Progeny with blood group 'O' can be obtained cross

Options

A. `A xx A`
B. `A xx B`
C. `O xx AB`
D. `B xx B`

Answer

To determine how progeny with blood group 'O' can be obtained from a cross, we need to understand the inheritance of blood groups. Blood groups are determined by the ABO blood group system, which involves three alleles: A, B, and O.

### Step-by-Step Solution:

1. **Understanding Blood Group Inheritance**:
- The ABO blood group system consists of three alleles: A, B, and O.
- Blood group A can have genotypes AA or AO.
- Blood group B can have genotypes BB or BO.
- Blood group AB has the genotype AB.
- Blood group O has the genotype OO.

2. **Identifying Possible Parent Genotypes**:
- For a child to have blood group O (genotype OO), at least one parent must contribute an O allele.
- This means that neither parent can have a genotype that lacks the O allele.

3. **Possible Crosses**:
- The following crosses can produce a child with blood group O:
- **O x O**: Both parents have blood group O (genotype OO).
- **A x O**: One parent has blood group A (genotype AA or AO) and the other has blood group O (genotype OO).
- **B x O**: One parent has blood group B (genotype BB or BO) and the other has blood group O (genotype OO).
- **A x B**: One parent has blood group A (genotype AA or AO) and the other has blood group B (genotype BB or BO), which can produce an O group child if both parents are heterozygous (AO and BO).

4. **Conclusion**:
- Therefore, progeny with blood group O can be obtained from the following crosses:
- O x O
- A x O
- B x O
- A x B (if both parents are heterozygous).

### Final Answer:
Progeny with blood group 'O' can be obtained from the cross of O with A or B, or from A with B if both are heterozygous.

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