- Home
- Standard 12
- Biology
4.Principles of Inheritance and Variation
medium
A colour blind man marries a woman with normal sight who has no history of colour blindness in her family. What is the probability of their grandson being colour blind ?
A
$Nil$
B
$0.25$
C
$0.5$
D
$1$
(NEET-2015)
Solution
(b) : When a colour blind man $(X^cY)$ marries a normal woman $(XX)$, all of their daughters are carriers and all of their sons are normal, as shown in following figure: When the carrier daughter $(XX^c)$ is married to a normal man, the probability of their son being colour blind is $0.25$, as shown in following figure:From above crosses, it is clear that the probability of occurrence of colour blindness in the grandson of a colour blind man and a normal woman is $0.25$.
Standard 12
Biology
