Human skin colour is controlled by 3 genes A, B and C. Which of the following genotypes will have a skin colour different from the rest?

Options

A. AaBbCc
B. AAbbCc
C. aabBCC
D. AabbCc

Answer

To solve the problem of determining which genotype will have a skin color different from the rest, we need to analyze the given genotypes based on the inheritance of skin color controlled by three genes: A, B, and C.

### Step-by-Step Solution:

1. **Understanding Polygenic Inheritance**:
- Skin color in humans is controlled by three genes (A, B, and C). This type of inheritance is known as polygenic inheritance, where multiple genes contribute to a single trait.
- Dominant alleles (capital letters) lead to higher melanin production, resulting in darker skin, while recessive alleles (lowercase letters) lead to lower melanin production, resulting in lighter skin.

2. **Analyzing the Genotypes**:
- **Option 1**: AABBCC
- All alleles are dominant. This genotype will produce maximum melanin, resulting in dark skin.

- **Option 2**: AABBCc
- This genotype has two dominant alleles (A and B) and one mixed (C). It will also produce a significant amount of melanin, resulting in dark skin.

- **Option 3**: AaBbCc
- This genotype has all alleles in a heterozygous state. It will produce a moderate amount of melanin, resulting in medium skin color.

- **Option 4**: Aacc
- This genotype has one dominant allele (A) and two recessive alleles (c). This will lead to lower melanin production, resulting in very light skin.

3. **Identifying the Different Genotype**:
- Comparing the skin colors produced by each genotype:
- Options 1, 2, and 3 will result in darker skin tones.
- Option 4 (Aacc) will result in a significantly lighter skin tone.
- Therefore, the genotype that will have a skin color different from the rest is **Aacc**.

### Conclusion:
The genotype that will have a skin color different from the rest is **Aacc**.

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