Q40. How many meiotic divisions and successive mitotic rounds normally produce the mature female gametophyte from one megaspore mother cell?
[NEET 2025]
(A) One meiosis and three mitotic rounds
(B) Three meioses and one mitotic round
(C) One meiosis and one mitotic round
(D) Two meioses and four mitotic rounds
Answer: (A) One meiosis and three mitotic rounds
Explanation: One megaspore mother cell completes meiosis to yield four haploid megaspores, usually leaving one functional megaspore. That megaspore undergoes three successive mitotic divisions, yielding eight nuclei, which organise into the familiar seven-celled mature embryo sac.
Q39. Which tree has a highly specialised pollination relationship with a coevolved insect that is effectively its specific pollinator?
[UPSC CSE Prelims 2024, General Studies]
(A) Fig
(B) Mahua
(C) Sandalwood
(D) Silk cotton
Answer: (A) Fig
Explanation: Fig trees and fig wasps demonstrate a specialised mutualism. Female wasps enter fig inflorescences for egg laying while transferring pollen. Many fig species are associated with particular wasp pollinators, making the relationship a classic illustration of coevolution.
Q38. Which of the following is NOT normally a floral whorl or component of a flower?
[SSC CGL Tier I, 13 September 2024, Shift 3]
(A) Androecium
(B) Corolla
(C) Spines
(D) Calyx
Answer: (C) Spines
Explanation: Calyx, corolla, androecium and gynoecium constitute the four principal floral whorls. Spines are usually modified vegetative organs serving protection or reducing browsing. They are not counted among the standard reproductive or accessory whorls of a typical flower.
Q37. Which part of the flower normally develops into a seed following fertilisation?
[SSC MTS, 28 October 2024, Shift 1]
(A) Stamen
(B) Petal
(C) Ovule
(D) Stigma
Answer: (C) Ovule
Explanation: The ovule contains the embryo sac and develops into a seed following fertilisation. Its integuments form the seed coat, while the zygote forms an embryo. The enclosing ovary, rather than the ovule, normally develops into the fruit.
Q36. Why can pollen grains remain preserved for exceptionally long periods as fossils?
[NEET 2024, Re-examination]
(A) Because of lignin in the intine
(B) Because sporopollenin occurs in the exine
(C) Because pollen contains no water
(D) Because pollen is made entirely of cellulose
Answer: (B) Because sporopollenin occurs in the exine
Explanation: Sporopollenin, present in the outer exine wall of pollen grains, is exceptionally resistant to physical, chemical and biological degradation. This durability allows the pollen wall to survive for long periods, providing a useful record for palaeobotanical and environmental studies.
Q35. How does the association between flowers and honeybees chiefly benefit the flowers?
[UPSC NDA II, General Ability, 3 September 2023]
(A) It accelerates vegetative growth
(B) It promotes pollination
(C) It directly causes seed germination
(D) It increases flower size immediately
Answer: (B) It promotes pollination
Explanation: Honeybees visit flowers to collect nectar or pollen. While moving between flowers they can transfer pollen grains from anthers to receptive stigmas. This promotes pollination and, following compatible pollen-tube growth and fertilisation, may result in fruit and seed formation.
Q34. During which of these events is the chromosome number reduced by half in flowering plants?
[UPSC NDA II, General Ability, 3 September 2023]
(A) Seed germination
(B) Fruit ripening
(C) Flower opening
(D) Formation of microspores during pollen development
Answer: (D) Formation of microspores during pollen development
Explanation: Microspore mother cells in the anther undergo meiosis, a reduction division that changes the chromosome number from diploid to haploid. The resulting microspores develop into pollen grains. Germination, flower opening and fruit ripening do not themselves cause this reduction.
Q33. Which process is NOT a form of asexual reproduction in plants?
[SSC CHSL Tier I 2022 cycle, held 10 March 2023, Shift 1]
(A) Vegetative propagation
(B) Spore formation
(C) Pollination
(D) Budding
Answer: (C) Pollination
Explanation: Pollination involves transfer of pollen grains from anther to stigma and belongs to the sexual reproductive pathway of flowering plants. Vegetative propagation, budding and many forms of spore reproduction can create new individuals without fusion of male and female gametes.
Q32. What chiefly distinguishes microsporogenesis from megasporogenesis in flowering plants?
[CGPSC Mains 2023, General Science — MCQ adapted from descriptive PYQ]
(A) Microsporogenesis makes pollen precursors; megasporogenesis makes megaspores
(B) Both processes occur only inside mature seeds
(C) Microsporogenesis forms ovaries; megasporogenesis forms petals
(D) Microsporogenesis occurs in the style; megasporogenesis in the stigma
Answer: (A) Microsporogenesis makes pollen precursors; megasporogenesis makes megaspores
Explanation: Microsporogenesis is meiosis in microspore mother cells inside anthers, producing haploid microspores. Megasporogenesis is meiosis in a megaspore mother cell within an ovule, producing megaspores. Their developmental locations and gametophyte pathways differ, although both start with reduction division.
Q31. After fertilisation, which floral structures normally wither, while sepals may sometimes persist?
[RRB Group D, 27 September 2022, Shift 1]
(A) Only stigma, never petals
(B) Petals, stamens, stigma and style
(C) Only ovary and ovules
(D) Entire flower, including developing ovary
Answer: (B) Petals, stamens, stigma and style
Explanation: Following fertilisation, petals, stamens, stigma and style usually senesce because they have completed their roles. The ovary persists and enlarges to form a fruit. Sepals may sometimes remain attached as persistent calyx, as seen in several plant species.
