What is the number of alleles for blood group in an individual

Options

A. 1
B. 2
C. 3
D. 4

Answer

To determine the number of alleles for blood group in an individual, we can follow these steps:

### Step 1: Understand the ABO Blood Group System
The ABO blood group system consists of three alleles: IA, IB, and IO. Each allele corresponds to a specific blood type based on the presence of certain antigens on the surface of red blood cells.

### Step 2: Recognize the Alleles
- **IA**: This allele produces type A blood.
- **IB**: This allele produces type B blood.
- **IO**: This allele produces type O blood and does not add any antigen.

### Step 3: Identify the Combinations
In an individual, the blood group is determined by the combination of two alleles. The possible combinations and their corresponding blood groups are:
- IA + IA = Type A
- IA + IB = Type AB
- IA + IO = Type A
- IB + IB = Type B
- IB + IO = Type B
- IO + IO = Type O

### Step 4: Determine the Number of Alleles in an Individual
Since humans are diploid organisms, they have two alleles for each trait. Therefore, even though there are three possible alleles (IA, IB, IO), an individual can only have two of these alleles at any given time.

### Conclusion
Thus, the number of alleles for blood group in an individual is **2**.

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