Question

How many pollen grains and ovules are likely to be formed in the anther and the ovary of an angiosperm bearing 25 microspore mother cells and megaspore mother cells respectively?

Answer 1

Pollen is a powdery material made up of pollen grains, which are male microgametophytes that create male gametes in seed plants (sperm cells). The gametophytes are protected by a hard layer of sporopollenin on pollen grains as they travel from the stamens to the pistil of flowering plants or from the male cone to the female cone of coniferous plants.

Complete answer:
Pollen is generated in the male cone of a conifer or other gymnosperm's microsporangia, or the anthers of an angiosperm flower's anthers. Pollen grains have a broad range of forms, sizes, and surface patterns that are unique to each species (see electron micrograph, right). Pine, fir, and spruce pollen grains have wings. Ovules are immature seeds that are made up of a stalk, the funiculus, a megasporangium (also known as the nucellus), from which the megasporocyte and female gametophyte grow, and one or two integuments.
It is the process of gamete formation. Inside the anther, male gametes are produced. Microsporogenesis and microgametogenesis are two of the stages. Megasporogenesis and megagametogenesis are the two stages involved in the formation of female gametes inside the ovules. Since every microspore mother cell produces a tetrad with four pollen grains, a mother cell with 25 microspores will produce 100 pollen grains. Each megaspore mother cell produces a single megaspore, which develops into an ovule, resulting in a total of 25 ovules from 25 megaspore mother cells.

Thus, there are 100 pollen grains and ovules are likely to be formed in the anther and the ovary of an angiosperm bearing 25 microspore mother cells and megaspore mother cells respectively.

Note:
Various angiosperms have different patterns of female gametophyte growth; for example, the female gametophyte of some evening primrose (Oenothera) species may only have four nuclei, whereas the female gametophyte of Peperomia may have as many as sixteen. The development of the female gametophyte in lily involves all four megaspore nuclei.