In human, blue eyes is recessive to brown eye. If a boy has brown eyes and his mother and sister has blue eyes then what will be genotype and phenotype of his father?

Options

A. Genotype - Bb
Phenotype - Brown eyes
B. Genotype - BB
Phenotype - Brown eyes
C. Genotype - bb
Phenotype - blue eyes
D. Both (b) and (c )

Answer

To solve the problem, we need to determine the genotype and phenotype of the boy's father based on the given information about eye color inheritance.

### Step-by-Step Solution:

1. **Identify the Traits**:
- Blue eyes (recessive trait) is represented by the genotype 'bb'.
- Brown eyes (dominant trait) is represented by the genotype 'B_' (where '_' can be either 'B' or 'b').

2. **Analyze the Boy's Eye Color**:
- The boy has brown eyes, which means his genotype could either be 'BB' (homozygous dominant) or 'Bb' (heterozygous).

3. **Analyze the Mother's and Sister's Eye Color**:
- Both the mother and sister have blue eyes, which means their genotype must be 'bb'.

4. **Determine the Father's Genotype**:
- Since the mother is 'bb', she can only contribute a 'b' allele to her offspring.
- The boy has brown eyes, which means he must have received a 'B' allele from his father.
- Therefore, the father must have at least one 'B' allele. This means the father could either be 'BB' or 'Bb'.

5. **Evaluate the Possibilities**:
- If the father were 'BB', all children (including the boy and sister) would have brown eyes, which contradicts the fact that the sister has blue eyes.
- Therefore, the father must be heterozygous (Bb) to allow for the possibility of having a child with blue eyes (bb).

6. **Conclusion**:
- The father's genotype is 'Bb' (heterozygous).
- The father's phenotype is brown eyes.

### Final Answer:
- **Father's Genotype**: Bb
- **Father's Phenotype**: Brown eyes