The number of types of genotypes that can be produced by the multiple alleles A, B, O that determine human blood groups is

Options

A. Three
B. Four
C. Five
D. Six

Answer

To find the number of types of genotypes that can be produced by the multiple alleles A, B, and O that determine human blood groups, we can follow these steps:

### Step 1: Identify the alleles
The alleles for human blood groups are:
- I^A (A allele)
- I^B (B allele)
- i (O allele)

### Step 2: Determine possible genotypes
We need to consider all combinations of these alleles to find the possible genotypes. The genotypes can be formed by pairing these alleles in different combinations.

### Step 3: List the combinations
1. **Blood Group A**:
- I^A I^A (homozygous)
- I^A i (heterozygous)

2. **Blood Group B**:
- I^B I^B (homozygous)
- I^B i (heterozygous)

3. **Blood Group AB**:
- I^A I^B (co-dominant)

4. **Blood Group O**:
- ii (homozygous)

### Step 4: Count the genotypes
Now, we can count the unique genotypes:
- For Blood Group A: 2 genotypes (I^A I^A, I^A i)
- For Blood Group B: 2 genotypes (I^B I^B, I^B i)
- For Blood Group AB: 1 genotype (I^A I^B)
- For Blood Group O: 1 genotype (ii)

### Step 5: Total the genotypes
Adding these together gives us:
- 2 (A) + 2 (B) + 1 (AB) + 1 (O) = 6 unique genotypes.

### Conclusion
Therefore, the total number of types of genotypes that can be produced by the multiple alleles A, B, and O is **6**.

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