Colour Blidness : It is a sex-linked disorder due to defect in either red or green cone of eye resulting in failure to discriminate between red and green colour. This defect is due to mutation in certain genes present in the X chromosome. It occurs in about 8 per cent of males and only about 0.4 per cent of females. This is because the genes that lead to red-green colour blindness are on the X chromosome.( Answer questions 1 to 5)

Which of the following is impossible in this disease? (Question 1)

Diseased father to pass gene to his son.

The correct answer is option 4 : Diseased father to pass gene to his son.

In the context of a typical X-linked recessive genetic disorder:

• Carrier mothers can pass the gene to both sons and daughters.
• Diseased fathers can pass the gene to their daughters, who would then become carriers. However, they cannot pass the gene to their sons because they pass a Y chromosome to their sons, not an X chromosome carrying the recessive gene.