Human skin colour is polygenic trait with each dominant determing a part of melanin deposition while the recessive are coding for no melanin. If a very dark skinned person marries a very light skinned women, the chances of a very dark skinned offspring are

Options

A. O
B. `1//4`
C. `5//8`
D. `9//64`

Answer

To solve the question regarding the chances of a very dark-skinned offspring from a very dark-skinned man and a very light-skinned woman, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Polygenic Traits**:
- Human skin color is a polygenic trait, meaning it is controlled by multiple genes. Each dominant allele contributes to melanin deposition, while recessive alleles contribute to a lack of melanin.

2. **Genetic Representation**:
- Let's denote the dominant alleles (for melanin deposition) as "A" and the recessive alleles (for no melanin) as "a". A very dark-skinned person would likely have a genotype with multiple dominant alleles (e.g., AABBCC), while a very light-skinned person would have a genotype with recessive alleles (e.g., aabbcc).

3. **Crossing the Genotypes**:
- When we cross a very dark-skinned person (AABBCC) with a very light-skinned person (aabbcc), the offspring will inherit one allele from each parent. The dark-skinned parent can only pass on dominant alleles, while the light-skinned parent can only pass on recessive alleles.

4. **Offspring Genotypes**:
- The possible genotypes for the offspring from this cross will be AaBbCc. This means that all offspring will have at least one dominant allele for each gene, but they will also inherit recessive alleles from the light-skinned parent.

5. **Phenotype of Offspring**:
- Since the offspring will have at least one dominant allele for each gene, they will have some level of melanin deposition. However, the presence of recessive alleles means that they will not be as dark as the very dark-skinned parent.

6. **Chances of Very Dark-Skinned Offspring**:
- To have a very dark-skinned offspring, the offspring would need to inherit a combination of dominant alleles that results in a high level of melanin. Given that the light-skinned parent contributes only recessive alleles, the chances of producing an offspring that is very dark-skinned (like the dark-skinned parent) is effectively zero.

### Conclusion:
Thus, the chances of a very dark-skinned offspring from this pairing is **0**.

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