from the primitive substratum, where there was no previously any sort of living matter. The first group of plants established there are known as pioneers, primary community, or primary colonizers and the last group is of climax community formed of tall trees.
   • The time taken for the development of forest climax or sand-dune or barren land is about 1000 yrs. Time taken is about 50-100 yrs in the case of grassland and more than 200 yrs for a forest
2. Autotrophic Succession. This type of succession is dominated by autotrophs which represent the first serial stage. lt occurs on a substratum having excess mineral matter but little organic matter.
3. Heterotrophic Succession. It occurs on a substratum having an excess of organic matter. This type of succession is always dominated by detrivores i.e., fungi and bacteria.
4. Induced Succession. It occurs due to extensive external interference. Here the initial community has high productivity which gradually decreases. The agriculture can be deemed as an example of induced succession.
   • Here a steady state is maintained for an ultimate good harvest. Elimination of weeds can be deemed as a step towards retrogression as it inhibits the arrival of a stable state.
5. Autogenic Succession. When the plants themselves gradually modify the environment to the extent that the habitat itself becomes unfavorable for the existing vegetation, a new type of succession starts. The old communities disappear and new ones come up for whom the environment is more suitable. This has been described as autogenic succession.
6. Allogenic Succession. The habitat may change due to external thrust i.e. of the environment. The succession taking place on account of this is called as allogenic.
7. Retrogressive Succession. Due to environmental thrust and human interference the climax vegetation may retrograde into shrubland or savannah. This is referred to as retrogressive succession.
8. Deflated Succession. When the succession doesn’t proceed through its normal course and sidetracks the advancement line, it is called as deflated succession. If the normal stages are 1 → 2 → 3 → 4 and the succession occurs as 1 → 2 → 3A → 3B → 4 is deflated.
9. Cyclic Succession. It occurs within the normal discourse of succession. If at a certain stage, the normal succession line is substituted by repetition of a previous stage due to external thrust, the succession is called cyclic for example 1 → 2 ⇔ 3 → 4.

Causes Of Succession

1. Initiation.
   • Physiographic factors include erosion, deposition, submergence, and emergence.
   • Climatic Factors produce secondary, barren areas including wind, water, snow, hail, re, and draught.
   • Biotic Factors produce secondary barren areas including animals, mankind, and microorganisms.
2. Continuation. Once started succession continues
3. Stabilization

Process Of Succession: The various stages are

1. Nudation
2. Migration
3. Ecesis
4. Aggregation
5. Competition
6. Co-action
7. Reaction and
8. Stabilization.

Secondary Succession Subsere. It occurs when an early community has been damaged leaving a few organisms and considerable organic matter.

• Ecological Succession in dry habitats, bare rock, sandy soil, and aquatic habitats are respectively called Xerosere, lithosere, psammosere, and hydrosere.
• In hydrosere (or hydrarch), pioneers in an ecological succession are submerged hydrophytes.
• In lithosere, the pioneers in an ecological succession are crustose (Saxicaulous lichens, Graphis, Rhijocaibon).
• The dominant species are different for each succession stage in the series.
• The last succession in a series is called the climatic climax or climax.

Energy Flow In Ecosystem NEET Study Material

NEET Biology Ecosystem Different Stages In Hydrosere With Component Plants

Phytoplankton Stage: (blue-green and green algae pioneer, Diatoms, bacteria.)

Rooted submerged Stage: Hydrilla, Vallisnaria Utricularia, Potamogeton Elodea, Najas, Ceratophyllum, certain got volume crunch as choro ano Nitalla

Floating Stage: Nelumbo, Nymphala, Zolle hemna, Trapa

Reed Swamp Stage: (Typha, Sagittaria Phragmites, Sagittaria, Siripus (Amphibious stage)

Sedge Meadow Stage: (Cyperus, Juncus, Eleocharis, Carix)

Wood Land Stage: (Salix, Populus, Alnus) (Climax community) Forest stage (Temperate mixed tropical rain and tropical deciduous)

NEET Biology Ecosystem Different Stages In Xerosere With Component Plants

NEET Biology Ecosystem Differences Between Terrestrial And Aquatic Succession

NEET Biology Ecosystem Differences Between The Seral And Climax Community During Succession

Dominance of a species:

Any one or more species is present in a majority during succession in every stage, and that species is the dominant species in the community. For instance, a location may be classified according to the species that predominate the region, such as a teak forest or pine forest.

The dominant species significantly influences the community and the surrounding environment. At any stage, it is not requisite for a single species to dominate; multiple species may coexist in dominance. For example, in the rainforests of tropical regions, 10 to 12 species dominate.

NEET Biology Ecosystem Biogeochemical Cycle

The circular paths of the chemical elements between organisms and the environment are known as biochemical cycles.

Cycles of material are classified into gaseous and sedimentary cycles,

1. For Gaseous cycles, the reservoir of materials is the atmosphere or water. The four major elements in living organisms: carbon, hydrogen, oxygen, and nitrogen, are predominantly gaseous;
2. In the Sedimentary cycle involving minerals, like phosphorus, sulfur, and calcium, the reservoir is the lithosphere.

Energy Flow In Ecosystem NEET Study Material

Oxygen Cycle: The oxides can be reduced both chemically as well as biologically to produce oxygen. Microbial oxidation can also occur. O₂ content of the atmosphere has remained constant for the last several million years.

Most of the O₂ lost is replenished by photosynthesis.

Greenhouse gases tire (CO₂ CH₄, dust, HO₂, NO₂, SO₂) are transparent to incoming solar radiations but are strong absorbers of long wave or infrared radiations emitted by the earth’s surface.

Carbon Cycle: The three main sources of carbon in the non-living world are:

1. CO₂ of air as well as dissolved in water
2. Carbonates of rocks in the earth’s crust
3. Coal and petroleum of fossil fuels.

Most CO₂ enters the living world through photosynthesis.

• The amount of carbon fixed by photosynthesis is 7 x 10¹³ kg per year.
• One hectare of healthy forest produces about 10 tonnes of O₂ and absorbs 30 tonnes of CO₂ every year.

Nitrogen Cycle: N₂ forms 4/5 part of the atmosphere; picked up as inorganic compounds by plants and some prokaryotes (NO^–₃ and NH₄) and converted into organic N₂.

N₂ Fixation Is Of Three Types

1. Atmospheric-electrochemical and photochemical reactions (35 mg/ m²/ yr).

2. Biological by free-living bacteria (Azotobacter, Clostridium), symbiotic bacteria (Rhizobium), and cyanobacteria (Anabaena, Nostoc) [140-700 mg/m²/yr].

Proteins (Nitrogenous Compounds)

Ammonifying bacteria are Bacillus vulgaris and Bacillus remosa.

