NEET Previous Year Questions (2016-21): Sexual Reproduction in Flowering Plants Notes | Study Biology Class 12 - NEET

Q.1. The term used for transfer of 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, is:     (2021)
(a) Chasmogamy
(b) Cleistogamy
(c) Xenogamy
(d) Geitonogamy
Ans. (c)
Explanation: Xenogamy – Transfer of pollen grains from anther to the stigma of a different plant. This is the only type of pollination which during pollination brings genetically different types of pollen grains to the stigma.

Q.2. A typical angiosperm embryo sac at maturity is:     (2021)
(a) 7-nucleate and 7-celled
(b) 8-nucleate and 8-celled
(c) 8-nucleate and 7-celled
(d) 7-nucleate and 8-celled
Ans. (c)
Explanation: 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.

Q.3. In some members of which of the following pairs of families, pollen grains retain their viability for months after release?     (2021)
(a)  Poaceae; Solanaceae
(b) Rosaceae; Leguminosae
(c) Poaceae; Rosaceae
(d) Poaceae; Leguminosae
Ans. (b)
Explanation: In some cereals such as rice and wheat, pollen grains lose viability within 30 minutes of their release, and in some members of Rosaceae, Leguminoseae and Solanaceae, they maintain viability for months.
 

Q.4. Ray florets have:     (2020)
(a) Hypogynous Ovary
(b) Half inferior Ovary
(c) Inferior Ovary
(d) Superior Ovary
Ans. (c)
Explanation: Ray florets have inferior ovary and the reason is that the other parts of the flower are attached above the level of ovary. Example of such an ovary is ray florets of sunflower.Flower showing Ray Floret
Q.5. The plant parts which consist of two generations one within the other:  (2020)
(i) Pollen grains inside the anther
(ii) Germinated pollen grain with two male gametes
(iii) Seed inside the fruit
(iv) Embryo sac inside the ovule
(a) (iii) and (iv)
(b) (i) and (iv)
(c) (ii) only
(d) (i) only
Ans. (b)
Explanation:
(i) Pollen grain inside the anther (2n).

• Pollen grains are haploid (n) and gametophyte which is present inside the anther (diploid and sporophyte).

(iv) Embryosac inside ovule female gametophyte (2n).

• Embryo sac is haploid and gametophyte which is present inside the ovule (diploid and sporophyte).

Q.6. The body of the ovule is fused within the funicle at     (2020)
(a) Nucellus
(b) Chalaza
(c) Hilum
(d) Micropyle
Ans. (c)
Explanation: The body of the ovule fuses with the funicle in the region called the hilum. The funicle is a stalk through which the ovule is attached to the placenta.Q.7. The ovary is half inferior in:     (2020)
(a) Sunflower
(b) Plum
(c) Brinjal
(d) Mustard
Ans. (b)
Explanation:

• Plum/peach belongs to the family Rosaceae and it shows half-inferior ovary. So the flowers are perigynous. 
• Sunflower have inferior ovary.
• Brinjal (Solanaceae) has a superior ovary. 
• Mustard have superior ovary.

Q.8. In water hyacinth and water lily, pollination takes place by:     (2020)
(a) wind and water
(b) insects and water
(c) insects or wind
(d) water currents only
Ans. (c)
Explanation: In a majority of aquatic plants such as water hyacinth and water lily, the flowers emerge above the level of water and are pollinated by insects or wind as in most of the land plants. Their stem part which is above the thalamus is not in the water. The pollen grains are in the upper part of thalamus so pollination can't done by water. That's why it is done by insects and wind.

Q.9. Persistent nucellus in the seed is known as    (2019)
(a) Tegmen
(b) Chalaza
(c) Perisperm
(d) Hilum
Ans: (c)
Explanation: 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.

Q.10. What is the fate of the male gametes discharged in the synergid?    (2019)
(a) One fuses with the egg and other fuses with central cell nuclei.
(b) One fuses with the egg, other(s) degenerates in the synergid.
(c) All fuse with the egg.
(d) One fuses with the egg, other(s) fuse(s) with synergid nucleus.
Ans: (a)
Explanation: 

• During double fertilisation in angiosperms, one male gamete fuses with the egg to form the diploid zygote (syngamy or generative fertilisation). 
• The diploid zygote finally develops into embryo. 
• The other male gamete fuses with the two polar nuclei (or secondary nucleus) to form the triploid primary endosperm nucleus, PEN (triple fusion or vegetative fertilisation).

