A man whose father was colour blind marries a woman who has a colour blind mother and normal father .What percentage of male childern of this couple will be colour blind ?

Options

A. `25%`
B. `0%`
C. `50%`
D. `75%`

Answer

To solve the question, we need to analyze the genetic inheritance of color blindness in the offspring of the given couple. Here’s a step-by-step breakdown of the solution:

### Step 1: Determine the Genotype of the Man
- The man’s father was color blind, which means he had the colorblind allele on his X chromosome (X^c). Since males have only one X chromosome, the man must have inherited his father's Y chromosome and a normal X chromosome from his mother.
- Therefore, the man's genotype is X^N Y (where X^N represents the normal vision allele).

### Step 2: Determine the Genotype of the Woman
- The woman has a colorblind mother (X^c X^c) and a normal father (X^N Y).
- She must have inherited one X chromosome from her mother (X^c) and one from her father (X^N).
- Therefore, the woman’s genotype is X^N X^c (she is a carrier for color blindness).

### Step 3: Set Up a Punnett Square
- The man can produce gametes with either X^N or Y.
- The woman can produce gametes with either X^N or X^c.
- We can set up a Punnett square to determine the possible genotypes of their offspring:

| | X^N (from man) | X^c (from woman) |
|---------|----------------|------------------|
| **X^N (from woman)** | X^N X^N (normal female) | X^N X^c (carrier female) |
| **Y (from man)** | X^N Y (normal male) | X^c Y (colorblind male) |

### Step 4: Analyze the Offspring
- The possible offspring genotypes from the Punnett square are:
1. X^N X^N (normal female)
2. X^N X^c (carrier female)
3. X^N Y (normal male)
4. X^c Y (colorblind male)

### Step 5: Calculate the Percentage of Colorblind Male Children
- Out of the four possible offspring, there is one colorblind male (X^c Y) and one normal male (X^N Y).
- Therefore, the percentage of male children that will be colorblind is:
- 1 colorblind male out of 2 total males = 1/2 = 50%.

### Final Answer
- **50% of the male children of this couple will be colorblind.**

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