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NEET Biology Respiratory System In Animals

Respiration. It is an oxidising and energy-liberating phenomenon. It involves the intake of O₂ enters the body, and oxidises the nutrients (Glucose) to form CO₂ and H₂O.

• Energy is liberated in steps and stored in high-energy phosphate bonds in ATP. CO₂ thus formed is expelled out.
• Aerobic respiration. It is the common method of respiration. It is carried out in the presence of free molecular O₂ in most plants and animals.
• Anaerobic respiration or anaerobic metabolism. It is mostly carried out by bacteria, and yeasts. RBC and endoparasites.It is a process of energy liberation in the absence of free O₂.

External respiration. All animals require a medium for respiration.

• The gaseous exchange takes place between the external environment and blood through respiratory organs.
• External respiration is the exchange of gases between the air spaces of the lungs and blood in pulmonary capillaries.
• In external respiration, pulmonary capillary blood gains O₂ and loses CO₂.
• The percentage of oxygen in inhaled air is about 2.1 and the oxygen content of the air we expire is about 16.
• The carbon dioxide amount in the atmosphere is 0.033%, and carbon dioxide in the air we expire is about 3.6%.

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Internal respiration. Internal respiration is an exchange of gases between blood in systemic capillaries and tissue.

• When there is a difference in partial pressures, oxygen diffuses outward from the arterial end of capillaries into surrounding tissues.
• Carbon dioxide diffuses from the tissues into the bloodstream towards the venous end of capillaries.

1. Modes of respiration. Cutaneous respiration. It occurs in the skin, For Example, Frog, or earthworm.
2. Branchial respiration. It is carried out in aquatic animals and respiratory organs are gills For Example Fish, prawns, mussels, and tadpole larvae.
3. Buccopharyngeal respiration. The lining of the buccopharyngeal cavity acts as a respiratory surface For Example Frog, Toad.
4. Pulmonary respiration. It occurs in lungs For Example, amphibians, reptiles, birds, and mammals.

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Characteristics of the respiratory surface

1. It should be extensive. Lager the surface area, the greater id the exchange of respiratory gases.
2. It must be thin-walled, moist highly Vascular,
3. It should Iv easily permeable to oxygen mid-carbon dioxide,

NEET Biology Respiratory System In Animals Respiratory Structures

Plasma Membrane. External respiration in (lie protists occurs principally by diffusion of oxygen-dissolved
in water and carbon dioxide in opposite directions through the plasma membrane.

Body Wall. In sponges, cnidarians, platyhelminths, annelids and small aquatic animals, respiratory gas exchange occurs through the diffusion of gases across the general body wall.

1. In Hydra, gases are exchanged by diffusion between individual cells and the surrounding water.
2. Earthworms have no special respiratory organs; they exchange O₂ and CO₂ using their entire Imdy surface.

Gills. Gills are the gas exchange organs of aquatic animals.

• Gill are an outgrowth of the body surface which is highly folded or convoluted to increase the surface area available for gas exchange,
• Aquatic animals like prawns (Crustacea), fishes and tadpoles respire with gills.
• Gases are exchanged between the surrounding aqueous medium and blood in the gill capillaries.
• Gills are best developed and understood in bony fishes.
• Gills consist of several gill arches from which extend two rows of gill filaments.
• Upon each filament are rows of gill lamellae, which is the site of gas exchange.
• Water and blood flow in opposite directions i.e. counter current.
• Water is moved over the gills by the pumping action of the mouth and the opercular cavity. A dual pump operates. endodermal outgrowth from the oesophagus, For Example, protopterus.

Trachea. Tracheal respiration occurs in insects.

• A well-developed system of ectodermal cuticular tubes called trachea open to the outside by 10 pairs of spiracles or stigmata on the dorsolateral margin of the tergum.
• Each spiracle is bounded by a peritreme, the spiracles open behind into the atrium (2 pairs thoracic and 8 pairs abdominal).
• There are 6 main trunks connected through commissures.
• It branches distally into tracheoles (without cuticular rings) within a tissue or the cell known as the transition or stellate cells or tracheoblasts.
• The trafficking of air through spiracles is guided by valves. Most of these (all abdominal) spiracles remain closed during expiration to prevent the loss of water from the body.
• Spiracles can be opened or shut.
• Gas exchange takes place in the walls of tracheoles.
• Insects have blood, but it is not important in gas transport, since the tracheal system spreads throughout the body.

Book Lungs. Booklungs are respiratory organs in arachnids like scorpions.

Respiration In Fresh Water Fishes (Labeo). Respiration in Labeo is aquatic, the fish depend on O₂ dissolved in water.

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Respiratory organs. Labeo respires with 4 pairs of filiform gills supported by the first 4 pairs of gill arches. Four gills are present on either side of the pharynx in a common gill chamber.

• Each gill chamber is covered externally by a skin flap, the operculum, supported by bony plates. A branchiostegal membrane is attached to the posterior margin of the operculum.
• The chamber opens to the outside by a large crescentic branchial or gill aperture behind the operculum and in front of the pectoral fin. Each gill consists of two rows (hemibranchs) of slender gill filaments.
• In Labeo and other teleosts, the filaments are attached to an extremely reduced interbranchial septum so that their distal ends hang freely in the gill chamber. This type of gill is called filiform or pectinate.
• In contrast, the gills of dogfish and other elasmobranchs are called lamellibranchs in which the gill lamellae are attached throughout their length to an elongated septum.
• Every gill filament bears several minute transverse plates or lamellae covered with thin epithelium and containing capillaries between the afferent and efferent branchial arteries.

Mechanism of respiration. Breathing movements occur in two steps, the gill chambers working as suction pumps.

• Inspiration. During inspiration, opercula and branchiostegal membranes press against the body keeping the two external branchial apertures tightly closed.
• The gill arches bulge laterally enlarging the internal capacity of the bucco-pharyngeal cavity which acts like a suction pump. As a result, the oral valves open and water flows in through the opened mouth to fill the bucco-pharyngeal cavity.
• Expiration. Now the oral valves close shutting the mouth, the gill arches contract and the opercula and branchiostegal membranes lift, opening the external branchial apertures.
• Consequently, water under pressure is forced to pass over gill filaments and out through the external branchial apertures.
• Physiology of respiration. The afferent branchial artery bringing deoxygenated blood breaks up into capillaries into lamellae of gill filaments where the exchange of gases occurs by osmosis through their thin walls.
• As first respiratory Water passes over gill filaments, their blood gives up CO₂, and absorbs O₂, from water. The efferent branchial artery carries away oxygenated blood from the gill to the body. it soon needs a constant supply of fresh O₂-bearing water for life.
• If water is depleted of O2 or fish is removed from the water, it soon dies due to lack of oxygen, called asphyxiation.

NEET Biology Respiratory System In Animals Respiration In Frog

Amphibians such as frogs carry out:

1. Cutaneous respiration
2. Buccopharyngeal respiration
3. Pulmonary respiration
   • During hibernation (winter sleep), frog respires with the help of moist skin only.
   • In frogs, skin is seen as an accessory organ of respiration.
   • In frogs, cutaneous respiration takes place always.
   • The lungs of frogs are spongy masses of tissues.
   • Compared to a mammal, pulmonary respiration of a frog is not very efficient.
   • In frogs, the diaphragm is absent and is not related to respiration.
   • Contraction of sternal muscle during breathing in frogs lowers the floor of the buccopharyngeal cavity.
   • Contraction of propyl muscle during breathing in frogs raises the floor of the buccopharyngeal cavity.
   • The epithelial lining of the alveoli of a frog’s lung-facing lung cavity is columnar and ciliated.
   • During pulmonary respiration of a frog, the mouth remains closed.
   • In frogs, the glottis is controlled by the muscle of the arytenoid cartilage.

NEET Biology Respiratory System In Animals Respiratory Organs of Human

The respiratory system is derived from the ectoderm. It consists of the respiratory tract and respiratory organs (lungs)

Nasal Chamber. Nasal chambers communicate to the exterior by two openings called nostrils or external nares (separated by mesethmoid bone); a cavity inferior to the cranium and superior to the mouth; internally (posteriorly) opens in the pharynx through two internal nares.

1. Four paranasal sinuses called frontal, sphenoidal, maxillary and ethmoidal along with nasolacrimal ducts open into the nasal chamber.
2. Ethmoid bone forms the roof and palatine maxilla and hard palate forms the floor of the nasal chamber.
3. A vertical nasal septum divides the anterior part of the nasal cavity into right and left vestibules surrounded by cartilage and lined with coarse hairs to filter dust particles.
4. The posterior cavity has projections of superior, middle and inferior conchae or turbinal bone and is lined with the mucous membrane.
5. The superior part of the cavity has an olfactory region lined with a Schneiderian membrane. Below it, there is the lining of pseudostratified cells which also secrete mucus.
6. As the air passes around and over the turbinal, it is wanned or cooled and disinfected and the moistened mucus traps the dust particles. Thus breathing through the nose is always preferred to breathing through the mouth.

NEET Biology Respiratory System In Animals Pharynx

• It is 13 cm long, starting with the soft palate area representing the crossing point of the air route and food route. Uvula, the free posterior and muscular part of the soft palate divides it as the anterior oropharynx and posterior nasopharynx.
• The nasopharynx is (ho posterior part of the pharynx behind the nasal cavity. Tltcrc openings in its walls, two internal narcs and two openings or Eustachian tube.
• The lower part of the pharynx is called InrynRophnrynx extends down the hyoid bone, and opens into the oesophagus(gullet) and larynx (glottis) anteriorly; lined with stratified squamous epithelium.

NEET Biology Respiratory System In Animals Larynx Voicebox

• The upper part of the trachea makes a cartilaginous box with a pair of arytenoid cartilage and three single cartilage pieces: thyroid cartilage, cricoid cartilage and epiglottis. The other two supporting cartilages are corniculate and cuneiform.
• Adam’s apple in males is formed by enlargement of thyroid cartilage due to the effect of male sex hormones after puberty. The epiglottis acts as a valve over the glottis.

Trachea (windpipe). A tube of about 6 cm in length and 2.5 diameters supported with dorsally incomplete (C-shaped) rings of hyaline cartilage.

1. The trachea lies mainly in the median plane anterior to the oesophagus.
2. The cartilages are incomplete posteriorly and even when there is no air, the trachea does not collapse due to the presence of incomplete ‘C’ shaped cartilaginous rings (tracheae of cockroaches also have non-collapsible walls).
3. The mucosa of the trachea is lined with a ciliated pseudostratified epithelium containing mucus-secreting goblet cells and this helps in pushing mucus out.
4. Bronchi: In the thorax, the trachea divides into the right and left primary bronchus with the cartilaginous ring.
5. Within the lungs, it branches into bronchioles—primary, secondary and tertiary (or terminal) bronchioles leading to alveoli. Bronchioles are without cartilaginous rings.

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NEET Biology Respiratory System In Animals Lungs The Respiratory Organs

These are paired, cone-shaped, spongy organs in the thoracic cavity enclosed within the pleural cavity. The outer pleuron attached to the wall of the thoracic cavity is called the parietal pleura and the inner layer is called the visceral pleuron.

• The two layers of pleura are separated by a thin pleural cavity, filled with a small amount of pleural fluid secreted by epithelial cells.
• The space between the right and left pleural cavities is the mediastinum.
• The trachea lies mainly in the median plane anterior to the oesophagus.
• The mucosa of the trachea is lined with a ciliated pseudostratified epithelium containing mucus-secreting goblet cells and this helps in pushing mucus out.
• The right and left lungs are divided into three and two lobes respectively.
• The left lung contains a concavity called the cardiac notch in which the heart lies.
• The right lung is thicker and broader but shorter than the left lung because the diaphragm is higher on the right side to accommodate the liver lying below it.
• Terminal (or respiratory) bronchioles divide to form many alveolar ducts or atria with many alveoli around.
  1. Each lung is a blunt cone; the tip or apex points superiorly.
  2. The broad inferior portion or base of each lung rests on the superior surface of the diaphragm.
  3. The lungs possess distinct lobes that are separated by deep fissures.
  4. In man, the right lung has three lobes; superior, middle and inferior, separated by the horizontal and oblique fissures.
  5. The left lung has only two lobes superior and inferior, separated by the oblique fissure.
  6. Medially, the left lung contains a concavity, the cardiac notch, in which the heart lies.
  7. Branches of pulmonary artery supply deoxygenated blood to each lung.

NEET Biology Respiratory System In Animals Diaphragm

The diaphragm (dia, across; phragm, wall) is characteristic of mammals.

1. The diaphragm is a dome-shaped muscular structure separating the thoracic and abdominal cavities.
2. The diaphragm forms the floor of the thoracic cavity and the roof of the abdominal cavity.
3. The diaphragm is composed of a peripheral muscular portion mid a central portion called the central tendon.
4. The most important function of the diaphragm of mammals is to aid in respiration.
5. Puncturing of the diaphragm results in a stoppage of breathing and is fatal.
6. The term ‘phrenic’ is associated with the diaphragm.
7. The diaphragm is supplied by the phrenic nerves.

NEET Biology Respiratory System In Animals Mechanism Of Respiration

1. The process is completed in three steps breathing, pulmonary ventilation and transport of gases in blood.
2. Breathing (Pulmonary ventilation). It means inflow (inspiration) and outflow (expiration) of air
3. Breathing is affected by the expansion and contraction of the lungs. Since the lung capillaries are constantly removing oxygen from the air and putting carbon dioxide in the alveoli, the need for replacing the air in the lungs is obvious.
4. If a normal breath consists of about 500 ml of air, this could be multiplied by 16 to yield a volume of about 8 litres per minute.
5. In human beings and other mammals the ribs, chest muscles (intercostal) and diaphragm are easily movable and the volume of the chest cavity can be increased or decreased at will.
6. The downward and upward movement of the diaphragm lengthens and shortens the chest cavity. At the floor of the chest cavity, the diaphragm, contracts decreasing its convexity and consequently enlarging the cavity.
7. Because the space is closed, this increase in volume results in a lowering of the pressure in the lungs, and when it falls below atmospheric pressure air from the outside rushes in through the trachea and its branches to the air sacs and alveoli.
8. The elevation and depression of ribs increase or decrease the diameter of the chest cavity. During inspiration, the rib muscles contract, drawing the front ends of the ribs upward and outward, an action made possible by the hinge-like connection of the ribs with the vertebrae.
9. During inspiration the lungs are distended as they are filled with air, when the rib muscles relax, the ribs are permitted to return to their original position and the simultaneous relaxation of the diaphragm permits the abdominal organs to push it back up to its previous convex shape.
10. These factors decrease the chest cavity and allow the distended elastic lungs to contract and expel the air which had been inhaled.
11. In big and heavy animals, the diaphragm plays a more important role than the ribs (elephants), on the other hand, jumping animals like kangaroo and monkeys utilize rib muscles rather than the diaphragm in breathing.
12. Breathing using ribs is believed to the relatively more pronounced in human females than in males.
13. This difference in respiratory mechanism is merely an adaptation brought about by pregnancy during which period the presence of a growing foetus interferes somewhat with the freedom of the movement of the diaphragm.
14. During inspiration the alveolar pressure falls below atmospheric one so air rushes in and during expiration, alveolar pressure goes above the atmospheric pressure and thus air goes out. Thus normal breathing is negative pressure breathing.
15. Lungs act as suction pumps
16. During the exhalation of air or expiration, the diaphragm relaxes and the lungs are compressed.
17. During exhalation, the capacity of the thoracic cavity decreases due to inward as well as downward movement of rib cages as well as inward movement of the diaphragm.
18. During exercise rate of breathing increases (Exchange and transport of gases are discussed separately).

NEET Biology Respiratory System In Animals Exchange Of Gases

1. Exchange of Gases. Between the process of inspiration and expiration, the interchange of aspirating gases occurs.
2. This interchange takes place between the blood of the capillary network which suspends the alveoli and the air in the alveoli of the lungs.
3. In external as well as internal respiration, gases always tend to diffuse from high partial pressure to low partial pressure i.e., down the concentration gradient.
4. The Pressure of gases in the Wood is usually expressed as gas tensions, (Partial pressure) The oxygen tension in alveolar air lOOmm of Hg. Oxygen tension in venous blood = 40mm Hg. A pressure difference of 60mm of Hg serves to drive Oxygen from the alveoli of the lung into the blood.
5. The CO2 tension in alveolar air = 40 mm Hg CO₂ census venous blood = 46 mm of Hg. A relatively small difference of 6 nun flag is sufficient to drive CO₂ from the blood into the lung.
6. During internal respiration i.e. interchange of gases between the tissue and the blood takes place. The physical basis of gas diffusion is the same i.e., down the concentration gradient.

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NEET Biology Respiratory System In Animals Transport Of Gases

Transport of Oxygen by Blood

• Oxygen is transported in the blood by a respiratory pigment, haemoglobin, which is a conjugated protein.
• Haemoglobin consists of a large protein molecule, the globin consisting of four polypeptide chains (two a and two p chains) each of which attached a prosthetic heme group. Heme is based on a structure known as porphyrin ring structure which includes four pyrol groups around a central Fe.
• The transport of oxygen by the blood from the lungs to the tissues is mainly due to the ability of haemoglobin to combine reversibly with oxygen. Since one molecule of haemoglobin has four heme groups, and each Hb molecule is capable of taking up four molecules of O₂.
• Haemoglobin is dark red whereas oxyhaemoglobin is bright red. Oxyhaemoglobin on reaching the tissue dissociates into free O₂ and haemoglobin. Again O2 diffuses into tissue because of the difference in partial pressure.

Transport of CO₂ from tissues to lungs

1. A small amount of CO₂ is transported in a dissolved state in the plasma of blood.
2. About 70% of CO₂ produced enters R.B.C. by diffusion. Each decilitre (100 ml) of blood receives 3.7 ml of CO₂ from tissue and the rest of the CO₂ diffuses into blood plasma to form carbonic acid with water.
3. CO₂ is also transported as carbamino-haemoglobin (reduced haemoglobin) inside R.B.C

NEET Biology Respiratory System In Animals Haldane Effect

• Oxyhaemoglobin behaves as a strong acid and as more and more oxyhaemoglobin is formed, it releases more H+ ions which decreases the pH of blood.
• Role of haemoglobin in the transport of oxygen from lungs to tissue
• In a normal healthy person, there is about 15 gm of Haemoglobin per 100 ml of blood.
• The capacity of 1 gm of Hb to combine with oxygen is 1.34 ml. Thus on average, 100 ml of blood transports 20 ml (19.4) ml of oxygen.
• When oxygen diffuses into the blood in external respiration most of it enters the red blood or erythrocytes and unites with the haemoglobin in these cells forming a compound called oxyhaemoglobin.
• Haemoglobin is a complex protein compound containing iron which has a great affinity for oxygen. This property of haemoglobin enables the blood to carry about 50 times more oxygen than the plasma alone can carry.
• As the blood passes through the alveolar capillaries, the haemoglobin becomes saturated with oxygen. This reaction may be represented as follows :
• Oxyhaemoglobin is a very unstable compound and, when the blood reaches the capillaries in the tissue, throughout the body where the oxygen tension is low, the compound breaks down into haemoglobin and oxygen and the oxygen diffuses into the cells.
• The reaction which occurs in the tissue capillaries may be indicated in the following way:
  • Hb + O₂→HbO₂
• Oxyhaemoglobin has a bright scarlet colour while reduced haemoglobin has a dull purplish colour. This counts for the difference in colour between arterial and venous blood.

Role of carbonic unitydruse enzyme In the transport of gases during respiration. Carbonic is an enzyme found in the erythrocytes. It takes part in the joining of CCK with water to form Carbonic acid. It is completed in less than one second.

• HbO₂→Hb + O₂

NEET Biology Respiratory System In Animals Hamburger’s Phenomenon

1. When whole blood is saturated with CO₂. the following changes are commonly seen :
2. The bicarbonate content of plasma and corpuscle is increased.
3. The chloride (Cl‾) of plasma is diminished and that of the cells (RBCs) is increased.
4. The total base (cation) of both corpuscles and plasma remains unchanged.
5. Water content and the volume of CO₂ are increased in blood.

But when CO₂ is removed from the blood, reverse changes occur. Now it is evident that when CO₂ enters blood, chlorine from plasma enters the RBC while Na is left behind. When CO₂ escapes from the blood, Cl‾ leaves the cells, enters the plasma and combines with the base Na. Due to this alternate movement of Cl‾, this phenomenon is called the chloride shift

NEET Biology Respiratory System In Animals Haemoglobin

• The oxygen carrier or respiratory pigment in the blood of vertebrates is haemoglobin.
• Haemoglobin is a protein (5% haeme and 95% globin), its molecule is made up of four polypeptides, two -chains and two chains.
• The O₂ dissociation curse for Myoglobin is rectangular hyperbola.
• Each of the four chains is linked to a prosthetic group: iron-containing Heme group with the amino acid histidine acting as the linker site.
• The total molecular weight, of haemoglobin, is 34.000.
• Here is the respiratory carrier part and each unit contains a central iron atom which is in the ferrous (Fe+ +) state.
• It is this iron atom that combines with oxygen.
• The metal constituent of haemoglobin is iron.
• One molecule of haemoglobin can carry as much as four oxygen molecules.
• The chemical formula of oxyhaemoglobin is Hb(O₂)4.
• A normal person has bout 15 grams of haemoglobin per 100 rnL of blood.
• One gram of haemoglobin binds about 1.34 mL of O₂. Thus, 100 tnL of pure blood carries about 20 mL of oxygen.
• Oxygen is transported from the lungs to the tissues combined with Hb rather than dissolved in blood plasma.
• The oxygen content of blood leaving the lungs is greater than that of blood entering the lungs.
• The blood coming out of the lungs is richer in oxygen than of blood entering the lungs.
• 100 mL of oxygenated blood contains only about 1.5% oxygen dissolved in plasma. The remaining 98.5% is carried in the form of HbO₂.

