Q20. Which description most accurately defines double fertilisation in angiosperms?
[NEET 2018]
(A) Two eggs fuse with two separate pollen grains
(B) One male gamete fuses with egg and another with the central-cell nuclei
(C) One sperm fuses twice with the same egg
(D) Two male gametes fuse with each other
Answer: (B) One male gamete fuses with egg and another with the central-cell nuclei
Explanation: Angiosperms exhibit two fusion events within the embryo sac. Syngamy produces a diploid zygote from an egg and male gamete. Triple fusion produces the primary endosperm nucleus from the other male gamete and two polar nuclei.
Q19. Cleistogamous flowers are invariably associated with which form of pollination?
[RPSC Senior Teacher Grade II, Science, 1 July 2017]
(A) Autogamy
(B) Geitonogamy
(C) Xenogamy
(D) Hydrophily
Answer: (A) Autogamy
Explanation: Because cleistogamous flowers never open, the pollen released from their anthers can reach only their own stigmas. They therefore undergo autogamy, producing seeds even without pollinators. The closed floral condition prevents ordinary cross-pollen entry.
Q18. What does the term pollination mean?
[SSC MTS, 18 September 2017, Shift 1]
(A) Transfer of pollen from anther to stigma
(B) Germination of pollen alone
(C) Visit of ants to flowers only
(D) Growth of embryo after fertilisation
Answer: (A) Transfer of pollen from anther to stigma
Explanation: Pollination is the transfer of pollen grains from anther to stigma. It precedes fertilisation; pollen must subsequently germinate and deliver male gametes through a pollen tube. Wind, water and animals can act as pollinating agents in different plants.
Q17. Pollination in water hyacinth and water lily commonly takes place through which agents?
[NEET 2016, Phase 2]
(A) Bats alone
(B) Water currents exclusively
(C) Insects or wind
(D) Birds exclusively
Answer: (C) Insects or wind
Explanation: Although water hyacinth and water lily are aquatic, their flowers emerge above the water surface. Pollination therefore occurs mainly through insects or wind rather than underwater currents. True hydrophily is relatively uncommon among flowering plants and occurs in species such as Vallisneria.
Q16. The liquid inside a tender coconut is an example of what tissue or developmental stage?
[NEET 2016, Phase 1]
(A) Cellular endosperm
(B) Free-nuclear endosperm
(C) Perisperm
(D) Nucellus
Answer: (B) Free-nuclear endosperm
Explanation: Tender coconut water represents the liquid free-nuclear phase of endosperm development. Nuclear division initially proceeds without immediate cell-wall formation. As the coconut matures, the peripheral endosperm becomes cellular and forms the white edible kernel.
Q15. Transfer of pollen from anther to stigma of the same flower is called which process?
[WBCS Preliminary Examination 2015]
(A) Allogamy
(B) Geitonogamy
(C) Xenogamy
(D) Autogamy
Answer: (D) Autogamy
Explanation: Autogamy is pollination within a single flower. It is favoured when pollen release and stigma receptivity overlap and the reproductive structures are close together. It differs from geitonogamy, which involves two flowers on the same plant.
Q14. Which type of pollination may require an external pollinator but is genetically similar to autogamy?
[AIPMT 2015, cancelled-paper question]
(A) Xenogamy
(B) Apogamy
(C) Cleistogamy
(D) Geitonogamy
Answer: (D) Geitonogamy
Explanation: Geitonogamy transfers pollen between separate flowers of the same plant, often using insects or another agent. Because the source and recipient belong to one individual, the pollen is not genetically independent in the way it generally is in xenogamy.
Q13. What is the function of the filiform apparatus in the synergid?
[AIPMT 2014]
(A) Storage of starch
(B) Guidance of pollen tube towards the egg apparatus
(C) Formation of seed coat
(D) Release of pollen from anther
Answer: (B) Guidance of pollen tube towards the egg apparatus
Explanation: The filiform apparatus is a specialised wall thickening near the micropylar tip of a synergid. It plays an important role in attracting and guiding the pollen tube into the embryo sac, where the two male gametes are released.
Q12. Perisperm differs from endosperm mainly because perisperm is what?
[NEET 2013]
(A) Persistent diploid nucellus of maternal origin
(B) Triploid tissue formed by triple fusion
(C) Diploid tissue formed by syngamy
(D) Embryo-derived cotyledonary tissue
Answer: (A) Persistent diploid nucellus of maternal origin
Explanation: Perisperm is persistent nucellus, a maternal diploid tissue present before fertilisation. Endosperm, by contrast, normally develops from the triploid primary endosperm nucleus after triple fusion. The two tissues may both store food, but their developmental origins differ.
Q11. In which condition are both autogamy and geitonogamy prevented?
[AIPMT 2012, Preliminary Examination]
(A) Monoecious plant bearing unisexual flowers
(B) Dioecious plant bearing unisexual flowers
(C) Plant with bisexual cleistogamous flowers
(D) Plant bearing two bisexual flowers
Answer: (B) Dioecious plant bearing unisexual flowers
Explanation: Dioecious plants bear staminate and pistillate flowers on separate individuals. Neither a single flower nor two flowers on the same plant can accomplish both pollen donation and reception. Thus autogamy and geitonogamy are both prevented, making cross-plant pollination obligatory.
