Meiosis is a special kind of cell division, also called as reduction division, which occurs in germ cells or sex cells of male and female reproductive organs of plants and animals. They produce male

and female gametes that take part in sexual reproduction.

1 hour 20 minutes

These are the 4 subsequent cell divisions to produce 16 cells and each division takes $=20 \mathrm{~min}$ Total time $=20 \times 4=80$ minutes or 1 hr 20 minutes

So, 1 cell produces 16 cells in 1 hour 20 minutes and 2 cells produces 32 cells in 1 hour 20 minutes.

All the cells in the human body are somatic cells except germinal cells in the male and female reproductive organs. The somatic cells divide by mitotic cell division for growth and regeneration. These can be used to demonstrate mitosis.

Chromatid is one copy of a duplicated chromosome, which is joined to the other copy centromere. The duplication of chromosome material takes place at synthetic phase of cell cycle.

During mitosis, late metaphase and early anaphase, there is longitudinal splitting of chromosomes and thus two chromosome get separated, to get divided into the daughter cells.

The homologous chromosomes lie parallel to each other in leptotene stage. Each chromosome has four chromatids and are bivalent. The non-sister chromatids of homologous chromosomes cross over in pachytene stage of prophase- I.