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NEET Biology Respiratory System In Animals Oxygen Dissociation Curve

Normally haemoglobin (respiratory pigment) combines with oxygen. Each iron atom of the iron porphyrin ring complex can attach with one molecule of O₂ and when all the sites are occupied, the haemoglobin cannot take on any more since it is fully loaded or saturated.

• This situation varies greatly. In other words, the proportion of oxyhaemoglobin to haemoglobin present in the blood at any time is dependent upon the tension of O₂ in the blood. This is known as the dissociation curve of haemoglobin.

In this way, the actual relationship between the partial pressure of O₂ and the degree of saturation of haemoglobin with O₂ can be shown by the remarkable oxygen haemoglobin dissociation curve.

Shifting Of Oxyhaemoglobin Dissociation Curve

1. In all the following conditions the dissociation curve (Sigmoid-shaped) shifts to the right-hand side and the affinity of haemoglobin for oxygen decreases to release or dissociate more oxygen to the tissues.
2. When the concentration of carbon dioxide increases (CO2, conc.↑↑)
3. When temperature increases (Temp.↑ )
4. When acidity increases or pH decreases (acidity↑)
5. When altitude increases (Altitude↑)
6. When amount of2, 3 DPG (Diphosphoglyceraldehyde( increases in RBCs (2, 3 DPG).
7. When conditions are opposite, the curve shifts to the left-hand side.

Bohr’s Effect. When the pH of the blood decreases (acidity increases) the p50 value increases and the affinity of haemoglobin for oxygen decreases. This effect or law is called Bohr’s effect.

NEET Biology Respiratory System In Animals Breathing Control

Breathing control. Breathing is regulated through nerve impulses and chemical impulses.

Nervous control. Russian Scientist N. Mislavsky (1885) reported that the Respiratory centre (inspiratory and expiratory) is located on the floor of the medulla oblongata and pneumonitis centre in pons Varolii.

1. From this centre impulse is transmitted via the phrenic nerve to the diaphragm and rib muscles which then contract and enlargement of alveoli stimulates stretch receptors, and the impulse is transmitted by the vagus nerve back to the medulla, stopping the impulse of the phrenic nerve.
2. The muscles relax, reducing the cavity and the body exhales. The process is repeated. However, forced breathing is under the control of the cerebrum.

Chemical control. Kussumal and Tenner postulated that the venosity of blood of cerebral circulation also influences respiration. A chemical-sensitive area located close to the respiratory centre in the medulla maintains the proper concentration of O₂, CO₂ and H+ in the blood and body fluid. It is sensitive to changes in CO₂ or pH in blood although the oxygen content is hardly changed.

Hering Breurer reflex. Located in the walls of bronchi and bronchioles are certain centres. They are stimulated when the lungs are overstretched and transmit impulses through the vagus nerve to the respiratory centre. It serves as a protective mechanism for preventing lung inflation.

Bohr effect. Changes in CO₂ concentration in the blood greatly affect the oxygenation of blood in the lungs as well as the release of O₂ from the blood in the tissue because deoxygenation of haemoglobin is directly proportional to the CO₂ of blood. It is called Bohr’s effect.

According to this effect, as blood passes through the lungs, CO₂ readily. diffuses from it into the alveoli. This reduces blood CO₂ and increases its pH. Both these changes make the media unsuitable for deoxygenation but suitable for oxygenation of haemoglobin. Hence, these enhance the binding of more and more O₂ with haemoglobin.

NEET Biology Respiratory System In Animals Pulmonary Air Volumes

• Pulmonary air volume. It is because of the pressure gradient that the air flows into and out of the lungs. The amount of air exchanged during breathing is measured by an apparatus called a spirometer.
• The following terms explain various pulmonary air volumes. Tidal volume (TV). The amount of air that flows in and out of the lungs with each respiratory movement at rest. (500 ml in adults).

1. Inspiratory reserve volume (1RV). The volume of forced inspired air in addition to normal inspired air (tidal volume) is called inspiratory reserve volume. (About 2000-2500 ml).
2. Expiratory reserve volume (ERV). The volume of air that expires forcefully in addition to normal expired air is called expiratory reserve volume (About 1000 ml).
3. Residual volume (RV). The volume of air left in the lungs and respiratory passage is called residual volume (1500 ml).
4. Vital capacity. The quantity of air that a person can expel by forcible exhalation after the deepest inhalation (4000 ml in adult man).
5. Total lung capacity. It is the total of vital capacity and residual volume. (5 to 6 litres).
   • The combinations of specific lung volumes are termed lung capacities. Four lung capacities are :
   • Inspiratory Capacity (IC) is the sum of tidal volume and inspiratory reserve volume (500 + 3100 = 3600 mL).
   • Functional Residual Capacity (FRC) is the sum of residual volume and expiratory reserve volume (1200 + 1200 = 2400 mL).
   • Vital Capacity (VC) is the sum of inspiratory reserve volume, tidal volume and expiratory reserve volume (3100 + 500 + 1200 = 4800 mL).
   • Total Lung Capacity (TLC) is the sum of the vital capacity and residual volume (4800 + 1200 = 6000 mL).

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NEET Biology Respiratory System In Animals Protective Response Of Respiratory System

1. Coughing. Coughing results from irritation of the larynx, trachea and bronchi caused by smoking and allergy to dust and pollen. It involves deep inspiration, closure of vocal cords, and violent expiration due to vigorous contractions of abdominal muscles accompanied by sudden gaping of vocal cords.
2. Sneezing. Spasmodic contraction of muscles of expiration forcefully expels air through the nose and mouth. Stimulus may be an irritation of the nasal mucosa. It involves a deep inspiration (“ah”) and a violent expiration (“…… choo”) through the nose and mouth.
3. Shut Down. When air containing noxious chemicals, such as acid vapour, is inhaled, the respiratory system is momentarily shut down.

Respiratory Disorders

1. Hypoxia. Lack of O₂ in body fluids is called hypoxia.
2. Artificial Hypoxia. It results from a shortage of oxygen in the air at high (over 2400 m.) altitudes. It causes mountain sickness characterised by breathlessness, headache, dizziness, nausea, vomiting, mental fatigue and a bluish tinge on the skin and mucous membranes.
3. Anaemic Hypoxia. It results from the reduced oxygen-carrying capacity of the blood due to anaemia (decreased haemoglobin content in blond) or carbon monoxide poisoning (some haemoglobin occupied by CO). In both cases, less haemoglobin is available for carrying O2
4. Histotoxic hypoxia. It is oxygen deficiency at the tissue level caused by cyanide poisoning which inactivates the enzyme system of the electron transport chain or cells,
5. Emphysema. It is a disorder of the lungs as they lose their elasticity and permanently get distended.
6. Asphyxia (suffocation). The O, content of blood falls whilst the CO, content rises and paralyses the respiratory centre. Breathing stops and detail occurs.
7. Orthopnea. Inability to breathe in a horizontal position.
8. Hypercapnia. It means excess of CO2 in the body fluids.
9. Pleurisy (plcuritis). Inflammation of pleural membranes.
10. Epistaxis. It is the nose bleeding.
11. Cyanosis. It means blueness of the skin and its cause is an excessive amount of deoxygenated haemoglobin in the skin’s blood vessels.
12. Bad cold. Disease-causing microbes present in the air attack the respiratory tract, producing inflammation of the mucous membrane in various regions and increased secretion
    • Rhinitis in the nasal chambers;
    • Sinusitis in the sinuses;
    • Pharyngitis in the pharynx, often called sore throat, is usually accompanied by tonsillitis (enlargement of tonsils);
    • Laryngitis in the larynx, causes a hoarse voice and difficulty in speaking.
    • Bronchitis in the bronchioles;
13. Pneumonia. The disease of the lungs and respiratory tract is caused by the bacterial infection Diplococcus pneumoniae. It results in a deficiency of 0₂ as these organs get clogged.
14. COPD. Chronic Obstructive Pulmonary Disease which includes Emphysema, Chronic bronchitis and Asthma.
15. Whooping cough or Pertussis. An infectious disease caused by the bacterium Bordetella pertussis.
16. Asthma – Difficult breathing due to spasms in branchial muscles and narrowing of bronchi.
17. Sleep Apnoea Syndrome (SAS). Persons with snoring habit suffer from sleep apnoea syndrome because their upper respiratory tract closes on inhalation leading to apnoea and sleep breaks.
18. Atelectasis. Mean collapse of alveoli. Lack of surfactant also leads to atelectasis.
19. Pleuritis – Inflammation of pleural membrane.

NEET Biology Respiratory System In Animals Larynx

It is also called a voice box or Adam’s apple. It is a small, wide, thin-walled, tubular chamber present at the beginning of the neck. It is more developed in males after attaining puberty so they have a deeper voice. It is supported by four cartilages

• Thyroid cartilage. It is the largest sized and C – C-shaped cartilage which supports the anterior and lateral sides of the upper part of the larynx.
• The posterior border of each lamina gives two processes- superior and inferior cornu while the ventral side of its anterior part gives a bilobed cartilaginous process called epiglottis to close the glottis during swallowing.
• Arytenoids. These are two smallest-sized, pyramid-shaped cartilages which support the posterior wall of the upper part of the larynx.
• Cricoid. It is a ring-shaped cartilage which completely supports the lower part of the larynx. Within the larynx, there are two yellow fibrous folds called vocal cords extending between the arytenoids and thyroid cartilages.
• Vocal cords are longer in males (about 2-3 ) than in females (about 1.7 cm). Each vocal cord is covered by a stratified squamous epithelium. Between two vocal cords, there is a slit-like glottis which is usually open to allow the unobstructed supply of air but can be closed by epiglottis during swallowing.
• Vocal cords can be stretched or relaxed, and the size of the glottis can be changed with the help of the Laryngeal muscle.

• Certain small amphibians, such as Plcurodont salamander have no lungs and respire only by skin.
• Respiratory quotient. The ratio of the volume of carbon dioxide evolved and oxygen consumed during a given period of respiration is termed respiratory quotient (R.Q.).
• Sachs (1890) discovered anaerobic respiration. Hacmocynnin is blue-coloured when oxygenated and colourless when deoxygenated.
• The trachea of man is supported by “C” shaped cartilaginous rings and that of insects by conidia (spiral cuticular) lining. In some turtles, the cloaca acts as a respiratory organ.
• The respiratory centre is situated in the medulla oblongata of the man.
• Forced breathing is regulated by the cerebrum. The dissociation curve is associated with haemoglobin. Annelids (mostly earthworms) have two respiratory pigments i.e. haemoglobin and erythrocruorin. The breathing rate increases with an increase in the body temperature of a man.
• Rats have the highest metabolic rate.
• Decompression sickness is also known as Caisson Disease or Diver paralysis.
• Molpadin respiratory pigment occurs in Molpadia. Examples: Class Holothuroidea of phylum echinodermata.
• Philip Drinker, an American Engineer invented a tank respirator or iron lung in 1929.
• Turbinals (nasal conchae) are derived from nasals, maxillae and ethmoids.
• The diaphragm forms the concave surface of the floor of the thoracic cavity and the convex surface of the abdominal cavity.
• The diaphragm plays a 75% part in abdominal breathing.
• The diaphragm is supplied with blood by the phrenic artery.
• The diaphragm is innervated by the phrenic nerve.
• Ribs and sternum play a 25% part in breathing, i.e. thoracic breathing.
• Chloride shift is also called Hamburger’s phenomenon.
• A swim bladder is not found in flatfishes.
• A slug (a mollusc) is purely an air breather.
• Zinc is a constitutent of enzyme carbonic anhydrase.
• The haemoglobin of the foetus has a higher affinity for oxygen than the mother’s haemoglobin.
• Vocal cords in the larynx are attached to the arytenoid cartilage.
• Cartilage of Santorini. It is the band at the apex of the arytenoid cartilage.
• In the larynx, the cartilages present are thyroid cartilage (largest), cricoid cartilage, and arytenoid cartilage.
• The wall of the alveoli is lined by squamous epithelium.
• In frog respiration = Cutaneous : 35% + Buccopharyn- cs> gcal: 9% + Pulmonary : 56%
• Water lungs are present in the holothuria of chinodermata.
• In some marine annelids such as sandworm [Nereis] the locomotory appendages called parapodia are adapted for the exchange of gases.
• Prawn has 8 pairs or rows of gills while common carp (Labeo) has 4 pairs of gills.
• The counter-current flow of blood and water in the gills maximises the absorption of oxygen.
• Peripatus breathes through the trachea.
• Breathing with the help of ribs is more pronounced in females.
• About half a litre of water goes out during expiration per day.
• During single circulation, only 25% of haemoglobin gives up oxygen.
• Larvae of urodeles and anurans draw a current of water through the nasal chamber, Marine turtles snakes, and many land lizards have salt-secreting- nutria! gland anterior and median to Jacobson’s organ, They remove NaCl from the body.
• In Kiwi, the external nares lie almost at the tip of the beak.
• Marine birds such as herring gulls, pelicans, cormorants etc. have salt glands that supplement in excreting NaCl.
• Visceral pouches called gill pouches, branchial pouches or visceral clefts put the pharynx in communication with the exterior. The openings of branchial pouches into the pharynx are known as internal gill slits and those to the exterior as external gill slits.
• The skin of certain fishes carries on respiration For Example. Periopthalmia, goggle-eyed fishes of India.

Respiration In Plants NEET Exam Preparation

NEET Biology Respiratory System In Animals Questions from Competitive Examinations

Question 1. Which of the following cells do not respire :

1. Epidermal cells
2. Erythrocytes
3. Sieve Cells
4. Conical cells.

Answer: 2. Erythrocytes

Question 2. Which of the following represents Adam’s apple?

1. Thyroid cartilage of larYnx
2. Arytenoid cartilage of larynx
3. Cricoid cartilage of larynx
4. All of the above.

Answer: 1. Thyroid cartilage of larYnx

Question 3. What is the amount of oxygen absorbed by one gram of haemoglobin?

1. 135 ml
2. 13.4 ml
3. 1.34 ml
4. 20 ml.

Answer: 3. 1.34 ml

Question 4. What is called insufficiency of O₂?

1. hypoxia
2. xeroxia
3. angina
4. cough.

Answer: 1. hypoxia

Question 5. Tidal volume is :

1. 5000 ml
2. 1000 ml
3. 500 ml
4. 800 ml.

Answer: 3. 500 ml

Question 6. R.Q. is infinite in :

1. aerobic respiration
2. anaerobic respiration
3. carbohydrates
4. None of these.

Answer: 2. anaerobic respiration

Question 7. The end products of fermentation are :

1. ethyl alcohol and CO₂
2. ethyl alcohol and O₂
3. methyl alcohol and CO₂
4. methyl alcohol only.

Answer: 1. ethyl alcohol and CO₂

Question 8. CO₂ is carried mainly in the form of:

1. bicarbonates
2. carboxy haemoglobin
3. plasma
4. none of the above.

Answer: 1. bicarbonates

Respiration In Plants NEET Syllabus Topics

Question 9. The air that enters our lungs :

1. Is warm
2. Is filtered
3. Some oxygen is extracted
4. Some CO₂ is added.

Choose The Correct Option 

1. A, B, C, D
2. B and D
3. A and B
4. C and D

Answer: 2. B and D

Question 10. The exchange of gases in the lungs is by :

1. Simple diffusion
2. Active transport
3. Passive transport
4. Osmosis

Answer: 1. simple diffusion

Question 11. Artificial respiration at the rate of 10-15 times per minute is being given to a man saved from drowning. This is because :

1. Water in the respiratory passage is cleared fast at this rate
2. Choking is least at this rate
3. It is a normal rate of respiration
4. Lungs are ventilated best at this rate.

Answer: 4. Lungs are ventilated best at this rate.

Question 12. Pasteurization of milk means that :

1. All bacteria are killed
2. Pathogenic bacteria are killed
3. Milk is enriched with vitamins
4. Milk casein is partially digested.

Answer: 1. All bacteria are killed

Question 13. In which one of the following do the two names refer to the same thing?

1. Tricarboxylic acid cycle and citric acid cycle
2. Citric acid and Calvin cycle
3. Tricarboxylic acid cycle and urea cycle
4. Krebs cycle and Calvin cycle,

Answer: 1. Tricarboxylic acid cycle and citric acid cycle

Question 14. What is the coned sequence of air passage in man?

1. Nasal cavity→ pharynx→ larynx → trachea → bronchi → bronchioles → alveoli
2. Nasal cavity → larynx-→ bronchi→ pharynx → trachea → bronchioles→ alveoli
3. Nasal cavity → larynx → pharynx → trachea→ bronchi→ bronchioles→ alveoli
4. Nasal cavity → pharynx → trachea → larynx → bronchi→ bronchioles→ alveoli.

Answer: 1. Nasal cavity -→ pharynx → larynx→ trachea→ bronchi → bronchioles→ alveoli

Question 15. When protein is aerobically oxidised, the R.Q. value will be :

1. One
2. Zero
3. More than one
4. Less than one.

Answer: 4. Less than one

Question 16. During expiration, the diaphragm becomes :

1. Normal
2. Flattened
3. Dome-shaped
4. Oblique.

Answer: 3. Dome-shaped

Respiration In Plants NEET Syllabus Topics

Question 17. An example of the Pasteur effect is :

1. Saccharomyces
2. Nostoc
3. Penicillium
4. Pinnularia.

Answer: 1. Saccharomyces

Question 18. Respiratory quotient (R.Q.) is represented by :

1. O₂ / CO₂
2. C/N
3. N₂/O₂
4. CO₂/O₂

Answer: 4. CO₂/O₂.

Question 19. Severe Acute Respiratory Syndrome (SARS) is :

1. Caused by a variant of Pneumococcus pneumonia
2. An acute form of asthma
3. Caused by a variant of coronavirus
4. Affects non-vegetarians faster.

Answer: 3. Caused by a variant of coronavirus

Question 20. When CO₂ concentration in the blood increases, breathing becomes :

1. Slow and deep
2. Faster and deeper
3. Shallower and slow
4. No effect on breathing.

Answer: 2. Faster and deeper

Question 21. The dough kept overnight in warm weather becomes soft and spongy because of :

1. Cohesion
2. Osmosis
3. Absorption of CO₂ from the atmosphere
4. Fermentation.

Answer: 4. Fermentation.

Question 22. In glycolysis, during oxidation electrons are removed by :

1. NAD⁺
2. Molecular oxygen
3. ATP
4. Glyceraldehyde-3-phosphate.

Answer: 1. NAD⁺

Question 23. Blood analysis of a patient reveals an unusually high quantity of carboxyhaemoglobin content. Which of the following conclusions is most likely to be correct? The patient has been inhaling polluted air containing unusually high content of :

1. Carbon disulphide
2. Chloroform
3. Carbon dioxide
4. Carbon Monoxide

Answer: 4. Carbon Monoxide

Question 24. The major function of respiration is

1. Transfer of Co₂
2. Release of CO₂
3. Release of O₂
4. Anabolism

Answer: 2. Release of CO₂

Question 25. The respiratory quotient is defined as :

Answer: 2.

Question 26. Respiration is controlled by  :

1. Medulla oblongata
2. cerebellum
3. hypothalamus
4. cerebrum.

Answer: 1. Medulla oblongata

Respiration In Plants NEET Notes

Question 27. R Q. of fat is :

1. more than one
2. one
3. less than one
4. infinite.

Answer: 3. less than one

Question 28. Which does not affect the oxyhaemoglobin curve :

1. high O₂ and low CO₂
2. high body temperature
3. high O2 and high haemoglobin
4. high pH.

Answer: 3. high O₂ and high haemoglobin

Question 29. After taking a long deep breath we do not respire for some seconds due to :

1. More CO₂ in blood
2. More O₂ in the blood
3. less CO₂ in blood
4. less O₂ in blood.

Answer: 1. More CO₂ in blood

Question 30. Formation of non-functional methaenoglobin causes blue-baby syndrome. This is due to :

1. excess of arsenic concentration in drinking water
2. excess of nitrates in drinking water
3. deficiency of iron in food
4. increased methane content in the atmosphere.

Answer: 2. an excess of nitrates in drinking water

Question 31. Maximum amount of oxygen is exchanged from the blood in the

1. capillaries-surrounding tissue cells
2. arteries of the body
3. left auricle of the heart
4. capillaries surrounding the alveoli.

Answer: 1. capillaries-surrounding tissue cells

Question 32. Match the disorders given in Column 1 with symptoms under Column 2. Choose the answer which gives the correct combination of alphabets with numbers.

1. A = 4. B = 2. C = 5. D = 1
2. A = 5. B = 3. C = 2, D = 1
3. A = 3. B = 1. C = 5. D = 4
4. A = 2. B = 4. C = 1. D = 3.

Answer: 4. A = 2. B = 4. C = 1. D = 3

Question 33. If R.Q is 0.6 in respiratory metabolism, it would mean that

1. Carbohydrates are used as respiratory substrates.
2. Organic Acids are used as respiratory substrates.
3. The oxidation of the respiratory substrate consumed  more oxygen than the amount of CO2 released
4. The oxidation of the respiratory substrate consumed less oxygen than the amount of CO2 released

Answer: 3. The oxidation of the respiratory substrate consumed  more oxygen than the amount of CO2 released

Question 34. Statements

A. Carbonic anhydrase is present in the erythrocytes

B. In erythrocytes the carbon dioxide combines with water and is transported.

1. statement A is correct and is responsible for statement B
2. statement A is not correct but statement B is correct
3. both statements A and B are wrong
4. statement A is correct but not involved in statement B
5. statement A is correct and statement B is wrong.

Answer: 1. statement A is correct and is responsible for statement B

Question 35. Which of the following statements are true/false?

1. The blood transports CO₂ comparatively easily because of its higher solubility.
2. Approximately 8.9% of CO₂ is transported being dissolved in the plasma of blood
3. The carbon dioxide produced by the tissues, diffuses passively into the bloodstream and passes into red blood corpuscles and reacts with water to form H₂C₃.
4. The oxyhaemoglobin (HbO₂) of the erythrocytes is basic.
5. The chloride ions diffuse from plasma into the erythrocytes to maintain ionic balance.