Dead bodies of plants and animals also contain nitrogenous compounds, for example, Bacillus, actinomycetes, and fungi.

3. Industrial – Haber’s process

Water Cycle: 60-90% of the body weight of an organism is made up of water.

• The water or hydrological cycle is actually made up of two overlapping cycles: Larger ‘global’ and smaller ‘local’
• Precipitation is of three main types. Rain, Snow, and Hail.
• The total world precipitation amounts to 4.46 x 10²⁰ G per year. (1G = 10²⁰ gm).
• Biogeochemical Cycle. The cycling of materials between living and non-living components of the biosphere is called the biogeochemical cycle.

Phosphorus Cycle: The atmospheric or gaseous cycle for phosphorus is absent. Guano (excreta of marine birds) is a good source of phosphorus.

Sulfur Cycle: In the sulfur cycle, the gaseous phase is reduced. In nature, sulfur occurs in the elemental form (as metal sulfides and sulfates) and some amount as SO₂ gas.

• Sulfur is available to plants as sulfate
• Sulfur is available to plants as sulfate. (SO₄^2-) ions which are produced by the oxidation of exposed acid eroded rock surfaces. Most of this oxidation is biological and is carried out by specialized bacteria which derive energy from the process.
• In plants, absorbed SO₄^2- ions are incorporated into the thiol (-SH) groups of amino acids and proteins. In this form, the sulfur passes through the various trophic levels being released from living organisms only as a constituent of feces.
• Decomposing bacteria break down the protein of dead organisms, reducing the -SH groups to H₂S (hydrogen sulfide). It is the presence of this gas that sometimes gives the characteristic odor of rotten eggs to decomposing matter. The H₂S produced may be oxidized to SO₄^2- by certain bacteria but this is only possible under aerobic conditions.
• Specialized photosynthetic bacteria living in sulfur springs use H₂S instead of H₂O as a raw material in the manufacture of carbohydrates and this sulfur returns to earth’s sediments.

Calcium, Magnesium, And Other Minerals: They are also cycled like other materials. These elements are slowly released from the rocks by the action of water and wind. These are either blown into the air as dust or are absorbed by plants through their roots.

Some organisms, such as mollusks and corals, deposit a substantial quantity of calcium in their shells and skeletons that are not available for quick cycling.

• The vertical distribution of different species occupying different levels is called stratification
• Components of the ecosystem are seen to function as a unit with the following consideration

Energy Flow In Ecosystem NEET Study Material

Productivity

• Gross Primary Productivity (GPP)
• Net Primary Productivity (GDP)
• Secondary Productivity

Primary Productivity Depends Upon:

• Plant species Environmental factors
• Availability of nutrients
• Photosynthetic capacity

Decomposition. Steps: Fragmentation, Leaching, Catabolism, Humification, Mineralization (Temperature, Soil moisture, Oxygen and detritus composition regulate decomposition,

Energy Flow: Producers → Primary → Secondary

• Detritus Food Chain (DFC)
• Grazing Food Chain (GFC)

Food Web. The natural interaction of food chains makes the food web.

• The number of trophic levels is restricted as the transfer of energy follows 10 percent law Ecological pyramids
• The pyramid of energy is always upright
• The pyramid of number and biomass is generally upright
• The pyramid of biomass in the sea is generally inverted
• The pyramid of biomass of a small standing crop of phytoplankton supports a large standing crop of zooplankton thus it is inverted.

NEET Biology Ecosystem Ecosystem Synopsis

The deep sea constitutes an incomplete ecosystem due to the absence of producers. Koala bears are monophagous and will perish in the absence of eucalyptus leaves.

• The pH of oceans exhibits minimal variation.
• Snails and earthworms are absent in acidic soils.
• Euglena and other flagellates are prevalent in acidic aquatic environments.
• Organisms with calcareous shells inhabit environments with neutral or alkaline pH levels.
• Snails inhabit soils abundant in calcium.
• Animals counteract seawater salinity via salt-secreting glands.
• Terrestrial animals are unaffected by alterations in pH levels. Nonetheless, it dictates the distribution of terrestrial flora and edaphic creatures.
• Sloths are exclusively arboreal in their environment.
• Some creatures function as both producers and consumers, such as insectivorous plants like Nepenthes (pitcher plant) and Drosera (Sundew plant).
• Omnivores such as humans and bears occupy multiple trophic levels.

Ecological equivalents. Animals occupying similar ecological niches (similar food) in different geographical areas for example both owls and cats feed upon shrews and rats in woodland areas and near human habitations respectively.

• There is the highest species diversity in the Tropical rainforest ecosystem.
• Gujarat has the largest number of salt lakes in India.
• Brine is water that has a high concentration of salt.
• Herbs other than grass are called forb.
• The number of biomes on a mountain range decreases with the increase in the latitude of the mountain.
• Brackish lakes are always oligotrophic for example Sambhar Lake of Rajasthan.
• Detritus trophic level – The last trophic level is constituted by decomposers.
• Detritivores are decomposers as well as scavengers.

The detritus food chain is the shortest. Dystrophic lakes are rich in bogs (undecomposed organic matter), poor in CaCO₂ and other inorganic matter, and poor in oxygen for example marshy lakes.

• With increasing dependence on animal diets, the human population will need more farm produce.
• Britain receives 2500 cal/cm²/yr of solar radiation while the amount at Varanasi in India is 75000 cal/ cm²/yr.
• The fish ‘Hilsa’ is found in both fresh and marine waters.
• Gauses hypothesis or Principle of competitive exclusion.
• No two species can occupy the same ecological niche. In case it happens, only one survives while the other is excluded.
• Tropical region occurs between 23°N and 23°S.
• Secchi disc is used in measuring turbidity.

Plagiosere. It is a deflected sere where plant succession deviates from its natural course due to human activity and other forms of external intervention.

• The climax of plagiosere is known as plagioclimax or disclimax.
• The daily tidal cycle recurs after every 12.4 hours.
• Characteristic vegetation beyond the timberline is Elfin scrub and Alpine meadows.
• The water cycle is made up of two overlapping cycles — larger global and smaller local.
• Matter occupies a space. It can be seen, smelled, tasted, and touched while energy does not occupy space and it can be felt through specific receptors for example heat, sound, light.
• Earth is a closed system as far as materials are concerned.
• Beijerinck (1888) isolated Bacillus radicicola and showed its ability to produce root nodules.
• Winogradsky (1891) discovered nitrogen fixation.
• Sea birds excrete uric acid, which is deposited to form guano in littoral islands. It is rich in uric acid and phosphorus and used as fertilizer.

