Question

Study the following statements and select the correct option.
I. Tapetum nourishes the developing pollen grains.
II. Hilum represents the junction between ovule and funicle.
III. In aquatic plants such as water hyacinth and water lily, pollination is by water.
IV. The primary endosperm nucleus is triploid.

• A. I, II, and IV are correct, but III is incorrect
• B. I and II are correct, but III and IV are incorrect
• C. I and IV are correct, but II and III are incorrect
• D. I, Ill and IV are correct, but I is incorrect

Answer 1

Answer: (A)

I, II, and IV are correct, but III is incorrect

Tapetum is the innermost wall layer of microsporangium. It is a nutritive layer which releases enzymes as well as hormones. It nourishes the developing pollen grains. Its cells produce various enzymes, hormones, amino acids and other nutritious materials which are essential for the development of pollen grains. It secretes sporopollenin, which is required for the function of exine of the pollen grains.

The megasporangium is also known as an ovule. It 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.

Not all aquatic plants use water for pollination. In aquatic plants such as water hyacinth and water lily, pollination is not by water. The flowers emerge above the level of water and are pollinated by insects or wind as in most of the land plants. Pollination by water is quite rare in flowering plants and is limited to about 30 genera, mostly monocotyledons.

The primary endosperm nucleus is triploid because it is formed by triple fusion. Triple fusion is the fusion of one male gamete and two polar nuclei (or secondary nucleus; if the two have already fused) in the central cell of embryo sac to form primary endosperm nucleus. It takes place in the central cell of an embryo sac. Three nuclei are involved in triple fusion, i.e., one male nucleus and two polar nuclei in the central cell; therefore primary endosperm nucleus is triploid. So, the correct answer is option A.