1. 1, 3 and E are true, 2 and 4 are false
2. 1, 3 and E are false, B and D are true
3. 1, 2 and D are true,  3and 5 are false
4. 1, 2 and D are false, 3 and E are true
5. 1, 2 and 3 are true, and 4 and 5 are false.

Answer: 1

Glycolysis And Krebs Cycle NEET Study Material

Question 36. People living at sea level have around 5 million RBCs per cubic millimetre of their blood whereas those living at an altitude of 5400 metres have around 8 million.

1. people eat more nutritive food, therefore more RBCs are formed
2. people get pollution-free air to breathe and more oxygen is available
3. atmospheric O₂ level is less and hence more RBCs are needed to absorb the required amount of O₂ to survive
4. there is more UV radiation which enhances RBC production.

Answer: 3. atmospheric O₂ level is less and hence more RBCs are needed to absorb the required amount of O₂ to survive

Question 37. Column A represents diseases and Column B represents their symptoms, which of the following pairs is the correct match for them?

1. A- (3),  B – (1),  C – (2)
2. A- (2),  B – (1),  C – (3)
3. A- (3),  B – (1),  C – (1)
4. A- (2),  B – (1),  C – (1)

Answer: 1. A- (3),  B – (1),  C – (2)

Question 38. Maximum amount of oxygen is lost from the blood in the

1. capillaries surrounding the tissue cells
2. arteries of the body
3. capillaries surrounding the alveoli
4. left auricle of the heart.

Answer: 3. capillaries surrounding the alveoli

Question 39. Identify the correct statement with reference to the transport of respiratory gases by blood.

1. Haemoglobin is necessary for the transport of carbon dioxide and carbonic anhydrase for the transport of carbon dioxide
2. Haemoglobin is necessary for the transport of oxygen and carbonic anhydrase for transport of carbon dioxide
3. Only oxygen is transported by blood
4. Only carbon dioxide is transported by blood.

Answer: 2. Haemoglobin is necessary for the transport of oxygen and carbonic anhydrase for the transport of carbon dioxide

Question 40. The figure given below shows a small part of the human lung where the exchange of gases takes place. In one of the options given below, one part A, B, C or D is correctly identified along with its function.

Options :

1. C: arterial capillary – passes oxygen to tissues
2. A: alveolar cavity – the main site of exchange of  respiratory gases
3. D: capillary wall – exchange of O₂ and CO₂ takes place here.
4. B: red blood cell – transport of CO₂ mainly.

Answer: 2. A: alveolar cavity – the main site of exchange of  respiratory gases

Question 41. The ‘blue baby’ syndrome results from :

1. excess of dissolved oxygen.
2. excess of TDS (total dissolved solids)
3. excess of chloride
4. methenoglobin.

Answer: 4. methemoglobin

Question 42. Which one of the following statements is incorrect?

1. In insects, circulating body fluids serve to distribute  oxygen to tissues
2. The residual air in the lung slightly decreases the efficiency of respiration in mammals
3. The principle of counter-current flow facilitates efficient respiration in the gills of fishes
4. The presence of non-respiratory air sacs increases the efficiency of respiration in birds.

Answer: 1. In insects, circulating body fluids serve to distribute  oxygen to tissues

Question 43. Arrange the following in the order of increasing volume :

1. Tidal volume
2. Residual volume
3. Inspiratory reserve volume
4. Vital capacity.

Choose The Correct Option 

1. 1 < 3 < 2 < 4
2. 1 < 2 < 3 < 4
3. 1 < 4 < 3 < 2
4. 1 < 4 < 2 < 3.

Answer: 2. 1 < 2 < 3 < 4

Question 44. A large proportion of oxygen is left unused in the human blood even after its uptake by the body

1. Acts is a reserve during muscular exercise
2. Raises the Pco₂ of blood to 75 mm of Hg
3. Is enough to keep oxyhaemoglobin saturation at 96%
4. Helps in releasing more O₂ to the epithelial tissues.

Answer: 3. Is enough to keep oxyhaemoglobin saturation at 96%

Electron Transport Chain In Plants NEET Important Points

Question 45. Which of the following factors raises the Pco₂ of value and shifts the HbO₂, dissociation curve to the right and vice versa?

1. Rise in Pco₂
2. Fall in temperature
3. Rise in H+ ions (= fall in pH)
4. Fall in d iphospho glyceric acid.

Answer codes :

1. A and B are correct
2. B and D are correct
3. A and D are correct
4. A, B and C are correct.

Answer: A and D are correct

Question 46. “Increased asthmatic attacks in certain seasons are related to :

1. low temperature
2. inhalation of seasonal pollen
3. hot and humid environment
4. eating fruits preserved in tin containers.

Answer: 2. inhalation of seasonal pollen

47. Two friends are eating together at a dining table. One of them suddenly starts coughing while swallowing some food. This coughing would have been due to improper movement of :

1. Epiglottis
2. Diaphragm
3. Neck
4. Tongue.

Answer: 1. Epiglottis

Question 48. Oxygen toxicity is related with :

1. blood poisoning
2. collapse of alveolar walls
3. failure of ventilation of lungs
4. Both 1 and 2

Answer: 3. failure of ventilation of lungs

Question 49. Which of the following statements is not true?

1. A partial pressure of oxygen in deoxygenated blood is 40 mm Hg.
2. The partial pressure of oxygen in oxygenated blood is 95 mm Hg
3. The partial pressure of carbon dioxide in deoxygenated Blood is 95 mm Hg.
4. The partial pressure of oxygen in the alveolar air is 104 mm kg
5. The partial pressure of carbon dioxide in the Match the items in Column I with Column II and choose the correct option

Answer: 3. The partial pressure of carbon dioxide in deoxygenated Blood is 95 mm Hg.

Question 50. Match the items in Column I with Column II and choose the correct option

1. A = 3, B = 4, C = 2, D = 1, E = 5
2. A = 3, B = 1, C = 4, D = 5, E = 4
3. A = 3, B = 1, C = 2, D = 5, E = 4
4. A = 5, B = 4, C = 2, D = 1, E = 2
5. A = 4,  B = 3, C = 2,   D = 1   E = 5.

Answer: 3. A = 5, B = 4, C = 2, D = 1, E = 2

Question 51. The functions of surfactant are/are :

1. to reduce tire surface tension on the alveoli
2. maintaining the stable si/e of the alveoli
3. facilitating lung expansion
4. all of the above.

Answer: 4. all of the above

Question 52.  The number of KBCs in man increases if he lives at a higher altitude because :

1. there is less oxygen in mountains
2. there is more oxygen in the mountains
3. There are no germs in the air in the mountain
4. More heat is required to be produced in the body to keep warm.

Answer: 1. there is less oxygen in mountains

Question 53. About 97% of O₂. is transported by RBC. The remaining 5% is :

1. dissolved in plasma and transported
2. remains in lungs
3. attached to cell membranes
4. inside the mitochondria
5. in peroxisomes.

Answer: 1. Dissolved in plasma and transported

Question 54. What is the vital capacity of our lungs?

1. Total lung capacity minus residual volume
2. Inspiratory reserve volume plus tidal volume
3. Total lung capacity minus expiratory reserve volume
4. Inspiratory reserve volume plus expiratory reserve volume.

Answer: 4. Inspiratory reserve volume plus expiratory reserve volume

55. Which two of the following changes (a-d) usually tend to occur in the plain dwellers when they move to high altitudes (3,500 m or more)?

1. Increase in red blood cell size
2. Increase in red blood cell production
3. Increased breathing rate
4. Increase in thrombocyte count.

Changes occurring are :

1. C and D
2. A and D
3. A and B
4. B and C.

Answer: 4. B and C

Question 56. Listed below are four respiratory capacities (a-d) and four jumbled respiratory volumes of a normal human adult :

Which one of the following is the correct matching of two opacities and volumes?

1. 1200 mL,2500 mL
2. 3500 mL,1200 mL
3. 4500 mL,3500 mL
4. 2500 mL, 4500 mL

Answer: 2. 3500 mL,1200 mL

Question 57. Which one of the following is the correct statement for respiration in humans?

1. Neural signals from the pneumotoxic centre in the pons region of the brain can increase the duration of inspiration.
2. Workers in grinding and stone-breaking industries may suffer from lung fibrosis
3. About 90% of carbon dioxide (CO₂) is carried by haemoglobin as carabinero-haemoglobin.
4. Cigarette smoking may lead to inflammation of the bronchi.

Answer: 2. Workers in grinding and stone-breaking industries may suffer from lung fibrosis

Question 58. The volume of Anatomical dead space air is normal.

1. 230 ml
2. 210 ml
3. 190 ml
4. 150 ml

Answer: 4. 150 ml

Question 59. Choose the right sequential phenomena among the following during the delivery of O2 from blood to tissue.

1. P: Absorption hr CO₂ by the blood.
2. Q: Reaction of absorbed CO₂ with H₂O to form H₂CO₃ with RBC and its conversion into H+ and HCO₃ ions.
3. R: Reaction of absorbed CO2 with H₂Oin plasma to form H₂CO3 and its conversion into H+ and HC₃ ions.
4. S: Combination of H+ with heme portion of Hb0₂ to release O₂.
5. T: Combination of HCO₃ with heme portion HbO₂ to form reduced haemoglobin and release of O₂.

Choose The Correct option 

1. P, Q, T
2. P, R, S
3. P, Q, S
4. P, R, T.

Answer: 3. P, Q, S

Question 60. The figure shows a diagrammatic view of the human respiratory system with labels 1 2, 3 and 4. Select the option which gives correct identification and main function and/or characteristics.

1. Pleural membrane-surround ribs on both sides to provide cushion against rubbing.
2. Alveoli-thin walled vascular bag-like structures for exchange of gases.
3. The lower end of the lungs-diaphragm pulls it down during inspiration
4. Trachea-long tube supported by complete cartilaginous rings for conducting inspired air.

Answer: 2. Alveoli-thin walled vascular bag-like structures for the exchange of gases

Question 61. The figure shows the schematic plan of blood circulation in humans with Iaoels 1 to 4. Identify the label and give its functions.

1. Pulmonary artery – takes blood from heart to lungs, PO₂ = 90mm Hg
2. Vena Cuva – takes blood from body parts to the right auricle, PCO₂ = 45mm Hg
3. Dorsal aorta – takes blood from Heart to body Part PO₂ = 95 mm Hg
4. Pulmonary vein – takes impure blood from body parts, PO₂ = 60 mm Hg

Answer: 2. Vena Cuva – takes blood from body parts to the right auricle, PC0₂ = 45mm Hg

NEET Biology Blood Circulatory System Circulation Of Fluids

Types of circulation. The circulatory system is the transport system of the body and circulating fluid transports nutrients, respiratory gases, metabolic intermediates and hormones, (informational molecules) to all parts of the body.

• It maintains homoeostasis, uniformity of heat etc. all over the body.
• It acts as the centre for the defence system.
• It carries metabolic intermediates For Example lactic acid (muscle to liver), and information molecules (hormones).
• The circulating fluid also distributes water, H+, chemicals and heat uniformly all over the body parts.
• Circulation may be intracellular or extracellular
• Intracellular circulation takes place inside the cell For Example In Amoeba and Paramecium it is called cytoplasmic movement and cyclosis respectively.
• Extracellular circulation takes place outside the cell.
• Extraorganismic circulation is also called water circulation For Example Leucosolenia (sponge), Hydra etc.

A gastrovascular cavity in acoelomate aquatic invertebrates performs the function of an internal circulatory system.

Read and Learn More NEET Biology Notes

• Coelomate invertebrates do have a circulatory system, which may be closed or open type.
• Intraorganismic circulation. In this, body fluids circulate in the body For Example blood and lymph.
• Blood vascular system. In this case, the circulating fluid is blood.

Components of the blood vascular system

1. Blood
2. The heart
3. The blood vessels

Blood Circulatory System In Animals NEET Notes

Lymphatic system. In this case, the circulating fluid is lymph.

• Parenchymal circulation takes place in Platyhelminthes in special tissue-the parenchyma.
• Body cavity circulation takes place in the body cavity, a watery fluid, called hydro-lymph, without a respiratory pigment as in Nematodes, ectoprocts and rotifers.
• Closed type of circulatory system. Blood flows in closed vessels and the heart For Example, vertebrates as in man.
• Blood vessels form a complete circuit in the body, carrying blood to and from the organs. Free haemo coelomic spaces outside the system are generally reduced or absent altogether.
• Open type of circulatory system. Blood does not flow in closed vessels but is present in the body cavity For Example, arthropods and molluscs have an open type of circulatory system.

In the open type, the blood is pumped by the heart into blood vessels that open into blood sinuses (spaces). There is no capillary system.

The circulatory system of cockroach. It is open type. It consists of 13 chambered heart t modified dorsal blood vessel), colourless blood, and haemolymph, comprising plasma and white corpuscles termed haemocytes Haemocoel is divided into three sinuses

1. Pericardial sinus (Dorsal sinus)
2. Periviscreal sinus
3. perineural Sinus

The flow of blood is kept in constant flow by contraction of alary muscles.

NEET Biology Blood Circulatory System Blood

Haematology. Study of the formation, composition, function and diseases of the blood.

• Blood. Blood is a fluid (mesodermal origin) connective tissue. Blood is a transporting material of the body and transports 0₂, salts, vitamins, hormones, food substances etc.
• To all parts and cells of the body and collects metabolic wastes (CO₂, and NH3) from them and passes them to the lung and kidneys respectively for giving out. The blood contains 45% corpuscles (formed elements) and 55% plasma (fluid).

Corpuscles. (R.B.C., W.B.C. and platelets)

R.B.C. Their number is about 5.5 million per mm3 in males and about 4.8 million per mm- in females, which can be counted by haemocytometer. Each R.B.C. is biconcave, devoid of nucleus, mitochondria and centriole in mammals (except in camel and sloth where it is nucleated).

• The cell metabolism is maintained by 2-3 diphosphoglycerol (DPG), which is three times more in R.B.C. Each R.B.C. is 7- 8 pm in diameter, 3|im in width, with an average volume of 87 pm3 and can carry 109 mols of 0-> with it from lung to tissue.
• The colour of R.B.C. is due to respiratory pigment—haemoglobin (Fe-base), present in most of the vertebrates; Haemocyanin (Cu-base) – blue, present in Mollusca and Crustacea; Haemoerythrin (Fe-base) – Red, dissolved in plasma, present in siphunculus and branchiopods and Chlorocrurin (Fe-base) green dissolved in plasma present in polychaetes.
• The erythrocytic sedimentation rate (E.S.R.) in man is 6-10 gm/100 ml of blood in the first hour (during infection and disease the R.B.C. become lighter and E.S.R. is decreased). E.S.R is determined by Wintrobe’s tube and also by the Western blotting method.
• R.B.C. is 60% water and 40% solid. Its percentage in the following is as – haemoglobin— 29. phospholipids—4, cholesterol—19, fats—07, glucose —06, non-protein nitrogen—044; Urea —11 and inorganic salts 0-7 to 1%.
• Haemoglobin. It consists of 1 molecule of heme (iron porphyrin) and 4 molecules of globulin (protein). The average haemoglobin percentage in males is 16 gms and in females 14 gm/100 ml of blood (at birth it is 23 gm/100 ml of blood). The percentage of haemoglobin decreases during illness or in loss of blood and causes anaemia in animals.
• W.B.C. White blood corpuscles are nucleated and show diapedesis (amoeboid movements and can pass through capillaries into lymphatic spaces as wandering cells). W.B.C. number varies from 5000 to 9000/Cubic nun.
• In stress, strain, infection and disease, their number is increased as they do phagocytosis and work as organs of offence and defence besides helping in healing the wounds. They are of two types :
• Agranulocytes. 20-25%, without azurophilic granules (lymphocyte, 6-lOj.tm in diameter, monocytes- 3-8%, 9- 12(im in diameter) Monocytes are largest W.B.C., kidney-shaped excentric nucleus.
• Granuloolev 75-80%. the nucleus is longitudinal (two or more lobes). They are of llwee i\pcs Kosinophils 4%). bilobed nucleus, sentinel by acidic dyes and spherical in shape Rasophils tO.5-2%) S-shaped nucleus, stained in basic dyes.
• Neutrophils (60-70%). nucleus, show amoeboid movement highest, in number and physiologically not important. stained by natural dyes.
  • Plasma. It contains 90% water and 10% other substances like :
  • Proteins. 5.5 to 7.6*7- (albumin 3.3 to 5.6%. globulin — 1.6 to 3.4%, fibrinogen is about 2 to .4%).
  • Organic Constituents. 1-2% non-nitrogenous fat, carbohydrates lipids and nitrogenous urea, uric acid, creatinine, ammonia, amino acids, and xanthine.
  • Inorganic Constituents. Chlorides, bicarbonates, sulphates and phosphates of K, Na. Ca. Mg and Fe.
  • Enzymes. Lipase, amylases, protease, esterase, nuclease and oxidase etc.
  • Hormones. Thyroxine, insulin, pituitrin, adrenaline, estrogen androgen etc.
  • Gases. 0₂, CO₂,. N₂,

The plasma is the transport medium of blood, even some 02 is also transported by it.

Blood Circulatory System In Animals NEET Notes

Blood platelets

1. Number. The platelets are fewer than the red corpuscles and more than the white corpuscles in number. There are about 250,000 platelets in a cubic millimetre of blood. An increase and decrease in the number of platelets are known as thrombocytosis and thrombocytopenia respectively.
2. Structure. The platelets are flat, non-nucleated fragments of large cells in the bone marrow, rather than true cells. They. are bounded by a membrane and contain a few organelles and secretory granules in the cytoplasm.
3. They have at the centre a group of basophilic granules, which give the appearance of a nucleus. At the site of injury, the platelets release platelet factor or thromboplastin that helps in blood clotting.
4. Formation. The platelets are formed in the red bone marrow. Their formation is known as thrombopoiesis.
5. Life Span and Disposal. The platelets survive for 3 – 7 days only. They are disposed of by phagocytosis in the blood itself.
6. Spindle Cells or Thrombocytes. These are biconvex, nucleated cells with granular cytoplasm. They are found in vertebrates other than mammals. The spindle cells aid in the clotting of blood like the platelets of mammals.

NEET Biology Blood Circulatory System Coagulation Of Blood

Soluble blood protein fibrinogen (dissolved in plasma) is changed into fibrous protein. Fibrin entangles the platelets and corpuscles and the blood clots. This clotting involves various factors :

1. The place of injury produces thromboplastin. Under the influence of thrombokinase, the phospholipid is given by rupturing platelets, Ca + + ions, and antihero-philic factor.
2. Prothrombin and heparin. Produced by the liver are present in blood. Heparin acts as an anticoagulant. Under the influence of thromboplastin, the prothrombin is broken into thrombin and heparin.
3. Thrombin in the presence of Ca ++ ions acts on fibrinogen (a soluble protein present in the blood) and converts into fibrous protein fibrin. Fibrin makes a mesh of delicate fibres and platelets entangle them to form a clot.
4. Blood stored in the blood bank is added with oxalate, and carbonate, which precipitate v/ith Ca and blood does not coagulate due to suppression or removal of calcium salts.

Factos in coagulation are numbered up to 13.1 — Fibrinogen; II — Prothrombin, Vit K; III — Thromboplastin; IV — Calcium ions, V — Proaccolerin; VI — denied; VII — Proconvertin; VIII — Anti-haemophilic globulin (AHG) IX — Christmas factor (platelets factor II), X — Stuart factor, XI — Plasmo thromboplast Antecedent (PTA) XII — Hegeman’s factor (contact factor), XIII — Fibrin stabilizing factor (FSH factor).

• If blood does not clot, it is called bleeder’s disease ‘haemophilia’.

NEET Biology Blood Circulatory System Theories of Blood Coagulation

1. Best and Taylor’s theory. According, to this theory prothrombin is essential for clotting.
2. Howell theory. Ca₂ + ions play an important role in clotting
3. Fuel and Spiro theory. Thrombokinuse is important for clotting.
4. Cascade theory by Macferlanc (Most recent)
5. According to Cascade’s theory, there are ID factors presently in blood dolling.
6. Best and Taylor gave 4 factors of blood clotting
7. Howell worked upon Limulus.

Encephalic Thrombus – Formation of Thrombus in blood vessels of the brain

1. The mammalian circulation route is a closed-type circuit consisting of two main subsystems:
2. Pulmonary circulation constitutes 16% of total blood (7% in the heart and 9% in pulmonary vessels.)
3. The route of blood is – Right Auricle→Right ventricle → Pulmonary aorta→ Lungs Pulmonary vein →Left auricle.

Systemic Circulation consists of 84% of total blood (64% in veins, 15% in arteries and 5% in capillaries and the route of blood are:

1. Left auricle→ Left ventricle→Systemic aorta → Organs or tissues → Veins→ Right auricle.
2. Systemic veins are called blood reservoirs.
3. Other sub-systems are also considered as part of systemic circulation. These are :

Cerebral circulation. The brain gets blood through four (two external and two internal) carotid arteries, but at the base of the brain these fuse to form a circle of Willis, from which arteries branch off to supply the brain.

Blood Circulatory System In Animals NEET Notes

Hepatic circulation. The liver receives blood from two sources, the hepatic portal vein and the hepatic artery and the mixed blood leaves through the hepatic vein.

1. Blood also remains stored in blood sinuses within the liver.

Coronary circulation. Supply of blood to the heart muscle itself and left coronary arteries arise from the base of the systemic aorta and supply to respective parts of the heart.

Blood vascular system. It is a closed type and consists of a triangular muscular pumping organ heart, tube-like blood vessels (arteries, veins and capillaries) and transporting medium blood which acts as carriers.

