Question

In majority of angiosperms
A. Reduction division occurs in the megaspore mother cells.
B. A small central cell is present in the embryo sac.
C. Egg has a filiform apparatus.
D. There are numerous antipodal cells.

Answer 1

Hint:- Angiosperms are known as flowering plants, and are the major group of land plants. They exhibit a life cycle similar to that of gymnosperms. The angiosperms may be bisexual or unisexual depending upon the presence of male and female flowers.

Complete Answer:-All angiosperms are heterosporous, that is, they produce two different types of spores, including megaspores and microspores. During megasporogenesis, a single diploid megasporangium undergoes meiosis and gives rise to 4 haploid megaspores, and only one out of these four megaspores becomes functional whereas the other three degenerate. This functional megaspore undergoes mitosis and develops into the female gametophyte that eventually produces an egg.

In the most common type of gametophyte development in flowering plants, the megaspore undergoes three consecutive mitotic divisions giving rise to seven cells. Thus, the matured female gametophyte within the ovule is a 7-celled and 8-nucleated structure. It consists of 1 egg, two synergids, three antipodals and one centrally located cell with un-fused nuclei. The function of the synergids present on either side of the egg is to protect the egg cell. The egg cell, along with the synergids is known as the egg apparatus. However, the antipodals perform a function of providing nutrition.

 During double fertilization, one male gamete fuses with the egg cell forming the zygote and the other with the central nuclei giving rise to the primary endosperm nucleus that provides nutrition to the developing embryo. The filiform apparatus are specialized structures found at the base of embryo sac which guides the pollen tube in entering into the embryo sac.
Hence, reduction division often occurs in the megaspore mother cells in the majority of angiosperms.


The correct answer is option A, which states reduction division occurs in the megaspore mother cells.

Note:- In angiosperms, the dominant phase is sporophytic, that is the main plant body is sporophytic. The megasporangium is generally diploid, so it undergoes reduction division to give rise to haploid megaspores.