In: Biology
Solution
Comon type of red-green color blindness is an X linked recessive trait
Remember males are XY and Females are XX sex chromosomes
Possible genotype of colourblind man = XCY (XC represent defective gene)
Possible genotype of mother = XCX (mother do dot have colourblindness but she is a carrier)
Possible genotype of their daughter who is colour blind is XCXC . Because for a female to become colour blind, she should have two defective X chromosome (remember color blindness is an X linked recessive trait)
Look at the following Punnet square
Where,
XXC is carrier female
XCXC is colour blind female
XCY is colour blind male
XY is normal male
From the above punnet square the following conclusions can be made
The probability that their next child (either male or female) is colourblind is (2/4)* 100 = 50% or 1/2
The probability that their next child (either male or female) is normal is (2/4)* 100 = 50% or 1/2