NEET Biology Blood Circulatory System Types of Hearts based on Morphology

Pulsating hearts. Simple blood vessels with a relatively heavy muscular wall, which contract in peristaltic waves For Example Annelids, and Amphioxus.

1. Tubular hearts. A pulsating vessel is highly developed and present in the pericardial cavity or sinus For Example Arthropods, some tunicates.
2. Ampullar accessory hearts. These are booster pumps which provide sufficient driving force to pump blood through some peripheral regions of circulation For Example Crustacean, insects and some cephalopods.
3. Chambered hearts. The heart is thick-walled, muscular and chambered vertebrates, molluscs.

NEET Biology Blood Circulatory System Heart

It is a hollow, muscular pumping organ formed of cardiac muscle fibres and beats spontaneously and rhythmically throughout life. It is enclosed in a double-walled pericardium. It is a three-layered

1. Endocardium
2. Myocardium
3. Pericardium (Heart lies in it ). The heart is four-chambered with left and right auricles and ventricles. The walls of the ventricle are thicker than the auricle. The wall of the left ventricle is 3-6 times more thicker than the right ventricle.

Cardiac valve. Prevents the backflow of blood.

• Bicuspid or Mitral valve in between left auricle and left ventricle and tricuspid valve in between right auricle and right ventricle (Bicuspid made two membranous cusps and tricuspid with three cusps.)
• The tricuspid valve is a distinguishing characteristic of the mammalian heart. (In lower chordates the valves are muscular Jtujt in mammals they become membranous.)
• The lower border of valves is provided, with many slender but strong Chordae tendineae which at their other ends are connected either directly to the walls of ventricles and interventricular septum or to papillary muscles of the ventricle.
• A modified blood vessel, made of cardiac muscles (= myogenic) for pumping blood, mesodermal in origin.

1. In early forms (fishes) it is like a straight tube with tandem chambers :
2. sinus venosus → auricle →ventricle → truncus arteriosus.
3. Auricles and ventricles are true chambers the other two are auxiliary chambers.
4. In fishes, it is two-chambered (1 auricle + 1 ventricle) and. called a ‘venous heart’ since only venous blood flows through it.

From Amphibians to mammals it is first like muscular structure with auricle (thin-walled) and ventricle (thick-walled) as main chambers.

• The anterior broader end (auricle) is the base and the narrow posterior end (ventricle) is the apex.
• A distinct line of depression between the mile and ventricle is economy selects,
• Enclosed within two layers of pericardium. It is situated in the mediastinal space of the thorax.
• Histologically the outer layer is the epicardium followed by a thick muscular myocardium and lining of the endocardium.

The blood supply of the tissue is made by coronary circulation.

Blood Circulatory System In Animals NEET Notes

NEET Biology Blood Circulatory System Opening And Valves Of Heart

1. The tricuspid valve is present in the right auriculoventricular aperture.
2. A bicuspid valve is present in the left auriculoventricular aperture.)’
3. Semilunar valves are present between ventricles and aortic arches.
4. The valve of Thebesius guards the opening of coronary sinus v;
5. Haversian valve is present on the end of the opening of precavals.

Eustachius valve: present on the opening of the postcard.

Foramen of Pcnizee: It is the aperture that connects two ventricle

Foramen of Ovale: The aperture present between two auricles in the embryonal stage.

Fossa ovalis: It is the depression in the interauricular septum of the heart of an adult.

NEET Biology Blood Circulatory System Heart Beat

The rate of heart beat in man varies from 50 to 100 i.e. ± 72 beats per minute. The rate of females’ heartbeat is faster than that of males.

• It is the number of heartbeats per minute (72 in a man);
• Directly proportional to temperature and physical activity; becomes double with the rise of every 10°C but, ceases at 44°C.
• Ca++ accelerates the heart rate while Na+ and K+ make it slow.
• Increases also due to emotions, feelings, love, fear, pain anger, etc.

It is inversely proportional to the body weight of animals, as shown in the box.

NEET Biology Blood Circulatory System Cardiac Cycle

• Arterial systole – 0.1 sec. arterial diastole 0.762 see to 0.862 see. Ventricular systole 0.379 sec: Ventricular diastole- 0.483 sec to 0.862 sec. Auriculo-ventricular interval 15 seconds.
• Factors influencing heartbeat. Size of body, age, physical Fitness etc., lower the rate, heart beat, whereas muscular work, temperature, eating, bath, high altitude etc. increases the heart beats 100-150 beats/sec.
• Heartbeats can be recorded on a kymograph, the process is called kymography. Besides, sympathetic nerves accelerate the metabolic rate i.e. the heartbeat, respiration etc. while the parasympathetic nerves do the opposite work, hence’ they protect the heart.
• lung and other vital organs from overwork and excessive response to stimuli. Transmission of heartbeat. Heart is connected with the central nervous system by two nerves (1) Vagus (autonomic) (2) Cervical (sympathetic) Heart’s action is automatic (.involuntary), i-e. it does not depend on outside impulses.
• Its impulse node lies within the heart, such a heart is known as a myogenic heart. It is also controlled by the nervous system, therefore it is neurogenic also. The hearts of amphibia, reptilia, aves and mammals are myogenic.
• In frogs – the sinus venosus beats first and passes inner stimulus to the auricle, which passes it to the ventricle which contracts. Contraction of the sinus venous is followed by the contraction of auricles and the ventricle undergoes diastole.
• Pace-maker or S A Node (Sinu-auricular node) lies in the wall of the right atrium (auricle) near the opening of the right precaval. In mammals, cardiac impulse originates in the SA Node, This is the first structure of the heart which becomes electrically negative.
• The impulse originated from here contracts both the auricles and causes a systole sound and systolic pressure i.e., 120 mm of Hg. From this node, the impulse is carried to the AV Node, which lies at the inter-auricular septum.
• The AV Node gives rise to a bundle of nerve fibres called the Bundle of this. The fibres bifurcate at the extremity of the ventricle and form the Purkinje fibres, which spread in both the ventricles. The AV Node causes contraction of the ventricle and a diastolic sound and diastolic pressure i.e. 80 mm of Hg.
• The SA Node and AV Node produce the impulses at the difference of 10-15 seconds, which is called the rest period. A healthy person’s heart has 75 beats per minute and pumps 5 litres of blood per minute. A 50-year-old man’s heart on average beats about 2 billion times and pumps about 13 crore litres (1 lakh 30 thousand tons).
• Nerve Supply to the Heart. In addition to the intrinsic stimulation of the myocardium described above, the heart is influenced by nerves originating in the cardiac centre in the medulla oblongata which reach the autonomic nervous system. These are the parasympathetic and sympathetic nerves and they are antagonistic to one another.
• The vagus nerves (parasympathetic) try to slow the rate at which impulses are produced by the sinoatrial node, therefore decreasing the rate and force of the heartbeat.

The sympathetic nerves tend to speed up the rate of impulse production by the sinuatrial node, thus increasing the rate and force of the heartbeat.

1. The rate of the heartbeats is the result of a fine balance of sympathetic and parasympathetic effects. It is usually decreased during rest and increased during excitement, exercise and when the blood is decreased.
2. Hormonal regulation. Hormones from the adrenal medulla viz. Epinephrine accelerates the heartbeat at the time of emergency whereas norepinephrine does so under normal control.

Open And Closed Circulatory Systems NEET Biology

Ionic regulation. According to Ringer, inorganic ions such as Ca⁺4^– and K⁺ also control the activity of the heart. High K⁺ follow a diastolic arrest while high Ca₄ is a systolic arrest ‘clearly in frog heart. The reverse is true in many invertebrates and vertebrates according to Er and Brown (1961).

NEET Biology Blood Circulatory System Blood Vessels

1. Angiology is the study of blood vessels.
2. father of Angiology = William Harvey
3. Blood Vessels—Arterioles are ultimate fine branches of arteries having 0.2 mm diameter.
4. Artery– 15% to 20′, V- blood is present in the aorta and arteries = 900 ml.
5. 50% blood is present in capillaries = 150ml.
6. 70 % to 75% blood in large veins.

Capillaries—0.5 to .01 mm in dia. The average diameter is about 0.01 mm.

1. Ultimate branches of blood vessels (Malpighi-1661) are made of only simple squamous epithelium, the endothelium connects the arterial and venous parts of the circulation.
2. Maximum length of branches 0.5 to I mm and diameter of 7.5 p to 9
3. The total length of the human body is about 60,000 miles (or 96,000 km) and its total surface area is 500 nr,
4. The number of capillaries in tissue is directly proportional to their activity.
5. The more active organ has more capillaries (skeletal muscle 15 lakh/inch2) while no capillaries in the lens of the eye.
6. The distribution of blood in the various capillary beds is regulated by sphincters. Highest level of amino acids-Hepatic portal vein.

The lowest level of amino acids the hepatic vein.

1. Veins. In veins, the muscular and elastic tissues are less developed while connective tissues are more developed.
2. Venules. Ultimate fine branches of veins. Special type of blood vessels.
3. Arteriovenous Anastomosis. Arterioles are connected with venules directly. These open at too low a temperature for retaining heat.
4. They are found at the extremities like lips, pinna, tongue, fingertip, eyelids, nose etc., this helps in preventing heat loss.
5. Blood sinuses are the blood spaces replacing capillaries in the liver, spleen bone marrow etc. with even thinner walls,
6. Sinusoids. The arteries and veins are connected by way of irregular anastomosing vessels which are lined with discontinuous epithelium having phagocytic cells.
7. Rete Mirabilia. Arteries or veins divide into vessels which are as small as capillaries and reunite to form arteries or veins For Example, Glomeruli in the kidney.
8. Portal vein. A vein which collects blood from an organ and on its way to the heart divides into a network of capillaries in an intermediate organ.
9. Vasa vasorum are the vessels within the walls of the main vessels.

Open And Closed Circulatory Systems NEET Biology

NEET Biology Blood Circulatory System Portal System

1. A vein that carries blood from one capillary network to another is called a portal vein.
2. Frog has both a renal portal system and a hepatic portal system.
3. The renal portal system is absent in mammals, only the hepatic portal system is present.
4. The hepatic portal vein receives blood from gastrointestinal organs and the spleen and delivers it to sinusoids of the liver.
5. Hypophyseal portal system. Blood from the hypothalamus is collected by the hypophyseal portal vein which ends in the anterior pituitary.

NEET Biology Blood Circulatory System Blood Pressure

1. The pressure exerted by the blood on the walls of blood vessels is called blood pressure (BP).
2. Is the result of the sum of.
3. Osmotic colloidal pressure of blood
4. Elastic recoil of blood vessel’s wall and
5. Pumping force of the heart.

• First measured by British physiologist Stephan Hales (1733) in the carotid artery of the mare.
• In humans, it was first measured by Vaivre (1856) using a Ludwig mercury manometer.
• Riva Rocci (1896) discovered a sphygmomanometer, the instrument to measure B.P.
• In adults, the normal BP is 120/80.
• 120 mm of Hg is systolic pressure during contraction of ventricles, and 80 mm of Hg is diastolic pressure during relaxation of ventricles.
• In children, the BP is low as compared to adults.
• In old age, the average BP is 150/90, as the arterial wall becomes less elastic.

The chemicals which are vasodilators decrease blood pressure while vasoconstrictors increase blood pressure. Histamine is a vasodilator and adrenaline is a vasoconstrictor.

NEET Biology Blood Circulatory System Pulse

1. Pulse is a wave of distension, i.e., a rhythmic expansion and relaxation (not contraction) of arteries.
2. PI use is felt at the radial artery of the wrist.
3. With the help of a pulse, the heartbeat can be measured.

NEET Biology Blood Circulatory System Pulse Pressure

1. It is the difference between systolic and diastolic pressure.
2. In normal adults, the value of pulse pressure is 40 mm of Hg (120 mm- 80 mm).

NEET Biology Blood Circulatory System Heart Sound

During each cardiac cycle, the heart generates four sounds; however, only the first and second sounds are audible using a stethoscope. The following noises are delineated below: Closure of the Bicuspid and Tricuspid valves.

The method of listening to heart sounds is known as auscultation.

First Sound (Sj:

The phenomenon primarily results from the closure of the semilunar valves in the systemic and pulmonary aorta at the conclusion of ventricular systole, coinciding with the T wave on the ECG.

1. It resembles LUBB.
2. It has an extended duration.
3. It is a lower frequency (low pitch).
4. The volume is increased.

The second heart sound (S2):

2 nd sound (Sa) Occurs with the closure of the semilunar valves of the systemic and pulmonary aorta after ventricular systole, coinciding with the T wave of the ECG. This is attributable to:

1. It appears to resemble DUP.
2. It is brief.
3. It possesses more sharpness (high frequency).
4. It is less intense (low volume).

Open And Closed Circulatory Systems NEET Biology

NEET Biology Blood Circulatory System Stroke Volume (Stroke Output)

The volume of blood ejected out by heart per beat i.e. = 70 ml.

Cardiac Output (Heart Output). The amount of blood leaving the right or left ventricle per minute is known as cardiac output or minute volume. The major factor that directly influences the cardiac output is the amount of blood flowing into the ventricle during the diastole (diastolic intake).

• The volume of blood ejected per minute (heart rate x stroke volume i.e. 72 x 70 ml. = 5 litres); denoted as ml/100 gm of body weight/minute (man 5 – 10 ml; dog = 12-15 ml; cat = 65 – 70 ml). It increases by 20 to 30% at high altitudes.
• The entire blood of our body is circulated within just more than a minute and during exercise within less than 15 seconds. (In open-type circulation the velocity is very low i.e. in cockroaches it takes about 3-8 minutes for the entire blood to circulate)
• Cardiac output is not constant but varies with the physical activity.
• Vigorous exercise increases cardiac output to as much as 21L/min in a person in good condition.
• CO goes up to 35 L/min in world-class athletes.
• The difference between the maximum and resting cardiac output is called cardiac reserve.
• People with severe heart disease may have little or no cardiac reserve and little tolerance for physical exertion.

Of the blood pumped out (cardiac output) each minute by the heart, distribution to different parts are :

1. 10% to heart muscles
2. 15% to brain
3. 25% to the digestive system
4. 20% to kidneys
5. 30% to other organs

NEET Biology Blood Circulatory System Cardiac Index

The cardiac output per square metre of body surface area. This is about 3 litres in a man of 70 kg body weight with a body surface area of 1.7 meters.

NEET Biology Blood Circulatory System Pulse Rate

Following the ventricular systole a wave of distension (arterial pulse) passes along the arteries which is normally felt by putting a finger over the radial artery in the wrist. This wave is counted as the number of pulses per minute.

NEET Biology Blood Circulatory System Cardiac Activity

Includes all 3 components: cardiac rate, cardiac output and the force of contraction.

NEET Biology Blood Circulatory System Starling’s Law Of Heart

In stretched muscle, the force of contraction increases. Thus, if a higher amount of blood enters the heart its force of contraction increases proportionately.

1. Tachycardia, increased cardiac activity
2. Bradycardia decreases cardiac activity

Impulse conduction generates tiny currents in the heart, that spread through surrounding tissue to the surface of the body. If electrodes are properly placed on the body surface at specific places, the electric potentials generated by the heart during the transmission of impulses from an SA node through a conducting system can be recorded.

Such a record is called Electrocardiogram and the device used is an electrocardiograph. A normal ECG is composed of a P wave, A QRS complex and a T-wave.

1. Where P = depolarization of atrium indicates SA node activation wave
2. P-wave occurs slightly before the onset of Atrial contraction (systole).
3. QRS – waves (complex) begin slightly before the onset of ventricular systole.
4. T-wave occurs slightly before the end of ventricular systole.
5. PQ = Contraction of the auricle
6. QRS = depolarization of the ventricle.

Components Of Blood In Animals NEET Study Material

Q wave and ascent of R wave indicate the spread of impulse of contraction from AV Node,

1. Bundles of His, Purkinje fibres and ventricle muscles.
2. R-S and S-T interval = contraction of the ventricle.
3. T-Wave = Relaxation of ventricle.
4. ECG aids in the diagnosis of any irregularity in the heartbeat.

In rheumatic heart disease (valve damaged) and arteriosclerotic heart disease (due to the formation of plaque or calcification) there is inflammation of the atria and AV node, which results in the lengthening of the PR interval.

• When sore muscles receive insufficient oxygen (lesser supply of heart ischaemia), the SI segment is depressed and the l wave Is flattened.
• In acute myocardial infarction, the ST segment is elevated and Q & R waves are enlarged

In the case of hyperkalemia, the T wave is very tall and slender.

NEET Biology Blood Circulatory System Lymphatic System

The lymphatic system aids in maintaining optimal fluid equilibrium in tissues, conserving proteins, and eliminating bacteria and other particles from the tissues.

• The mammalian lymphatic system comprises lymphatic tubes and lymphoid organs.
• Lymph circulates unidirectionally from capillaries to progressively bigger lymphatic arteries, ultimately converging into a lymphatic duct that drains into a subclavian vein.
• Lymphoid nodules known as Peyer’s patches are located within the gut wall.
• Lymph is a transparent fluid contained within lymphatic tubes, originating from interstitial fluid.
• The lymphatic fluid in the arteries next to the gut postprandially is typically opaque due to the presence of chylomicrons.
• Lymph contains a lower concentration of antibodies compared to blood plasma.

Lymphocytes are produced in primary lymphoid tissue (thymus, embryonic liver, adult bone marrow) and migrate to secondary lymphoid tissue (spleen, lymph nodes, unencapsulated lymphoid regions of gut submucosa, respiratory and urinogenital regions).

1. Lymphoma is a tumour composed of lymph tissue.
2. Hodgkin’s disease is a malignant lymphoma of reticuloendothelial cells in lymph nodes and other lymphoid tissues.
3. Even a minor interference in the removal of tissue fluid will be noticed as tissue swelling a condition called oedema.

Lymph vessels. The lymphatic system helps to defend the body against diseases.

NEET Biology Blood Circulatory System Disorders Related To The Circulatory System

 The pressure exerted by the flow of blood on the walls of the arteries is tanned blood pressure.

1. Arterial blood pressure. The pressure of blood in the arteries is called arterial blood pressure.
2. Pulse pressure. The difference between systolic pressure and diastolic pressure is tanned pulse pressure.
3. Hypotension (Low blood pressure). It is caused due to permanent vasodilation of arteries or failure of the pumping action of the heart.
4. Hypertension (High blood pressure). It is caused by to rise in cholesterol levels, nervous strain, arteriosclerosis and kidney trouble.
5. Thrombophilia. A disorder of the haemopoietic system in which there is a tendency for the occurrence of thrombosis.
6. Thrombocytopenia. Fall in number of thrombocytes in blood.
7. Polycythemia. Increase in the number of RBCs in blood.
8. Leucopcnia. Abnormal fall in the number of WBCs in blood.
9. Leukaemia. It is a cancer of the blood in which bone marrow and lymph nodes produce more lymphocytes,
10. Diapedesis. Squeezing out of W.B.C. from blood capillaries.
11. Acapnia. Decreased amount of CO, in the blood.
12. Anaemia. It is a disorder resulting in either a decrease in R.B.C. or in the amount of haemoglobin. _
13. Sickle cell anaemia. It is a congenital haemolytic disease in which R.B.C. destruction occurs due to intracellular defects.
14. Pernicious anaemia. Macrocytic (large sized) R.B.C. with less 02 carrying capacity. It is due to an extracellular defect.
    • Haemoglobinomia is the disorder due to abnormal destruction of R.B.C. in the fluid and setting free Hb.
    • A marked decrease in concentration of plasma proteins is termed hypoproteinemia. Tachycardia. The heart beats rapidly.
15. Bradycardia. The heart beats slowly.
16. Dextrocardia. If the heart is placed towards the right side in the thoracic cavity an inborn defect.
17. Ectopia cordis. Sometimes heart becomes located outside in the thoracic cavity. The enlargement of the heart is termed cardiomegaly.
18. Cardiac arrest is a complete stoppage of a heartbeat.
19. Arteriosclerosis. It is also called the hardening of arteries, which results in arteries losing their elasticity because of the deposition of calcium salts in walls.
20. Heart block. The cardiac condition resulting from the defective transmission of impulses from the atrium to the ventricle is termed a heart block.
21. Heart murmur. The abnormal heart sound is produced as a result of defective valves. (Murmuring heart)
22. Patent Ductus Arteriosus. A congenital heart defect in which ductus arteriosus remains open. It must be closed by a surgical operation.
23. Angina. Heart pain of short duration is usually located in the front of the chest. Ischaemia (pronounced is-keema)—Inadequate flow of blood to a part of the heart caused by obstruction to its blood supply.
24. Myocardial infarction. Death of a part of the heart muscle following cessation of blood supply to it is an acute heart attack.
25. Haemolysis. It is the destruction of the blood corpuscles, causing the release of contained haemoglobin into the plasma.
26. Haemotoma. Blood is collected in the tissues outside the blood vessels, a common skin bruise due to blow.
27. Haemorrhage.Loss of blood from injured blood vessels.
28. Haemorrhoids. These are varicose veins in the walls of the rectum.
29. Oedema (Kdema). A Kval swelling is due to the accumulation of serous fluid in tissue caused by the defective circulation of blood or lymph.
30. In arborisation heaitbhvk. the defect lies in the Purkinjc’s fibres.
31. Angina Pectoris. Sevciv but temporary heart pain which is usually felt in the front of the chest and may pass into the arms.
32. Myocardial Ischaemia. Deficient blood supply to the heart muscle causes angina pectoris (G. Shein — to check, hame – blood)

NEET Biology Blood Circulatory System Blood Groups

The problem arises in the case of a condition when Rh- mother bears an Rh+ foetus. The second time if this happens it proves fatal to the foetus.

