If a colourblind woman marries a normal visioned man. Their sons will be

Options

A. All normal visioned
B. One half normal and one half colourblind
C. Three fourth colourblind and one fourth normal
D. All colourblind

Answer

To solve the question of whether the sons of a colorblind woman and a normal visioned man will be colorblind, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Genetics of Colorblindness**:
- Colorblindness is a recessive sex-linked trait, which means it is carried on the X chromosome.
- In females (XX), colorblindness will only be expressed if both X chromosomes carry the colorblind allele (Xc).
- In males (XY), since they have only one X chromosome, they will express colorblindness if their single X chromosome carries the colorblind allele (Xc).

2. **Determine the Genotypes**:
- The colorblind woman will have the genotype XcXc (both X chromosomes carry the colorblind allele).
- The normal visioned man will have the genotype XY (the Y chromosome does not carry the colorblind allele).

3. **Set Up the Punnett Square**:
- We can set up a Punnett square to visualize the potential genotypes of their offspring.
- The mother can only contribute Xc (colorblind allele), and the father can contribute either X (normal vision) or Y (male).
- The combinations will be:
- From the mother: Xc
- From the father: X or Y

4. **Analyze the Offspring**:
- The possible combinations from the Punnett square are:
- Xc from the mother and X from the father (daughter, carrier: XcX)
- Xc from the mother and Y from the father (son, colorblind: XcY)
- Therefore, all sons will inherit the Xc from their mother and Y from their father, resulting in the genotype XcY, which means they will be colorblind.

5. **Conclusion**:
- Since all sons will inherit the Xc allele from their colorblind mother, all sons will be colorblind.

### Final Answer:
All the sons will be colorblind.