Ozone-depleting gases are on NO₂ (6%) chloroform carbons (25%) halocarbon/halons, and CO₂ (57%)

Ecological Pyramids NEET Exam Preparation

Differences Between Grazing And Detritus Food Chains

Differences Between Wet Deposition And Dry Deposition

The Ecosystem Receives Nutrients By

1. Wet deposition
2. Dry deposition

NEET Biology Ecosystem Multiple Choice Questions And Answers

Question 1. The term ecosystem was coined by:

1. Sukachey
2. Vernadsky
3. Haeckel
4. Tansley.

Answer: 4. Tansley.

Question 2. Biotic components of an ecosystem include:

1. Producers
2. Consumers
3. Decomposers
4. All the above.

Answer: 4. All the above.

Question 3. Which is the most stable ecosystem?

1. Mountain
2. Desert
3. Forest
4. Ocean.

Answer: 4. Ocean.

Question 4. In a biotic community, primary consumers are:

1. Omnivores
2. Carnivores
3. Detritivores
4. Herbivores.

Answer: 4. Herbivores.

Question 5. If we completely remove the decomposers from an ecosystem, the ecosystem functioning will be adversely affected because:

1. Mineral movement will be blocked
2. Herbivores will not receive solar energy
3. Energy flow will be blocked
4. The rate of decomposition of another component will be very high.

Answer: 1. Mineral movement will be blocked

Question 6. The food chain will end with:

1. Carnivores
2. Herbivores
3. Decomposers
4. Secondary carnivores.

Answer: 4. Secondary carnivores.

Question 7. Which of the following is a way flow rather than a two-way or cyclic flow?

1. Carbon
2. Nitrogen
3. Potassium
4. Free energy.

Answer: 4. Free energy.

Ecological Pyramids NEET Exam Preparation

Question 8. The importance of the ecosystem lies in:

1. Flow of energy
2. Cycling of materials
3. Both (1) and (2)
4. None of the above.

Answer: 3. Both (1) and (2)

Question 9. The driving force for an ecosystem is:

1. Biomass
2. Producers
3. Food
4. Solar Energy.

Answer: 4. Solar Energy.

Question 10. About how much of solar energy that falls on the leaves of a plant is converted to chemical energy by photosynthesis?

1. 1%
2. 10%
3. 30%
4. 50%.

Answer: 1. 1%

Question 11. Energy and nutrients enter a community by way of:

1. Producers
2. Consumers
3. Scavengers
4. Detritivores.

Answer: 1. Producers

Question 12. A consumer whose carbon atoms have already passed through three species is a:

1. Scavenger
2. Tertiary Producers
3. Tertiary Consumers
4. Secondary Consumers.

Answer: 3. Tertiary Consumers

Question 13. The average annual precipitation in a desert biome is:

1. 15-25 cm
2. 25-30 cm
3. 50-75 cm
4. 75-100 cm.

Answer: 1. 15-25 cm

Question 14. A sequence of species through which the organic molecules in a community pass is called:

1. Pyramid of energy
2. Food chain
3. Food web
4. Nutrient cycle.

Answer: 2. Food chain

Question 15. Savannahs are:

1. Tropical rain forest
2. Desert scrubs
3. Grassland with scattered trees
4. Dense forests.

Answer: 3. Grassland with scattered trees

Ecological Pyramids NEET Exam Preparation

Question 16. Most food chains are composed of:

1. 1 or 2 species
2. 3 or 4 species
3. 9 or 10 species
4. More than 16 species.

Answer: 2. 3 or 4 species

Question 17. A micro-climate is controlled mostly by factors associated with:

1. The flatness of the terrain
2. Vegetation
3. Latitude
4. Longitude.

Answer: 3. Latitude

Question 18. In which of the following habitats does the diurnal temperature of soil surface vary most?

1. Desert
2. Grassland
3. Shrubland
4. Forest.

Answer: 1. Desert

Question 19. A biome with high temperature, high rainfall no seasonal change, and soil rich in minerals and humus is:

1. Shrub land
2. Coral reef
3. Tropical rain forest
4. Temperate evergreen forest.

Answer: 3. Tropical rainforest

Question 20. A plant eaten by herbivorous animals which in turn is eaten by a carnivorous animal, it forms a:

1. Food chain
2. Food web
3. Food pyramid
4. Biotic potential.

Answer: 1. Food chain

Question 21. A pond is a:

1. Biome
2. Agro-ecosystem
3. Natural ecosystem
4. Community.

Answer: 3. Natural ecosystem

Question 22. Which of the following communities would have trees?

1. Taiga
2. Littoral zone
3. Shrub land
4. Tundra.

Answer: 1. Taiga

Question 23. Which of the following has a vegetation structure with only one level?

1. Tropical rain forest
2. Taiga
3. Grassland
4. Shrub land.

Answer: 3. Grassland

Question 24. What type of pyramids are commonly referred to in ecological studies?

1. Lateral
2. Compound
3. Upright
4. Inverted.

Answer: 3. Upright

Question 25. Which type of system does the earth along with its atmosphere constitute?

1. Open
2. Closed system
3. Cut off system
4. Biogeochemical system.

Answer: 2. Closed system

Question 26. Enrichment of habitat (say pond) with nutrients is called:

1. BOD
2. Biological magnification
3. Eutrophication
4. Autopurification.

Answer: 3. Eutrophication

Question 27. Wolves and lions may be said to occupy the same trophic level because:

1. They both eat primary consumers
2. They both utilize their food with about 10% efficiency
3. They both live in a pond
4. Both are large mammals.

Answer: 1. They both eat primary consumers

Question 28. About how much of the chemical energy within the producer’s tissue becomes chemical energy within herbivore tissue.

1. 1%
2. 10%
3. 30%
4. 50%.

Answer: 2. 10%

Question 29. The most diverse oceanic communities are in the:

1. Abyssal zone
2. Littoral zone
3. Neritic zone
4. Oceanic zone.

Answer: 2. Littoral zone

Nutrient Cycling In Ecosystems NEET

Question 30. Which of the following aquatic ecosystems has very little primary productivity?

1. River
2. Estuary
3. Lake
4. Marsh.

Answer: 1. River

Question 31. Which of the following statements is true about ecological relationships?

1. Competition with members of other species is more severe than that with one’s own species
2. Competition with members of other species is less severe than with one’s own species
3. Competition with members of other species is as severe as that with one’s own species
4. Competition does not exist between members of different species.

Answer: 2. Competition with members of other species is less severe than with one’s own species

Question 32. The above represents:

1. Food chain
2. Food web
3. A population
4. Ecosystem.

Answer: 2. Food web

Question 33. Light compensation zone refers to the zone:

1. Where all light energy is used efficiently
2. Where light is available
3. Beyond which light does not penetrate
4. Where light is maximum.

