When sperm and egg cells undergo meiosis, the number of chromosomes goes from to . When an egg is fertilized by a sperm cell that number goes from to . 2 to 2; 1 to 1 1 to 1; 2 to 2 1 to 2; 2 to 1 2 to 1; 1 to 2

When sperm and egg cells undergo meiosis, the number of chromosomes goes from 2 to 1. When an egg is fertilized by a sperm cell that number goes from 1  to 2.

Explanation:

Meiosis is the reduction division which results in the formation of four haploid daughter cell from a diploid parent.

Meiosis is restricted to sex cells in sexually reproducing organisms.

Thus we understand that when  sperm and egg cells undergoes meiosis the chromosome number will be halved i.e the chromosome number will go to 2 to 1.

When a haploid egg cell is fertilized by a haploid sperm they form zygote which is diploid.

So we conclude that the number of chromosomes will go from 1 to 2.

segmentation=endoskeleton=backbone=coelom=tissues