Question

Males in animals always possess two distinct sex chromosomes, while females have the same sex chromosomes. Which of the following disproves this statement?

• A. There are many animals that have XO type of sex determination.
• B. In birds, males have the same type of sex chromosome, while females have a distinctive pair.
• C. Eggs can never possess the Y chromosome.
• D. Sperms can possess either an X or a Y chromosome.

Answer 1

The correct option is B

In birds, males have the same type of sex chromosome, while females have a distinctive pair.

Sex determination based on the chromosomes need not always be the same as we see in humans, where males have XY chromosome and females have XX chromosome. In fruit flies, males have only one X chromosome, while females have two X chromosomes. However, birds have a completely different set of chromosomes. The males possess ZZ sex chromosome and the females have ZW chromosome, which is a stark contrast to what we see in humans.