NEET Biology Notes – Sexual Reproduction in Flowering Plants

NEET Biology Sexual Reproduction In Plants

• Angiosperms are the most common vascular plants on Earth. The plant body is sporophyte, differentiated into true roots, stems and leaves. A flower is a reproductive organ. Stamen (part) has 2 anthers, and 4 pollen sacs, each pollen sac has tapetum and pollen mother cells. They produce haploid microspores (pollen grains) by microsporogenesis
• Carpel (part), the ovary possesses an ovule, and each ovule has two integuments, a nucellus and one megaspore mother cell. 4 haploid megaspores are produced by megasporogenesis.
• The main function of the flower includes the production of pollen grain and ovule, pollination, fertilization, development and dispersal of seeds and fruits.
• Embryology
• It is the study of the development of the embryo.
• It includes sporogenesis, fertilization and embryo formation. Sporogenesis. It is a mode of spore formation and involves meiosis. It is of two types microsporogenesis in the pollen sac of anther and megasporogenesis inside the ovule.
• Microsporogenesis. The mature anther is a two-lobed structure. It has four pollen sacs or microsporangia. The cavity of the microsporangium encloses a large number of The life cycle of an Angiospermic plant.

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• Encloses huge Mumbai to Microsoft mother cells, they are diploid. They undergo meiosis and each one of them produces 4 haploid cells or microspores that are arranged in distinct groups to tout or tetrad.
• These groups are surrounded by a common wall of spore mother cell, these microspores develop their wall within tetrad and later separate.

NEET Biology Sexual Reproduction In Plants Pollen Grain (Microspore)

It typically has a circular shape with a wall and an interior consisting of 2 to 3 cells. The wall comprises two layers: an exterior thick exline of spuropollenin and an interior thin inline of pectocellulose. Sporopollenin is an extremely durable lipidic compound associated with cutin. The exine is categorized into the inner endexine and the outer Kleine.

Sexual Reproduction In Flowering Plants NEET Notes

Ektexine is formed of three layers

1. Inner continuous foot layer
2. Middle discontinuous bacula layer and
3. Outer discontinuous tectum.

The tectum and bacula layers produce designs over the surface of the pollen grain. Exine is absent in certain areas called germ pores (if rounded) or germinal furrows (if elongated). Depending upon their number, the pollen grains are monocolpate, bioplate, tricolpate, etc.

• In monocots, the pollen grains generally possess one germinal furrow (monocolpate) while in dicots the pollen grains have generally three germ pores (tricolpate). The sculpturing, number and position of germ pores are characteristics of each species.
• The branch dealing with the study of pollen grain characteristics is known as palynology. Insect disseminated pollen grains have a covering of a yellow sticky substance called pollen kit. Internally the pollen grain has (/) tube or vegetative cell with a degenerating nucleus, vacuolate cytoplasm rich in starch and unsaturated oil and (n) one generative cell or two male gametes derived from it.

NEET Biology Sexual Reproduction In Plants Pollination

The process by which pollen is carried from the anther to the surface of the stigma in angiosperms is called pollination.

It is of two types :

1. The pollination of one plant by pollen from another individual is called cross-pollination ;
2. On the other hand, the pollination of a carpel by the pollen from the same flower or the same individual is called self-pollination.
   • The earlier information on the concept of pollination is available in the works of Herodotus, Theophrastus, Grew, Camerarius, Kolreuter etc.
   • The concept is divided into two categories: autogamy, involving one flower, and allogamy, involving two flowers.
   • Since this classification is genetically unsound, the concept is now divided into three categories autogamy, geitonogamy and xenogamy.
     1. Utogamy. It is the transference of pollen grains from the anther of a flower to the stigma of the same flower bisexual Example Pea, Wheat, Rice, etc.
     2. Geitonogamy. When pollen from one flower is deposited on the stigma of another flower bome on the same plant.
     3. Xenogamy. Pollination takes place between two flowers made by two separate plants of the same or allied species.

The contrivances which favour autogamy are homogamy and cleistogamy. In the latter case, self-pollination is the rule.

1. Homogamy. It is the condition in which anthers and stigmas in bisexual flowers attain maturity at the same time.
2. Cleistogamy. In cleistogamy, flowers never open to expose their sex organs and the pollens fall on the stigma of the same flower Example Commelina, Viola, Oxalis, Drosera etc. Cleistogamy is followed by geocarpy in plants like groundnuts (fruits are formed in the soil).
3. Bud Pollination. Pollination occurs in bud conditions, for example, in peas and wheat. The self-pollinated flowers develop many devices like a direct touch of anthers and stigma at maturity by bending the filament of stamen on the stigma (Mirabilis jalapa) or by curving the style on the anthers having terminal porous dehiscence (Solatium ).

Sexual Reproduction In Flowering Plants NEET Notes

In Vinca rosea the anthers are present at the mouth of the corolla tube and mature when the stigma passes through the mouth of the corolla tube, causing self-pollination. In sunflower self-pollination lakes are placed by the curving of the receptive surface of the stigma downward and inward, thus coming in contact with their pollen grain. This happens when cross-pollination fails in sunflowers.

