Q.Complete the following flow chart: Pollen mother cell → Pollen tetrad → Pollen grain. (Name the intermediate structures/events.)

The pollen mother cell (also called microspore mother cell or MMC) undergoes meiosis to produce four haploid cells arranged together as a pollen tetrad. Each of these four cells is a microspore. The tetrad then separates, releasing individual microspores. Each microspore undergoes mitosis (the first mitotic division) to form a two-celled structure: a larger vegetative cell and a smaller generative cell. This two-celled stage is the immature pollen grain. In some species, the generative cell divides again (second mitosis) before pollen is shed, producing two male gametes and making a three-celled mature pollen grain; in others, this division happens after pollination.

The complete flow is: …

The journey from a diploid pollen mother cell to a functional pollen grain is the story of how flowering plants build their male gametophyte, the structure that will eventually deliver sperm to the egg. This process unfolds in two major phases: a reduction division that creates haploid cells, and then a maturation step that organizes those cells into a delivery vehicle for fertilization.

Inside the anther, within chambers called microsporangia, you find diploid cells known as pollen mother cells or microspore mother cells. Each of these is destined to undergo meiosis. When meiosis I and meiosis II complete, one pollen mother cell has divided twice to yield four haploid cells. Because these four cells initially remain joined together by a common wall of callose (a special carbohydrate), they form a tight cluster called a pollen tetrad or microspore tetrad. The callose wall is temporary scaffolding.

Soon enzymes dissolve the callose, and the four cells separate. Each liberated haploid cell is now called a microspore (or sometimes a pollen grain at the one-celled stage, though terminology varies slightly). The microspore is still immature; it has work to do before it can function in pollination.

Each microspore then undergoes mitosis — a single equational division. This mitosis is asymmetric, producing two cells of unequal size that remain enclosed in the original microspore wall, which has by now developed into the tough, sculptured pollen wall (exine and intine). The larger cell is the vegetative cell (or tube cell), which will later form the pollen tube. The smaller cell, nestled within the cytoplasm of the vegetative cell, is the generative cell; it will eventually divide again (either before or after pollination, depending on the species) to produce two male gametes (sperm cells). …