A colour blind girl is rare because she will be born only when 

(1) Her mother and maternal grand father were colour blind

(2) Her father and maternal grand father were colour blind

(3) Her mother is colour blind and father has normal vision

(4) Parents have normal vision but grand parents were colour blind. 

A female whose father was colorblind marries and normal male whose father was also colorblind. What is the probablility that their daughter will be colorblind?

1. 0 %

2. 25 %

3. 50 %

4. 75 %

If a colourblind man marries a woman who is homozygous for normal colour vision, the probalility of their son being colourblind is 

(1) 0

(2) 0.5

(3) 0.75

(4) 1

A normal-visioned man whose father was colourblind, marries a woman whose father was also a colourblind. They have their first child as a daughter. What are the chances that this child would be colourblind?

(1) 100%

(2) 0%

(3) 25%

(4) 50%

If a colourblind woman marries a normal visioned man, their sons wil be :

(1) all normal visioned

(2) one-half colourblind and one-half normal 

(3) three-fourths colourblind and one-fourth normal

(4) all colourblind