NEET Biology Sexual Reproduction In Plants Contrivances Which Favour Allogamy

They are dicliny, self-sterility, dichogamy, herkogamy and heteromorphism. The contrivance best suited to allogamy is declined. The dichotomous flowers may be protandrous or protogynous. The heteromorphic flowers may lie dimorphic or trimorphic. The polymorphism may be due to heterostyly and or heterarchy.

1. Dicliny or Unisexunlity
   • Monoecious, Example. Maize, Cucurbits, Castor
   • Dioecious. Examples, are Carica papaya, Mulberry, and Cannabis.
2. Self-sterility or incompatibility: The pollen of a flower has no fertilizing effect on die stigma of the same flower, e.g., Passiflora, Malva, Potato.
3. Dichogamy. Male and female sex organs mature at different times.
   • Protandry. Anthers mature earlier dian die gynoecium, Example, China-rose, Lady’s finger. Foeniculum, Jasmium.
   • Protogyny. Carpels mature earlier than the stamens Example, the Four o’clock plant, Custard- apple.
4. Heterostyly. Two or more types of flowers concerning the length of the style and stamen arc formed, Example, Solatium, Oxalis, Lythrum, Primula.
5. Hereogamy. Male and female sex organs are so placed in a flower that the pollen grains die and they are unable to reach the stigmas in the same flower, for example, Carnation, Gloriosa, and Calotropis.

NEET Biology Sexual Reproduction In Plants Types Of Cross-Pollination Depending Upon Agencies

1. Anemophily. Small flowers are pollinated by wind. Plants produce enormous amounts of pollen Example. Oak, Betula, grasses, rice, bamboo, Pinus (Winged Pollen grains).

• Anemophilous flowers are small and inconspicuous; never coloured or showy; do not emit any smell and nor do they secrete any nectar.
• Pollen grains are produced in large quantities which are very small, dry, smooth and light so they can be easily disseminated by wind over a wide area, helping cross-pollination.
• Stigmas are hairy and branched to licit they may entangle the pollen grains floating in the air.

2. Hydrophily: Pollination through the agency of water is called hydrophily. When pollination occurs below the water level, it is described as hypohydrogamie and when it occurs at the die level of water, it is called epiliydrogamic.

• In plants like Potamugeton, Myriophyllum etc. when? the inlloirsociKT pmlnulcs mil of witter level, wind pollimilinn occurs.
• Hydmphilv is commonly seen in the members of Ceralopliyllncene, and Najiiclaecnc. Hvdiwharitaecac, Potumogetonuceue, Aponogctonucene etc. Hypohydrogumie pollination is seen in plants like Ccralopliyllum, Najas etc.
• An interesting pollination mechanism is seen in plants like Ruppia Maritime and Vallisncria spiralis. In Ruppia the flowers; are bisexual and protandrous. The anthers release pollen into the water and the grains float on the water’s surface.
• Now the peduncle and pedicel elongate till the stigma reaches the water surface and comes in contact with the floating grains. After pollination, the stalk contracts and the fruit matures under water. In Vallisncria, which is a rooted submerged aquatic plant, the male flowers are born in a spadix and the females are solitary.
• The male flowers are set free below water level but they open on the surface where they float. The pedicel of the female flower elongates till it reaches the water surface where it comes in contact with the pollen grains.

3. Zoophily. Pollination by the agency of animals.

1. Chiropterophily. Pollination by bats, Example, Anthocephcilus, Bauhinia, Kigelia pinnata, Adensonia (Boabab tree)
2. Ornithophily. Pollination by birds, for example, Bignonia, Erythrina indica, Bombax, Agave, and Grevillea.
3. Malacophily. Pollination by slugs and snails, Example, Arisaema. and other aroids.
4. Entomophily. Pollination by insects, for example, Jasmine, Rosa, and Magnolia.

Pollination And Fertilization In Plants NEET

These flowers possess the following characteristic features :

• The insect-pollinated flowers are fragrant and omit scent and odour, for Example, Cestrum, Jasmine etc. Rafflesia gives out obnoxious and repelling odours.
• The insect-pollinated flowers are beautifully coloured. In flowers, most petals are brightly coloured.
• Sometimes, when flowers themselves are not conspicuous, other parts may become coloured and showy to attract the insects Example bracts in Bougainvillea, leaves in Euphorbia pulcherrima, one sepal in Mussaenda etc.
• The nectariferous glands produce nectar for feeding the visiting insects.
• Nectariferous glands are present at such positions on floral parts to encounter the anthers and stigmas.
• In Viola (pansy), markings on petals (nectar guides) are present which guide the insects to nectaries.
• In entomophilous plants, the pollen grains become sticky or spiny so that they may easily get attached to the bodies of visiting insects.
• To catch the pollen grains, the stigmas become sticky.
• Flowers become more conspicuous by grouping Example capitulum, corymb etc.
• In plants like Papaver, Rosa, Clematis etc. edible pollen grains are produced.
• Some of die pollen grains stick to the body of insects while feeding on the edible pollen grains.
• In orchid Ophrys, the shape and colour of the petals are like a female wasp. Male wasp mistakes the flowers of Ophrys for female wasp and tries to copulate, thus pollinating the flowers.
• In Yucca, Yucca-moth bores a hole in the ovary of the Yucca flower and lays its eggs in it. Then it collects pollen from several flowers and pushes the whole of the pollen down the hollow end of the stigma.
• Fertilization takes. place and seeds develop. Larvae feed on developing seeds.
• Some seeds remain unconsumed to propagate the species. Moth cannot survive without Yucca flowers and Yucca fails to reproduce sexually without moth.

