Write a note on ZO-ZZ type of sex determination.
In case of ZO-ZZ type of sex determination the female produces two types of eggs. The one-half of eggs is with Z-chromosome and the other half without Z-chromosome. The male has homomorphic sex chromosomes and is homogametic. It forms only one kind of sperms each with Z-chromosome. On fertilisation by a sperm with Z-chromosome, the Z-containing egg gives rise to male offspring ZZ and Z- lacking egg produces female offspring ZO. Such type of sex determination is found in the case of butterflies and moths.
