What are the events that cause the chromosome number of gametes to go from 2n, n,and again back to 2n during reproduction

The process that causes the chromosome number of gametes to go from 2n to n and back to 2n during reproduction involves several key events:

1. Meiosis: This is the process that reduces the chromosome number from 2n (diploid) to n (haploid). It occurs in the sex cells or gametes of an organism. Meiosis involves two divisions, Meiosis I and Meiosis II, and results in four haploid daughter cells.

2. Fertilization: This is the event that brings the chromosome number back to 2n. When a sperm cell (n) fertilizes an egg cell (n), the two sets of chromosomes combine to form a zygote with 2n chromosomes.

3. Mitosis: After fertilization, the zygote begins to divide by mitosis, a process that maintains the 2n chromosome number in all body cells as the organism grows and develops.

So, in summary, the chromosome number goes from 2n to n during meiosis, and then back to 2n during fertilization. The 2n chromosome number is then maintained during mitosis as the organism grows.