Find odd one out. W.r.t codominance.

Options

A. Heteroxygous sickle celled individual
B. AB blood group
C. MN blood group
D. Flower colour in Pisum

Answer

### Step-by-Step Solution:

1. **Understand Co-dominance**: Co-dominance is a genetic scenario where both alleles in a heterozygote are fully expressed, resulting in a phenotype that is neither dominant nor recessive. This contrasts with the law of dominance, where one allele masks the expression of another.

2. **Identify the Options**: The question asks to find the odd one out with respect to co-dominance. The options typically include examples of genetic traits or conditions.

3. **Analyze Each Option**:
- **Option A**: Heterozygous sickle cell individual - In sickle cell anemia, the presence of one normal allele and one sickle cell allele results in a phenotype where both alleles are expressed (co-dominance).
- **Option B**: AB blood group - The AB blood type results from the co-dominance of the A and B alleles, where both antigens are expressed.
- **Option C**: MN blood group - Similar to AB blood group, the MN blood group shows co-dominance between the M and N alleles.
- **Option D**: Flower color in Pisum (garden pea) - In garden peas, flower color follows Mendel's law of dominance, where violet is dominant over white. There is no co-dominance here; only the dominant phenotype is expressed.

4. **Conclusion**: The odd one out is **Option D (Flower color in Pisum)** because it does not demonstrate co-dominance; instead, it follows the law of dominance.

### Final Answer:
**Option D: Flower color in Pisum is the odd one out regarding co-dominance.**

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