1. This condition is called Erythroblastosis foetalis; when maternal antibodies diffuse across the placenta into the foetal blood causing agglutination of red blood corpuscles, blockage of the capillaries and haemolysis leading to anaemia.
2. If one parent belongs to group A and the other to group B, the possible blood groups of children will be AB, A, 0. and B,0.
3. If a woman with blood group 0 marries a man with blood group AB, the blood group of their child will be either A or B
4. Persons with Blood group 0 are known as universal donors because their blood has no antigen in RBCs. They can donate blood to all the groups but can receive blood only from their own group.
5. Individuals with Blood group AB are called universal recipients because their blood has no antibodies in plasma. They can receive blood from any group but can donate blood to their own group.
6. DPF – Di isopropyl fluorophosphate. It is used in the estimation of the life span of blood platelets

Components Of Blood In Animals NEET Study Material

Clumping of RBC may take place when the blood of one person is mixed with the blood of another person if their Blood groups are not compatible due to antigen-antibody reaction. Blood group antigens occur in Red blood corpuscles while antibodies occur in plasma.

NEET Biology Blood Circulatory System Useful Information

Welker’s method IN employed for measuring a total amount of blood, plasma or RBC.

• 1 % of R R C. daily is destroyed in our body.
• Damaged or defective S A node can be corrected by implanting an artificial pacemaker.
• This instrument stimulates the heart artificially at regular intervals.

1. Vasodilator. A drug that opens up the narrow blood vessels.
2. Sphygmomanometer. An instrument used to measure blood pressure.
3. Cardioscope. An instrument fitted with a lens and light for examining the inside of the heart.
4. Angiography. X-ray of the blood vessels after injection of radio-opaque substance.
5. Coronary Angiography. When the contrast medium dye is injected into coronary arteries (arteries of the heart) and pictures are taken, it is known as coronary angiography.

• Clearing a blockage in the coronary artery by balloon surgery is called coronary angioplasty.

1. Angiogram. Film showing the arterial system after injecting radio-opaque material.
2. Haemodialysis. Removal of waste products from the blood kidney.
3. Arteriosclerosis different from atherosclerosis

Atherosclerosis. In this disease, a lumpy thickness develops on the inner walls of the arteries that prevents die dilation of vessels (arteries). The vessels become smaller in diameter and cannot fully expand.

1. In such cases, the platelet-derived growth factor (PDGF) is released which provides a rough surface to platelets. If such plaques are formed in a coronary artery, it may cause blockage of blood to the heart and result in heart attack or stroke.
2. However, in the case of arteriosclerosis, there is hardening and loss of elasticity of arteries. Sclerosis of the artery may cause pain in the chest, co RBC: WBC = 600: 1

The largest vein in the human body is the inferior vena cava, and the Largest Artery is the aorta.

• Smallest blood vessel in the body — blood capillary, co The giraffe’s blood pressure may be the highest.
• In human males, normally haemoglobin is 15.8 g/100 ml blood, and in human females 13.7 g/100 ml.
• Infants, at birth, have 23 g/100 ml. co ] gm. of haemoglobin when fully saturated combined with 1.34 ml oxygen.
• In Earthworm haemoglobin is dissolved in blood plasma and is not contained in blood cells, co Among all animals, the metabolic rate is the slowest in elephants.

Due to defective valves, blood keeps on leaking and the sound of a murmur is produced.

• Sympathetic nerves increase the rate of heartbeat. cO In fishes only deoxygenated blood flows through the heart,
• The sinoauricular node is composed of special muscle fibres, The spleen also controls some volume of blood, but blood volume is mainly controlled by veins, co In walls of ventricles, papillary muscles are present, and co Hepatic portal system is found in all chordates.
• At birth, the number of WBCs is more than the RBCs. co Frog has two pairs of lymph hearts, co Urea Transport. The blood in the hepatic vein contains the maximum amount of urea and the renal vein has the minimum amount.
• Several RBCs increase if one lives at a higher altitude because there is less oxygen on mountains, co Fish Without Haemoglobin.
• The Antarctic ice fish, Chaemocephalus, has transparent blood with little iron and no red corpuscles. Oxygen seems to be carried only by physical solution in the plasma,

Components Of Blood In Animals NEET Study Material

1. Blue Baby. A baby with a blue tinge to the skin due to insufficient oxygenation of the blood. It indicates a congenital heart or lung defect.
2. Insufficiency of Blood. The body does not contain enough blood to fully vascularise all the tissues. After a heavy meal, more blood flows to the gut and less to the brain. This makes one feel sleepy.
3. Slowest Blood Flow. Blood flow is slowest in the capillaries to allow enough time for the exchange of materials.
4. Ringer Solution. A solution containing chlorides of sodium. potassium and calcium that maintain the beating of an isolated frog’s heart is called Ringer’s solution.
5. Maturation of RBCs. It requires vitamin Bp and folic acid. Deficiency of these vitamins causes anaemia.
6. Spindle Cells. These occur in amphibian blood and help in blood clotting like the mammalian platelets, cs* With the removal of the spleen, the leucocyte count rises, cs* Excess calcium ions cause increased heartbeat.
7. The heart is wrapped around the rectum of a freshwater mussel. It means the rectum of freshwater mussel passes through the heart.
8. Keber’s organs’ pericardial glands discharge excretory products into the pericardial cavity in the freshwater mussel.
9. Crocodilian Heart. Among reptiles, crocodilians are exceptional in having a 4-chambered heart.

Invertebrate Hearts. Earthworm has 4 pairs of hearts. Cockroach has a 13-chambered, tubular heart, about as long as the body. In freshwater mussel, the rectum passes through the ventricle of the heart.

• Anophilin is the anticoagulant produced by blood.
• Daily about 30% of WBCs are destroyed.
• Heart Transplant. The world’s first human heart transplant was performed by Prof. Christian Bernard on December 21, 1967, in Cape Town, South Africa.
• India’s first human heart transplant was done by cardio surgeon P. Venugopal on August 3, 1994, at the All Indian Institute of Medical Sciences (AIIMS), Delhi.

NEET Biology Blood Circulatory System Questions from Competitive Examinations

Question 1. The pulmonary artery differs pulmonary vein in having :

1. No endothelium
2. Valves
3. Large lumen
4. Thick muscular walls.

Answer: 4. Thick muscular walls

Question 2. Match the names of the parts listed under column 1 with the names of the organs listed under column 2; Choose the answer which gives the correct combination of the alphabet:

1. A — s, B — r, C — p, D — t
2. A — r, B — t, C — s, D — p
3. A — r, B — s, C — t, D — p
4. A — S, B — q, C — p, D — t.

Answer: 3. A — r, B — s, C — t, D — p

Question 3. The blood protein involved in blood coagulation is :

1. Fibrin
2. Thrombin
3. Prothrombin
4. Fibrinogen.

Answer: 4. Fibrinogen

Question 4. Blood vessel which brings oxygenated blood to the left atrium are:

1. Precaval vein
2. Postcaval vein
3. Pulmonary vein
4. Pulmonary artery.

Answer: 3. Pulmonary vein

Structure And Function Of The Heart NEET Exam Preparation

Question 5. A sample of blood shows clumping with antiserum A but not with antiserum B. The blood group would be :

1. O
2. A
3. B
4. AB.

Answer: 2. A

Question 6. A person with the AB blood group can receive blood from :

1. AB only
2. O only
3. Both A and B
4. All the above.

Answer: 4. All the above.

Question 7. Blood group B means the person :

1. Can form antibody for B
2. Cannot form antibody for B
3. Can receive the blood of AB group
4. Cannot receive blood group O.

Answer: 2. Cannot form antibody for B

Question 8. Which one carries oxygen?

1. Plasma
2. Lymph
3. Blood
4. Serum.

Answer: 3. Blood

Question 9. Collecting of WBCs at the site of injury occurs due to:

1. Phagocytosis
2. Hemolysis
3. Diapedesis
4. All the above.

Answer: 3. Diapedesis

Question 10. In Prawn, the heart pumps :

1. Deoxygenated blood
2. Oxygenated blood
3. Both (1) and (2)
4. Mixed blood.

Answer: 2. Oxygenated blood

Question 11. Blood circulation is open in :

1. human
2. cow
3. apes
4. cockroach.

Answer: 4. cockroach

Question 12. Heart sound which is longer is :

1. lubb
2. dup
3. both equal
4. sometimes (1) and sometimes (2).

Answer: 1. lubb

Question 13. Adrenaline directly affects:

1. S. A. node
2. P – cells of Langerhans
3. Dorsal root of the spinal cord
4. Epithelial cells of the stomach.

Answer: 1. S. A. node

Question 14. Continuous bleeding from an injured part of the body is due to a deficiency of :

1. Vitamin A
2. Vitamin B
3. Vitamin K
4. Vitamin E.

Answer: 3. Vitamin K

Question 15. Impulse of heartbeat originates from :

1. S. A. node
2. A. V. node
3. Vagus nerve
4. Cardiac nerve.

Answer: 1. S. A. node

Question 16. Organs which get only oxygenated blood are:

1. lungs
2. gills
3. liver
4. spleen.

Answer: 4. spleen.

Question 17. Bundle of His is a network of:

1. nerve fibres found throughout the heart
2. muscle fibres distributed throughout the heart walls
3. left auricle and left ventricle in higher vertebrates
4. nerve fibres distributed in ventricles.

Answer: 3. left auricle and left ventricle in higher vertebrates

Structure And Function Of The Heart NEET Exam Preparation

Question 18. Systemic heart refers to :

1. the two ventricles together in humans
2. the heart that contracts under stimulation from the nervous system
3. left auricle and left ventricle in higher vertebrates
4. entire heart in lower vertebrates.

Answer: 3. left auricle and left ventricle in higher vertebrates

Question 19. The diagram below shows how things get to and from the liver. They are labelled as A, B, C, D, E and F. Which one of the following labellings is the correct one?

1. A is the hepatic portal vein and E is the hepatic vein
2. C is the intestine and F is the hepatic portal vein
3. D is the hepatic portal vein and F is the hepatic vein
4. B is the pancreatic artery and E is the hepatic artery
5. D is the hepatic portal vein and E is the hepatic vein.

Answer: 3. D is the hepatic portal vein and F is the hepatic vein

Question 20. Choose the correct proportion with respect to the distribution of blood in the body of man :

1. 5% to heart muscles, 15% to brain, 25% to liver, 25% to kidney, 15% to bones, 15% to other organs.
2. 20% to heart muscles, 10% to brain,10% to liver, 25% to kidney, 10% to bones, 25% to other organs.
3. 10% to heart muscles, 10% to brain, 10% to liver, 40% to kidney, 15% to bones, 15% to other organs
4. 10% to heart muscles, 20% to brain, 20% to liver, 15% to kidney, 5% to bones, 35% to other organs
5. 15% to heart muscles, 20% to brain, 30% to liver, 40% to kidney, 5% to bones, 4% to other organs.

Answer: 3. 10% to heart muscles, 10% to brain, 10% to liver, 40% to kidney, 15% to bones, 15% to other organs

Question 21. The rate of the heartbeats and their conduction is represented in the pathway :

1. AVN-bundle of His network of Purkinje fibres
2. Network of Purkinje fibres – AVN – SAN-bundle of His
3. AVN – SAN – a bundle of this – Purkinje fibres
4. SAN – AVN – the bundle of this ^Purkinje fibres
5. SAN – AVN Purkinje fibres – a bundle of His.

Answer: 1. AVN-bundle of this network of Purkinje fibre

Question 22. Of the following the one which is an example of a buffer system in blood is :

1. haemoglobin and oxyhaemoglobin
2. oxygen and carbon dioxide
3. albumin and globulin
4. sodium bicarbonate and carbonic acid
5. oxygen and carbon monoxide.

Answer: 4. sodium bicarbonate and carbonic acid

Question 23. The chamber of the human heart, which has the thickest wall:

1. right atrium
2. left atrium
3. right ventricle
4. left ventricle.
5. None of these.

Answer: 3. right ventricle

Question 24. A person with blood group A has :

1. Antigen A and antibody b
2. Antigen B and antibody a
3. Both antibodies
4. No antibody and no antigen.

Answer: 1. Antigen A and antibody b

Question 25. The part of the antibody molecule which acts as a binding site for specific related antigens is :

1. Complete light chain
2. Complete heavy chain
3. Complete light and heavy chain
4. Variable parts of light and heavy chains.

Answer: 4. Variable parts of light and heavy chains

Question 26. The treatment of snake bite by antivenin is an example of :

1. Artificially acquired active immunity
2. Artificially acquired passive immunity
3. Naturally acquired passive immunity
4. Specific natural immunity.

Answer: 2. Artificially acquired passive immunity

Question 27. The percentage similarity in (3-chain of Hb in man and rhesus monkey is :

1. 2%
2. 4%
3. 8%
4. 40%.

Answer: 4. 40%.

Question 28. Serum is :

1. blood without fibrinogen
2. lymph without corpuscles
3. blood without corpuscles and fibrinogen
4. lymph.

Answer: 3. blood without corpuscles and fibrinogen

Question 29. The bundle of this is a group of :

1. nerve fibres
2. muscle fibres
3. connective tissue
4. ganglia.

Answer: 2. muscle fibres

Question 30. In which one of the following pair of terms both represent one and the same thing?

1. Mitral valve-bicuspid valve
2. Atrioventricular node—pacemaker
3. Leucocytes-lymphocytes
4. Plasma-serum.

Answer: 1. Mitral valve-bicuspid valve

Structure And Function Of The Heart NEET Exam Preparation

Question 31. The four-chambered heart is present in :

1. frog
2. crocodile
3. shark
4. lizard.

Answer: 2. crocodile

Question 32. The nucleus of a monocyte is :

1. two-lobed
2. kidney shaped
3. s-shaped
4. multi-lobed.

Answer: 2. kidney shaped

Question 33. You are required to draw blood from a patient and to keep it in a test tube for analysis of blood corpuscles and plasma. You are also provided with the following four types of test tubes. Which of these will you not use for the purpose?

1. test tube containing calcium bicarbonate
2. chilled test tube
3. test tube containing heparin
4. test tube containing sodium oxalate.

Answer: 3. test tube containing heparin

Question 34. Insulin and glucagon are transported to the target organ by :

1. lymph
2. blood
3. pancreatic duct
4. cystic duct.

Answer: 2. blood

Question 35. Which of the following is the correct pair?

1. Leucocytes—Lymphocytes
2. Haemophilia—Blood cancer
3. SA Node—Pacemaker
4. Malleus—Anvil.

Answer: 3. SA Node—Pacemaker

Question 36. An artificial pacemaker is implanted subcutaneously and connected to the heart in patients :

1. having 90% blockage of the three main coronary arteries
2. having a very high blood pressure
3. with irregularity in the heart rhythm
4. suffering from arteriosclerosis.

Answer: 3. with irregularity in the heart rhythm

Question 37. G—6-P dehydrogenase deficiency is associated with haemolysis of :

1. Lymphocytes
2. RBCs
3. Platelets
4. Leucocytes.

Answer: 2. RBCs

Blood Vessels Types And Functions NEET Biology

Question 38. Which of the following substances, if introduced into the bloodstream, would cause coagulation of blood at the site of its introduction?

1. Fibrinogen
2. Prothrombin
3. Heparin
4. Thromboplastin.

Answer: 4. Thromboplastin.

Question 39. Different factors play important roles in the coagulation of blood, some of the factors are listed in list-I and their nomenclatures are given in list-II. Find out the accurate matching

1. A: 2, B: 1, C: 4, D:3
2. A: 1, B: 2, C : 3, D: 4
3. A : 3, B: 4, C: 2, D: 1
4. A: 4, B: 4, C: 2, D: 1

Answer: 1.  A: 2, B: 1, C: 4, D:3

Question 40. Which of the following statements is wrong?

A. Leucocytes disintegrate in the spleen and liver.

B. RBC, WBC and blood platelets are produced by bone marrow.

C. Neutrophils bring about the destruction and detoxification of toxins of protein origin.

D. The important function of lymphocytes is to produce antibodies.

1. (A) and (C) only
2. (A) and (D) only
3. (A) and (C) only
4. (B) and (C) only
5. (B) and (D) only.

Answer: 3. (A) and (C) only

Question 41. What happens when the pacemaker is non-functional?

1. Only the auricles will contract rhythmically.
2. The cardiac muscle does not contract in a coordinated manner rhythmically.
3. Only ventricles will contract rhythmically.
4. Cardiac muscle will contract in a coordinated manner rhythmically.
5. Auricles and ventricles contract simultaneously.

Answer: 2. The cardiac muscle does not contract in a coordinated manner rhythmically.

Question 42. In sickle cell anaemia glutamic acid is replaced by

1. proline
2. alanine
3. serine
4. valine.

Answer: 4. valine.

Question 43. The process of formation of blood corpuscles is called.

1. Haempoeisis
2. Haemolysis
3. Haemozoin
4. None of these.

Answer: 1. Haempoeisis

Question 44.  Leech secretes which of the following anticoagulants?

1. Heparin
2. Hirudin
3. Serotonin
4. Histamine.

Answer: 2. Hirudin

Question 45. Mark the odd one :

1. Monocyte
2. Lymphocyte
3. Neutrophil
4. Erythrocyte.

Answer: 4. Erythrocyte.

Question 46. Find out the incorrect answer from the following?

1. veins are typically larger in diameter than arteries
2. because of their small size, capillaries contain blood that is moving more quickly than in other parts of the circulatory system
3. the walls of arteries are elastic, enabling them to stretch and shrink during changes in blood pressure
4. veins contain more blood than any other part of the circulatory system.

Answer: 2. because of their small size, capillaries contain blood that is moving more quickly than in other parts of the circulatory system

Question 47. How many times a red blood corpuscle will have to pass through the heart in its journey from the hepatic artery

1. Two times
2. Only once
3. Several times
4. Many times

Answer: 1. Two times

Question 48. ‘Heart to Heart ‘ is

1. SA node
2. AV node
3. Long bones
4. All of these

Answer: 1. SA node

Question 49. SA-node is located in :

1. Lower lateral wall of the right atrium
2. Upper lateral wall of the right atrium
3. Upper lateral wall of the left atrium
4. Lower lateral wall of left atrium

Answer: 2. Upper lateral wall of the right atrium

Question 50. Yellow bone marrow is found especially in the medullary cavity of:

1. Short bones
2. Spongy bones
3. Long bones
4. All of these.

Answer: 3. Long bones

Question 51. An insect bite may result in inflammation of that spot. This is triggered by the alarm chemicals such as :

1. Histamine and dopamine
2. Histamine and Kinins
3. Interferons and osponins
4. Interferons and histamine.

Answer: 2. Histamine and Kinins

Blood Vessels Types And Functions NEET Biology

Question 52. Which one of the following four secretions is matched with its source, target and nature of action?

Answer: 4.

Question 53. Closure of which of the following makes the louder sound of a heartbeat?

1. mitral valve
2. semilunar valve
3. auriculo-ventricular valve
4. tricuspid valve.

Answer: 3. auriculo-ventricular valve

Question 54. The diagram given here is the standard ECG of a normal person, The P-wave represents the following:

1. Initiation of the ventricular contraction
2. Beginning of the system
3. End of systole
4. Contraction of both the atria.

Answer: 4. Contraction of both the atria.

Question 55. In ECG, what does wave represent?

1. Diastole of auricles
2. Diastole of ventricles
3. Systole of ventricles
4. Diastole of auricles and ventricles.

Answer: 4. Diastole of auricles and ventricles

Question 56. Which leucocytes release heparin and histamines in the blood?

1. Eosinophil
2. Basophil
3. Neutrophil
4. Lymphocytes
5. Monocytes.

Answer: 2. Basophil

Question 57. Graveyard of blood is :

1. spleen
2. liver
3. kidney
4. thymus.

Answer: 1. spleen

Question 58. The given figure shows an angiogram of the coronary blood vessel. Which one of the following statements correctly describes, what is being done?

1. It is the coronary artery which has a cancerous growth that is being removed
2. It is the coronary artery which is blocked by a plaque and the same is being cracked
3. It is a coronary vein in which the defective valves are opened
4. It is a coronary vein blocked by a parasite (blood fluke) that is being removed.

Answer: 2. It is the coronary artery which is blocked by a plaque and the same is being cracked

Question 59. A drop of each of the following is placed separately on four slides. Which of them will not coagulate?

1. Blood serum
2. Sample from the thoracic duct of the lymphatic system
3. Whole blood from pulmonary vein
4. Blood plasma.

Answer: 4. Blood plasma.

Question 60. The valve situated between the left atrium and left ventricle is called :

1. mitral valve
2. bicuspid value
3. tricuspid valve
4. Eustachian valve.

Answer: 1. mitral valve

Blood Vessels Types And Functions NEET Biology

Question 61. The open circulatory system is present in

A. arthropods

B. annelids

C. chordates

D. molluscs

1. C only
2. C and B
3. A and B
4. D only
5. A only

Answer: 5. A only

Question 62. In humans, blood passes from the postcard to the diastolic right atrium of the heart due to :

1. the pressure difference between the portocaval and atrium
2. stimulation of the sino-auricular node
3. pushing open the venous valves
4. suction pull.

Answer: 1. pressure difference between the portocaval and atrium

Question 63. Which one of the following statements is correct regarding blood pressure :

1. 130/90 mmHg is considered high and requires treatment
2. 100/55 mmHg is considered an ideal blood pressure
3. 105/50 mmHg makes one very active
4. 190/110 mmHg may harm vital organs like the brain and kidneys.

Answer: 4. 190/110 mmHg may harm vital organs like the brain and kidney.

Question 64. Arteries are best defined as the vessels which :

1. Supply oxygenated blood to the different organs
2. Carry blood away from the heart to different organs
3. Break up into capillaries which reunite to form a vein
4. Carry blood from one visceral organ to another visceral organ.

Answer: 2. Carry blood away from the heart to different organs

Question 65. ‘Bundle of His’ is a part of which one of the following organs in humans?

1. Brain
2. Heart
3. Kidney
4. Pancreas.

Answer: 2. Heart

Question 66. Which one of the following plasma proteins is involved in the coagulation of blood?