NEET Biology Sexual Reproduction In Plants Development And Formation Of Male Gametes

Development of male gametophyte starts in pollen grains, while still present in the microsporangium or pollen sac (precocious germination). Microspore undergoes only two mitotic divisions.

• First mitotic division leads to the formation of a vegetative cell and a generative cell.
• The vegetative cell is also called the tube cell. These cells do not possess any cell wall and, hence are represented only by cell membranes. A temporary callose wall is laid down between the two cells (Groska-Bry-Lass, 1967).
• The callose wall spreads between the generative cells and the intestine to finally pinch it off.
• Soon, this callose wall dissolves and the generative cell lies freely in the cytoplasm of the vegetative cell. Generative cells may be elliptical, lenticular or even spindle-shaped.
• The cytoplasm contents of the generative cells are almost hyaline and do not possess much-stored food material. The large vegetative cell contains fat.
• starch and some type of protein granules. It is usually at this two-celled stage that pollen grains are liberated from pollen sacs of anther lobes.
• Rarely generative cells may further divide to form two male gametes. All these stages for the development of male gametophytes are grouped under pre-pollination stages.
• After the falling of pollen grains on the stigma, post-pollination changes occur.
• Pollen grain absorbs water and nutrients of the stigmatic secretion through its germ pores. The intine protrudes out through one of the germ pores or a germ furrow.
• The generative nucleus divides to form two male nuclei, which become surrounded by cytoplasmic masses and appear as distinct male gametes. Protruded intine forms pollen tube. The tube nucleus migrates to the pollen tube. The formation of male gametes can occur in vegetative cells or pollen tubes.
• Usually, generative cell comes down into pollen tubes and then divide to form the male gametes. The hindered region of the pollen tube is highly vacuolated. This region is plugged from the anterior part by the development of callose. The male gametophyte in angiosperms is highly reduced.
• Usually, there is a single pollen tube and pollen grains are termed monosphonous. In Malva, Althea and other members of the family Malvaceae and Cucurbitaceae, the condition is polysiphonous with as many as 14 pollen tubes.

NEET Biology Sexual Reproduction In Plants Megasporogenesis And Development Of The Female Gametophyte

The ovule develops as a small outgrowth from the tissue of the placenta, A single hypodermal cell in the nucellus starts functioning as an archesporium which, is also called a primary archesporial cell. This cell divides by a periclinal wall to form a primary parietal and sporogenous cell.

• The primary parietal cell undergoes repeated divisions forming a parietal tissue. The primary sporogenous cell functions directly as the megaspore mother cell which divides twice the first division being mciotic and the second mitotic, forming four haploid cells arranged in a row.
• Three of the upper cells degenerate and the remaining lowermost cell forms die functional megaspore. In the meantime, two integuments are disclosed from the base of the ovule, which envelops the mature ovule. ‘1 The megaspore represents the first cell of the female gametophyte.
• The megaspore nucleus divides thrice to give rise to eight nuclei. Four of the nuclei migrate to one pole and the remaining four die opposite jxilc; one nucleus from the cadi of the pole comes to lie in the centre of die embryo sac where the two lose together to form a secondary nucleus.
• The three nuclei at the base form the antipodal tells and the three nuclei at the apex organise into an egg apparatus, consisting of two synergies and an egg between them.
• The ovule is a rounded structure attached to the placenta by a stalk, die funicle, The place of attachment of the funicle to the body of the ovule is called a Lilium. Hie basal region of the ovule, where integuments arise, is termed a thalaza. ‘The lire ovule consists of integuments mid nucellus.

1. Orthotropous or atropous straight. ovule is erect. Funcile, and chalaza micropyle lie on the same verticle line e.g polygonum, Rumex
2. Anatropous or Inverted or resupinate. Ovule bends along the funnel. Micropyle lies close to the hilum. Micropyle and chalaza lie on the same vertical line Example Solanum, Anemone, Helianthus.
3. Amphitropous or Transverse. The ovule is placed transversely or at a right angle to its stalk, for Example, Lenina and some crucifers.
4. Campylotropous or Curved. Chalaza and micropyle do not lie in a straight line, for example, Capparis, Mustard, Pisum, and family Chenopodiaceae.
5. Circinotropous. This ovule is inverted at an angle of 360° so that the ovule again fir becomes orthotropous and coiled around by funiculus Example opuntia.
6. Hemianatropous. It is intermediate between ortho and anatropous types of ovules, for example, members of Primulaceae, Ranunculaceae and some crucifers.

Pollination And Fertilization In Plants NEET

NEET Biology Sexual Reproduction In Plants Fertilization

The process of nuclear fusion between the male nucleus and an egg nucleus is referred to as fertilization. It produces a diploid zygote. The second male gamete amalgamates with the secondary nucleus. Double fertilization is a common occurrence.