Q.11. Which one of the following statement regarding post-fertilisation development in flowering plants is incorrect?    (2019)
(a) Ovules develops into embryo sac.
(b) Ovary develops into fruit.
(c) Zygote develops into embryo.
(d) Central cell develops into endosperm.
Ans: (a)

Explanation: Following are the post-fertilisation changes:

• Ovule → Seed
• Ovary → Fruit
• Zygote → Embryo
• Central cell → Endosperm.

So, the correct answer is 'Ovules develop into embryo sac'

Q.12. Which is the most common type of embryo sac in angiosperms?    (2019)
(a) Tetrasporic with one mitotic stage of divisions
(b) Monosporic with three sequential mitotic divisions
(c) Monosporic with two sequential mitotic divisions
(d) Bisporic with two sequential mitotic divisions
Ans: (b)

Q.13. What type of pollination takes place in Vallisneria?    (2019)
(a) Pollination occurs in submerged condition by water.
(b) Flowers emerge above surface of water and pollination occurs by insects.
(c) Flowers emerge above water surface, pollen is carried by wind.
(d) Male flowers are carried by water currents to female flowers at surface of water.
Ans: (d)

Explanation: 

• Vallisneria is an aquatic plant. In case of Vallisneria water is the agent for cross pollination. 
• In female Vallisneria, the flower reaches to the surface of water by the long stalk and the male flower or pollen grains are released into the surface of water. 
• Female flowers or stigma carried them by water current.

Q.14. which one of the following, both autogamy and geitonogamy are prevented?    (2019)
(a) Wheat
(b) Papaya
(c) Castor
(d) Maize
Ans: (b)

Explanation: Autogamy and geitonogamy are two forms of self-pollination. In autogamy, pollen falls on stigma of the same flower. While in geitonogamy pollens from a flower fall on the stigma of some other flower on the same plant. Papaya is a dioecious plant thus both autogamy and geitonogamy are prevented in it.

Q.15. Which of the following has proved helpful in preserving pollen as fossils?    (2018)
(a) Pollenkitt
(b) Cellulosic intine
(c) Oil content
(d) Sporopollenin
Ans: (d)

Explanation: Exine of pollen grain is made up of highly resistant fatty substance called sporopollenin, which is not degraded by any enzyme. It is not affected by high temperature, strong acid or strong alkali. Because of the sporopollenin, pollen grains are well preserved as microfossils.

Q.16. Winged pollen grains are present in    (2018)
(a) Mustard
(b) Cycas
(c) Mango
(d) Pinus
Ans: (d)

Explanation: Each pollen grain of Pinus has two wing-like structures which enable it to float in the air, as an adaptation for dispersal by wind. Pollen grains of mustard, Cycas and mango are not winged.

Q.17. Double fertilisation is    (2018)
(a) Fusion of two male gametes of a pollen tube with two different eggs
(b) Fusion of one male gamete with two polar nuclei
(c) Fusion of two male gametes with one egg
(d) Syngamy and triple fusion.
Ans: (d)

Explanation: 

• Double fertilisation is unique and universal feature of angiosperms. Total number of nuclei involved in double fertilisation is five, i.e., 2 in syngamy and 3 in triple fusion. 
• Syngamy is fusion of one male gamete with egg to form zygote. 
• Triple fusion occurs when the second male gamete with 2 polar nuclei or secondary nucleus to form triploid primary endosperm nucleus.

Q.18. Functional megaspore in an angiosperm develops into an    (2017)
(a) Endosperm
(b) Embryo sac
(c) Embryo
(d) Ovule
Ans: (b)

Explanation: In angiosperms, the functional megaspore is the first cell of female gametophyte. It enlarges and Undergoes three nuclear mitotic divisions to form embryo sac.

Q.19. Attractants and rewards are required for    (2017)
(a) Entomophily
(b) Hydrophily
(c) Cleistogamy
(d) Anemophily
Ans: (a)
Explanation:

• Entomophily is the most common type of zoophily where pollination takes place through the agency of insects. Entomophilous flowers are brightly coloured and secrete nectar to attract visiting insects.
• Anemophily (wind pollination) and hydrophily (water pollination) do not require attractants and rewards due to the involvement of abiotic pollination. 
• Cleistogamy is self-pollination in, close flowers.