1. An albumin
2. Serum amylase
3. A globulin
4. Fibrinogen.

Answer: 4. Fibrinogen.

Question 67. The vem which is formed from the capillaries of an organ and terminates into capillaries in some intermediate organ before entering the heart is called :

1. Pulmonary vein
2. Coronary vein
3. Portal vein
4. Systemic vein

Answer: 3. Portal vein

Question 68. In a normal human, the cardiac output (stroke volume) is :

1. 47 ml
2. 20 ml
3. 5 litres
4. 3.3 litre.

Answer: 3. 5 litres

Question 69. Which one of the following is incorrect for ‘atherosclerosis’?

1. Constriction of the arterial lumen reduces blood flow.
2. Loss of dilation ability of the arterial wall and its rupture.
3. Cholesterol deposition at the inner wall of the artery.
4. Proliferation of the vascular muscles.

Answer: 2. Loss of dilation ability of the arterial wall and its rupture.

NEET Biology Plant Water Relations

• Permeability. A large number of substances enter the cell and a large amount goes out of the cell during various biological activities. This is due to the permeability exhibited by cells.
• Solute. A substance that is dissolved in a liquid is called a solute,
• Solvent. The liquid in which substances are dissolved is called solvent,
• Solution. A liquid with substances dissolved in it is called a solution,
• Hypotonic solution. Less concentrated solution than cell sap.
• Hypertonic solution. More concentrated solution than cell sap.
• Isotonic solution. Two solutions with the same concentration of solute and have the same osmotic pressure.
• Molal Solution is a solution having 1 gm mole of a solute dissolved in 1 liter of solvent. Molal solution is also called weight solution,
• The molar solution is that solution when 1 gm mole of a solute is dissolved in water to make the volume 1 liter.
• Permeable membrane. These membranes allow diffusion of both solvent and solute molecules or ions across them, For Example, cellulose cell wall.
• Differentially permeable membrane. It is a membrane that allows some substances to pass through, but not others, For Example, Plasma membrane,
• Impermeable membranes. Such membranes prohibit the diffusion of both solvent and solute particles through them e.g. heavily cutinized or suberized cell walls,
• Semipermeable membranes. Such membranes allow diffusion of solvent molecules but do not allow the passage of solute molecules e.g. plasma membrane.

Read and Learn More NEET Biology Notes

Plant Water Relations NEET Notes

NEET Biology Plant Water Relations Chemical Potential

• It is the free energy of one mole of a substance in a system under constant temperature and pressure) All reactions under pressure involve a decreased chemical potential of free energy. The chemical potential of pure water is taken as zero. It is represented by the symbol Ω/ (psi) and is measured in_bars and atmosphere.
• Water potential is determined by three major” sets of internal factors. Matric potential (ψm), solute potential (ψs), and pressure potential (ψp). Water potential is written as

1.  ψ=ψ_m + ψ_s + ψ_p
2. Osmotic pressure O.P. = C.R.T.
3. O.P. = C.R.T, where C = Concentration, R – Gas const. T = Temp. It is a +ve pressure.

• Osmotic pressure can be defined as “the actual pressure which develops in a solution when it is separated from pure water using a semipermeable membrane.
• The pressure needed to prevent the passage of water into the solution through a semipermeable membrane, thus preventing an increase in the volume of the solution.
• It is the maximum pressure that can develop in an osmotically active solution when it is separated from its pure solvent by a semipermeable membrane under ideal conditions. An osmometer is an apparatus that is used to measure the osmotic pressure of a solution.

The osmotic pressure of a solution depends upon :

1. The concentration of solute particles. An increase in the concentration of solute in the solution increases the osmotic pressure of a solution.
2. Ionisation of solute particles. If the solute ionizes in solution, the number of particles increases, so raising the osmotic pressure. The osmotic pressure of a solution of an ionizing substance would be greater than the equimolar concentration of a non-ionizing substance.
3. Temperature. An increase in temperature raises the osmotic pressure of a solution.
4. The osmotic pressure of a given solution (non-electrolyte) such as sucrose can be calculated by using the following relationship.
5. O.P. = CRT
6. C is the molar concentration of the solution
7. R is the gas constant which is 0.082 and
8. T is the absolute temperature i.e. 273 + t°C.]

Plant Water Relations NEET Notes

A molar solution of sucrose solution separated from pure water by a semipermeable membrane has an O.P. of approximately 22.4 ms. at 0°C.

NEET Biology Plant Water Relations Turgor Pressure (Tp) And Wall Pressure (Wp)

• The outward pressure exerted on the cell wall by the cell contents is called turgor pressure.
• Wall pressure. The inward pressure exerted on the cell contents by the stretched cell wall is called wall pressure.
• The two pressures are equal and opposite in direction.
• At equilibrium TP = WP.
• T.P∝ to the amount of water absorbed.
• When TP > WP → cell will burst.
• TP < WP→ cell will not get turgid.
• Thus, T.P. causes the dilution of cell sap.
• T.P. maintains the turgidity and rigidity of”the ceils.
• The upright position of a shoot in a very young seedling depends on T.P.
• W.P. acts against the osmotic entry of water into the cell.

NEET Biology Plant Water Relations Diffusion Pressure Deficit (Dpd)

The disparity between osmotic pressure (OP) and turgor pressure (TP) is referred to as suction pressure (SP) or diffusion pressure deficit (DPD). It is sometimes referred to as Suction Pressure.

NEET Biology Plant Water Relations Plasmolysis

It is the shrinkage of the contents of a cell when it is placed. in a hypertonic solution.

It is of three types :

1. Limiting Plasmolysis. Cell size is minimum but cytoplasm does not withdraw from the cell wall.
2. Incipient Plasmolysis. Cytoplasm withdraws itself from the cell wall.
3. Evident Plasmolysis. Cytoplasm withdraws itself from the cell wall except at a few points.
4. Limiting plasmolysis is used for studying osmotic potential.
5. Deplasmolysis.It is the absorption of water by the plasmolyzed cell so that it becomes turgid.

Plant Water Relations NEET Notes

NEET Biology Plant Water Relations Adsorption

The concentration of molecules or ions of a substance at a surface or boundary between two substances.

NEET Biology Plant Water Relations Osmosis

1. It is the movement of solvent molecules from their place of high cone, to their place of the low cone when both are separated by selectively permeable membrane. Through this process roots absorb. water. It is of two kinds i.e. exosmosis and endosmosis.
2. Importance of osmosis for plants. Several physiological processes are intimately associated with osmosis. Osmosis plays an important role in

• Entry of water into plant cells from the soil through root hairs.
• The distribution of water across the cell,
• The turgidity of plant cells is required for the maintenance of the forms of the plant
• The turgor pressure of guard cells is essential for the opening of stomata,
• The growth of young cells is brought about by OP and turgor pressure of the cells. Many plant movements depend upon the turgidity of cells. (W)fAutochoryjin fleshy fruits.

1. Diffusion. It is the movement of gases, liquids, and solutes from a place of their higher cone to the lower cone. This process is helpful in photosynthesis and respiration.
2. Imbibition. It is the physical process of absorption of water by the hydrophilic colloids of dry substances. The seeds swell up due to it.
3. Imbibants or swelling substances exert considerable pressure which is called imbibition pressure (IP).

• imbibants hold water by capillarity and adsorption.
• D.P.D. = IP – TP
• The magnitude of this pressure (IP) is very significant e.g. Dried wooden piece when inserted into a rock, due to the swelling of the wood, enough pressure is created and cracks appear in the rock.
• In the same way, seeds in the bottle will break the bottle due to the swelling of the seeds.
• Imbibition is the first step in the absorption of water by the roots of higher plants and in the germination of seeds.
• Proteins have very high imbibing capacity, starch less, and cellulose least. This is why the proteinaceous seeds example: Pea, swell more on imbibition than those of starchy wheat seeds.

NEET Biology Plant Water Relations Absorption Of Water

• Roots absorb water from the soil. Root hairs play a key role in this purpose. Water absorption may be active or passive.
• Active absorption of water occurs due to the utilization of energy. It may be osmotic or non-osmotic.
• Passive absorption takes place due to surface force or Transpiration pull produced in leaves.

1. A plant root is distinguishable into five regions. Maximum absorption of water occurs through the region of root hair. Internally, a root is distinguishable into the epidermis, cortex, and endodermis enclosing the stele. Unthickened passage cells are present in endodermis opposite to protoxylem groups.
2. The soil complex comprises inorganic matter, organic matter, soil solution, soil air, soil moisture, and soil organisms. The source of soil water is atmospheric precipitation.
3. The soil contains water in four different forms, namely capillary water, hygroscopic water, combined water, and water vapors. Of these, only capillary water is available to plants.
4. The maximum water retaining capacity of soil is indicated by the term field capacity. A plant wilts permanently at the arrival of a permanent wilting percentage. The sum of the osmotic potential of the soil solution and soil moisture tension is called total soil moisture stress (TSMS).
5. A plant may absorb water from the soil actively under no tension conditions or passively under the influence of a high rate of transpiration.
6. An increased rate of transpiration increases the DPD of mesophyll cells. As a result, water is drawn from neighboring cells. The deficiency of water is then conveyed from the leaf xylem to the stem xylem and then to the root xylem. The root xylem takes water from the pericycle and tire deficiency is conveyed finally to the root hair.
7. The root hair absorbs water due to increased suction tension endosmotically from the soil.
8. The active osmotic absorption of water occurs by simple endosmosis through the root hair. It passes across the cortex along a gradient of DPD. A high concentration in the xylem is maintained by the addition of salts or sugars.

NEET Biology Plant Water Relations Absorption Of Water By Aerial Parts

The aerial portions of plants, especially the leaves, can absorb water from the atmosphere to a limited degree, contingent upon the water potential. The cutin and pectin layers of apple leaves exhibit significant water-absorbing ability.

• Breazeale et al. (1951) state that if water potential gradients are advantageous, water absorbed by the leaves of tomato and maize might go negatively, i.e., downward to the soil.
• Uptake of mineral salts. It occurs through both passive and aggressive mechanisms. In the initial scenario, energy is not implicated.
• They are assimilated through diffusion or ionic exchange methods. In the second scenario, the active absorption of minerals occurs via specific carriers, and ATP utilization is also involved.

Water Relations In Plant Cells NEET Study Material

NEET Biology Plant Water Relations Ascent Of Sap

The absorbed water ascends to the apex of the plant via the xylem. This phenomenon is referred to as the Ascent of sap. The xylem is the conduit for the upward movement of sap.

• This can be demonstrated using ringing tests (Malpighi, Stephen, and Hertig). Sap consists of water and mineral salts.
• It is relocated inside the xylem tissue, as evidenced by many investigations. Among the several theories proposed.
• Dixon’s idea regarding the cohesiveness of water and the transpiration pull theory is valid. It indicates that the ongoing loss of water from the aerial portions generates tension or a transpiration pull at the apex of the plant.
• It draws water from the base to the apex. Despite being influenced by transpiration pull, water molecules remain together because to the substantial cohesive forces of water.
• The water column remains intact, allowing the ascent of water (sap).

NEET Biology Plant Water Relations Theories To Explain Mechanism Of Ascent of Sag

Any acceptable theory to explain the mechanism of the ascent of sap must take into account the following features :

• Large quantities of water are conducted at very high speeds (average rate 1 meter/ hour).
• Xylem vessels are dead tubes with narrow lumens.

To move water through such tubes to the height of a tall tree requires great pressure (approximately 13 atm. pressure is required to raise water to the top of a 416 ft tall tree).

1. Three types of theories have been proposed to explain the mechanism of the ascent of sap; vital theories, physical theories, and root pressure theory. According to vital theories, living cells are responsible for the ascent of sap.
2. The physical theories believe that it is a physical phenomenon. The root pressure theory is partly physical and partly vital.
3. According to the relay pump hypothesis of Godlewski, the water rises in the stem due to the activity of the cells of medullary rays and xylem parenchyma.
4. The pulsation hypothesis of Bose suggests that water rises in the stem due to activity taking place in the innermost layer of the cortex.
5. The root pressure is the pressure experienced by the tracheary elements due to the metabolic activity of root cells. Its presence is confirmed by bleeding and guttation. Root pressure is the positive hydrostatic pressure developed in roots due to the accumulation of absorbed water.

The term ‘root pressure’ was coined by Stephen Hales (1727). Stocking (1956) considered root pressure as an active process and defined it as “pressure developing in the tracheary elements of the xylem as a result of the metabolic activities of roots.”

• Root pressure is responsible for guttation and bleeding in plants. It is measured by a manometer. Maximum root pressure recorded in plants is 2 to 3 bars (0.2 to 0.3 MPa).
• This is sufficient to raise the column of water to a height of 21 meters.
• The role of root pressure in the ascent of sap in all plants is uncertain. At the most, it may be useful for the ascent of sap in herbs.

The main drawbacks of root pressure theory are :

1. Root pressure is absent in gymnosperms which are some of the tallest trees.
2. Root pressure is absent in actively transpiring plants.
3. The ascent of sap was observed in plants even if the root system was removed.
4. According to Boehm water rises in the stem due to the joint force of capillary and atmospheric pressure. Sachs, on the other hand, believed that the ascent of sap is due to the force of imbibition.
5. The cohesion theory of Dixon and Jolly suggests that water rises in stem due to the cohesion of water molecules, continuity of the water column, and transpiration pull.

The main features on which this theory is based are :

• • Right from the root hairs to the tips of the leaves, water forms a continuous network in the plants.
  • Water molecules have high cohesion between them i.e., these tend to stick to each other, because, being polar, these are electrically attracted to each other, being held by hydrogen bonds. The high cohesive force means that a relatively large tension is required to break a column of water. In other words, the water column has a great tensile strength.
  • The Lignocellulosic cell walls of xylem vessels have a strong affinity (adhesion) for water molecules. Therefore, a strong adhesive force exists between the walls of the xylem vessels and water i.e., water tends to ‘stick’ to the vessel wall.
  • As the water is lost from the leaf surface by transpiration, the osmotic pressure of the ‘ leaf cells increases. As a result, the cells develop low water potential and water from the leaf veins (xylem) moves into leaf cells.
  • The xylem vessels, in turn, draw water from the xylem of the main stem. A negative (pulling) pressure is thus exerted by all the leaves on the stem. The combined pressure, called transpiration pull, is strong enough to pull up the column of water to great heights.
• The tension of -80 bars can raise the column of water in the tallest tree. However, gravitational force prevents the transport of water. This hypothesis also suggests the conducting efficiency of tracheids over vessels which cannot be accepted.

NEET Biology Plant Water Relations Transpiration

The evaporation of water from the aerial parts of plants is called transpiration. It may be stomatal, epidermal, cuticular or lenticular.

About 98 percent of the water absorbed by land plants evaporates from the aerial parts of the plant and is lost into the atmosphere. 0.2% is used in photosynthesis.

Sites of transpiration. Transpiration may occur from the following three sites :

1. Stomata. Approximately 90% of the transpiration occurs due to evaporation of water from leaf cells through stomata.
2. Cuticle. Up to 10% of transpiration may take place from the outer walls of epidermal cells through the waxy cuticle. In herbaceous plants, it may reach up to 50%.
3. Lenticels. A small fraction of transpiration occurs through lenticels (0.1%.)

Water Relations In Plant Cells NEET Study Material

Stomata. A stoma consists of two kidney-shaped or dumbbell-shaped guard cells. They cover hardly 1-2% of the leaf surface and may be surrounded by subsidiary cells. The number of stomata on the lower epidermis range between 10,000-58,000.

• The inner tangential walls of the guard cells are thick and they also show the radial arrangement of micelle (radial micellation).
• A leaf may be amphistomatic, hypostomatic, or epistomatic. Based on distribution, we differentiate apple type, potato type, oat type, water lily type, and Potamogeton type stomata.
• Based on daily movement (rhythmicity) three types of stomata are differentiated, namely, alfalfa type (Leucerene), which opens the whole day and close during the night, e.g. Pea, radish, mustard, turnip, beet, apple, grapes, bean, potato type, open all day and night except a few hours in the evening e.g. Onion, Cucurbita, Tulip, Bananas, barley (cereal) type, open only for a few a hours in a day e.g. maize, wheat, and Equisetum type, open all the time.

Photoactive and Scotoactive Stomata. Stomata that open during the day and close at night are called photoactive stomata. Generally, the stomata are photoactive. But, the stomata that close during the day and open at night are called scotoactive stomata. These are found in succulents like Bryophyllum, Opuntia, and Cacti.

NEET Biology Plant Water Relations Theories Of Opening And Closing Of Stomata

1. The thickening of the inner tangential wall of the guard cells or the radial oscillation of the cell wall is thought to cause the opening and closing of stomata when they are turgid and flaccid.
2. According to Von Mohl, the guard cells prepare some osmotically active substance which causes the opening of stomata. Linsbauer, on the other hand, thinks that it is the change in the permeability of guard cells that causes the opening and closing of stomata.
3. According to Llyod, the conversion of starch into sugar in the daytime and vice versa at night causes the opening and closing of stomata. Sayre and Scarth are of the view that this conversion is controlled only by the pH of the guard cells whereas Steward regards that this is partly enzymatic and partly controlled by pH.
4. Inamura reported that cytokinin and CAMP also require accumulation of K+ in the guard cells whereas Willmer et al. found the conversion of starch into organic acids and vice versa responsible for the opening and closing of stomata, while the opening of stomata is controlled by the accumulation of K+, Cl- and organic acid (malic acid), the closing is initiated by ABA.

The theory of K+ transport and hormonal regulation may be represented as :

Levitt proposed a synthetic, proton transport hypothesis that states that the opening and closing of stomata is controlled by active K⁺ transport and pH of the guard cells.

Factors Affecting Stomatal Movement

The stomata] movement is affected by light. CO₂ concentration. pH of the guard cells, H~ K“ CT. organic acid temperature. ABA and conditions of water stress. The stomata do not open under U  far-red and green wavelength. The best stomatal opening occurs under blue light.

Factors affecting transpiration. Several environmental factors influence transpiration such as humidity, temperature, light, wind atmospheric pressure, and available soil water.

• The transpiration rate is directly proportional to saturation deficit and inversely to atmospheric pressure.
• The plant factors that influence transpiration are root-shoot ratio, leaf area, and leaf structure. Pruning of plants increases transpiration per unit leaf area.
• High temperature and low humidity In the atmosphere increase the rate of transpiration.
• An increase in the wind velocity increases the rate of transpiration by removing the water vapor from the vicinity of the plant However excessive wind velocity decreases the rate of transpiration inducing the closure of stomata due to loss of water from the guard cells by drying.

Significance of transpiration. Transpiration is thought to maintain the temperature of the plant, absorption, and ascent of sap, the maintenance of turgidity, and mineral translocation. But these activities seem to be independent of transpiration.

Water Relations In Plant Cells NEET Study Material

Measurement of Transpiration

1. Measurement of stomatal opening can be done directly under the microscope, by Molisch’s injection method and perimetry. The porometers are of two types-viscous flow porometer and diffusion porometer.
2. Transpiration can be measured qualitatively by the cobalt chloride method (Hygroscopic method) and quantitatively by photometers and the calcium chloride method.
3. In Ganong’s photometer an air bubble moves whereas in Farmer’s photometer the entire water column moves. The latter instrument is regarded as the best one for measuring transpiration. By photometers, we measure suction due to transpiration.

By the calcium chloride method, we find out the change in the weight of CaCl, due to cuticular or stomatal transpiration.

• Transpiration flux is the quantity of water transpired by a unit area of leaf surface in a unit of time.
• Transpiration ratio (Lowes 1850). The amount of water lost per unit of dry matter produced during the growing season is called transpiration ratio,
  • 50 Units—CAM plants
  • 100-200 Units—C4 plants
  • 300-500 Units—Mesophytes
  • 900 Units—Alfalfa

Guttation. It is the loss of water through hydathodes. The term guttation was coined by Bergerstein. Guttation is a normal process in Colocasia antiquorum. (200 ml) Nasturtium. tomato, potato.

• Water is essential for all physiological activities of plants and acts as an excellent solvent, helping in the uptake and distribution of mineral nutrients and other solutes required for growth and distribution.
• The potential energy of water is termed water potential,
• The common measurement unit of water potential is pas¬ cal, Pa (J Megapascal, Mpa = 10 bars) and is represented By the Greek letter psi.ψ
• Three factors influence water potential arc Concentration, pressure, and gravity.
• ψ=ψ_s+ψ_p+ψ_g
• TheoreticalIy  ψ  of pure water is taken as zero and therefore ψ inside plant cell is negative.,
• The term ψs is called solute potential or osmotic potential, lFp as pressure potential or hydrostatic pressure, and ψp as gravity potential.
• The watering root moves through the apoplast pathway, symplast pathway, and vacuolar pathway.

The Casparian strip is composed of a wax-like substance called Suberin which blocks water and solute movement through the cell wall of the endodermis.

1. A solution has an osmotic potential (solute potential) which is negative of osmotic pressure (πpi) thus
2. ψ_s=-π
3. Imbibition pressure is also known as matric potential,
4. Two conditions are necessary for imbibition to take place. i.e. water potential gradient between the surface of the adsorbent or liquid imbibed and affinity between adsorbent and imbibed liquid.
5. The three most important theories of water translocation are root pressure, capillary, and cohesion theory.

Stomatal Frequency and Stomatal Index The number of stomata per unit area of the leaf is described as stomatal frequency.

1. Stomatal frequency is not fixed for a species. It differs with the position of the leaves on the plant and external conditions like humidity.
2. Stomatal frequency is also affected by the osmotic pressure of the leaf cells.
3. The stomatal index is defined as the percentage number of stomata as compared to all the epidermal cells (in-eluding stomata) in a unit area of the leaf. Salisbury (1927) found a correlation between the number of stomata and the epidermal cells per unit area.
4. I=S\E+S×100
5. Here I = Stomatal Index, number of stomata for unit area, E = number of epidermal cells per unit area. The Stomatal Index is independent of environmental conditions and not affected by conditions like the position of the leaf and the age of the plant.

