AB-Blood group shows :-

Options

A. CO-dominance
B. Complete dominance
C. Mixed inheritance
D. Composite inheritance

Answer

To solve the question regarding the AB blood group, we need to understand the genetics behind blood types and the specific inheritance patterns involved. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the ABO Blood Group System
The ABO blood group system is determined by three alleles:
- IA (which codes for type A blood)
- IB (which codes for type B blood)
- i (which is recessive and codes for type O blood)

### Step 2: Determine the Genotypes for Each Blood Type
- **Type A Blood**: Can be either IAIA (homozygous) or IAi (heterozygous).
- **Type B Blood**: Can be either IBIB (homozygous) or IBi (heterozygous).
- **Type AB Blood**: The genotype is IAIB, where both A and B alleles are present.
- **Type O Blood**: The genotype is ii.

### Step 3: Identify the Inheritance Pattern for AB Blood Group
The AB blood group (genotype IAIB) is unique because it expresses both alleles equally. This means that both the A and B antigens are present on the surface of red blood cells.

### Step 4: Define Co-Dominance
Co-dominance is a form of inheritance where both alleles in a heterozygote are fully expressed, resulting in offspring with a phenotype that is neither dominant nor recessive. In the case of AB blood group, both IA and IB are expressed, which is a classic example of co-dominance.

### Step 5: Evaluate the Options Given
- **Co-dominance**: Correct, as both A and B alleles are expressed in AB blood group.
- **Complete dominance**: Incorrect, as this would imply one allele completely masks the other.
- **Mixed inheritance**: Incorrect, as this suggests blending of traits rather than co-expression.
- **Composite inheritance**: Incorrect, as this also implies blending rather than co-dominance.

### Conclusion
The correct answer to the question "AB blood group shows:" is **co-dominance**.

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