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 .

2n to n, n to 2n

Explanation:

Meiosis is known as reductional division because in meiosis the chromosome number gets reduced to half in daughter cells so when sperm and egg cells undergo meiosis than the chromosome numbers get reduced from 2n to n. In humans, the chromosome number is 46 and it gets reduced to 23 after meiosis.  

When egg is fertilized by the sperm than the two chromosomes comes in the same cell and the number goes from n to 2n that mean in human it goes from 23 to 46.

enzyme speed up the reactions

what in the weirdo : o