Question

The number of chromosomes in male grasshopper is

A) 8

B) 45

C) 46

D) 23

Answer 1

Hint: Grasshopper shows XX-XO type of male heterogamety where males contain one less chromosome than females. 24 (2n) chromosomes are present in female grasshoppers.

Complete answer:

Insects such as bugs, grasshoppers, and cockroaches females have two X chromosomes and males have one X chromosome. This is called male heterogamety. These organisms contain 23 chromosomes in males and 24 chromosomes in females.

Additional Information:

• Sex of a species in which the sex chromosomes are not same is referred to as heterogametic sex. it is a type of sex determination.

• It includes male heterogamety and female heterogamety. If males produce similar gametes and females produce different gametes, it is called female heterogamety. If females produce similar gametes and males produce different gametes it is called male heterogamety.

• Male heterogamety is of two types namely XX-XO and XX-YY (XX refers to a female). Female heterogamety is of two kinds ZO-ZZ and ZW-ZZ

• In organisms like bugs, cockroaches, and grasshoppers they show XX-XO type of male heterogamety.

• The unpaired X chromosome refers to the male sex. The karyotype of the male is AAXO and the female is AAXX. All the ova contain AX component and in sperm, half of them contain A component and the other half depends on the type of sperm that fertilizes.

• So in grasshoppers, males have 23 chromosomes and females have 24 chromosomes.

Therefore, the correct answer is option (D) ‘23’.

Note: 

• McClung discovered male heterogamety in grasshoppers.
• An example of XX-YY male heterogamety type is drosophila, ZO-ZZ female heterogamety type is fumea and the ZW-ZZ type is birds, reptiles, and some fishes.