Question

In gymnosperms, how many male gametes are produced by each pollen grains?
A. 4
B. 3
C. 2
D. 1

Answer 1

In gymnosperms, generative cells are divided to form body cell and stalk cell in which only the body cell is divided into pollen grains.

Complete Answer:
Gymnosperms are plants that are flowerless and develop cones and seeds. As gymnosperm seeds are not encased inside an ovary, the word gymnosperm simply means "naked seed." Gymnosperms are vascular plants of the Embryophyta sub-kingdom, including ginkgoes, cycads, conifers, and gnetophytes.

Now, let us find the solution from the options-
- The pollen grain or the male gametophytes are produced from the microspores of gymnosperms. In gymnosperms, at the 3-celled, 4-celled or 5-celled stage, microspores are released at different stages, but finally 2 male gametes are produced.
- Let’s explain this by an example, in Cycas; microspores are released into the air at the 3-celled stage. The microspore has a prothallial cell, a small generative cell and a big tube cell at this stage. After pollination, further development of this 3-celled male gametophyte occurs in the ovule's pollen chamber. In order to create a stalk cell and a body cell, this generative cell then separates.
- While the body cell divides to form 2 male gametes said as antherozoids, the stalked cell does not differentiate further.
From these we came to know that options A, B, and D are incorrect.

Thus, the correct answer is option (C) 2.

Note: In gametophyte structures, called archegonia, located in ovulate cones, female gametes (megaspores) are formed. In pollen cones, male gametes (microspores) are created and develop into pollen grains. Some species of gymnosperm have female and male cones on the same tree, while others have separate trees that grow male or female cones. Gametes must interact with one another in order for pollination to occur. Usually, this happens through animal, wind, or insect transfer.