1. Each organism has a fixed number of chromosomes.
2. This number has to be maintained in its offspring.
3. Any sudden change in the number of chromosomes will be harmful to the offspring. Assume parent has 10 chromosomes.
4. In the absence of meiosis during sexual reproduction gametes will also have the same number of chromosomes as parent i.e., 10 chromosomes.
5. Union of female and male gametes occur forming zygote during sexual reproduction. The number of chromosomes doubled in zygote will have 10+10 chromosomes.
6. In the next generation, the offspring will have forty chromosomes. If this continues cells in the offsprings will have thousands of chromosomes within few generation.
7. This results in formation of abnormalities in each generation. Hence by way of meiotic division, the chromosome number is maintained constant from generation to generation.