Q.20. Flowers which have single ovule in the ovary and are packed into inflorescence are usually pollinated by    (2017)
(a) Bee
(b) Wind
(c) Bat
(d) Water
Ans: (b)
Explanation: Single ovule in the ovary and flowers racked into inflorescence are characteristics of wind-pollinated flowers.

Q.21. A dioecious flowering plant prevents both     (2017)
(a) Autogamy and geitonogamy
(b) Geitonogamy and xenogamy
(c) Cleistogamy and xenogamy
(d) Autogamy and xenogamy.
Ans: (a)
Explanation: Dioecious plants are those plants in which male flowers and female flowers are borne on different plants. Therefore, they prevent both autogamy and geitonogamy.

Q.22. Double fertilisation is exhibited by    (2017)
(a) Algae
(b) Fungi
(c) Angiosperms
(d) Gymnosperms
Ans: (c)
Explanation: Out of two sperms, when one sperm fertilizes with egg to form a diploid zygote. While the other sperm fuses with the two polar nuclei to develop triploid endosperm, the process is known as double fertilization. Double fertilization is the characteristic feature of angiosperm.

Q.23. In majority of angiosperms    (2016)
(a) Egg has a filiform apparatus.
(b) There are numerous antipodal cells.
(c) Reduction division occurs in the megaspore mother cells.
(d) A small central cell is present in that embryo sac.
Ans: (c)
Explanation:

• 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.

Q.24. Pollination in water hyacinth and water lily is brought about by the agency of    (2016)
(a) Water
(b) Insects or wind
(c) Birds
(d) Bats
Ans: (b)
Explanation:

• 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.

Q.25. The ovule of an angiosperm is technically equivalent to    (2016)
(a) Megasporangium
(b) Megasporophyll
(c) Megasporem other cell
(d) Megaspore
Ans: (a)
Explanation:

• 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.

Q.26. The coconut water from tender coconut represents    (2016)
(a) Free nuclear proembryo
(b) Free nuclear endosperm
(c) Endocarp
(d) Fleshy mesocarp
Ans: (b)
Explanation: 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.

Q.27. Which one of the following statements is not true?    (2016)
(a) Pollen grains of many species cause severe allergies.
(b) Stored pollen in liquid nitrogen can be used in the crop breeding programmes.
(c) Tapetum helps in the dehiscence of anther.
(d) Exine of pollen grains is made up of sporopollenin.
Ans: (c)
Explanation:

• The tapetum is a specialized layer of nutritive cells found within the sporangium, particularly within the anther, of flowering plants, where it is located between the sporogenous tissue and the anther wall. 
• Tapetum is important for the nutrition and development of pollen grains, as well as a source of precursors for the pollen coat, however, it does not help in the dehiscence of the anther.

So, the correct answer is 'Tapetum helps in the dehiscence of anther.'

Q.28. Seed formation without fertilisation in flowering plants involves the process of   (2016)
(a) Somatic hybridisation
(b) Apomixis
(c) Sporulation
(d) Budding
Ans: (b)
Explanation: 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.

Q.29. Which of the following statements is not correct?    (2016)
(a) Pollen germination and pollen tube growth are regulated by chemical components of pollen interacting with those of the pistil.
(b) Some reptiles have also been reported as pollinators in some plant species.
(c) Pollen grains of many species can germinate on the stigma of a flower, but only one pollen tube of the same species grows into the style.
(d) Insects that consume pollen or nectar without bringing about pollination are called pollen/ nectar robbers.
Ans: (c)
Explanation:

• Pollen-pistil interaction is the group of events that occur from the time of pollen deposition over die stigma to the time of pollen tube entry into ovule. 
• It is a safety measure to ensure that illegitimate Crossing does not occur. 
• Number of pollen grains may settle over a stigma. The pollens belonging 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.

Q.30. Proximal end of the filament of stamen is attached to the    (2016)
(a) Placenta
(b) Thalamus or petal
(c) Anther
(d) Connective
Ans: (b)
Explanation: 

• Thalamus is the basal thickened part of the stem to which all floral appendages are found attached. Petals are the coloured structural unit of the corolla.  
• The placenta is the region of the wall of the ovary to which ovules are found attached. A stamen consists of anther and filament. 
• Anther is a broad knob part of the stamen that contains two long and cylindrical microsporangia in its lobes. The middle parenchymatous tissue that joins two anther lobes together is termed as connective tissue. 
• The proximal ends of the filament are found attached to thalamus or petals while the distal end carries anther.