• The pollen tube infiltrates the embryo sac. The pollen tube enters the embryo sac from many locations.
• These represent Porogamy: the ingress of the pollen tube through the micropyle.
• Illustration Lily chalazogamy refers to the introduction of the pollen tube through the chalazal end, exemplified by Juglans (walnut) and Casuarina. Mesogamy refers to the passage of the pollen tube through the funiculus or integuments. Example: Cucurbita, Populus.
• The apex of the pollen tube ruptures within the embryo sac, discharging both male gametes. One gamete penetrates the egg and amalgamates with its nucleus to create an oospore or zygote.
• The amalgamation of the male gamete with the ovum nucleus is referred to as fertilization.
• In angiosperms, the 8-nucleate Polygonum-type embryo sac comprises two polar nuclei centrally located. The polar nuclei amalgamate to create a diploid secondary nucleus (2N).
• The 2nd male gamete (N) of the pollen grain fuses with this secondary nucleus (2N) to form triploid endosperm (3N). This technique is referred to as twofold fertilization.

Endosperm

Endosperm is usually triploid and is formed as a result of triple fusion after fertilization. The endosperm provides food to the young embryo.

Three different types of endosperms have been reported in angiosperms

1. Nuclear endosperm
2. Cellular endosperm
3. Global endosperm.

Development of endosperm. Endosperm develops after double fertilization in angiosperms. It is triploid and develops from the primary endosperm nucleus.

It is meant to nourish the embryo. As the endosperm develops fully in the fertilized ovules, it may show the effect of genes present in the male gamete.

It is called Xenia. Endosperm development is accompanied by degeneration of the nucellus. Some food is also obtained from plants as well as the endothelium.

Types Of Endosperm

1. Nuclear endosperm. In nuclear endosperm development, the nucleus divides by free nuclear division, there is the appearance of the central vacuole, all the nuclei are pushed towards the periphery then starts cytokinesis and results in the formation of cells as in Capsella bursapastoics, but in coconut vacuole persists which is filled with fluid.
2. Cellular endosperm. In cellular endosperm every division is followed by cytokinesis, so endosperm is cellular from the very beginning Example Datura, Petunia.
3. Helobial endosperm. It is intermediate between cellular and nuclear endosperm. The first division is followed by. cytokinesis to form two unequal cells, a micropylar cell and a chalazal cell. Further divisions in each cell are free nuclear divisions. This type of endosperm is found in the order Helobiales.

The endosperm may persist in the seed or be consumed by the developing embryo. In the latter case, the food is generally stored in cotyledons. Ruminate or convoluted endosperm occurs in Areca (Betel nut) and Passiflora. The hard endosperm is found in Date, vegetable Ivory and Areca.

Embryo Development

The embryogeny (Crucifer /Onagrad type). The zygote or oospore divides by a transverse wall into an upper suspensor cell and a lower embryonal cell. The suspensor cell which lies towards the micropylar end, divides by transverse divisions to constitute 7-10 cells called suspensor.

• The upper cell of the suspensor filament towards the micropylar end is called the historical cell, whereas the cell lying above the embryo cell is called hypophysis.
• The haustorial cell enlarges in size and attaches the suspensor to the tip of the embryo sac. The embryonal cell divides by a second longitudinal division at a right angle to the first and then by transverse division to form an octant or eight-celled embryo.
• Out of these eight cells, the lower four cells of octant away from the die suspensor give rise to the plumule and the two cotyledons, while dying above four cells of octant near the suspensor from the hypocotyl and stele of the radicle.
• Now this octant divides by a periclinal division to form an outer single-layered dermatogen from which arises the epidermis layer. The inner cells further divide to form periblem below’ die dermatogen and die central plerome. The periblem forms the cortex while the plerome gives the stele of the embryo.
• The lowermost cell of the suspensor, which lies just above die octant cells, is known as hypophysis. The hypophysis divides to give rise to the dermatogen and periblem of the radicle. A fully developed embryo of dicotyledons has an embryonal axis differentiated into a plumule, two cotyledons and a radicle.
• In die beginning embryo is globular. When two cotyledons differentiate from the sides with faint plumule in the centre, the embryo becomes heart-shaped. Now the embryo undergoes rest and the ovule is transformed into a seed.

Stages Of Sexual Reproduction In Plants NEET

Monocot Embryogeny (Sagittaria Type)

The zygote or oospore divides transversely, producing a vesicular suspensor cell towards the micropylar end and an embryonal cell towards the chalazal end. The embryo cell divides transversely again into a terminal and a middle cell. The terminal cell divides vertically and transversely into a globular embryo. It forms a massive cotyledon and a plumule.

• The growth of cotyledon pushes the plumule to one side. Remains of second cotyledon occur in some grasses. It is called epiblast. The single cotyledon of monocots is called scutellum. It is shield-shaped and appears terminal.
• The middle cell gives rise to hypocotyl and radicle. It may add a few cells to the suspensor. Both radicle and plumule develop covering sheaths called coleorhiza and coleoptile respectively. They appear to be extensions of the scutellum.

Polyembryony

It is defined as the development of two or more embryos within an ovule. It was discovered by Leeuwenhoek in 1719 in orange. In angiosperms, the multiple embryos are produced in the following ways.