Answer: 3. Beyond which light does not penetrate

Question 34. Aquatic ecosystem covers how much of the earth’s surface?

1. 87%
2. 23%
3. 72%
4. 49%.

Answer: 3. 72%

Question 35. A biome with high temperature, and high rainfall is:

1. Shrub land
2. Coral reef
3. Semi-desert scrub
4. Tropical rain forest.

Answer: 4. Tropical rainforest.

Question 36. The importance of the ecosystem lies in:

1. Cycling of materials
2. Flow of materials
3. Both of the above
4. None of the above.

Answer: 3. Both of the above

Question 37. What are biotic components?

1. The living components
2. The non-living components
3. Both living and non-living
4. None of the above.

Answer: 1. The living components

Question 38. The flora and fauna in lakes and ponds are;

1. Lentic biota
2. Lotic biota
3. Abiotic
4. None of the above.

Answer: 1. Lentic biota

Question 39. The source of energy in an ecosystem is:

1. The heat from the soil
2. Heat reflected by leaves
3. Burning of sugar
4. Sunlight is received by leaves.

Answer: 4. Sunlight received by leaves.

Nutrient Cycling In Ecosystems NEET

Question 40. The energy storage at the consumer level is called:

1. Gross primary productivity
2. Secondary productivity
3. Net primary productivity
4. Net productivity.

Answer: 2. Secondary productivity

Question 41. The hardest competition for food, light, and space is seen in:

1. Closely related species growing in the same niche
2. Closely related species growing in different habitats
3. Distantly related species growing in the same niche
4. Distantly related species growing in different habitats.

Answer: 1. Closely related species growing in the same niche

Question 42. Given below is an imaginary pyramid of numbers. What could be one of the possibilities about certain organisms at some of the different levels?

1. Level PC is “insects” and level SC is “small insectivorous birds”
2. Level PP is “phytoplanktons” in sea and “Whale” on top-level TC
3. Level one PP is “pipal trees” and the level SC is “sheep”
4. Level PC is “rats” and level SC is “cats”.

Answer: 1. Level PC is “insects” and level SC is “small insectivorous birds”

Question 43. Which of the following relations is correct regarding the GPP and NPP of an ecosystem?

1. NPP = GPP – Animal consumption
2. NPP = GPP + Plant respiration
3. NPP = GPP – Plant respiration
4. NPP = GPP + Animal consumption.

Answer: 3. NPP = GPP – Plant respiration

Question 44. An ecosystem resists change because it is in a state of:

1. Imbalance
2. Shortage of components
3. Homeostasis
4. Deficiency of light

Answer: 3. Homeostasis

Question 45. The ecosystem has two components:

1. Plants and animals
2. Weeds and trees
3. Biotic and abiotic
4. Frogs and men.

Answer: 3. Biotic and abiotic

Question 46. The number of producers within a specified area would be maximum in:

1. Pond ecosystem
2. Grassland
3. Desert
4. Forest ecosystem.

Answer: 1. Pond ecosystem

Question 47. In an ecosystem, a big fish eats small fishes which eat water fleas supported by phytoplanktons. The water fleas in this ecosystem are:

1. Producers
2. Primary consumers
3. Secondary consumer
4. Top consumers.

Answer: 2. Primary consumers

Question 48. Which one of the following represents the largest population in an ecosystem?

1. Consumers
2. Top consumers
3. Decomposers
4. Producers.

Answer: 4. Producers.

Question 49. With regard to the ecological food chain, man is a:

1. Consumer
2. Producer
3. Producer and consumer
4. Producer and decomposer.

Answer: 1. Consumer

Nutrient Cycling In Ecosystems NEET

Question 50. The first link in a food chain is always a green plant because:

1. It has the capacity to synthesize organic food
2. Plants are fixed to a place
3. Plants are present everywhere
4. There are more herbivorous animals than carnivorous animals.

Answer: 1. It has the capacity to synthesize organic food

Question 51. A food chain is represented by :

1. Producers
2. Decomposers in succession
3. Primary consumers
4. Producers—consumers—decomposers.

Answer: 4. Producers—consumers—decomposers.

Question 52. Organisms linked in a food chain represent:

1. Food web
2. Trophic levels
3. Ecosystem
4. Community.

Answer: 2. Trophic levels

Question 53. Free-floating organisms are termed:

1. Planktons
2. Benthos
3. Nekton
4. All algae.

Answer: 1. Planktons

Question 54. The bottom-dwelling organisms are:

1. Nektons
2. Phytoplankton
3. Benthos
4. Zooplanktons.

Answer: 3. Benthos

Question 55. The first trophic level is represented by :

1. Herbivores
2. Carnivores
3. Insectivores
4. Autotrophs.

Answer: 4. Autotrophs

Question 56. In a grassland, top consumers are:

1. Herbivores
2. Carnivores
3. Bacteria
4. Tall pine tree.

Answer: 2. Carnivores

Question 57. The food chain in which micro-organisms absorb and break the energy-rich compounds synthesized by the producers is

1. Predator food chain
2. Parasitic food chain
3. Detritus food chain
4. None of the above.

Answer: 3. Detritus food chain

Question 58. Lichens do not normally grow in cities :

1. Because of the absence of the right type of algae and fungi
2. Because of the lack of moisture
3. Because of air pollution
4. Because natural habitat is missing.

Answer: 3. Because of air pollution

Question 59. Primary productivity of the ecosystem refers to:

1. Increase in primary consumers
2. Net production of primary producers
3. CO₂ fixation of organic carbon
4. Increase in mortality of primary producers.

Answer: 3. CO₂ fixation of organic carbon

Question 60. The individuals in the uppermost ring of the pyramid represent the one with:

1. Maximum number
2. Maximum biomass
3. The ultimate consumer in the chain
4. Minimum biomass.

Answer: 3. The ultimate consumer in the chain

Ecosystem NEET Notes

Question 61. The pyramid of a number of individuals per unit area in a grassland ecosystem will be:

1. Linear
2. Upright
3. Irregular
4. Inverted.

Answer: 2. Upright

Question 62. The ecological niche is:

1. Place of dwelling
2. Place of origin
3. Competitive ability
4. Function with habitat.

Answer: 4. Function with habitat.

Question 63. Which of the following food chains is correct?

1. Fallen leaves-bacteria-insect larvae
2. Phytoplankton -zooplankton-fish
3. Grasses-fox-rabbit
4. Grasses-chameleon -insect-bird.

Answer: 2. Phytoplankton -zooplankton-fish

Question 64. ‘Greenhouse effect’ is:

1. Growing maximum green plants in home gardens
2. Reduction of the green part of sunlight reaching the earth
3. Growing vegetables in green-coloured houses
4. Retention of heat radiation from the earth by CO₂

Answer: 4. Retention of heat radiation from the earth by CO₂

Question 65. For recycling of materials which one is necessary?

