Chromosome number in a gamete of rat is ______.

21

The correct answer is Option (2) → 21

In diploid organisms, specialised cells called meiocytes (gamete mother cell) undergo meiosis. At the end of meiosis, only one set of chromosomes gets incorporated into each gamete. Rats have a diploid chromosome number of 42 in their somatic (body) cells. The gametes (sperm or egg cells) contain half the number of chromosomes as the somatic cells. Therefore, the chromosome number in a gamete of a rat is 21.