1. By fertilization of synergids or antipodal cells by sperms introduced in the pollen sac by additional pollen tubes, Example, Plantago, Poa, Allium
2. By cleavage of the single zygote or a young embryo into 2 or more parts, each of which develops into an embryo, For Example, members of Orchidaceae
3. One or more cells of the nucellus or integuments develop into embryos which soon project into the embryo sac and are nourished by the endosperm, For Example, Citrus, Mangifera, Eugenia
4. The occurrence of more than one embryo sacs which usually develop from the
   derivatives of a single or more than one megaspore mother cell, for example, Brassica,

• The flowers of Asteraccac ami Labiatae families are generally pollinated by bees and butterflies.
• The two cells are unequal. A large one is called a tube cell or vegetative cell and the small one is called a generative cell.
• This division occurs when microspores are still inside the pollen sac.
• Microspores are shed at this 2-celled stage. Later, the development of male gametophyte occurs after pollination.] The pollination by birds is common in coral trees, bottle brushes, Iiulca monospen and silk cotton trees.
• Hie pollination by bats is carried out in Adansonia and Kigelia. The wind-pollinated flowers are generally unisexual, as in coconut palm, dale palm, maize, and many grasses. Cannabis. Hydrophilv is common in water plants especially submerged ones, like Vallisneria, Ceratophyllum, Zostera

Differences between self-pollination and cross-pollination.

NEET Biology Sexual Reproduction In Plants Quanta To Memory

• Entomophily. In angiosperms, entomophily occurs in about 80% of the flowers. Pollen kit is characteristic of entomophilous pollen.
• Most of the entomophilous flowers are pollinated by members of Hymenoptera, Lepidoptera, Diptera and Coleoptera and only a few by other groups.
• An interesting pollination mechanism is seen in many plants. While Centaurea shows a piston mechanism for pollination, Salvia exhibits a lever mechanism.
• Pollination by water is called hydrophily. Pollination may occur below the water level (hypohydrogamic) or at the level of water (epihydrogamic).
• Translator Mechanism. In Calotropis and related plants, pollen grains are aggregated to form translators, each having two pollinia attached by a corpusculum. The translator is picked up and transferred by an insect visiting flowers for nectar”.
• Erythrina. It is pollinated by crows as well as squirrels.
• Adansonia. A flower bears 1500—2000 stamens.
• The effect of pollen grain on the characters of endosperm is called xenia.
• Sometimes pollen grains are present in a sac-like mass known as pollinium, for Example, Calotropis and Orchids etc.
• In some plants Example, Malva, and Althaea, 10-14 pollen tubes develop from the same pollen grain, but only one becomes functional.

Stages Of Sexual Reproduction In Plants NEET

NEET Biology Sexual Reproduction In Plants Questions From Competitive Examinations

Question 1. In the Kigcllia prenatal /Sausage tree, pollination is performed by :

1. Bats
2. Birds
3. Insects
4. Wind.

Answer: 1. Bats

Question 2. Apple growers usually keep bees in the orchard even though apples are usually wind-pollinated because :

1. Wind pollination results in apples of inferior quality
2. Insect pollination results in apples of superior quality
3. Wind pollination may fail at the right time and bees would bring about pollination in such a situation
4. Bees can inject honey into the apples and make them sweeter.

Answer: 3. Wind pollination may fail at the right time and bees would bring about pollination in such a situation

Question 3. Self-pollination means :

1. Occurrence of male and female sex organs in the same flower
2. Germination of pollen within the same anther
3. Transference of pollens from anther to stigma within the same flower
4. Transference of pollen from one plant to the stigma of a neighbouring plant.

Answer: 3. Transference of pollens from anther to stigma within the same flower

Question 4. Stigma is always rough and sticky in :

1. Entomophilous flowers
2. Anemophilous flowers
3. Hydrophilous flowers
4. All types of flowers.

Answer: 1. Entomophilous flowers

Question 5. Progeny resulting from cross-pollination :

1. Show greater genetic variability and are evolution- nary important
2. Homozygous and show phenotypic uniformity
3. Arc always sterile
4. Always show recessive characters.

Answer:  1. Show greater genetic variability and are evolution- nary important

Question 6. Maturation of stamens and pistils at different times in the same flower is called :

1. Dichotomy
2. Dichogamy
3. Heterospory
4. Heterostyly.

Answer: 2. Dichogamy

Question 7. Pollination by ants is :

1. Malacophily
2. Myrmccophily
3. Omithophily
4. Entomophily.

Answer: 2. Myrmccophily

Question 8. Some flowers possess pleasant odour and attractive colours for:

1. Hydrophily
2. Anemophily
3. Entomophily
4. All of the above.

Answer: 3. Entomophily

Question 9. Anemophily means :

1. Pollination by wind
2. Pollination by birds
3. Pollination by animals
4. Animal-loving plants.

Answer: 1. Pollination by wind

Gametogenesis And Embryo Development NEET

Question 10. Wind pollination is common in :

1. Legumes
2. Lilies
3. Grasses
4. Orchids.

Answer: 3. Grasses

Question 11. In which one of the following pollination is autogamous?

1. Geitonogamy
2. Xenogamy
3. Chasmogamy
4. Cleistogamy.

Answer: 4. Cleistogamy.

