Two genes 'A' and 'B' are linked. In a dihybrid cross involving these two genes, the `F_(1)` hetrozygote is crossed with homozygous recessive parental type (aa bb). What would be the ratio of offspring in the next generation?

Options

A. 1 : 1 : 1 : 1
B. 9 : 3 : 3 : 1
C. 0.12569444444444
D. 1 : 1

Answer

To solve the problem, we need to understand the concepts of linked genes, dihybrid crosses, and how to determine the offspring ratios from such crosses.

### Step-by-Step Solution:

1. **Identify the Genotypes**:
- The F1 heterozygote will have the genotype AaBb (where A and B are dominant alleles, and a and b are recessive alleles).
- The homozygous recessive parent has the genotype aabb.

2. **Understand Linked Genes**:
- Since genes A and B are linked, they are located on the same chromosome and tend to be inherited together. This means that the gametes produced by the F1 heterozygote will be limited to combinations of the alleles that are present together on the same chromosome.

3. **Gamete Formation**:
- The F1 heterozygote (AaBb) can produce two types of gametes due to linkage:
- AB (dominant alleles together)
- ab (recessive alleles together)
- The homozygous recessive parent (aabb) can only produce one type of gamete:
- ab

4. **Crossing the Gametes**:
- We will now perform the cross between the gametes of the F1 heterozygote and the homozygous recessive parent:
- Gametes from AaBb: AB and ab
- Gametes from aabb: ab
- The possible combinations from the cross are:
- AB (from AaBb) × ab (from aabb) = AaBb (dominant phenotype)
- ab (from AaBb) × ab (from aabb) = aabb (recessive phenotype)

5. **Phenotypic Ratio**:
- From the combinations above, we can see that:
- 1 offspring will be AaBb (dominant phenotype)
- 1 offspring will be aabb (recessive phenotype)
- Therefore, the phenotypic ratio of the offspring will be 1:1.

6. **Conclusion**:
- The final ratio of offspring in the next generation is 1:1.

### Final Answer:
The ratio of offspring in the next generation is **1:1**.