NEET Previous Year Questions (2016-2025): Sexual Reproduction in Flowering Plants | Biology Class 12 PDF Download

Ans: (a) 

Assertion (A): True
A mature embryo sac in angiosperms is typically 8-nucleate and 7-celled: 1 egg cell, 2 synergids, 3 antipodal cells, 1 central cell with 2 polar nuclei → Total: 7 cells, 8 nuclei

Reason (R): False
The egg apparatus consists of: 1 egg cell, 2 synergids. It does NOT contain the polar nuclei.
The 2 polar nuclei are found in the central cell, not in the egg apparatus.

Therefore, the correct answer is: 1. (A) is True but (R) is False.

Ans: (c)

• Assertion (A): True
  Flowers pollinated by wind (anemophily) and water (hydrophily) are generally not showy, lack fragrance or nectar, and are not brightly coloured, since they do not need to attract pollinators like insects or animals.

• Reason (R): True
  To compensate for the lack of targeted pollination, such flowers produce a very large quantity of pollen grains to increase the chance that some will reach the female flower.

• R is the correct explanation of A because the absence of showy structures and nectar is an adaptation linked to the indiscriminate pollination mechanisms (wind/water), and high pollen production ensures successful pollination despite low efficiency.

Ans: (c) 

• Tapetum is the innermost layer of the anther wall and plays a vital role in nourishing developing pollen grains.
• Assertion (A): True
  Tapetal cells are metabolically active, possess dense cytoplasm, and often become binucleate or multinucleate either by mitosis without cytokinesis or by nuclear fusion.
• Reason (R): True
  The multinucleate condition enhances metabolic activity and protein synthesis, thereby increasing the efficiency of nourishment provided to the developing microspores (pollen grains).

Ans: (d)
To determine the correct set of statements, we need to analyze each statement individually based on the characteristics of water-pollinated plants and specific examples given:

Statement A: "The flowers of Vallisneria are colourful and produce nectar."
This statement is incorrect. Vallisneria is an example of a water-pollinated (hydrophilous) plant. Unlike insect-pollinated flowers, which are often colorful and produce nectar to attract pollinators, water-pollinated flowers typically lack bright colors and nectar because they do not need to attract insects or other animals. Vallisneria flowers are small and inconspicuous.

Statement B: "The flowers of water lily are not pollinated by water."
This statement is correct. Water lilies are typically pollinated by insects, not by water. The large and colorful flowers of water lilies are adapted to attract insect pollinators, contrasting starkly with the typical features of water-pollinated flowers.

Statement C: "In most of water-pollinated species, the pollen grains are protected from wetting."
This statement is correct. In water-pollinated plants, the pollen grains often have a covering or are structured in a way that prevents them from becoming waterlogged and sinking. This adaptation allows them to float on the water's surface and reach the female parts of other plants.

Statement D: "Pollen grains of some hydrophytes are long and ribbon like."
This statement is correct. In some water-pollinated plants, such as seagrasses (e.g., Zostera), the pollen grains are indeed elongated and ribbon-like, which helps them to be transported more effectively by water currents.

Statement E: "In some hydrophytes, the pollen grains are carried passively inside water."
This statement is also correct. Many hydrophytes have pollen grains that are transported by water currents, rather than being actively carried by animal pollinators or the wind. This passive transport is typical in water-pollinated species.

Based on the analysis, Statements B, C, D, and E are correct, while Statement A is incorrect.
Therefore, the correct answer is: Option D: B, C, D, and E only

Ans: (a)
The given diagram shows a wind pollinated plant showing compact inflorescence and well exposed stamens.
Stamens are exposed so complete autogamy does not occur.

Ans: (d)
The ovule is a small structure attached to the placenta by means of a stalk called funicle. The body of the ovule fuses with funicle in the region called hilum. Thus, hilum represents the junction between ovule and funicle. Each ovule has one or two protective envelopes called integuments. Integuments encircle the nucellus except at the tip where a small opening called the micropyle is organised. Opposite the micropylar end, is the chalaza, representing the basal part of the ovule

Ans: (b)
The embryo sac is the female gametophyte in plants, and it develops within the ovule. It contains the egg cell, which is fertilized during reproduction.

Ans: (c)
The floral reward is a mutualistic relationship where the flower provides a benefit (such as a safe place or food) to the pollinator in exchange for pollination. In this case, Amorphophallus flowers provide a safe place for the pollinator to lay eggs.

Ans: (a)
The nucellus is the central part of the ovule that stores reserve food material. This food is utilized by the developing embryo during seed development.