Question 12. Embryo sac is :

1. Microgametophyte.
2. Microsporangium
3. Megagametophyte
4. Megasporangium.

Answer: 3. Megagametophyte

Question 13. The 8-nucleate embryo sac is :

1. Monosporic
2. Bisporic
3. Tetrasporic
4. All the above.

Answer: 4. All the above.

Question 14. A mature male gametophyte is formed from pollen mother cell by :

1. One meiotic division
2. Two meiotic divisions
3. One meiotic and two mitotic divisions
4. Three meiotic divisions.

Answer: 1. One meiotic division

Question 15. Passage of pollen tube through micropyle while reaching the embryosac is :

1. Monogamy
2. Porogamy
3. Dicliny
4. Dichogamy.

Answer: 2. Porogamy

Question 16. The polygonum type of embryo sac is:

1. 8-nucleate
2. 16-nucleate
3. 24-nucleate
4. 32-Nucl

Answer: 1. 8-nucleate

Question 17. Tapetum occurs in:

1. 8-nucleate
2. Ovary Wall
3. Male gametophyte
4. Female gametophyte

Answer: 1. 8-nucleate

Gametogenesis And Embryo Development NEET

Question 18. Which one is produced as a result of double fertilization?

1. Seed
2. Fruit
3. Megaspore
4. Endosperm

Answer: 4. Endosperm

Question 19. A component of the female reproductive system is:

1. Stamens
2. Anther
3. Microscope
4. Embryo

Answer: 4. Embryo

Question 20. Mango and Guava ate propagated through.lt :

1. Tissue culture
2. Grafting
3. Stem cuttings
4. Layering.

Answer: 2. Grafting

Question 21. In a grafted plant, slock has 48 chromosomes while scion has 2d chromosomes. Idle chromosome numbers for root cells and eggs are :

1. 48and 24
2. 24and 24
3. 24and 12
4. 48 and 12.

Answer: 4. 48 and 12.

Question 22. Pollen grains are non-green due to :

1. Absence of plastids
2. Degeneration of plastids
3. Conversion of plastids into chromoplasts
4. Attraction of vectors.

Answer: 3. Conversion of plastids into chromoplasts

Question 23. The pollen grain of a tetraploid plant brings about fertilization in a diploid plant. The endosperm of the seed will be :

1. 2
2. 3
3. 4
4. 5

Answer: 3.  4

Question 24. Multinucleate condition is present in :

1. Quiescent centre
2. Maize
3. Meristematic tissue
4. Liquid endosperm of Coconut.

Answer:  4. Liquid endosperm of Coconut.

Question 25. If meiosis occurs inside pollen grain and egg nuclei, it will be :

1. Zygotic ineiosis
2. Gametic meiosis
3. Sporic meiosis
4. None of the above.

Answer: 2. Gametic meiosis

Structure Of Flower And Reproductive Organs NEET

Question 26. Formation of the embryo from vegetative cells derived from the zygote is called :

1. Apoinixis
2. Adventive polyembryony
3. Apospory
4. Diploid polyembryony.

Answer: 2. Adventive polyembryony

Question 27. The formation of an organiser from a single, male gamete without fusion with an egg is an example of:

1. Parthenogenesis
2. Apogamy
3. Apospory
4. Parthenocarpy.

Answer: 1. Parthenogenesis

Question 28. Adventive embryonic in Citrus is due to :

1. Nucellus
2. Integuments
3. Zygotic embryo
4. Fertilized egg.

Answer: 1. Nucellus

Question 29. In grasses what happens in the microspore mother cell for the formation of mature pollen grains :

1. One meiotic and two mitotic divisions
2. One meiotic and one mitotic divisions
3. One meiotic division
4. One mitotic division.

Answer: 2. One meiotic and one mitotic division

Question 30. Which of the following statements is wrong :

1. Naked seeds are seen in gymnosperms
2. Pteridophyta produces endosperm
3. Basidiocarpous fruiting body of fungs
4. Capsule is the sporophyte

Answer: 2. Pteridophyta produces endosperm

Question 31. Double fertilization was given by :

1. Nawaschin
2. Maxwell
3. Einstein
4. Antony Hewert

Answer: 1. Nawaschin

Question 32. Hydroponics is :

1. Plant growth in mineral-deficient soil
2. Soil conservation
3. Plant growth under laboratory conditions
4. Plant growth in liquid culture medium.

Answer: 4. Plant growth in liquid culture medium.

Sexual Reproduction In Flowering Plants NEET Exam Preparation

Question 33. Number of nuclei present in common embryo sac tire :

1. Six
2. Eight
3. Twelve
4. Twenty-four.

Answer: 2. Eight

Question 34. Perisperm is :

1. Remains of nucellus
2. The outer part of the embryo sac
3. Degenerated synergid
4. Degenerated secondary nucleus

Answer: 1. Remains of nucellus

Question 35. In a flowering plant, archesporium gives rise to :

1. Only tapetum and sporogenous cells
2. Only the wall of the sporangium
3. Both the wall and the sporogenous cells
4. Wall and the tapetum.