1. Producers
2. Consumer
3. Man
4. Decomposers.

Answer: 4. Decomposers

Question 66. Energy flow in an ecosystem is:

1. Multidirectional
2. Bidirectional
3. Unidirectional
4. None of the above.

Answer: 3. Unidirectional

Question 67. The pyramid of energy in a terrestrial ecosystem may be:

1. Inverted
2. Upright
3. Upright and inverted
4. None of the above.

Answer: 2. Upright

Ecosystem NEET Notes

Question 68. Green plants are:

1. Complete food chain
2. First trophic level
3. Second trophic level
4. Third trophic level.

Answer: 2. First trophic level

Question 69. Solar energy can be trapped to the maximum capacity by:

1. Planting trees
2. Crops
3. Grasses
4. Xerophytic plants.

Answer: 3. Grasses

Question 70. The equilibrium of species is disturbed by

1. Overgrazing
2. Selective grazing
3. Fanning
4. None of the above.

Answer: 1. Overgrazing

Question 71. A food chain starts with:

1. Decay
2. Photosynthesis
3. Respiration
4. Nitrogen fixation.

Answer: 2. Photosynthesis

Question 72. Biological equilibrium is an equilibrium among the:

1. Producers
2. Producers and consumers
3. Decomposers
4. Producers, consumers, and decomposers.

Answer: 4. Producers, consumers, and decomposers.

Question 73. When the number of organisms at successive levels are plotted, they assume the shape of a pyramid. This is called:

1. Pyramid of Numbers
2. Pyramid of Energy
3. Pyramid of Biomass
4. None of these.

Answer: 1. Pyramid of Numbers

Question 74. The salt concentration in the open sea is about:

1. 35 per cent
2. 3.5 per cent
3. 85 per cent
4. 0.8 per cent.

Answer: 2. 3.5 per cent

Question 75. The upper vertical zone up to the depth of 200 meters is known as:

1. Photic zone
2. Aphotic zone
3. Abyssal zone
4. None of these.

Answer: 1. Photic zone

Question 76. In a food chain, the largest number is of:

1. Decomposers
2. Consumers
3. Predators
4. Producers.

Answer: 4. Producers.

Question 77. The ecosystem is a self-sustaining unit because it consists of:

1. Plants and animals only
2. Physical environment only
3. Microbes only
4. All the above.

Answer: 4. All the above.

Question 78. A component of the physical environment of an ecosystem is:

1. Sunlight
2. Decomposers
3. Water
4. Temperature.

Answer: 1. Sunlight

Question 79. In a food chain animals constitute the:

1. First trophic level
2. Second trophic level
3. Intermediate trophic level
4. Ultimate trophic level.

Answer: 3. Intermediate trophic level

Ecosystem NEET Notes

Question 80. Second-order consumers are:

1. All heterotrophs
2. Animals feeding on plants
3. Animals preying on herbivorous animals
4. Larger animals.

Answer: 3. Animals preying on herbivorous animals

Question 81. Active swimmers are:

1. Phytoplankton
2. Nektons
3. Benthos
4. Zooplankton.

Answer: 2. Nektons

Question 82. A food web is constituted by:

1. Various interlinked food chains in a community
2. Relationship between organisms and their environment
3. Relationship between plants and animals
4. Relationship between plants, animals and microbes.

Answer: 1. Various interlinked food chains in a community

Question 83. Vegetation found around the Mediterranean coast is called:

1. Savannah
2. Prairie
3. Chaparral
4. Melee.

Answer: 3. Chaparral

Question 84. An ecosystem is a complex interacting system of:

1. Individuals
2. Population
3. Communities and their physical environment
4. Communities and their soil condition.

Answer: 3. Communities and their physical environment

Question 85. Which of the following is truly a biome?

1. Wheat crop field
2. Pond ecosystem
3. Greenfield
4. Deciduous forest.

Answer: 4. Deciduous forest.

Question 86. The ecological niche of an organism is its:

1. Way of life
2. Habitat
3. Habitat as well as climate
4. Defended territory.

Answer: 1. Way of life

Question 87. Which of the following forests is more diverse?

1. Coniferous evergreen
2. Deciduous evergreen
3. Tropical rain forest
4. Sub-tropical rain forest.

Answer: 3. Tropical rainforest

Question 88. The solar energy is trapped to the maximum by:

1. Wheat
2. Rice
3. Sugarcane
4. Grams.

Answer: 1. Wheat

Question 89. Agroecosystem is a:

1. Natural ecosystem
2. Man-made ecosystem
3. Balanced ecosystem
4. Peripheral ecosystem.

Answer: 2. Man-made ecosystem

Question 90. Mangrove vegetation is found in:

1. Dehradun valley
2. Kulu valley
3. Western ghats
4. Sunderbans.

Answer: 4. Sunderbans.

Question 91. In a grassland ecosystem, the pyramid of energy is as:

1. Inverted
2. Upright
3. Inverted or upright
4. None of the above.

Answer: 2. Upright

Question 92. Which of the following is one-way flow rather than two directions or cyclic?

1. Nitrogen
2. Potassium
3. Free energy
4. Both (2) and (3).

Answer: 4. Both (2) and (3).

Question 93. The photic zone is spread up to a depth of:

1. 10 m
2. 10-100m
3. 100-300 m
4. 200 m.

Answer: 4. 200 m.

Question 94. Chaparral occurs in the Mediterranean area and rainfall occurs during:

1. Throughout the year
2. Summer
3. Winter
4. Spring.

Answer: 3. Winter

Components Of Ecosystem NEET Biology

Question 95. The most diverse oceanic communities are in the:

1. Abyssal zone
2. Littoral zone
3. Neritic zone
4. Oceanic zone.

Answer: 2. Littoral zone

Question 96. Daily tidal cycle recurs after:

1. 8 hrs
2. 12.4 hrs
3. 10.4 hrs
4. 12 hrs

Answer: 2. 12.4 hrs

Question 97. The pyramid of numbers is based on

1. Unit per area
2. Food per individual
3. Individuals with trophic levels
4. None of the above.

Answer: 3. Individuals in trophic levels

Question 98. Bach couple should produce only two children which will help in

1. Checking pollution
2. Stabilizing the ecosystem
3. Fertility of soil
4. Improving food web.

Answer: 2. Stabilising the ecosystem

Question 99. The trophic level of Woji in a forest ecosystem is:

1. T₃
2. T₄
3. T₂
4. T₁

Answer: 2. T₄

Question 100. About how much of the net primary productivity of a terrestrial ecosystem is eaten and digested by herbivores?

