In sexually reproducing organisms, the same chromosome number is maintained across generations due to the process of meiosis and fertilization. Meiosis reduces the number of chromosomes in gametes (sperm and egg cells) to half the number found in the parent cell’s somatic cells, making them haploid. When a sperm and egg fuse during fertilization, they combine their haploid chromosome sets, restoring the diploid number of chromosomes found in the parent.
Here’s a more detailed explanation:
1. Meiosis:
During meiosis, the parent cell undergoes two rounds of division, resulting in four haploid gametes (sperm or egg). Each gamete contains only one set of chromosomes, half the number present in the parent cell’s somatic cells.
2. Gamete Fusion:
When a sperm and an egg fuse during fertilization, they combine their haploid chromosome sets. The sperm contributes one set of chromosomes, and the egg contributes the other.
3. Zygote Formation:
The resulting cell, called a zygote, contains the full diploid set of chromosomes, matching the number found in the parent organism’s somatic cells.
Therefore, the offspring inherits the same number of chromosomes as its parents because the gametes, produced through meiosis, carry half the chromosome number, and their fusion restores the full diploid set.