Both the alleles express themselves equally in F1 generation, except

Options

A. Antirrhinum
B. Sickel cell anaemia
C. AB blood group
D. Roan cattle

Answer

To solve the question "Both the alleles express themselves equally in F1 generation, except," we need to identify the exception among the given options where both alleles do not express equally in the F1 generation.

### Step-by-Step Solution:

1. **Understand the Concept of Dominance**:
- In genetics, alleles can be dominant or recessive. The dominant allele masks the effect of the recessive allele in a heterozygous condition. This is known as Mendel's law of dominance.

2. **Identify Co-Dominance**:
- Co-dominance occurs when both alleles in a heterozygous organism are fully expressed, resulting in a phenotype that shows both traits. Examples include:
- Sickle cell anemia (HbA and HbS)
- ABO blood groups (IA and IB)
- Coat color in Rowan cattle (black and white)

3. **Recognize Incomplete Dominance**:
- Incomplete dominance is a situation where neither allele is completely dominant, resulting in a phenotype that is a blend of the two traits. An example is the flower color in Antirrhinum (snapdragon), where crossing red and white flowers produces pink flowers.

4. **Analyze the Options**:
- The question asks for the exception where both alleles do not express equally.
- Among the examples provided, Antirrhinum (snapdragon) is the only case where neither allele expresses fully, leading to an intermediate phenotype.

5. **Conclusion**:
- Therefore, the correct answer to the question is that in Antirrhinum, both alleles do not express equally in the F1 generation, making it the exception.

### Final Answer:
The exception where both alleles do not express themselves equally in the F1 generation is Antirrhinum (snapdragon), which exhibits incomplete dominance.