A and B genes are linked . What shall be genotype of progeny in a cross between AB/ab and ab/ab :

Options

A. Aabb and aabb
B. AaBb and aabb
C. AABB and aabb
D. None of these

Answer

To solve the problem of determining the genotypes of the progeny from a cross between AB/ab and ab/ab, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Genotypes of the Parents**:
- The first parent has the genotype AB/ab, which means it is heterozygous for both genes A and B.
- The second parent has the genotype ab/ab, which is homozygous recessive for both genes.

2. **Determine the Gametes Produced by Each Parent**:
- The first parent (AB/ab) can produce four types of gametes due to the heterozygosity:
- AB (dominant A and dominant B)
- Ab (dominant A and recessive b)
- aB (recessive a and dominant B)
- ab (recessive a and recessive b)
- The second parent (ab/ab) can only produce one type of gamete:
- ab (recessive a and recessive b)

3. **Set Up the Punnett Square**:
- Since the second parent can only produce one type of gamete (ab), we can combine this with the four gametes from the first parent. The combinations will be:
- AB (from first parent) with ab (from second parent) → Progeny: AB/ab
- Ab (from first parent) with ab (from second parent) → Progeny: Ab/ab
- aB (from first parent) with ab (from second parent) → Progeny: aB/ab
- ab (from first parent) with ab (from second parent) → Progeny: ab/ab

4. **List the Possible Progeny Genotypes**:
- From the combinations above, the possible genotypes of the progeny are:
- AB/ab (heterozygous for both genes)
- Ab/ab (heterozygous for A, homozygous recessive for B)
- aB/ab (homozygous recessive for A, heterozygous for B)
- ab/ab (homozygous recessive for both genes)

5. **Consider Linkage**:
- Since genes A and B are linked, the parental types (AB/ab and ab/ab) will be more frequent in the progeny than the recombinant types (Ab/ab and aB/ab). Thus, the progeny will predominantly resemble the parental combinations.

6. **Conclusion**:
- The genotypes of the progeny will be predominantly AB/ab and ab/ab, with the other two genotypes appearing at a lower frequency.

### Final Answer:
The progeny will predominantly have the genotypes AB/ab and ab/ab due to the linkage of genes A and B.