Which of the following is incorrect regarding ZW-ZZ type of sex determination ?

Options

A. It occurs in birds and some reptiles
B. Females are homogametic and males are heterogametic
C. `1:1` sex ratio is produced in the offsprings
D. all of these

Answer

B

Explanation

In ZW-ZZ type of sex determination, the male has two harmorphic sex chromosomes (ZZ) and is homogametic, and the female has two heteromorphic sex chromosomes (ZW) and is heterogametic, There are thus two types of eggs : with Fertilisation of an egg with Z chromosome by a sperm with Z chromosome gives a zygote with ZZ chromosomes (male). Fertilisation of an egg with W chromosome by a sperm with Z chromosome yields a zygote with ZW chtomosomes (female). This mechanism operates in some vertebrates (fishes, reptiles and birds).