Sexual Reproduction in Flowering Plants

Correct answer: A. Pollen tube

Explanation: When a pollen grain germinates on the stigma, it produces a pollen tube. The tube grows through the style and enters the ovule, eventually reaching the embryo sac and delivering the two male gametes. The embryo sac, integument, and style are separate structures and do not themselves transport the gametes.

Correct answer: A. Transfer of pollen grains from the anther to the stigma

Explanation: Pollination is the transfer of pollen grains from the anther to the stigma. It may occur within the same flower or between flowers of the same or different plants. Therefore, option A is correct. Option B describes fertilisation, option C describes pollen germination and pollen-tube formation, and option D describes seed development from an ovules after fertilisation.

Correct answer: B. Embryo sac

Explanation: In flowering plants, the female gametophyte is called the embryo sac. It develops within the ovule and contains the egg cell and other cells involved in reproduction. A pollen grain is the male gametophyte, the pollen tube transports the male gametes, and the ovule is the structure that contains the embryo sac.

Correct answer: B. Seven

Explanation: A typical mature angiosperm embryo sac is seven-celled and eight-nucleate. It contains three cells forming the egg apparatus, three antipodal cells, and one central cell. The central cell contains two polar nuclei, so there are eight nuclei but only seven cells. This distinction makes seven the unambiguous answer.

Correct answer: B. 8

Explanation: The governing concept is the organisation of a typical angiosperm embryo sac. It is seven-celled but eight-nucleate: three antipodal cells contribute three nuclei, two synergids contribute two, and the egg contributes one. The central cell contains two polar nuclei. Thus the total is 3 + 2 + 1 + 2 = 8, making option B correct. Seven refers to cells, not nuclei.

Correct answer: B. Chalazal end

Explanation: In a typical mature angiosperm embryo sac, three antipodal cells occur at the chalazal end, which is opposite the micropyle. The micropylar end contains the egg apparatus—one egg cell and two synergids. The stigma and pollen tube are not ends or cellular groups of the embryo sac, so they cannot be correct.

Correct answer: A. Providing nourishment to the developing embryo

Explanation: Endosperm is a nutritive tissue that generally develops after triple fusion during double fertilisation in angiosperms. Its main function is to nourish the developing embryo by supplying stored materials such as starch, proteins, and oils. The seed coat develops from the integuments, not from the endosperm.

Correct answer: B. Monocots and dicots

Explanation: In the traditional school-level classification of angiosperms, embryos with one cotyledon are called monocots, whereas embryos with two cotyledons are called dicots. Roots and stems are plant organs, algae and fungi are different biological groups, and male and female refer to sex rather than cotyledon number.

Correct answer: A. Scutellum

Explanation: The single cotyledon of a monocot embryo is called the scutellum, especially in the standard description of a grass embryo. It helps absorb nutrients from the endosperm. The coleoptile protects the plumule, the coleorhiza protects the radicle, and the epiblast is an additional structure rather than the cotyledon.