1. 10%
2. 1%
3. 30%
4. 50%.

Answer: 1. 10%

Question 101. About how much of the net primary productivity of an aquatic ecosystem is eaten and digested by herbivores?

1. 1%
2. 10%
3. 40%
4. 90%.

Answer: 4. 90%

Question 102. Life without air is:

1. Free from oxidative damage
2. Impossible
3. Anaerobic
4. Reduction in life spam

Answer: 3. Anaerobic

Question 103. Tropical dense forest is due to:

1. High temp, and excess rain
2. Low temp, and excess rain
3. High temp, and less rain
4. Wild animals like tigers, lions, bears.

Answer: 1. High temp, and excess rain

Question 104. The pyramid of energy is always:

1. Inverted
2. Upright
3. Both upright and inverted
4. Inverted in the forest ecosystem.

Answer: 2. Upright

Question 105. A kite eats mice, mice live on grains, Hence the kite is a:

1. Primary producer
2. Secondary consumer
3. Primary consumer
4. Secondary producer.

Answer: 2. Secondary consumer

Question 106. The composition of soil air is affected by:

1. Pore size
2. Soil organisms
3. Type of roots
4. All of these.

Answer: 4. All of these

Components Of Ecosystem NEET Biology

Question 107. Plants growing in alpine zone are short due to:

1. Low temperature
2. High wind velocity
3. High light intensity
4. None of these.

Answer: 2. High wind velocity

Question 108. Plants growing in the seashore are generally resistant to:

1. Lodging
2. Erosion
3. Salt spray
4. Injuries.

Answer: 3. Salt spray

Question 109. An anatomical feature that exclusively develops to counter the high velocity of wind:

1. Reaction wood formation
2. Absence of secondary growth
3. Absence of leaves
4. Absence of more branches.

Answer: 1. Reaction wood formation

Question 110. The classification of plant groups on the basis of temperature differentiating four zones such as mega therms was proposed by:

1. Clements
2. Raunkiaer
3. Odum
4. Warming.

Answer: 2. Raunkiaer

Question 111. Flowering is induced if germinating seeds are exposed

1. Low temperature
2. High temperature
3. Temperature below freezing
4. Temperature above 45°C.

Answer: 1. Low temperature

Question 112. The percentage of light from total solar input utilized by plants:

1. About 1 %
2. 3-5%
3. 7-8%
4. 14%.

Answer: 1. About 1 %

Question 113. Albido value refers to:

1. Turbidity of solar radiations
2. Percentage of solar absorption
3. Percentage of reflected light by a surface
4. Amount of light absorbed by forests.

Answer: 3. Percentage of reflected light by a surface

Question 114. According to Geiger, the percentage of light reflected by the clouds is

1. 9%
2. 10%
3. 48%
4. 33%.

Answer: 4. 33%.

Question 115. The albedo value of a forest is around:

1. 1-2%
2. 3-5%
3. 5-10%
4. 20-30%.

Answer: 3. 5-10%

Question 116. The aquatic thermal strata where no temperature gradients are observed is called as:

1. Hypolimnion
2. Metalimnion
3. Epilimnion
4. Thermocline.

Answer: 1. Hypolimnion

Components Of Ecosystem NEET Biology

Question 117. The alpine forests are classed under the plant group called:

1. Mesotherms
2. Hekistotherms
3. Microtherms
4. Megatherms.

Answer: 2. Hekistotherms

Question 118. The optimum temperature for seedling growth in the upper Gangetic plains is around:

1. 10°-15°C
2. 5°-10°C
3. 0°-25°C
4. 30°—40°C.

Answer: 3. 0°-25°C

Question 119. When a plant of ho^ climate is transferred to colder regions, it gets an injury called:

1. Chilling
2. Thermal death
3. Desiccation
4. Freezing.

Answer: 1. Chilling

Question 120. In the western Himalayas, the Betula trees usually occur in:

1. Tropical zone
2. Sub-tropical zone
3. Alpine zone
4. Temperate zone.

Answer: 3. Alpine zone

Question 121. Annual carbon fixation by photosynthesis is:

1. 7 x 10¹³
2. 7×10¹⁰
3. 7 x 10¹²
4. 7 x 10²⁰

Answer: 1. 7 x 10¹³

Question 122. Annual world precipitation is:

1. 7 x 10¹⁰ g
2. 7 x 10¹⁰ g
3. 4.46 x 10¹⁰ g
4. 4.46 x 10²⁰ g.

Answer: 4. 4.46 x 10²⁰ g.

Question 123. Maximum oxygen comes from:

1. Phytoplankton
2. Grasslands
3. Forests
4. Herbs and shrubs.

Answer: 1. Phytoplankton

Question 124. The main nitrogen reservoir in the biosphere is:

1. Atmosphere
2. Ocean
3. Organisms
4. Rocks.

Answer: 1. Atmosphere

Energy Flow In Ecosystem NEET Study Material

Question 125. Which one of the following pairs is a sedimentary type of biogeochemical cycle?

1. Phosphorus and CO₂
2. Oxygen and Nitrogen
3. Phosphorus and Nitrogen
4. Phosphorus and Sulphur.

Answer: 4. Phosphorus and Sulphur

Question 126. The largest reservoir of phosphorus in the biosphere is the

1. Atmosphere
2. Ocean
3. Organisms
4. Rocks.

Answer: 4. Rocks

Question 127. Which one of the following pairs is a sedimentary type of biogeochemical cycle?

1. Phosphorus and CO₂
2. Oxygen and Nitrogen
3. Phosphorus and Nitrogen
4. Phosphorus and Sulphur.

Answer: 4. Phosphorus and Sulphur

Question 128. Sedge is:

1. Polygonum
2. Potamogeton
3. Carex
4. Typha.

Answer: 3. Carex

Question 129. The perennial grass stage is represented by:

1. Aristida
2. Heteropogon
3. Poa
4. Tortula.

Answer: 2. Heteropogon

Question 130. The series of changes on the previously barren area is:

1. Sere
2. Climax community
3. Primary succession
4. Secondary succession.

Answer: 3. Primary succession

Question 131. Crustose lichen is:

1. Rhizocarpon
2. Pannelia
3. Dermatocarpon
4. Cladonia.

Answer: 3. Dermatocarpon

Energy Flow In Ecosystem NEET Study Material

Question 132. Secondary succession will not be completed if the bare area is invaded by:

1. Sphagnum
2. Lantana
3. Eichhomia
4. All the above.

Answer: 4. All the above

Question 133. Plant succession occurring in a sandy area is:

1. Psammosere
2. Halosere
3. Xerosere
4. Hydrosere.

Answer: 1. Psammosere

Question 134. A plant growing on rock is:

1. Psammophyte
2. Eremophyte
3. Lithophyte
4. Chersophyte.

Answer: 3. Lithophyte

NEET Biology Ecosystem Questions From Competitive Examinations

Question 1. Green plants constitute:

1. First trophic level
2. Second trophic level
3. Third trophic level
4. Fourth trophic level.

Answer: 1. First trophic level

Question 2. Tip of an ecological pyramid is occupied by:

1. Producers
2. Herbivores
3. Carnivores
4. None of the above.

Answer: 3. Carnivores

Question 3. Zooplanktonic forms are:

1. Primary producers
2. Carnivores
3. Primary consumers
4. Secondary consumers.

Answer: 3. Primary consumers

Question 4. Which of the following occurs in the abiotic component of the ecosystem?

