If two persons with 'AB' blood group marry and have sufficiently large number of children, these children could be classified as 'A' blood group : 'AB' blood group : 'B' blood group in 1 : 2 : 1 ratio. Modern technique of protein electrophoresis reveals presence of both 'A' and 'B' type proteins in 'AB' blood group individuals. This is an example of

Options

A. codominance
B. incomplete dominance
C. partial dominance
D. complete dominance

Explanation

To solve the question regarding the inheritance of blood groups in children of two individuals with 'AB' blood group, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Blood Group Genetics**:
- Blood groups are determined by alleles. The A and B blood groups are controlled by two different alleles, IA (for A) and IB (for B). The O blood group is controlled by the i allele, which is recessive.
- Individuals with the AB blood group have one IA allele and one IB allele.

2. **Parental Genotypes**:
- Both parents have the genotype IAIB (AB blood group).

3. **Possible Gametes**:
- Each parent can produce two types of gametes: one carrying the IA allele and the other carrying the IB allele.

4. **Punnett Square Analysis**:
- When we set up a Punnett square for the cross between two AB individuals, we have:
- Parent 1: IAIB
- Parent 2: IAIB
- The possible combinations of alleles from these gametes would be:
- IAIA (Blood group A)
- IAIB (Blood group AB)
- IBIA (Blood group AB)
- IBIB (Blood group B)

5. **Resulting Genotypic Ratio**:
- From the combinations, we can see:
- 1 IAIA (A)
- 2 IAIB (AB)
- 1 IBIB (B)
- This gives us a genotypic ratio of 1:2:1 for the blood groups A:AB:B.

6. **Observation of Proteins**:
- The presence of both A and B type proteins in individuals with AB blood group indicates that both alleles are expressed in the phenotype.

7. **Conclusion**:
- Since both alleles (IA and IB) are expressed equally in the AB blood group, this phenomenon is an example of **co-dominance**.

### Final Answer:
The correct answer is **co-dominance**.

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