Question

Two parents with normal vision have two sons, one color deficient and one with normal vision. If this couple then has six daughters, can you predict what percentage of the daughters will have normal color vision?

A) 0%
B) 100%
C) 25%
D) 50%

Answer 1

The correct answer is D) 50%.

Step-by-step explanation:

Based on the information provided, we know that both parents have normal vision. If the couple has two sons, one of whom is color deficient and the other has normal vision, this indicates that the color deficiency is a recessive trait carried on the X chromosome.

Since the father does not have color deficiency, we can assume he has two normal copies of the gene (XY). The mother, being a carrier, would have one normal copy and one copy of the color deficiency gene (XcX).

When the couple has daughters, they will inherit one X chromosome from each parent. The daughters have a 50% chance of inheriting the mother's normal X chromosome (X) and a 50% chance of inheriting the mother's X chromosome with the color deficiency gene (Xc).

Therefore, the percentage of daughters with normal color vision would be 50%.

The correct answer is D) 50%.

Answer 2

In the case of X-linked recessive traits like red-green colorblindness, females must inherit two copies of the gene to show the trait. Since the father has normal vision, all daughters will have normal color vision, but they could be carriers. Thus, 100% of the daughters will have normal color vision.

Step-by-step explanation:

Understanding Color Vision Deficiency Inheritance

Red-green colorblindness, also known as color vision deficiency, is an X-linked recessive trait. This means that the gene responsible for this condition is located on the X chromosome. Since males have one X and one Y chromosome (XY), they need to inherit only one copy of the recessive gene to be colorblind. Females, on the other hand, have two X chromosomes (XX) and must inherit two copies of the gene, one from each parent, to express colorblindness.

When two parents with normal vision have a colorblind son, it indicates that the mother is a carrier of the colorblind gene (XCXc), as the father cannot pass on his only X chromosome with the recessive gene to a son, and the father must have normal vision (XYXC). Their daughters would inherit one X chromosome from the mother and one from the father. Since the father provides an X chromosome with the normal vision allele, none of the daughters would be colorblind, but they all have a 50% chance to be carriers like their mother.

As for the probability question, all their daughters will have normal color vision, but they could be carriers. Therefore, the correct option in the final answer to the question 'What percentage of the daughters will have normal color vision?' is B) 100%.