1. Flow of energy
2. Cycling of materials
3. Consumers
4. Flow of energy and cycling of materials.

Answer: 2. Cycling of materials

Question 5. A treeless biome is:

1. Tundra
2. Grassland
3. Desert
4. All the above.

Answer: 4. All the above

Question 6. A man-made micro-ecosystem is:

1. Plants grown in a pond
2. Crop field
3. Tank formed naturally in your courtyard
4. Lake in a forest.

Answer: 2. Crop field

Energy Flow In Ecosystem NEET Study Material

Question 7. Which one has always a steeper vertical gradient?

1. Pyramid of mass
2. Pyramid of energy
3. Pyramid of numbers
4. Pyramid of energy in aquatic ecosystem.

Answer: 2. Pyramid of energy

Question 8. Which one is exclusive of xerophytic adaptation?

1. Absence of stomata
2. Long tap root system
3. Stipular leaves
4. Spines.

Answer: 4. Spines.

Question 9. Which one has evergreen vegetation and drought-adapted animals?

1. Chaparral
2. Savannah
3. Tundra
4. Deciduous forest.

Answer: 1. Chaparral

Question 10. Which part of the world has a high density of organisms?

1. Grasslands
2. Savannahs
3. Deciduous forests
4. Tropical rain forests.

Answer: 4. Tropical rainforests

Question 11. Viviparity and pneumatophores are features of:

1. Hydrophytes
2. Halophytes
3. Mesophytes
4. Xerophytes.

Answer: 2. Halophytes

Question 12. The flora and fauna in lakes or ponds are:

1. Lefitic biota
2. Lotic biota
3. Abiotic biota
4. Field layer.

Answer: 1. Lefitic biota

Components Of Ecosystem NEET Biology

Question 13. Trophic levels are formed by:

1. Only plants
2. Only animals
3. Only carnivores
4. Organisms linked in food chains.

Answer: 4. Organisms linked in food chains.

Question 14. An ecosystem has which of the following two components?

1. Frogs and men
2. Weeds and trees
3. Biotic and abiotic
4. Plants and animals.

Answer: 3. Biotic and abiotic

Question 15. The atmospheric/humidity is measured by

1. Potometer
2. Photometer
3. Hygrometer
4. Auxanometer.

Answer: 3. Hygrometer

Question 16. The concept of ecological pyramids was developed by

1. Elton
2. Darwin
3. Odum
4. Reiter.

Answer: 1. Elton

Question 17. Feeding on herbivorous insects is:

1. Primary consumer
2. Secondary consumer
3. Tertiary consumer
4. Top carnivore.

Answer: 2. Secondary consumer

Question 18. Maximum biomass of autotrophs in oceans is made of:

1. Benthic brown algae, coastal red algae, and daphnids
2. Benthic diatoms and marine viruses
3. Seagrasses and slime molds
4. Free-floating microalgae, cyanobacteria, and nanoplankton.

Answer: 4. Free-floating microalgae, cyanobacteria, and nanoplankton.

Question 19. Terai forest is:

1. Tropical
2. Coniferous
3. Deciduous
4. Temperate deciduous.

Answer: 1. Tropical

Components Of Ecosystem NEET Biology

Question 20. Savannah is found commonly in :

1. U.S.A.
2. U.S.S.R.
3. Australia
4. India.

Answer: 3. Australia

Question 21. A recently discovered ecosystem is:

1. Crater
2. Tundra
3. Floating Iceberg
4. Vent.

Answer: 1. Crater

Question 22. Controlling factors in the ecosystem is:

1. Soil moisture
2. Food
3. Trepidation
4. Temperature.

Answer: 3. Trepidation

Question 23. The transition zone between the two vegetational types is:

1. Ecotone
2. Ecotype
3. Ecocline
4. Ecosystem.

Answer: 1. Ecotone

Question 24. Plant decomposers are:

1. Monera and fungi
2. Fungi and plants
3. Protista and Animalia
4. Animalia and Monga.

Answer: 1. Monera and fungi

Question 25. The ecosystem consists of:

1. Producers
2. Consumers
3. Decomposers
4. All of these.

Answer: 4. All of these.

Question 26. Desert can be converted into green land by planting:

1. Oxylophytes
2. Psammophytes
3. Halophytes
4. Tropical trees.

Answer: 2. Psammophytes

Question 27. In the food chain, the lion is a:

1. Primary consumer
2. Secondary producer
3. Tertiary consumer
4. Secondary consumer.

Answer: 3. Tertiary consumer

Question 28. Which ecosystem shows maximum genetic diversity?

1. Tropical rain forests
2. Temperate forests
3. Coniferous forests
4. Subtropical forests.

Answer: 1. Tropical rainforests

Question 29. Which of the following is correctly matched?

1. Butterfly camouflage
2. Garden lizard mimicry
3. House lizard autotomy
4. None of these.

Answer: 3. House lizard autotomy

Nutrient Cycling In Ecosystems NEET

Question 30. Organisms found at the bottom of the sea are:

1. Planktons
2. Benthos
3. Nektons
4. Phytons.

Answer: 2. Benthos

Question 31. X is eating curd/yogurt. For this food intake in a food chain, he should be considered as occupying:

1. First trophic level
2. Second trophic level
3. Third trophic level
4. Fourth trophic level.

Answer: 3. Third trophic level

Question 32. These belong to the category of primary consumers:

1. Eagle and snake
2. Insects and cattle
3. Snake and Frog
4. Water insects.

Answer: 2. Insects and cattle

Question 33. If the high-altitude birds become rare or extinct, the plants that may disappear along with them are:

1. Pine
2. Oak
3. Orchids
4. Rhododendrons.

Answer: 2. Oak

Question 34. An ecosystem that can be easily damaged but can recover after some time if the damaging effect stops will have the following:

1. Low stability and low resilience
2. High stability and high resilience
3. Low stability and high resilience
4. High stability and low resilience.

Answer: 3. Low stability and high resilience

Question 35. Which of the following is expected to have the highest value (gm/m²/year) in a grassland ecosystem?

