Question

In which group of organism, the male has one less chromosome than female?

• A. Roundworms
• B. All insects
• C. Birds
• D. Reptiles
• E. Round worms and few insects

Answer 1

The correct option is E Round worms and few insects

Sex determination in birds and some reptiles is of ZW-ZZ types in which females are heteromorphic (ZW) and males have homomorphic sex chromosomes (ZZ) which. In roundworms, and few insects (grasshopper), XX-XO mechanism of sex determination is present where females are homogametic (XX) but the male carries only one sex chromosome (XO). Hence, the male grasshopper carries XO sex chromosomes. Some insects (butterflies and moths) show ZO-ZZ type of sex determination wherein males are homogametic (ZZ) but the female carries only one sex chromosome (ZO). Thus, the correct answer is option E.