Ans: (c)
Pollen grains are preserved as fossils mainly because of the exine layer. The exine is the outermost layer of the pollen grain, made up of a durable substance called sporopollenin, which is highly resistant to decay, chemicals, and environmental conditions. This makes the exine layer an effective protective barrier, allowing pollen grains to be preserved over long periods of time as fossils.
The other layers (epidermal layer, tapetum, and intine layer) do not provide the same level of protection for fossilization as the exine layer.

Ans: (a)
Large, colorful, fragrant flowers with nectar are features that attract biotic pollinators. Insect pollinated plants, also known as entomophilous plants, often have these characteristics to attract insects such as bees, butterflies, and moths, which play a significant role in their pollination process.

Ans: (c)
Synergids are the cells of gametophyte and hence these are haploid Zygote is formed by fusion of two gametes and thus it is diploid.
Primary endosperm nucleus is formed by the fusion of diploid secondary nucleus with a male gamete. Therefore, it is triploid.

Ans: (b)
The correct answer is Option B : A is true but R is false.
Assertion A is true. In gymnosperms, the pollen grains are indeed released from the microsporangium and are typically carried by air currents, a method of pollination known as anemophily.
Reason R is false. Although it's true that air currents carry the pollen grains, the pollen grains do not directly reach the mouth of the archegonia in gymnosperms. Instead, they land on the ovule, where they germinate and form a pollen tube that delivers the male gametes to the egg. Therefore, a pollen tube is formed in gymnosperms, contrary to what Reason R suggests.

Ans: (c)
Windpollinated flowers often have a single ovule in each ovary and numerous flowers packed into an inflorescence; a familiar example is the corn cob – the tassels you see are nothing but the stigma and style which wave in the wind to trap pollen grains. Wind-pollination is quite common in grasses

Ans: (d)
In some plant families, the pollen grains are viable for extended periods, even for months. The families listed in Option D are known to have pollen grains that remain viable for long durations:

• Leguminosae (Fabaceae): Pollen grains of many legumes (e.g., beans, peas) can remain viable for an extended period.
• Solanaceae: Members of the Solanaceae family (e.g., tomatoes, peppers) also produce pollen that can remain viable for a longer time.
• Rosaceae: Pollen grains in many members of the Rosaceae family (e.g., apples, roses) can remain viable for months.

Thus, the correct set of families where pollen grains are viable for months is Leguminosae, Solanaceae, and Rosaceae.

Ans: (a)
Geitonogamy refers to the transfer of pollen grains from the anther to the stigma of another flower on the same plant. It is a form of cross-pollination but occurs between flowers of the same individual plant.

Here is a brief explanation of the other options:

• Xenogamy: This is the transfer of pollen from the anther of one plant to the stigma of a different plant, usually of the same species.
• Autogamy: This is self-pollination, where pollen from the anther of a flower fertilizes the stigma of the same flower.
• Cleistogamy: This is a type of self-pollination that occurs in closed flowers, where the flowers do not open, and pollination occurs without exposure to the external environment.

Thus, the correct term for pollen transfer between flowers of the same plant is Geitonogamy.

Ans: (d)
The formation of the female gametophyte (embryo sac) in angiosperms occurs in the ovule in a series of steps:

(C) Meiotic division in megaspore mother cell: The process begins with meiosis in the megaspore mother cell, which produces four megaspores, but only one of them is functional, and the others degenerate.

(B) Degeneration of 3 megaspores: Out of the four megaspores formed, three degenerate, and the remaining one becomes the functional megaspore.

(A) Three successive free nuclear divisions in the functional megaspore: The functional megaspore undergoes three rounds of free nuclear divisions, where no cell walls are formed, leading to the formation of eight nuclei.

(D) Migration of 3 nuclei towards each pole: The eight nuclei are arranged with three migrating towards the micropylar pole (the pole near the opening of the ovule), and three towards the chalazal pole (the opposite end).

(E) Formation of a wall resulting in the seven-celled embryo sac: After the migration of the nuclei, cell walls form around the nuclei, resulting in the formation of a seven-celled structure with the egg cell, two synergids, three antipodal cells, and a central cell with two polar nuclei.

Thus, the correct sequence of events is: (C), (B), (A), (D), (E).

Ans: (b)

Among the animals, insects, particularly bees are the dominant biotic pollinating agents.

Ans: (c)

Cleistogamous flowers does not open at all. In such flowers autogamy occurs. Lack of cross pollination is a disadvantage of cleistogamy.

