Question

Sex chromosomes of birds are -

Answer 1

The animals – birds, some fish and crustaceans like the enormous river prawn, some insects and some reptiles including Komodo dragons come under this category of sex determination. Gynandromorphism is a phenomenon that has been known to exist in insects, crustaceans and birds.

Complete answer:
By the letters ‘Z’ and ‘W’ the sex chromosomes in birds are designated. The male is homomorphic (ZZ) and the female is heterophic (ZW) in this case. It is seen in most birds, that it almost contains all the known sex linked genes and the ‘Z’ chromosome is a large chromosome usually the fourth or the fifth largest. However the ‘W’ chromosome is generally a much smaller micro chromosome that contains a high proportion of the repeat sequence of DNA. On the contrary, there is a confusion that, the presence of the ‘W’ chromosome that induces female features or whether instead of it, is the duplication of the ‘Z' chromosome that induces the males too. Although, unlike the mammals, birds with a double ‘W’ chromosome (ZZW) or a single ‘Z’ (ZO) are not yet discovered.

Note:
However, where the sperm determines the sex, within the ‘ZW’ system where the sex of the offspring is determined by the ovum, it happens in contrast to the ‘XY’ sex determination system as seen in humans and the ‘X0’ sex determination system as seen in the grasshoppers. It is mainly a rare and remarkable type of mutation that results in an organism being of both sexes.