Inheritance of roan coat in cattle is an example of

Options

A. incomplete dominance
B. codominance
C. multiple allelism
D. none of these

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the inheritance pattern of the roan coat in cattle. We need to identify whether it is an example of incomplete dominance, co-dominance, multiple allelism, or none of these.

2. **Defining Co-Dominance**: Co-dominance occurs when two different alleles are present in a genotype and both are fully expressed in the phenotype. This means that neither allele is dominant or recessive, and both traits appear together.

3. **Identifying the Alleles**: In the case of roan cattle, we have two alleles:
- Capital B (black coat)
- Small b (white coat)

4. **Crossing the Alleles**:
- When we cross a homozygous black coat (BB) with a homozygous white coat (bb), the offspring (F1 generation) will all be heterozygous (Bb), which exhibit the roan phenotype (a mix of black and white).

5. **Self-Crossing the F1 Generation**:
- When the roan individuals (Bb) are self-crossed, the resulting genotypic ratio is:
- 1 BB (black)
- 2 Bb (roan)
- 1 bb (white)
- This results in a phenotypic ratio of 1 black : 2 roan : 1 white.

6. **Conclusion**: The inheritance of the roan coat in cattle is an example of co-dominance because both black and white coat colors are expressed simultaneously in the roan phenotype.

**Final Answer**: The inheritance of roan coat in cattle is an example of **co-dominance**.

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