What is the inheritance of colour blindness of both parents having anormal vision but mother has a recessive gene for colour blindness :-

Options

A. `50%" "Nil`
B. `100%" "Nil`
C. `Nil" "100`
D. `Nil" "Nil`

Answer

To solve the question regarding the inheritance of color blindness when both parents have normal vision, but the mother carries a recessive gene for color blindness, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Genetics of Color Blindness**:
- Color blindness is a recessive sex-linked disorder, which means the gene responsible for it is located on the X chromosome. The normal vision allele is dominant (X) while the color blindness allele is recessive (Xc).

2. **Identify the Genotypes of the Parents**:
- The mother has normal vision but carries the recessive gene, so her genotype is XcX (where Xc is the X chromosome with the color blindness allele).
- The father has normal vision and does not carry the gene for color blindness, so his genotype is XY (where X is the normal vision allele).

3. **Determine the Gametes Produced**:
- The mother can produce two types of gametes: Xc (with the color blindness allele) and X (with the normal vision allele).
- The father can produce two types of gametes as well: X (with the normal vision allele) and Y (the male chromosome).

4. **Perform a Punnett Square Analysis**:
- Set up a Punnett square to visualize the possible combinations of gametes from both parents:
```
X | Y
----------------
Xc | XcX | XcY
----------------
X | XX | XY
```
- The resulting genotypes from the Punnett square are:
- XX (normal female)
- XcX (carrier female)
- XY (normal male)
- XcY (color blind male)

5. **Analyze the Results**:
- From the Punnett square, we see that:
- 50% of the offspring are females (XX and XcX), where XX is a normal female and XcX is a carrier female.
- 50% of the offspring are males (XY and XcY), where XY is a normal male and XcY is a color blind male.
- Thus, the daughters will be carriers, and the sons will have a chance of being color blind.

6. **Conclusion**:
- The inheritance pattern shows that 50% of the progeny will be normal, 25% will be carrier females, and 25% will be color blind males. The mother passes the recessive gene to her sons, making them color blind.

### Final Answer:
The inheritance of color blindness in this scenario results in 50% normal vision offspring (both male and female), 25% carrier females, and 25% color blind males.