Question

Male heterogametic sex, XX,XO type of sex determination is found in
a. Butterflies
b. Moths
c. Grasshoppers
d. Drosophila

Answer 1

Hint: 2 types of gametes are produced by males it is called heterogametic sex (male). The female sex has 2 'X' chromosomes (XX) and the male has only one 'X' chromosome. So at the time of gametogenesis it produces 2 types of gametes, 50% with 'X' chromosome while the other 50% without 'X' chromosome.

Complete answer:
Option A: Butterflies have ZW sex-determination system. Female butterflies have one Z and one W chromosome and male butterflies have two Z chromosomes. That means female butterflies can only inherit their W chromosome from their mothers and they also get their Z chromosome from their fathers. Therefore, butterflies do not have any XX-XO sex-determination system. So, this is the wrong option.

Option B: Moths have a similar ZW sex-determination system to butterflies. So moths also do not possess any XX-XO sex-determination system. So it is the incorrect answer.

Option C: Grasshoppers have XX-XO sex-determination system. Females have two X chromosomes (XX) and males have only one X chromosome (X0). So It is the correct answer.

Option D: Drosophila has an XX-XY sex-determination system. So this is not the correct option.

Hence, the correct answer is option (C).

Additional information:
To understand how the determination of sex happens, we need to know the following things:
- Humans possess 23 pairs of chromosomes. Out of these 23 pairs, 22 pairs are Autosomes and only one pair is called ‘Sex Chromosome’, it actively takes part in the process of sex determination.
- Both males and females carry two sets of sex chromosomes.
- Male contains one X and one Y (XY) sex chromosome in which both are active state.
- Female has both X (XX) sex chromosome, here only one is active.
- The XY sex-determination system is found in humans, mammals, in some insects, and in few plant species.

Note: In some organisms like crickets, grasshoppers, and some other insects, the female has XX and they are homogametic sex. The male has only one sex chromosome. The male in XX-XO systems produces gametes with (X) or without (O) a sex chromosome.