Answer: 3. Both the wall and the sporogenous cells

Question 36. Pollen grains can tolerate extremes of temperature and desiccation because their exine consists of:

1. Cutin
2. Suberin
3. Sporopollenin
4. Close

Answer: 3. Sporopollenin

Question 37. The plant part has two generations, one within the other:

1. Seed
2. Germinated pollen grain
3. Embryo
4. Unfertilized ovule

Answer: 1. Seed

Structure Of Flower And Reproductive Organs NEET

Question 38. Pollen tube usually enters the embryo sac :

1. Between one synergid and central cell
2. By knocking off antipodal cell
3. Through one of the synergids
4. Directly penetrate the egg.

Answer: 1. Between one synergid and central cell

Question 39. A plant root has 16 cells thus :

1. Gamete has 16 cells
2. Gamete has 8 cells
3. Endosperm has 16 cells
4. The endosperm has 8 cells.

Answer: 1. Gamete has 16 cells

Question 40. Which one of the following statements is correct?

1. Sporogenous tissue is haploid
2. Endothecium produces the microspores
3. Tapetum nourishes the developing pollen
4. The hard outer layer of pollen is called intine.

Answer: 3. Tapetum nourishes the developing pollen

Question 41. A diploid female plant is crossed with the tetraploid male. The ploidy of endosperm will be :

1. Tetraploidy
2. Diploidy
3. Triploidy
4. Pentaploidy.

Answer: 1. Tetraploidy

Question 42. Which of the following represents the edible part of the fruit of Litchi?

1. Pericarp
2. Mesocarp
3. Juicy aril
4. Endocarp.

Answer: 3. Juicy aril

Question 43. Through which cell of the embryo sac. does the pollen tube enter the embryo sac?

1. Egg cell
2. Central cell
3. Persistant synergid
4. Degenerated synergid

Answer: 4. Degenerated synergid

Question 44. Which one of the following mg represents an ovule, where the embryo sac becomes horse-shoe shaped and the funiculus and micropyle are close to each other?

1. uvinotiopous
2. Anatropous
3. Amphitropous
4. Atropous.

Answer: 3. Amphitropous

Question 45. Which is vivipary an undesirable character for annual crop plants?

1. It reduces the vigour of the plant.
2. The seeds cannot be stored under normal conditions for die next season.
3. The seeds exhibit long dormancy
4. It adversely affects the fertility of the plant.

Answer: 2. The seeds cannot be stored under normal conditions for die next season.

Question 46. In which one pair both dead plants can be vegetatively propagated by leal pieces?

1. Bryophyllum and Kalanchoe
2. Chrysandiemum and Agave
3. Agave and Kalanchoe
4. Asparagus and Bryophyllum.

Answer: 1. Bryophyllum and Kalanchoe

Question 47. In a type of apomixis known as adventive embryonic, embryos develop directly from the :

1. Nucellus or integuments
2. Synergids or antipodals in an embryo sac
3. Accessory embryo sacs in the ovule
4. zygote.

Answer: 1. Nucellus or integuments

Sexual Reproduction In Flowering Plants NEET Notes

Question 48. Double fertilization involves :

1. Fertilization of the egg by two male gametes
2. Fertilization of two eggs in the same embryo sac by two sperms
   brought by one pollen tube.
3. Fertilization of the egg and the central cell by two sperms brought
   by different pollen tubes.
4. Fertilization of the egg and central cell by two sperms brought by the same pollen.

Answer: 4. Fertilization of the egg and central cell by two sperms brought by the same pollen.

Question 49. In some plants anthers and sdgma grow and mature at the same time. This phenomenon is called

1. Homogamy
2. Syngamy
3. Allogamy
4. Fusion.

Answer: 1. Homogamy

Question 50. For the formation of a tetraspores embryo sac, how many megaspores mother cells are required?

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

Answer: 2. 2

Sexual Reproduction In Flowering Plants NEET Previous Year Questions

Question 51. The pollen sac in Cycas is called :

1. Megasporophyll
2. Megasporangium
3. Microsporophyl
4. Microsporangium.

Answer: 4. Microsporangium.

Question 52. Polygonum type of embryo sac is :

1. 8-nucleate and 7-celled
2. 8-nucleate and 8-celled
3. 8-nucleic and 8-called
4. 7-nuclcnlc ami 8 celled.

Answer: 1. 8-nucleate and 7-celled

Sexual Reproduction In Flowering Plants NEET Notes

Question 51. In die angiosperm ovule central cell of the embryo sac, before the entry of the pollen tube, contains;

1. A single haploid nucleus
2. One diploid and one haploid nuclei
3. Two Imploid polar nuclei
4. One diploid secondary nucleus

Answer: 4. One diploid secondary nucleus

Question 54. Xenia refer to :

1. Effect of pollen on stem
2. Effect of pollen on the taste of fruit
3. Effect of pollen on vascular tissue
4. Effect of pollen on endosperm.

Answer: 4. Effect of pollen on endosperm.

Question 55. Pollination by snails and slugs is known as :

1. Entomophilous
2. Omithophilous
3. Anemophilous
4. Malacophilous

Answer: 4. Malacophilous

Question 56. The arrangement of the nuclei in a normal embryo sac in the dicot plants is :

1. 2 + 4 + 2
2. 3 + 2 + 3
3. 2 + 3 + 3
4. 3 + 3 + 2

Answer: 2.  3 + 2 + 3

Question 57. Which one of the following is surrounded by a callose wall?

