A color-blind man and a woman with normal vision whose father was color blind have a child. Color blindness is

Question

caused by an X-linked recessive gene. What is the probability the child will be color blind?

a. .25 (or 25%)
b. .50 (or 50%)
c. .75 (or 75%)
d. 1.00 (or 100%)
e. none of the above.

thanks in advance.

Answer 1

Exactly 50%.

The woman's father: XY
The woman: XX (she's got the "faulty" gene from her father, but she's not color-blind, 'coz it's a _recessive_ gene).
Her children, of any sex, have a 50% chance of getting the "faulty" gene from her. If it's a girl, she'll get the other "faulty" gene from her father (100%), so she'll have a 50% chance of being color-blind, overall. If it's a boy, he'll get the Y chromosome from his father, but won't matter, 'coz he'll get the "faulty" chromosome from his mother (50% chance, again). So he too will have a 50% chance of being color-blind.

Now, the fact that the father is color-blind does matter, in fact, because if he weren't, his girl would be "color-adept" (or whatever you call it).

Sorry for the not-very-politically-correct way I chose my words, English is not my first language.

Answer 2

b. 50(or 50%)
father of woman passes x linked color blind gene to her daughter

Answer 3

If the kid's a boy, 75%. If it's a girl, 25%

Answer 4

Again, draw a punnett square for this cross, and then look at sons and daughters.

You need to learn how to answer these questions on your own.

Answer 5

B i just took this test in biology

Answer 6

a ?????