Question

In which group of organisms, the male has one less chromosome than female?
a. Roundworms
b. All insects
c. Birds
d. Reptiles
e. Roundworms and few insects

Answer 1

Hint: A biological system that determines the progression of sexual characteristics in an organism's sex-determination system. In general, the organisms are said to use sexual reproduction to create their offspring using two types of sexes. However, on the other hand, the presence of hermaphrodites in place of one or both sexes also exist.

Complete answer:
However, the mechanism of XX-XO is present in the roundworms and also in few insects just like grasshoppers. In such type of system of sex determination, the females are homogametic in nature (that is XX) but the male carries only one sex chromosome (that is XO). That means the XO sex chromosomes are only one which is present in the male grasshoppers.

The birds and some reptiles have the sex determination type of ZW-ZZ. It is a type in which the females are heteromorphic (that is ZW) and males have homomorphic sex chromosomes (that is ZZ)

The butterflies and moths are some insects that have the type of ZO-ZZ as their sex determination. The males are homogametic (ZZ) but the female carries only one sex chromosome (ZO) in this type of sex determination.

Hence, the correct answer is option (E).

Note: In most of the species, sex determination is said to be genetic in nature. It is scientifically proven that there exist different alleles or even different genes in males and females. They have that to specify their sexual morphology. The new offspring are formed through combinations of XY, ZW, XO, ZO chromosomes, or haplodiploidy.