1. Male gamete
2. Egg
3. Pollen grain
4. Microspore mother cell.

Answer: 2. Pollen grain

Question 58. Male gametes in angiosperms are formed by the division of:

Generative cell

Vegetative cell

Microspore mother cell

Microspore

Answer: 1. Generative cell

Question 59. Eight nucleate embryo sacs are :

1. Always diasporic
2. Always tetraspores
3. Always monosporic
4. Sometimes monosporic, sometimes diasporic and sometimes tetraspores.

Answer: 4. Sometimes monosporic, sometimes diasporic and sometimes tetraspores.

Question 60. Double fertilization (or triple fusion) leading to initiation of endosperm in angiosperms, requires :

1. Fusion of 4 or more polar nuclei and the second male gamete only
2. Fusion of 2 polar nuclei and second male gamete only
3. Fusion of one polar nucleus and second male gamete only
4. All the above types of fusions in different types of angiosperms.

Answer: 2. Fusion of 2 polar nuclei and second male gamete only

Question 61. Many scientists consider viruses as living entities because these:

1. Respire
2. Can cause diseases
3. Reproduce (inside host)
4. Respond to tough environment.

Answer: 3. Reproduce (inside host)

Question 62. The mode of asexual reproduction in Hamlet and.

1. Formation of gametes
2. Endospore formation
3. Conjugation
4. Zoospore formation

Answer: 2. Endospore formation

Pollination And Fertilization In Plants NEET

Question 63. Through which cell of the embryo sac. Does the pollen tube enter the embryo sac?

1. Egg cell
2. Central cell
3. Persistent synergid
4. Degenerated synergid

Answer: 4.Degenerated synergid

Question 64. Which one of the following represents an ovule, where the embryo w becomes horse-shoe shaped and funiculus and mu-ropy lc are close to each other?

1. Circinotropous
2. Antropous
3. Amphitropous
4. Atropous

Answer: 3. Amphitropous

Question 65. Which of the following represents the edible part of the fruit of litchi?

1. Pericarp
2. Mesocarp
3. Juicy aril
4. Endocarp.

Answer: 3. Juicy aril

Question 66. The study of pollen grain is called :

1. Etymology
2. Palynology
3. Paleobotany
4. M-taxonomy.

Answer: 2. Palynology

Question 67. Select the correct order of endosperm types :

1. Cellular, global, free nuclear
2. Cellular, free nuclear, global
3. Helobial, free nuclear, cellular
4. Free nuclear, cellular, and global
5. Free nuclear, global, and cellular.

Answer: 3. Free nuclear, cellular, and global

Question 68. Endosperm is consumed by developing embryo in the seed of:

1. Pea
2. Maize
3. Coconut
4. Castor.

Answer: 1. Pea

Question 69. Nucellar polyembryony is reported in species of:

1. Citrus
2. Gossypium
3. Triticum
4. Brassica.

Answer: 1. Citrus

Question 70. Filiform apparatus is a characteristic feature of:

1. Suspensor
2. Egg
3. Synergid
4. Zygote.

Answer: 3. Synergid

Question 71. What would be the number of chromosomes of the aleurone cells of a plant with 42 chromosomes in its root lip cells?

1. 42
2. 63
3. 84
4. 21.

Answer: 2.63

Question 72. I lie genomic consists of many free pistils in the lower of

1. Tomato
2. Papaver
3. Michelia
4. Aloe

Answer: 3. Michelia

Question 73. Both autogamy and geitonogamy are prevented by:

1. Cucumber
2. Castor
3. Maize
4. Papaya.

Answer: 4. Papaya.

Question 74. An organic substance that can withstand environmental extremes eminently he pleaded that any enzyme is :

1. Spoiopollenin
2. Lignin
3. Cellulose
4. Cuticle.

Answer: 1. Spoiopollenin

Question 75. Plnccntnlion in tomato and lemon is :

1. Free central
2. Marginal
3. Axile
4. Parietal.

Answer: 3. Axile

Question 76. Which of these is a condition that makes flowers invariably
autogamous?

1. Dioccy
2. Self-incompatibility
3. Cleistogamy
4. Xenogamy
5. Syngamy.

Answer: 3. Cleistogamy

Question 77. Math the items in column I with those in column II and choose the correct answer.

1. 1- B; 2- C; 3- E; 4 – D; 5 -A
2. 1-A; 2 – C; 3 – B; 4 – D: 5 – E
3. 1 – B; 2 – C; 3 – A; 4 – D; 5 – E
4. 1 – B; 2 – D; 3 – E; 4 – A; 5 – C
5. 1 – C; 2 – D; 3 – E; 4 – A; 5 – B

Answer:  1. 1- B; 2- C; 3- E; 4 – D; 5 -A

Question 78. Megasporangium is equivalent to :

1. Fruit
2. Nucellus
3. Ovule
4. Embryo sac

Answer: 3. Ovule

Question 79. The advantage of cleistogamy is :

1. More vigorous offspring
2. No dependence on pollinators
3. Vivipary
4. Higher genetic variability

Answer:  2. No dependence on pollinators

Question 80. Perisperm differs from endosperm in :

1. Having no reserve food
2. Being a diploid tissue
3. Its formation by the fusion of a secondary nucleus with several sperms
4. Being a haploid tissue

Answer:  2.  Being a diploid tissue