A cross between AaBb and aabb yields

Options

A. AaBb and aabb
B. AaBb, Aabb, aaBb and aabb
C. AaBb
D. Aabb

Answer

To solve the problem of a cross between AaBb and aabb, we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Genotypes**:
- The first parent is AaBb (heterozygous for both traits).
- The second parent is aabb (homozygous recessive for both traits).

2. **Determine the Gametes**:
- For the parent AaBb, the possible gametes are AB, Ab, aB, and ab.
- For the parent aabb, the only possible gametes are ab.

3. **Set Up the Punnett Square**:
- Create a Punnett square to combine the gametes from both parents. Since aabb can only produce one type of gamete (ab), we will only have one column for the gametes from aabb.
- The Punnett square will look like this:

| | ab |
|------|------|
| AB | AaBb |
| Ab | Aabb |
| aB | aaBb |
| ab | aabb |

4. **List the Offspring Genotypes**:
- From the Punnett square, we can see the resulting genotypes:
- AaBb (from AB and ab)
- Aabb (from Ab and ab)
- aaBb (from aB and ab)
- aabb (from ab and ab)

5. **Identify the Phenotypes**:
- Now, we can determine the phenotypes based on the genotypes:
- AaBb: Dominant for both traits (phenotype 1)
- Aabb: Dominant for the first trait, recessive for the second (phenotype 2)
- aaBb: Recessive for the first trait, dominant for the second (phenotype 3)
- aabb: Recessive for both traits (phenotype 4)

6. **Conclusion**:
- The cross between AaBb and aabb yields four different genotypes and corresponding phenotypes.

### Final Result:
The offspring from the cross between AaBb and aabb will yield the following genotypes: AaBb, Aabb, aaBb, and aabb.

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