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 occurs by water.
(iv) The primary endosperm nucleus is triploid.

• A. (i) and (ii) are correct but (iii) and (iv) are incorrect
• B. (i), (ii) and (iv) are correct but (iii) is incorrect
• C. (i), (iii) and (iv) are correct but (ii) is incorrect
• D. (i) and (iv) are correct but (ii) and (iii) are incorrect

Answer 1

Answer: (B)

A typical microsporangium consists of two parts- outer wall layers and inner sporogenous cells. Four wall layers generally surround the microsporangium- the epidermis, endothecium, middle layer, and the tapetum. The tapetum is the innermost wall layer that surrounds the sporogenous tissues and it provides nourishment to the developing pollen grains. The tapetum cells possess dense cytoplasm and more than one nucleus, generally (polyploids). It also helps in pollen wall formation and for the separation of microspore tetrad, the tapetum synthesizes the callase enzyme.
The ovule is attached to the placenta of the ovary by a stalk known as the funicle. The portion where the funicle fuses with the ovule is known as hilum.
In plants like water hyacinth and water lily, flowers come to the surface of water, and are then pollinated by entomophily or anemophily.
Angiosperms have devised double fertilisation. The syngamy results in the formation of diploid zygote when a haploid male gamete fuses with another haploid female gamete.
Male gamete (n) + Female gamete (n) = Zygote (2n)
The second male gamete fuses with the definitive nuclei (2n), thus resulting in the formation of triploid primary endosperm nucleus (PEN).
Male gamete (n) + Polar nuclei (2n) = PEN (3n)
Endosperm is triploid in nature which is formed by fusion of two polar nuclei and a haploid sperm cell.