Ans: (d)
Mostly nucellus is consumed after fertilisation due to absorption of food by developing embryo in a seed. Sometimes, the nucellus remains persistent in the seed and is called perisperm.

Ans: (c)
(b) There is no need to emasculate unisexual flowers of the selected female parent - This statement is correct because unisexual flowers do not have male reproductive parts (stamens), so there is no need to remove anthers (emasculate) to prevent self-pollination.
(c) Emasculated flowers are to be bagged immediately after cross-pollination - This statement is correct because, after cross-pollination with the desired pollen, the flowers need to be bagged to prevent further contamination from unwanted pollen or other pollinating agents.
(d) Emasculated flowers are to be bagged after removal of anthers - This statement is correct. The emasculated flowers should be bagged after anther removal and before cross-pollination. This prevents contamination with unwanted pollen. After cross-pollination, the flowers should be bagged again to avoid any further contamination.

The other options are incorrect :
(a) The female flower buds of plant producing unisexual flowers need not be bagged - This statement is incorrect because even unisexual flowers need to be bagged to prevent contamination from unwanted pollen or other pollinating agents.
(e) Bisexual flowers, showing protogyny, are never selected for cross - This statement is incorrect because protogyny (when the female reproductive part matures before the male reproductive part) can reduce the chances of self-pollination, making these flowers suitable for cross-pollination.

Ans: (c)

Xenogamy refers to the transfer to pollen grains from anthers of one plant to stigma of a different plant which during pollination, brings genetically different types of pollen grains to stigma.

Cleistogamy is a condition in which flower does not open.

Geitonogamy refers to the transfer of pollen grain from anther to stigma of another flower of the same plant.

Chasmogamy is a condition in which flowers remain open.

Ans: (c)

A typical angiospermic embryo sac has seven cells that are three antipodals, one central cell, one egg cell and two synergids.

The central cell has two polar nuclei, hence the embryo sac is eight nucleated.

Ans: (b)

In some members of Rosaceae, Leguminosae and Solanaceae pollen grains maintain viability for a month due to sporopollenin.

The outer wall or exine of pollen grains contains sporopollenin. It is one of the most resistant organic compounds known. It protects pollen grains from external factors such as temperature, acid, alkali, etc. because of sporopollenin, pollen grains are preserved as fossils.

Ans: (d)
Diadelphous condition is a condition of arrangement of filaments and stamen in a flower, e.g. Pea. In this condition, filaments of nine different stamens are connected into one unit and the tenth posterior stamen remains out of the bundle as a stand part. The androecium of pea flower is diadelphous because the filaments of the anther are united in two bundles. In the case of pea, out of ten, nine stamens form a staminal tube while one is free. Thus, the correct answer is 'Pea' which exhibit diadelphous condition

China rose has monoadelphous stamens while, Citrus has polyadelhphous stamens. Monoadelphous stamens are grouped in single bundle whereas polyadelphous stamens occur in more than two bundles.

Ans: (b)
Understanding the Components:

- The ovule consists of several parts: the chalaza, micropyle, and the body of the ovule itself. The funicle is a stalk that connects the ovule to the ovary wall.

2. Identifying the Junction:

- The question asks for the specific site where the ovule is attached to the funicle. This is critical to determine which of the given options is correct.

3. Analyzing the Options:

- Option 1: Hilum - This is the point where the ovule is attached to the funicle.

- Option 2: Micropyle - This is the opening at the opposite end of the ovule, not where it attaches to the funicle.

- Option 3: Nucellus - This is the tissue within the ovule but does not refer to the attachment point.

- Option 4: Chalaza - This is the end of the ovule opposite the micropyle, but it is not the point of attachment to the funicle.

4. Conclusion:

- The correct answer is Option 1: Hilum, as it is the specific site where the body of the ovule is fused with the funicle.

Final Answer:

The body of the ovule is fused within the funicle at the hilum.

Ans: (b)
The plant parts which consist of two generations one within the other are pollen grains inside the anther and embryo sac inside the ovule. Pollen grain is haploid inside the diploid anther. Embryo sac is haploid inside the diploid ovule.

Ans: (c)
In some seeds, remains of nucellus persist.
This residual nucellus which persists in the seed is called perisperm
Examples: Black pepper, coffee, castor, cardamom, Nymphaea.

Ans: (a)

In flowering plants,

Out of the two male gametes, one gametes fuses with the nucleus of the nucleus of the egg cell and forms the zygote. The process is known as syngamy.

The other male gamete fuses with the two polar nuclei located in the central cell to form a triploid primary endosperm nucleus (PEN). Since, the process involves the fusion of three haploid nuclei, it is known as triple fusion.

