Question

In $XO$ type of sex determination

• A. Females produce two types of gametes
• B. Males produce two types of gametes
• C. Females produce gametes with Y-chromosome
• D. Males produce gametes with Y-chromosome

Answer 1

Answer: (B)

$1.XOtype\left(XX—XOtype\right)$
• It was also observed that in a large number of insects the mechanism of sex determination is of the $XO$
type, i.e. all eggs bear an additional X-chromosome besides the other chromosomes (autosomes).
• On the other hand, some of the sperms bear the Xchromosome whereas some do not.
• Eggs fertilised by sperm having an X-chromosome become females and, those fertilised by sperms that do not have an X-chromosome become males.
• The number of chromosomes in the male and female are not equal.
• Due to the involvement of the X-chromosome in the determination of sex, it was designated to be the sex chromosome, and the rest of the chromosomes were named as autosomes.
• Grasshopper and cockroach is an example of XO type of sex determination in which the males have only one chromosome besides the autosomes, whereas females have a pair of X-chromosomes