Question

Which chromosome set is found in male grasshoppers?
A. 2A + XY
B. 2A +XO
C. 2A +YY
D. 2A + XX

Answer 1

A long DNA molecule that consists of a part or all of the genetic material is called chromosome. Chromosomes consist of a single molecule called DNA and proteins. The recombination of the chromosome during sexual reproduction plays a very important role in the sex determination of an organism. There are two types of chromosomes present in organism sex chromosomes and autosomal chromosomes.

Complete answer: A biological system that determines the development of sexual characteristics in an organism is called sex determination. Organisms that are produced by sexual reproduction have two sexes. Types of sex determination in organisms include environmental-based sex determination and genetic-based sex determination. Various combinations of chromosomes are XY, ZW, XO, ZO, and haplodiploidy. A female grasshopper consists of diploid chromosomes that are $2n=24$. Whereas the diploid chromosome in male grasshopper is $2n=23$. Sex determination in grasshopper takes place by the XX-XO mechanism. Female grasshoppers are homogametic and consist of XX chromosomes. Homogametic refers to the same set of chromosomes. Male grasshoppers consist of only one sex chromosome that is XO. Male grasshoppers consist of one sex chromosome less than the female grasshopper. Hence, male grasshoppers consist of a pair of autosomes and one sex chromosome less than female grasshoppers. Therefore, male grasshoppers consist of 2A + XO.
So, option B is the correct answer.

Note: There are two types of heterogamety found in different organisms - male heterogamety and female heterogamety. In Humans and Drosophila (fruit fly) show male heterogamety in which male has two different sex chromosome along with autosomes. In fowls, female heterogamety is found in which female has two different sex chromosome along with autosomes.