Since two kinds of fusions (syngamy and triple fusion) take place in an embryo sac it is known as double fertilisation

Ans: (a)

Central cell develops into Endopserm. Endosperm developes from the fusion of secondary diploid nucleus with one male nucleus formina primary endopsermm nucleus (PEN).

Ans: (c)
Parthenogenesis is the process, whereby the female gamete develops into new organism without fertilisation. Seedless fruits are formed by parthenogenesis.

Ans: (d)
The pinus seeds have a very hard seed coat so without fungal association the seed cannot absorb water. The mycorrhizae penetrate deep inside the seeds to moisten them.

Ans: (a)
In parietal placentation the ovules develop on the inner wall of ovary or in peripheral part. E.g. Mustard, Argemone, etc.

Ans: (d)

Sporopollenin cannot be degraded by enzyme; strong acids and alkali, therefore it is helpful in preserving pollen as fossil.

Ans: (d)

Winged pollen grains are present in Pinus. Each pollen grain has two wing-like structures which enables it to float in air, as an adaptation for dispersal by the wind.

Ans: (b)
In angiosperms, the functional megaspore is the first cell of female gametophyte. It enlarges and undergoes three nuclear mitotic divisions to form embryo sac.

Ans: (a)

Insect pollinated plants provide rewards as edible pollen grain and nectar as usual rewards. In order to materialize and maximize pollination flowers have developed a set of attributes which are aimed at attracting the pollinators called attractants.

Ans: (b)
Wind pollination or anemophily occurs in flowers which are having a single ovule in each ovary, and numerous flowers packed in an inflorescence. It is a non-directional pollination.

Ans: (a)
Autogamy occurs in bisexual flowers. Geitonogamous flowers are unisexual but present in the same plant. Dioecious condition is observed when unisexual male and female flowers are present on different plants and it prevents both autogamy and geitonogamy.

Ans: (c)
Double fertilisation is the characteristic feature of angiosperms. Here, two male gametes are released in the embryo sac or female gametophyte. One male gamete fuses with the egg cell to form zygote that gives rise to embryo whereas the other male gamete fuses with the secondary nucleus to form primary endosperm nucleus (PEN) that gives rise to endosperm.

Ans: (c)

• Megaspore mother cell of megasporangium undergoes meiosis and forms megaspore tetrad, out of which, one megaspore is functional. 
• Central cell of embryo sac is the large cell consisting of two polar nuclei. 
• Synergids, the flanking cells of the egg cell, have finger-like projections of the wall in their cytoplasm, the filiform apparatus.
• An embryo sac has three antipodal cells which provide nutrition to developing the embryo.

Ans: (b)

• Water lily has actinomorphic flowers and produce large number of stamen to favour anemophily (wind pollination). 
• Water hyacinth exhibit entomophily and is pollinated by insects that feed on its foliage.

Ans: (a)

• The archesporial cells (2n) of young ovule cut off the parietal cell and are differentiated into megaspore mother cells (2n). 
• The diploid megaspore mother cells then undergo meiosis to form a linear tetrad of megaspores. 
• Megaspore is the first cell of the female gametophyte. 
• Out of four, the functional megaspore undergoes megagametogenesis to 8-nucleate and 7-celled embryo sac. 
• Ovule serves as megasporangium wherein megaspores production occurs.

Ans: (b)
The coconut water from tender coconut represents the free nuclear or liquid endosperm. During the development of nuclear type of endosperm, the primary endosperm mother cell divides by free nuclear divisions, and these divisions are not followed by cell wall formation. Thus, the free nuclei remain in the cytoplasm of the embryo sac.

Ans: (c)

Tapetum is important for the nutrition and development of pollen grains, as well as a source of precursors for the pollen coat.

Ans: (b)
Apomixis is a reproductive process which does not involve gametic fusion. In apomictic flowering plants there is no fertilisation and embryos develop simply by division of a cell of ovule.

Ans: (c)

Pollen-pistil interaction is the group of events that occur from the time of pollen deposition over the stigma to the time of pollen tube entry into ovule. It is a safety measure to ensure that illegitimate crossing does not occur. Pollen grains of number of plants may settle over a stigma. The pollens belonging to same species would germinate while other fail to do so but the pollen tube of the compatible pollen will grow through the style to reach the ovule whereas growth of incompatible pollens will be arrested at stigmatic disc or sometimes in the beginning part of style.

Ans: (b)

The proximal end is attached to the thalamus whereas the distal end bears anther.