First child of a normal pigmented couple is albino. The possibility of a second child being an albino is

Options

A. 0.25
B. 0.5
C. 0.75
D. 1

Answer

To determine the possibility of the second child being an albino, we need to analyze the genetic makeup of the parents and the inheritance pattern of albinism.

### Step-by-Step Solution:

1. **Understand the Genetics of Albinism**:
- Albinism is caused by a recessive allele. This means that an individual must have two copies of the recessive allele (homozygous recessive, represented as "aa") to express the albino phenotype.

2. **Determine the Genotypes of the Parents**:
- Since the first child of a normal pigmented couple is albino, we can conclude that both parents must carry at least one recessive allele for albinism. Therefore, their genotypes must be:
- One parent: "Aa" (normal pigmentation, carrier of albinism)
- Other parent: "Aa" (normal pigmentation, carrier of albinism)

3. **Set Up a Punnett Square**:
- To predict the genotypes of the offspring, we can use a Punnett square. The alleles from each parent are placed on the top and side of the square:
```
A a
------------
A | AA | Aa |
------------
a | Aa | aa |
------------
```

4. **Analyze the Punnett Square Results**:
- From the Punnett square, we can see the possible genotypes of the offspring:
- 1 "AA" (normal pigmentation)
- 2 "Aa" (normal pigmentation, carriers)
- 1 "aa" (albino)
- This results in a ratio of:
- 3 normal pigmentation (AA or Aa) : 1 albino (aa)

5. **Calculate the Probability for the Second Child**:
- The probability of the second child being albino (aa) is 1 out of 4, or 25%.

### Conclusion:
The possibility of the second child being an albino is **25%**.

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