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)

If a colour blindness man marries a woman whose father was colour blind and mother was normal then which of the following is true for their progenies? (question 5)

50% of the daughters will be carrier.

• Color blindness is a recessive sex-linked trait.
• Father transfers its X chromosome to the daughters.
• The colorblind father will transfer its carrier X chromosome to the daughter.
• The women will be a carrier for colorblindness XX. The results are showing in the table given below :

      Normal woman                                                Colourblind man

         XX                                                                            X^cY

                                         Daughters                   Sons

Now according to the question , a colourblind man marries with a carrier woman so :
• The colorblind man will be X^CY and colorblind woman will be X^CY

                                           Daughters                   Sons
• The carrier female and color blind man will inherit the disease to 50% sons and 50% daughters and 50 % daughters will be carrier  and 50% sons will be normal.
Thereby a color-blind man marries the daughter of a color-blind man. Then in their progeny, 50% of all the daughters will be carrier.

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