• The principle involved in the osmotic theory of active water absorption

• Passive absorption of water was proposed by Kramer and Lachenmeir.
• The theory of passive absorption works on the following principle.

NEET Biology Plant Water Relations Quanta To Memory

• Lasitmts syndics sends its roots to a depth of four meters,
• Wclwitschid mirabilis can penetrate its roots to a distance of 18 meters.
• Dr. Dinner found that the total, length of roots (minus root hairs) formed by a rye plant in Four months is about 620 km. covering a total surface area of 255 sq. meters.
• The equimolar concentration of two solutions of non¬ionising substances will have the same osmotic pressure. In evident plasmolysis, cytoplasm withdraws itself from the cell wall. O.P. does not increase by the addition of insoluble solute in the solution.
• D.P.D. can become zero (fully turgid cell). T.P. can also become zero (flaccid cell). However, OP. of a cell can never be zero.
• Water does not move Inside the cell when T.P. = O.P.
• Suction pressure S.P.=O.P.-T.P.
• One gm. mole of solute dissolved in 1 lit./lOOO c.c. of the solution is the molal solution. However, one gm. mole of a solute when added to 1 lit./1000 C.c. of the solution is the molar solution.
• Root pressure is absent in gymnosperms.
• Less than 2 percent of all the water that a plant absorbs is required for its various uses.
  Severe drought stress or intense solar radiation causes the production of a plant hormone abscisic acid which signals the closure of stomata.
• Wilting and water-logging. In water-logged soils, the plants often show wilting. It is caused by the development of ethylene precursor by the roots (Bradford and Young, 1981) which reaching the shoot brings about wilted conditions.
• Plants with when turgor pressure inside the cells of such tissue go down below zero.
• Bajra, sorghum, and ragi require relatively low inputs of water while coffee, tea, coconut, rosewood, teak, willow, and bamboo need large quantities of water.
• Anti-transpirants increase leaf resistance to water vapor diffusion without affecting carbon dioxide uptake e.g. Phenyl mercuric acetate and waxy materials.
• Tensile Strength of Water. It is the ability of the water column to get stretched without breaking. The value is 45-207 atm (Dixon and Jolly, 1894). Tensile strength is due to cohesive force amongst molecules of water and adhesion between water molecules and walls of the xylem.
• J.C. Bose proved in the case of Desmodium gyrans that pulsating movement is developed in the cells that pump water to the next higher cell.
• The above fact was confirmed by Molisch.
• Stomatal opening in darkness was explained by Fujino (1967), Fisher (1968), Levitt (1974), and Rask (1975). The unit of water potential is bars
• Potometer. It is an apparatus for measuring the rate of transpiration.
• Poromcler. It is nil apparatus for knowing the relative sizes of stomata.

Osmosis And Plasmolysis NEET Question Bank

• Almometer. It is an apparatus for demonstrating and measuring pull caused by the evaporation of water In a porous pot,
• Psychrometer. It is an instrument for measuring both relative humidity and transpiration.
• Tramsiometer. It is an instrument that measures soil water tension.
• A barometer is used for measuring atmospheric pressure.
• A manometer is used for measuring pressure like root pressure
• A pressure chamber is used for measuring the water potential of whole leaves, shoots, etc.
• A cryoscopic osmometer measures the osmotic potential of the solution by measuring its freezing point.
• The term osmosis was coined by Nollct.
• The term “osmotic pressure” was proposed by PI’effer.
• The concept of “water potential” was proposed by Slatyer and Taylor.
• “Ringing experiments to prove that xylem is the path for the ascent of sap were first conducted by Malpighii (1672), Stephan Hales (1772), and Hartig.
• The term root pressure was coined by Stephen Hales (1727)
• Stocking (1956) considered guttation and bleeding as the manifestations of root pressure.
• Schwcndcner (1881) was the first to propose that the opening and closing of stomata occur due to the change in the turgor pressure of the guard cells.
• Levitt (1974) proposed an active K⁺ transport mechanism for opening and closing of stomata.
• Curtis (1926) considered transpiration “as a necessary evil” in plants.
• Bowling proposed a K⁺ ion transport mechanism for the opening of stomata (K⁺ ions as osmoticum).
• Zelitch proposed the role of glycolic acid in the opening of stomata.
• Absorption Lag (Kramer, 1937). It is the shortfall of the rate of water absorption over the rate of transpiration.
• The aerial roots of epiphytic roots have specialized tissue (velamen) for absorbing rainwater and condensed water vapors.
• Water logging reduces soil oxygen and decreases water absorption.
• Cell sap of root hair usually possesses higher OP (2-8 atm) compared to OP of soil water (<1 atm).
• No water is absorbed below the permanent wilting percentage or wilting coefficient.
• No water is absorbed in frozen soil as frozen soil is impermeable to water.
• The rate of water absorption decreases below 20°C because of increased viscosity of water, decreased permeability of the membrane, poor root growth, and low metabolic rate.
• Water is generally absorbed when the concentration of root hair cell sap is more than outer soil water.

NEET Biology Plant Water Relations MCQs

Question 1. The bullion cells of monocotyledon leaves show

1. Tropic movement
2. Autonomic movement
3. Nastic movement
4. Turgor movement.

Answer: 4. Turgor movement.

Question 2. Water will be absorbed by the root hairs when :

1. Plants are rapidly respiring
2. The concentration of salts in the soil is high
3. The concentration of solutes in the cell sap is high
4. They are separated from the soil by a permeable membrane.

Answer: 3. Concentration of solutes in the cell sap is high

Question 3. In which of the following plants would metabolism be hindered if the leaves were coated with wax on their upper surface?

1. Vallisneria
2. Pistici
3. Lotus
4. Hydrilla.

Answer: 3. Lotus

Question 4. Stomata open at night and close during the daytime in

1. Succulents
2. Mesophytes
3. Hydrophytes
4. Herbs.

Answer: 1. Succulents

Plant Water Relations NEET Mcqs

Question 5. During the rainy season, doors made up of wood generally swell up due to :

1. Osmosis
2. Had workmanship
3. Imbibition
4. Bad quality of wood.

Answer: 3. Imbibition

Question 6. Dumb-bell shaped guard cells are characteristics of:

1. Herbs
2. Dicot leaf
3. Isobilateral leaf
4. Scale leaf.

Answer: 3. Isobilateral leaf

Question 7. The closing and opening of stomata is due to an influx of:

1. K⁺ ions
2. Na ions
3. Fe ions
4. Mg ions.

Answer: 1. K⁺ ions

Question 8. Pure water has a water potential which is :

1. zero
2. Negative
3. High
4. Very low.

Answer: 1. zero

Question 9. The amount of water absorbed to compensate for the loss of transpiration is measured by :

1. Potometer
2. Crescograph
3. Manometers
4. Auxanometers.

Answer: 1. Potometer

Question 10. The inward pressure exerted on the cell contents by the stretched cell wall is termed :

1. Osmosis
2. Wall pressure
3. Turgor pressure
4. Osmotic pressure.

Answer: 2.  Wall pressure

Question 11. The form and structure of a growing cell is maintained due to :

1. Atmospheric pressure
2. Plasmolysis
3. Turgidity
4. Wall pressure.

Answer: 3. Turgidity

Question 12. The water potential and osmotic potential of pure water are :

1. 100 and zero
2. Zero and Zero
3. 100 and 100
4. Zero and 100.

Answer: 2. Zero and Zero

Plant Water Relations NEET Mcqs

Question 13. The membrane that allows certain molecules to enter into the cell and prevents others is known as:

1. Impermeable membrane
2. Permeable membrane
3. Selectively permeable membrane
4. Unit membrane.

Answer: 3. Selectively permeable membrane

Question 14.” The vacuolar membrane is known as :

1. Cell membrane
2. Plasmalemma
3. Chromoplast
4. Tonoplast.

Answer: 4. Tonoplast.

Question 15. Due to osmosis, water enters into a cell and results in hydrostatic pressure. This is known as :

1. Osmotic pressure
2. Wall pressure
3. Turgor pressure
4. Low pressure.

Answer: 3. Turgor pressure

Question 16. The plasmalemma, cytoplasmic film, and the vacuolated membrane in an osmotic system of a vacuolated cell constitute the :

1. Permeable membrane
2. Impermeable
3. Electively permeable membrane
4. Unit membrane.

Answer: 3. Electively permeable membrane

Question 17. Exosmosis takes place when a plant cell is put in :

1. Hypertonic solution
2. A hypotonic solution
3. An isotonic solution
4. Non-ionic solution.

Answer:1. Hypertonic solution

Question 18. Endosmosis occurs when a plant cell is put in :

1. A hypertonic solution
2. Hypotonic solution
3. An isotonic solution
4. Non-ionic solution.

Answer:2. Hypotonic solution

Question 19. If there is no net movement of water into a cell from the outside medium, the medium is :

1. Isotonic to the cell sap
2. Hypertonic
3. Hypotonic
4. Non-ionic.

Answer: 1. Isotonic to the cell sap

Question 20. During absorption of water by roots, the water potential of cell sap is lower than that of:

1. Pure water and soil solution
2. Neither pure water nor soil solution
3. Soil solution but higher than that of pure water
4. Pure wafer but higher than that of soil solution.

Answer: 1. Pure water and soil solution

Plant Water Relations NEET Mcqs

Question 21. When a cell is fully turgid, it:

1. O.P. = D.P.D.
2. OP = Zero
3. DCP.D = zero
4. D.P.D. = O.P.

Answer: 3. DCP.D = zero

Question 22. A cell increases in volume when placed in a solution which is:

1. Isotonic
2. Hypotonic
3. Hypertonic
4. None of the above.

Answer: 2. Hypotonic

Question 23. DPD stands for:

1. Diffusion pressure deficit
2. Diffusion pressure demand
3. Daily photosynthetic depression
4. Daily phosphorus demand.

Answer:1. Diffusion pressure deficit

Question 24. The force responsible for water entry into the cell is :

1. Diffusion
2. DPI
3. Osmotic pressure
4. Wall pressure.

Answer: 2. DPI

Question 25. Minerals are absorbed by the plants from the soil ;

1. By a process independent of water absorption
2. Independently of water
3. Only when soil solution is hypertonic to cell sap
4. Only when soil solution is hypotonic to cell sap.

Answer: 1.  By a process independent of water absorption

Question 26. The osmosis means :

1. Movement of molecules from an area of higher concentration into an area of lower concentration
2. Uptake of water by plant roots
3. Passage of solvent from a weak solution to a strong solution when the two are separated by a semi-permeable membrane
4. Passage of solute from a weak solution to a strong solution when the two are separated by a semi-permeable membrane.

Answer: 3. Passage of solvent from a weak solution to a strong solution when the two are separated by a semi-permeable membrane

Question 27. Starch is changed to organic acids during :

1. Stomatal initiation.
2. Stomatal closure
3. Stomatal opening
4. Stomatal growth.

Answer: 3. Stomatal opening

Question 28. Selective permeability is the main property of:

1. Osmosis
2. Diffusion
3. Active transport
4. Imbibition.

Answer: 3. Active transport

Question 29. When placed in water seeds swell, due to :

1. Hydrolysis
2. Osmosis
3. Imbibition
4. None of the above.

Answer: 3. Imbibition

Question 30. Most of the physiological reactions in plants occur at a pH of:

1. 4.0
2. 8.0
3. 7.0
4. 14.0.

Answer: 3. 7.0

Question 31. The movement of water from one cell of the cortex to the adjacent one in the roots is due to :

1. Accumulation of inorganic salts in the cells
2. Water potential gradient
3. Accumulation of organic salts in the cells
4. Chemical potential gradient.

Answer:  2. Water potential gradient

Plant Water Relations NEET Exam Preparation

Question 32. Which of the following factors is most important in the regulation of transpiration?

1. Temperature
2. Humidity
3. Light
4. Wind.

Answer:2. Humidity

Question 33. If the volume of a cell decreases after being placed in a solution, the solution is :

1. Isotonic
2. Hypertonic
3. Hypotonic
4. Normal.

Answer: 2. Hypertonic

Question 34. If cell A with, DPD, 4 bars are connected to cells B, C, and D whose OP and TP are respectively 4 and 4, 10 and 5, and 7 and j bar, the flow of water willies- 

1. C to A, B, and D ‘
2. A and D to B and C
3. A to B, C, and D ‘
4. B to A, C, and D.

Answer: 3.  A to B, C and D ‘

Question 35. The energy source that drives the upward flow of water is:

1. Temperature
2. Sucrose
3. Solar energy
4. ATP.

Answer: 4. ATP.

Question 36. To initiate cell plasmolysis, the salt solution should be

1. Isotonic
2. Hypertonic
3. Hypotonic
4. None of the above.

Answer: 2. Hypertonic

Question 37. Plant cells submerged in distilled water will become :

1. Turgid
2. Flaccid
3. Plasmolyzed
4. Impermeable.

Answer:1. Turgid

Question 38. Which of the following plant cells has more negative water potential?

1. Cell with high osmotic pressure
2. Cell with high turgor pressure
3. Cell with high wall pressure
4. Cell with low osmotic pressure.

Answer:1. Cell with high osmotic pressure

Question 39. Protoplasm is :

1. True solution
2. Colloidal solution
3. Suspension
4. None of the above.

Answer: 2. Colloidal solution

Question 40. Plasma membrane helps :

1. In protein synthesis
2. Regulates the passage of water only.
3. Regulates the passage of water and dissolved Substances into and out of cells
4. Protects the cell.

Answer: 3. Regulates the passage of water and dissolved Substances into and out of cells

Plant Water Relations NEET Exam Preparation

Question 41. The cell wall is permeable and can be observed from the passage of water and minerals from’?”

1. Root hair into cortical cells
2. Cortical cells into endodermis
3. Soil into root hairs
4. Cortical cells into pericycle.

Answer: 3. Soil into root hairs

Question 42. Deplasmolysis into the cell occurs which is placed in:

1. Isotonic solution
2. hypotonic solution
3. Hypertonic solution
4. None of these.

Answer:2. hypotonic solution

Question 43.  Purple cabbage leaves do not lose their color in cold water but do so in boiling water because :

1. The plasma membrane becomes permeable in boiling water and pigments come out
2. Hot water can enter the cells readily
3. The pigment is not soluble in cold water
4. The cell wall is killed by boiling water.

Answer: 1. The plasma membrane becomes permeable in boiling water and pigments come out

Question 44. Osmosis is defined as the process by which :

1. Water diffuses from lower concentration to higher concentration
2. Solutes diffuse from lower concentration to higher concentration
3. Active transport of ions takes place
4. Passive transport of ions takes place.

Answer:1. Water diffuses from lower concentration to higher concentration

Question 45. Water potential in the leaf tissue is positive (+ve) during :

1. Excessive transpiration
2. Low absorption
3. Low transpiration
4. Guttation.

Answer: 3. Low transpiration

Question 46. With the increase in turgidity of a cell surrounded by water the wall pressure will:

1. Increase
2. Decrease
3. Fluctuate
4. Remain unchanged.

Answer: 1. Increase

Question 47. The ultimate cause of water movement against gravity is :

1. Osmosis
2. Imbibition
3. Transpiration pull
4. Respiration.

Answer: 3. Transpiration pull

Plant Water Relations NEET Exam Preparation

Question 48. When a plant wilts, what will be a sequence of events :

1. Exosmosis, deplasmolysis, plasmolysis, temporary and permanent wilting
2. Exosmosis, plasmolysis, temporary and permanent wilting
3. Exosmosis, plasmolysis, deplasmolysis, temporary and permanent wilting
4. Endosmosis, plasmolysis, temporary and permanent wilting.

Answer: 2.  Exosmosis, plasmolysis, temporary and permanent wilting

Question 49. The process of osmosis stops when:

1. The solution is not isotonic
2. Water concentration becomes equal
3. There is no light
4. The leaves fall.

Answer: 2. Water concentration becomes equal

Question 50. The rate of absorption of water is slow at temperatures near the freezing point:

1. It is mainly a metabolic process
2. Cell membrane becomes more viscous
3. The growth of cells stop
4. Transpiration is retarded.

Answer: 4. Transpiration is retarded.

Question 51. The outward pressure exerted on the cell wall by the fluid contents of the cell wall is called:

1. Turgor pressure
2. Wall pressure
3. Osmosis
4. None of the above.

Answer: 1. Turgor pressure

Question 52. Dixon and Jolly’s are associated with :

1. Aerobic respiration
2. Calvin cycle allision
3. Cohesion theory of ascent of sap
4. Light reaction.

Answer: 3. Cohesion theory of ascent of sap

Question 53. Which plants do not generate root pressure?

1. Monocot grasses
2. Perennial shrubs
3. Conifer trees
4. Seasonal herbs.

Answer: 3. Conifer trees

Question 54. Transpiration cohesion tension theory operates in :

1. Active absorption
2. Passive absorption
3. Both active and passive absorption
4. None of the above.

Answer:2. Passive absorption

Question 55. Which plant is used for demonstrating plasmolysis in the laboratory?

1. Tropeolum
2. Patience balsamic
3. Tradescantia
4. All the above.

Answer: 4. All the above.

Question 56. Transpiration takes place from :

1. Leaves
2. Stem
3. All aerial parts of the plant
4. All parts of the plant body.

Answer: 3. All aerial parts of the plant

Question 57. Much of transpiration takes place through :

1. Epidermis
2. Lenticels
3. Stomata
4. Cuticle.

Answer: 3. Stomata

Question 58. Transpiration from plants will be more rapid when :

1. The atmosphere is saturated with water
2. There is excess water in the soil
3. Environmental conditions are dry
4. Air is still.

Answer: 3. Environmental conditions are dry

Question 59. Guttation takes place through :

1. Stomata
2. Hydathodes
3. Lenticels
4. Cuticle.

Answer: 2. Hydathodes

Question 60. If cohesion-tension transpiration theory is correct then a break in the water column in xylem vessels :

1. This should cause the mesophyll cells to become flaccid and result in the wilting of leaves.
2. Should increase the water contents of leaves
3. Should have no effect at all
4. Should increase the rate of photosynthesis.

Answer: 1. This should cause the mesophyll cells to become flaccid and result in the wilting of leaves.

Plant Water Relations NEET Previous Year Questions

Question 61. According to Scarth, opening and closing of stomata is controlled by :

1. Enzymes
2. pH value
3. NADP
4. Hormones.

Answer:2. pH value

Question 62. Stomata are bounded by guard cells and open when the cells are :

1. Turgid
2. Flaccid
3. Green
4. Small.

Answer: 1. Turgid

Question 63. Stomata open during the time because the guard cells :

1. Photosynthesize and produce osmotically active sugars
2. Are thick-walled
3. Are bean-shaped
4. Have to help in gaseous exchange.

Answer: 1. Photosynthesize and produce osmotically active sugars

Question 64. Which one is not related to transpiration?

1. Bleeding
2. Circulation of water
3. Absorption and distribution of mineral salts
4. Regulation of plant body temperature.

Answer:1. Bleeding

Question 65. A small mesophytic twig with green leaves is dipped into water in a big beaker under sunlight. It demonstrates :

1. Photosynthesis
2. Respiration
3. Transpiration
4. None of the above.

Answer: 3. Transpiration

Question 66. The phytohormone which is supposed to be one of the factor responsible for regulating the opening and closing of stomata:

1. ABA
2. GA
3. IBA
4. Kinetin.

Answer: 1. ABA

Question 67. Which of the following changes in the cell sap of the guard cell is responsible for keeping stomata open during the daytime?

1. Decrease in both osmotic and turgor pressure
2. Increase in both osmotic pressure and turgor pressure
3. Increase in osmotic pressure but decrease in turgor pressure
4. Decrease in osmotic pressure but increase in turgor pressure.

Answer: 2. Increase in both osmotic pressure and turgor pressure

Question 68. Guard cells differ from epidermal cells in having :

1. Mitochondrion
2. Chloroplast
3. Vacuole
4. Cell wall.

Answer: 2. Chloroplast

Question 69. If the C02 concentration of the atmosphere were to increase :

1. Stomata will close partially
2. Respiration will decrease
3. Stomata will open
4. Photorespiration will increase.

Answer: 1. Stomata will close partially

Question 70. Which one of the following factors is most important in the regulation of transpiration?

1. Light
2. Humidity
3. Temperature
4. Wind.

Answer: 1. Light

Question 71. Which of the following is the most likely cause for the wider opening of stomata?

1. The atmosphere outside the stoma is becoming less humid
2. Secretions of salt molecules by the adjacent guard cells take place
3. Water molecules enter the guard cells
4. The night temperature is going to fall.

Answer: 3. Water molecules enter the guard cells

Question 72. Cohesion tension theory of water transport is based on :

1. Root pressure
2. Activity of parenchyma to the proximity of conducting vessels and tracheids.
3. Activity of phloem
4. Transpiration pull.

Answer: 4. Transpiration pull

Question 73. The value of water potential (yw) can be obtained by :

1. π+WP
2. ψ_s+ψ_p
3. ψ + WP
4. ψ + TP.

Answer: 2. ψ_s+ψ_p

Question 74. The bulliform cells of leaves lose their turgidity during excessive :

1. Assimilation
2. Transpiration
3. Photosynthesis
4. Respiration.

Answer: 2.  transpiration

Plant Water Relations NEET Previous Year Questions

Question 75. A freshly cut potato chip is put into a strong solution of sugar. Later it is found to be :

1. Flaccid
2. Longer
3. Turgid
4. More full of starch.

Answer:1. Flaccid

Question 76. Which of the following processes in excess causes temporary wilting?

1. Respiration
2. Transpiration
3. Photosynthesis
4. Imbibition.

Answer: 2. Transpiration

Question 77. Osmotic pressure is responsible l\>v tho turgidity of plant colls which;

1. Causes cell elongation
2. Causes opening to stomata
3. Prevents willing to leave
4. All the three above,

Answer: 4. All the three above,

Question 78. Hydathodes are present:

1. On the upper sin face of the leaf
2. On the lower surface of the leaf
3. At the tip of the vein of the leaf
4. At the base of the veins of the leaf.

