Question

How many male gametes are produced by pollen grains?

Answer 1

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

Complete answer:
Pollen does not contain the male gamete. Vegetative (non-reproductive) cells (only one in most flowering plants, but several in other seed plants) and generative (reproductive) cells are found in each pollen grain. The pollen tube is produced by the vegetative tube cell, and the generative cell divides to form the two sperm nuclei in flowering plants.
In flowering plants, a single pollen grain produces two male gametes. At the two-celled stage, pollen grains are released from pollen-sacs, where the generative cell divides further to form two male gametes. The embryos are then released into the sac. They combine with female gametes to produce an embryo (egg) and endosperm (central cells).
The pollen tube grows up through the style and stigma and towards the ovules in the ovaries once pollination is complete. The germ cells divide in pollen grains. Two sperm cells are released, which travel down the pollen tube.
Single meiosis produces four pollen grains. Two male gametes are produced by each pollen grain. As a result, meiosis produces eight male gametes in total.
Thus, male gametes are produced by pollen grains.

Note:
Palynology is the study of pollen and is extremely useful in paleoecology, paleontology, archaeology, and forensics. In cross-pollination, pollen is used to transfer haploid male genetic material from the anther of one flower to the stigma of another. When self-pollination occurs, the pollen is transferred from the anther to the stigma of the same flower.