Question

If a male grasshopper with XO genotype produces sperm, what proportion of his sperm will carry the X chromosome?

Options

• 50% will carry the X chromosome and 50% will carry neither X nor Y

• 50% will carry both X and O

• 100% will carry the X chromosome

• 75% will carry the X chromosome

Answer 1

In grasshoppers using the XX–XO system, males have the XO genotype (one X chromosome and no second sex chromosome). During spermatogenesis, these males produce two equal types of sperm: 50% carry the X chromosome and 50% carry no sex chromosome (O). When O-bearing sperm fertilizes an egg, an XO male results; when X-bearing sperm fertilizes an egg, an XX female results.