Answer: 3. At the tip of the vein of the leaf

Question 79. The cohesion theory of the ascent of sap was given by ;

1. Sachs
2. Dixon and Jolly
3. Bose
4. Robert Brown,

Answer: 2. Dixon and Jolly

Question 80. Spraying of phenyl mercuric

1. Increases transpiration
2. Reduces transpiration
3. Increases rate of photosynthesis
4. Causes guttation.

Answer: 2. Reduces transpiration

Question 81. Silicone emulsions when used:

1. Increase transpiration
2. Reduce transpiration
3. Increase rate of photosynthesis
4. Cause guttation.

Answer: 2. Reduce transpiration

Question 82. With the increase in turbidity of a cell surrounded by water. the wall pressure will?

1. Increase
2. Decrease
3. Fluctuate
4. Remain unchanged.

Answer: 1. Increase

Question 83. Transpiration is:

1. Not necessary for plants
2. Necessary for plants
3. Avoidable
4. A necessary evil.

Answer: 4. A necessary evil.

Question 84. A plasmolyse cell can be plasmolyse by placing it in :

1. Pure water or hypotonic solution
2. Hypertonic solution
3. Isotonic solution
4. Saturated solution.

Answer: 1. Pure water or hypotonic solution

Question 85. Leaves of xerophytes have thick cuticle, hairs, fewer and sunken stomata in order to :

1. Facilitate transpiration
2. Slop transpiration
3. To minimize excessive transpiration
4. Store water.

Answer: 3.  To minimize excessive transpiration

Question 86. The rate of transpiration is regulated by the movement of:

1. Epidermal cells of the leaves
2. Guard cells of the stomata
3. Mesophyll tissue of the leaves
4. Cuticle.

Answer: 2. Guard cells of the stomata

Question 87. The low atmospheric pressure :

1. Increases the rate of transpiration
2. Decreases the rate of transpiration slowly.
3. Doesn’t affect the rate of transpiration rapidly
4. Decreases the rate, of transpiration rapidly.

Answer: 1. Increases the rate of transpiration

Plant Water Relations NEET Previous Year Questions

Question 88. If alcohol treated cell is kept in a hypertonic solution it:

1. Bursts
2. Plastnolysed
3. Remains same
4. None.

Answer: 3.  Remains same

Question 89. The distribution of stomata per unit area of leaf and their size affects the rate of:

1. Respiration
2. Transpiration
3. Guttation
4. Absorption.

Answer:2. Transpiration

Question 90. In a dorsiventral leaf, the number of stomata is:

1. Same on both sides
2. Large on the upper epidermis
3. Huge on the lower epidermis
4. Lesser on lower than upper epidermis.

Answer: 3. Huge on the lower epidermis

Question 91. The restoration of turgidity in a plasmolyse cell, when placed in a hypotonic solution is caused by :

1. Hydration
2. Electrolysis
3. Plasmolysis
4. Deplasmolysis

Answer: 4. Deplasmolysis

Question 92. Water In plants is transported by (Ascent of sap takes placed through)?

1. Cambium
2. Epidermis
3. Xylem or Xylem vessel elements
4. Phloem

Answer: 3. Xylem or Xylem vessel elements

Question 93. The principal pathway by which water is translocated in angiosperms is:

1. xylem and phloem together
2. sieve tube members of phloem only
3. sieve cells of the phloem
4. xylem vessels system,

Answer: 4. xylem vessels system

Question 94. For conducting a girdling experiment:

1. The cortex is removed
2. The cortex anil primary phloem arc removed
3. All tissue up to the xylem is removed
4. Bark alone is removed.

Answer: 3. All tissue up to the xylem is removed

Question 95. Active absorption of ions is facilitated by :

1. Oxygen
2. ATP
3. More effective plasma membrane
4. Slightly higher temperature.

Answer: 2. ATP

Question 96. Levitt’s explanation for stomatal action is due to the:

1. Increase in sugar content of guard cells
2. Variations in pH value
3. Starch is converted into organic acids
4. Light causes opening and darkness closure.

Answer: 3. Starch is converted into organic acids

Question 97. Stomatal aperture is measured by ;

1. Micrometer
2. Potometer
3. Photometer
4. Luxometer.

Answer: 1. Micrometer

Question 98. The loss of water through the cuticle may reach up to:

1. 5%
2. 10%
3. 20%
4. 40%.

Answer: 2. 10%

Question 99. Which of the following walls is of the guard cell is thick:

1. Outer
2. Inner
3. Sidewall
4. All the walls,

Answer: 2. Inner

Question 100. The chief role of transpiration in plants is to cause :

1. The rapid rise of minerals
2. The rapid ascent of sap
3. Cooling of plants
4. Loss of surplus waiter.

Answer: 2. The rapid ascent of sap

Question 101. The stomata are widely open in :

1. Red light
2. Blue and red light
3. Greenlight
4. Yellow light.

Answer: 2. Blue and red light

Plant Water Relations NEET Notes

Question 102. At Full turgor in a cell:

1. ψ=0 and hence ψ_s= ψ_w
2. ψ_a= 0
3.  ψp = ψw
4.  ψp = – ψs and ψw =0

Answer: 4.  ψp = – ψs and ψw =0

Question 103. Positive root pressure can be demonstrated :

1. At noon
2. The early morning
3. In the evening
4. Only during the night.

Answer: 4. Only during the night.

Question 104. The plant is said to be wilted permanently when it:

1. Fails to revive at all
2. Revives if the soil is watered
3. Revives if kept in a saturated atmosphere
4. Revives when it is fanned.

Answer: 1. Fails to revive at all

Question 105. The movement of water up through a tree trunk depends on:

1. The high boiling point of water
2. Exclusion of air molecules from the sap solution
3. The vapor pressure of water
4. Attraction between water molecules.

Answer: 4. Attraction between water molecules.

Question 106. The girdling experiments performed by Malpighii supported the theory that:

1. Water moves in a tree by the root pressure mechanism
2. Water moves in a tree by a transpiration-cohesion mechanism
3. The xylem is primarily responsible for conducting water from the roots to the leaves
4. Phloem is primarily responsible for conducting organic solutes.

Answer: 3. The xylem is primarily responsible for conducting water from the roots to the leaves

Question 107. The osmotic potential of a solution is denoted by the symbol :

ψx

Δψ

ψp

ψs.

Answer: 4. ψs.

Question 108. Osmosis is defined as :

1. The flow of solvent molecules from a region of higher concentration to a region of lower concentration through a semipermeable membrane
2. The flow of low-concentration liquid
3. The flow of solvent molecules from a higher concentration to a lower concentration region
4. The flow of solvent molecules from a lower concentration to a higher concentration region.

Answer: 1. The flow of solvent molecules from a region of higher concentration to a region of lower concentration through a semipermeable membrane

Question 109. A root concentrates minerals by :

1. Active transport
2. Facilitated diffusion
3. Osmosis
4. Diffusion.

Answer: 1. Active transport

Question 110. A cell placed in a hypertonic solution will:

1. Initially gets plasmolysed but later becomes turgid if actively metabolising
2. Get plasmolysed and die
3. Remain turgid if treated with auxin
4. All the above.

Answer: 4. All the above.

Question 111. When a bottle of perfume is placed in one corner of a room and the lid is opened, the scent spreads all over the room after some time. This happens by the process of :

1. Plasmolysis
2. Diffusion
3. Endosmosis
4. Transpiration.

Answer: 2. Diffusion

Plant Water Relations NEET Notes

Question 112. The path of water and solutes from the soil to the conducting tissue of the root is :

1. Soil → root hair→ cortex→ endodermis →pericycle  protoxylem →phloem
2. Soil → root hair →  cortex →A pericycle → endodermis →protoxylem → metaxylem
3. Soil  epidermal cell of the root  cortex → endodermis → pericycle → protoxylem → metaxylem → secondary xylem
4. Soil → root hair → cortex → endodermis → pericycle → protoxylem → metaxylem.

Answer: 4. Soil → root hair → cortex → endodermis → pericycle → protoxylem → metaxylem.

Question 113. Capillarity is regarded as relatively unimportant as a possible cause of sap rise because :

1. Vessels do not show capillarity
2. Capillarity would cause sap to rise only a few inches or a few feet
3. The tracheids and vessels are very narrow
4. Absorption between xylem walls and water molecules is very low.

Answer: 2. Capillarity would cause sap to rise only a few inches or a few feet

Question 114. What will be the nature of the sugar solution, if the cell of an epidermal peal of Rhoeo discolor shows plasmolysis :

1. Hydrophobic
2. Hypertonic
3. Isotonic
4. Hypotonic.

Answer: 2. Hypertonic

Question 115. Xylem channels of the rootlets maintain a low water potential due to :

1. Maintenance of high salt content
2. Presence of negative pressure of water tension
3. Both A and B
4. Occurrence of positive pressure.

Answer: 3. Both A and B

Question 116. Water and minerals move towards the vascular cylinder of a root, they must enter the cytoplasm of :

1. Xylem cells
2. Cortex cells
3. Endodermal cells
4. Pericycle cells.

Answer: 3. Endodermal cells

Question 117. Most vascular plants increase the absorption of minerals by:

1. Mycorrhizae
2. Convertible phloem
3. Casparian channels along the phloem
4. Companion cells.

Answer: 1. Mycorrhizae

Question 118. Endosmosis of water occurs when in comparison with the outer solution, the water potential of cell sap is :

1. Higher
2. Lower
3. Equal
4. None of the above.

Answer:2. Lower

Water Relations In Plant Cells NEET Study Material

Question 119. If the cell (X) with DPD = 5 atm. is surrounded by many cells with DPD = 4 atm :

1. The net movement of water will be from cell X to the surrounding cells
2. The net movement of water will be from the surrounding cells to cell X
3. Water will not move at all
4. Water movement will depend on other unknown factors.

Answer: 2. Net movement of water will be from the surrounding cells to cell X

Question 120. Uptake of mineral ions into the xylem is controlled by:

1. Epidermal cells
2. Cortex cells
3. Endodermal cells
4. Xylem cells.

Answer: 3. Endodermal cells

Question 121. The opening and closing of stomata in leaves of mesophytic plants is reduced by :

1. Changes in C02, K ions, and ABA concentration, with simultaneous changes in the turgidity/ flaccidity of guard cells.
2. Changes in the starch sugar concentration in the guard cells
3. Changes in the H+ concentration in the guard cells
4. Differential thickening of walls of the guard cells.

Answer: 1. Changes in C02, K ions, and ABA concentration, with simultaneous changes in the turgidity/ flaccidity of guard cells.

Question 122. Tick the correct statement:

1. The amount of water absorbed by closely packed and loosely packed imbibing will depend upon the temperature of the medium
2. Both will imbibe the same amount of water
3. The closely packed imbibing will imbibe less water than the loosely packed one
4. The closely packed imbibing will imbibe more water than the loosely packed one.

Answer: 3. The closely packed imbibing will imbibe less water than the loosely packed one

Question 123. Mark the correct statement:

1. The value of TP remains the same at the time of limiting, incipient, and evident plasmolysis
2. The value of T.P. becomes zero at the time of limiting plasmolysis and below zero during incipient and evident plasmolysis
3. The value of T.P. becomes below zero at the time of limiting plasmolysis and zero at the time of incipient and evident plasmolysis
4. The value of T.P. becomes negative in all the stages of plasmolysis. “

Answer: 2. The value of T.P. becomes zero at the time of limiting plasmolysis and below zero during incipient and evident plasmolysis

NEET Biology Plant Water Relations Questions For Competitive Examinations

Question 1. A twig kept in the water remains fresh for a longer time if some salt is added to it due to the:

1. Absorption of more water
2. Exosmosis
3. Decrease in transpiration rate
4. Decrease in bacterial degradation activity,

Answer. 3. Decrease in transpiration rate

Question 2. In the process of osmosis :

1. Both protoplasm and cell wall act as a single layer
2. Only protoplast acts as a single layer
3. Only the cell membrane acts as a single layer
4. None of the above.

Answer. 2. Only protoplast acts as a single layer

Question 3. 0.1 M solution of a solute has a water potential of:

1. -2.3 bars
2. 0 bar
3. 22.4 bars
4. +2.3 bars.

Answer. 1. -2.3 bars

Question 4. During absorption of water by roots the water potential of cell sap is lower than that of:

1. Pure water and soil solution
2. Neither pure water nor soil solution
3. Pure water but higher than that of soil solution
4. Soil solution but higher than that of pure water.

Answer. 1. Pure water and soil solution

Water Relations In Plant Cells NEET Study Material

Question 5. During osmosis, water moves through a membrane :

Answer. 4.

Question 6. Which ion accumulates in the guard cells at the time of
opening of stomata

1. P “
2. K
3. Mg
4. Ca.

Answer.  2. K

Question 7. Wilting occurs due to excessive :

1. Respiration
2. Absorption
3. Guttation
4. Transpiration.

Answer. 4. Transpiration.

Question 8. Bulliform cells respond to which change?

1. Turgor pressure
2. Osmotic pressure
3. Photosensitive
4. None of the above.

Answer. 1. Turgor pressure

Question 9. Glycolate induces the opening of stomata in :

1. Presence of oxygen
2. Low CO₂ concentration
3. High C0₂
4. C0₂ absent.

Answer. 2. Low CO₂ concentration

Question 10. Passive absorption of minerals depends on :

1. Temperature and
2. Metabolic inhibitor
3. Metabolic inhibitor
4. Humidity

Answer.4. Humidity

Osmosis And Plasmolysis NEET Question Bank

Question 11. When water moves through a semipermeable membrane, then which of the following pressures develops?

1. O.P.
2. S.P.
3. T.P.
4. W.P.

Answer. 1. O.P.

Question 12. In which of the following plant sunken stomata are found?

1. Nerium
2. Hydrilla
3. Mango
4. Guava.

Answer. 1. Nerium

Question 13. Match the names of the experiments listed under column I with the aim of the experiment given under column II; Choose the answer that gives the correct combination of die alphabets.

1. a – r, b-p, c-s, d-q
2. a-s, b-r, c-p, d-q
3. a-s,b-p, c-q, d-r
4. a-q, b-p, c-s, d-r.

Answer. 2.  a-s, b-r, c-p, d-q

Question 14. Dry wooden stakes if driven into a small crack in a rock and then soaked, can develop enough pressure to split the rock. Such a pressure is built up through the phenomenon of:

1. Imbibition
2. Buttress roots
3. Prop roots
4. Turgor pressure.

Answer. 1. Imbibition

Question 15. The cohesive force existing between molecules of water contributes to :

1. Ascent of sap
2. Translocation
3. Plasmolysis
4. Osmosis.

Answer. 1. Ascent of sap

Question 16. In root pressure :

1. Roots act like a pumping organ like the heart.
2. Each cell acts as a pump
3. Water potential plays a major role
4. None of the above.

Answer. 3. Water potential plays a major role

Question 17. To initiate cell plasmolysis, the salt concentration must be:

1. Isotonic
2. Hypertonic
3. Hypotonic
4. Atonic.

Answer. 2. Hypertonic

Plant Water Relations NEET Mcqs

Question 18. The most accepted theory for stomatal opening and closing is:

1. Transpiration
2. Guard cell photosynthesis
3. K+ efflux and influx
4. Starch glucose interconversion.

Answer. 3. K+ efflux and influx

Question 19. The ascent of sap is mainly attributed to 

1. Cohesion force
2. Imbibition
3. Root pressure
4. Capillarity.

Answer. 4. Capillarity.

Question 20. Water lost by transpiration is :

1. Rich in solutes
2. Rich in dissolved roots
3. Rich in dissolved minerals
4. Pure water.

Answer. 4. Pure water.

Question 21. The main function of Ienticels is:

1. Transpiration
2. Guttation
3. Gaseous exchange
4. Translocation.

Answer. 3. Gaseous exchange

Question 22. Solution concentration is higher in tire external solution.
The solution is :

1. Isotonic
2. Hypotonic
3. Hypertonic
4. one of the above.

Answer.  3. Hypertonic

Question 23. In CAM plants, stomata are :

1. Always open
2. Never open
3. Open during the day and close at night
4. Open during the night and close during the day.

Answer. 4 Open during the night and close during the day.

Question 24. Match the items in column I with the correct combination of column 11 :

1. p  q    r     s
2. r   s    t     q
3. r   s     q   t
4. s   r      t    q

Answer.  2. r   s    t     q

Question 25. Which one is responsible for opening and closing of stomata :

1. Rise in pH of guard cells, hydrolysis of starch
2. Cytokinins and CAMP required
3. Abscisic acid promotes closure
4. All the above.

Answer. 4. All the above.

Question 26. A plant cell becomes turgid due to :

1. Plasmolysis
2. Exosmosis
3. Endosmosis
4. Electrolysis.

Answer. 3. Endosmosis

Question 27. Bolometer works on the principle of :

1. The amount of water absorbed equals the amount that transpired
2. Osmotic pressure
3. Root pressure
4. The potential difference between the tip of the tube and that of the plant.

Answer. 1. The amount of water absorbed equals the amount that transpired

Question 28. Which of the following in the guard cell is responsible for for opening of stomata?

1. Decrease in CO₂ concentration and more H⁺ ion
2. Decrease in CO₂ concentration and less H⁺ ion concentration
3. Increase in C0₂ concentration and more H⁺ ion concentration
4. More free llf ion and less Cl ion.

Answer.  2. Decrease in CO₂ concentration and less H⁺ ion concentration

Question 29. Identify the correct relationship with reference to the water potential of a plant cell.

1. ψ_{w =} ψ_{m +} ψ_a + ψ_p
2. ψ_{w =}  ψ_{m + [}ψ_s  – ψ_{p ]}
3. ψ_{w =}  ψ_{m – [}ψ_s  + ψ_{p ]}
4. ψ_{w =}  ψ_{m –} ψ_a – ψ_p

Answer. 1. ψ_{w =} ψ_{m +} ψ_a + ψ_p

Question 30. Passive adsorption of water by the root system is the result of

1. Forces created in the cells of the root
2. Increased respiratory activity in root cells
3. Tension on the cell sap due to transpiration
4. Osmotic force in the shoot system.

Answer. 3. Tension on the cell sap due to transpiration

Question 31. Water is lost in a liquid state in some plants through hydathodes. These hydathodes

1. Remain closed at night
2. Remain closed during the day
3. Remain always open
4. Do not show any specificity in opening and closing.

Answer. 3. Remain always open

Plant Water Relations NEET Exam Preparation

Question 32. Choose the correct combination labeling of the stomatal apparatus of dicot and monocot leaves.

1. a = epidermal cells, b = subsidiary cells, c = chloroplast, d = guard cells, e = stomatal aperture
2. a = epidermal cells, b = guard cells, c = chloroplast, d = subsidiary cells, c – stomatal aperture
3. a = epidermal cells, b = subsidiary cells, c = chloroplast, d = stomatal aperture, e = guard cells
4. a = subsidiary cells, b = epidermal, c = chloroplastm. d = stomatal aperture, c = guard cells
5. a = guard cells, b = epidermal cells, c = stomatal aperture, d = subisidary cells, e = chloroplast.

Answer. 1. a = epidermal cells, b = subsidiary cells, c = chloroplast, d = guard cells, e = stomatal aperture

Question 33. Which of the following statements are true/false?

A. The positive hydrostatic pressure is called turgor pressure

B. Wall pressure is exerted to prevent the increase in protoplasm size

C. Diffusion is more rapid in liquids than in gases

D. The diffusion of water through a semi-permeable membrane is called imbibition

E. osmosis is the movement of substances that takes place along a diffusion gradient.

1. A and B are true & C, D, and E are false
2. A and C are true & B, D, and E are false
3. A and D are true & B, C, and E are false
4. A and C are true & b, C, and D are false
5. c, D, and E are true & A and B are false.

Answer. 1. A and B are true & C, D, and E are false

Question 34. Two cells A and B are contiguous. Cell A has an osmotic pressure of 10 atm, turgor pressure of 7 atm, and diffusion pressure deficit of 3 atm. Cell B has osmotic pressure S atm, turgor pressure 3 atm, and diffusion pressure deficit 5 atm. The result will be :

1. No movement of water
2. Equilibrium between the two
3. Movement of water from cell A to B
4. Movement of water from cell B to A.

Answer. 3. Movement of water from cell A to B

Question 35. Path of water movement from soil to xylem is:

1. soil → root hair →  cortex → pericycle → endodermis → metaxylem →  protoxylem
2. soil → root hair → cortex → endodermis → pericycle → protoxylem → metaxylem
3. soil → root hair →  epidermis → endodermis →  phloem →  xylem
4. soil → root hair →  epidermis →  cortex → phloem → xylem
5. soil → root hair → cortex →  protoxylem → phloem → metaxylem.

Answer. 2. soil → root hair → cortex → endodermis → pericycle → protoxylem → metaxylem

Question 36. In land plants, the guard cells differ from other epidermal cells in having :

1. Cytoskeleton
2. Mitochondria
3. Chloroplasts.
4. Endoplasmic reticulum

Answer. 4. Endoplasmic reticulum

Question 37. The ability to rise in thin tubes and the ability to resist a pulling force are respectively referred to as

1. Tensile strength and capillarity
2. Adhesion and capillarity
3. Cohesion and adhesion
4. Cohesion and capillarity
5. Capillarity and tensile strength.

Answer. 5. Capillarity and tensile strength.

Question 38. Which of the following criteria does not pertain to facilitated transport?

1. High selectivity
2. Transport saturation
3. Uphill transport
4. Requirement of special membrane proteins

Answer. 3. Uphill transport

Question 39. Lenticels are involved in :

1. Gaseous exchange
2. Food transport
3. Photosynthesis
4. Transpiration

Answer. 1. Gaseous exchange