Chromosome number in a gamete of rat is ______.

The correct answer is Option (2) → 21

Option (2) 21 — Correct. The rat has 42 chromosomes in its meiocytes (somatic cells). Gametes are formed by meiosis, which halves the number, so a rat gamete has 21.

Note: This question is from Chapter 1, Reproduction in Organisms, of the pre-rationalised NCERT book. This chapter is not in the present NCERT book (2026-27). The extract below is from the pre-rationalised edition.

NCERT Extract (Pre-rationalised edition, Chapter 1, Reproduction in Organisms):
Cell Division during Gamete Formation – “… 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.”