Question

ZZ/ZW type of sex determination is seen in

• A. Platypus
• B. Snails
• C. Cockroach
• D. Peacock

Answer 1

Answer: (D)

In birds and some reptiles both the sexes possess two sex chromosomes but Unlike human beings, the females contain heteromorphic sex chromosomes $(AA+ZW)$ while the males have homomorphic sex chromosomes $(A\sim$\ $+ZZ)$. Because of having heteromorphic sex chromosomes, the females are heterogametic (female heterogamety) and produce two types of eggs, $(A+Z)$ and $(A+W)$. The male gametes or sperms are of the one type $(A+Z).1:1$ sex ratio is produced in the offspring. So the correct answer is 'Peacock'.