Both the alleles express themselves equally in F1 generation, except

Options

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

Answer

To solve the question "Both the alleles express themselves equally in F1 generation, except," we need to analyze the given options and determine which one does not exhibit co-dominance. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the Concept of Co-dominance
Co-dominance is a genetic scenario where both alleles in a heterozygous individual contribute equally and visibly to the phenotype. This means that both traits are expressed at the same time.

### Step 2: Analyze Each Option
We will evaluate each option to see if it demonstrates co-dominance or not.

1. **A. Antirrhinum (Snapdragon)**
- In Antirrhinum, when red-flowered (RR) and white-flowered (WW) plants are crossed, the F1 generation produces pink flowers (RW). This is an example of incomplete dominance, not co-dominance, as the phenotype is an intermediate rather than a mix of both traits.

2. **B. Sickle Cell Anemia**
- In sickle cell anemia, individuals with one normal allele (HbA) and one sickle cell allele (HbS) show both types of hemoglobin in their blood. This is a classic example of co-dominance, as both alleles are expressed equally.

3. **C. AB Blood Group**
- The AB blood group results from the presence of both IA and IB alleles. In this case, both alleles are expressed equally, resulting in the AB phenotype. This is also an example of co-dominance.

4. **D. Roan Cattle**
- Roan cattle exhibit a mixture of red and white hairs when a red cow is crossed with a white bull. This is another example of co-dominance, as both colors are expressed in the phenotype.

### Step 3: Identify the Correct Answer
From the analysis:
- Antirrhinum is the only option that does not demonstrate co-dominance; instead, it shows incomplete dominance. Therefore, the answer to the question is **A. Antirrhinum**.

### Final Answer
**A. Antirrhinum**

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