1. Gross production (GP)
2. Net production (NP)
3. Secondary production
4. Tertiary production.

Answer: 1. Gross production (GP)

Question 36. If by radiation all nitrogenase enzymes are inactivated, then there will be no:

1. Conversion from nitrate to nitrite in the legumes
2. Conversion from ammonium to nitrate in soil
3. Fixation of nitrogen in the legumes
4. Fixation of atmospheric nitrogen.

Answer: 4. Fixation of atmospheric nitrogen.

Question 37. The Great Barrier Reef along the east coast of Australia can be categorized as:

1. Population
2. Community
3. Ecosystem
4. Biome.

Answer: 4. Biome.

Question 38. Which one of the following pairs is mismatched?

1. Savannah – acacia trees
2. Prairie – epiphytes
3. Tundra – permafrost
4. Coniferous forest – evergreen trees.

Answer: 2. Prairie – epiphytes

Question 39. Which one of the following is the correct matching of the plant, its habitat, and the forest type where it normally occurs?

1. Prosopis, tree, scrub
2. Saccharum, grass, forest
3. Shorea robusta, herb, tropical rainforest
4. Acacia catechu, tree, coniferous forest.

Answer: 2. Saccharum, grass, forest

Question 40. Given below is one of the types of ecological pyramids. This type represents:

1. Pyramid of numbers in a grassland
2. Pyramid of biomass in a fallow land
3. Pyramid of biomass in a lake
4. Energy pyramid in a spring.

Answer: 3. Pyramid of biomass in a lake

Question 41. Energy transferred from one trophic level to another is:

1. 5%
2. 10%
3. 15%
4. 20%.

Answer: 2. 10%

Question 42. Maximum absorption of rainfall water is done by:

1. Tropical deciduous forest
2. Tropical evergreen forest
3. Tropical savannah
4. Scrub forest.

Answer: 2. Tropical evergreen forest

Question 43. The pyramid of energy is always upright for any ecosystem. This situation indicates the fact that

1. Producers have the lowest energy conversion efficiency
2. Carnivores have a better energy conversion efficiency
3. Energy conversion efficiency is the same in all trophic levels
4. Herbivores have a better energy conversion efficiency than carnivores.

Answer: 4. Herbivores have a better energy conversion efficiency than carnivores.

Question 44. Which of the following is called as a detritivore?

1. An animal feeding on decaying organic matter
2. An animal feeding on a plant
3. A plant feeding on an animal
4. An animal feeding on another animal.

Answer: 1. An animal feeding on decaying organic matter

Question 45. Which one of the following is not used for the construction of ecological pyramids?

1. Dry weight
2. Fresh weight
3. Rate of energy flow
4. Number of individuals.

Answer: 2. Fresh weight

Nutrient Cycling In Ecosystems NEET

Question 46. In the given formula, what does “a” represent?

Formula: Assimilatory efficiency = \(\frac{\text{Use of energy in food}{“a”}}\) x 100.

1. Energy obtained through primary producer
2. Biomass at own level
3. Biomass at lower trophic level
4. Energy is obtained through food.

Answer: 4. Energy obtained through food.

Question 47. Increased asthmatic attacks in certain seasons are related to:

1. Eating fruits preserved in tin containers
2. Inhalation of seasonal pollen
3. Low temperature
4. Hot and humid environment.

Answer: 2. Inhalation of seasonal pollen

Question 48. Which one of the following ecosystem types has the highest annual net primary productivity?

1. Tropical deciduous forest
2. Temperate evergreen forest
3. Temperate deciduous forest
4. Tropical rain forest.

Answer: 4. Tropical rainforest.

Question 49. Identify which one of the following is an example of an incomplete ecosystem.

1. Cave
2. Grassland
3. River
4. Wetland.

Answer: 1. Cave

Question 50. Consider the following statements concerning food chains.

1. Removal of 80% of tigers from an area resulted in greatly increased growth of vegetation
2. Removal of most of the carnivores resulted in an increased population of deer
3. The length of food chains is generally limited to 3-4 trophic levels due to energy loss
4. The length of food chains may vary from 2 to 8 trophic levels.

Answer: 3. The length of food chains is generally limited to 3-4 trophic levels due to energy loss

Question 51. Large Woody Vines are more commonly found in:

1. Temperate forests
2. Mangroves
3. Tropical rainforests
4. Alpine forests.

Answer: 3. Tropical rainforests

Question 52. Which one of the following statements for the pyramid of energy is incorrect, whereas the remaining three are correct?

1. Its base is broad
2. It shows the energy content of different trophic-level organisms
3. It is inverted in shape
4. It is upright in shape.

Answer: 3. It is inverted in shape

Question 53. The mass of living matter at a trophic level in an area at any time is called:

1. Standing crop
2. Detritus
3. Humus
4. Standing state.

Answer: 4. Standing state.

Question 54. Of the total incident solar radiation, the proportion of PAR is:

1. About 70%
2. About 60%
3. Less than 50%
4. More than 50%.

Answer: 4. More than 50%.

Question 55. Identify the possible link, “A” in the following food chain:

Plan—insect—frog—‘ ‘A” —Eagle

1. Wolf
2. Cobra
3. Parrot
4. Rabbit.

Answer: 2. Wolf

Question 56. The upright pyramid of numbers is absent in:

1. Forest
2. Lake
3. Grassland
4. Rabbit.

Answer: 2. Lake

Question 57. An inverted pyramid of numbers and an inverted pyram of biomass are respectively seen in

1. Grassland and tree ecosystem
2. Sea and tree ecosystem
3. Tree and sea ecosystem
4. Sea and grassland ecosystem.
5. Tree and grassland ecosystem.

Answer: 3. Sea and grassland ecosystem

Question 58. Which of the following is a pioneer in xerarch success?

1. Phytoplanktons
2. Lichens
3. Bryophytes
4. Rooted hydrophytes
5. Sedges

Answer: 2. Lichens

Question 59. The natural reservoir of phosphorus is

1. Animal bones
2. Rock
3. Fossils
4. Sea water.

Answer: 2. Rock

Question 60. Which one of the following processes during decomposition is correctly described?

1. Humification leads to the accumulation of a dark coloured substance humus which undergoes microbial action at a very fast rate.
2. Catabolism-Last step decomposition under fully anaerobic condition
3. Leaching-Water soluble inorganic nutrients rise to the top layers of soil
4. Fragmentation- carried out by organisms such as earthworms.

Answer: 4. Fragmentation- carried out by organisms such as earthworms.

Question 61. Secondary productivity is the rate of formation of new organic matter by:

1. Parasite
2. Consumer
3. Decomposer
4. Producer.

Answer: 2. Consumer