Which parental combination represents outcross ?

Options

A. AA x BB
B. Aa x aa
C. aa x AA
D. Aa x AA

Answer

To determine which parental combination represents outcross, let's analyze the concept step by step.

### Step-by-Step Solution:

1. **Understanding Outcrossing**:
- Outcrossing refers to the mating of individuals from different genetic backgrounds. This typically involves crossing a hybrid (F1 generation) with a parent that has a known genotype, usually a homozygous dominant parent.

2. **Identifying the F1 Generation**:
- The F1 generation is the first filial generation, which is the result of a cross between two parental lines. This generation is typically heterozygous for the traits being studied.

3. **Recognizing the Parental Combinations**:
- We need to evaluate the provided options to see which one involves the F1 generation crossing with a dominant parent.

4. **Analyzing Each Option**:
- **Option A**: F1 crossed with a dominant parent. This is a classic example of outcrossing.
- **Option B**: F1 crossed with a recessive parent. This is a test cross, not an outcross.
- **Option C**: A normal cross between two homozygous parents. This is not outcrossing.
- **Option D**: F1 crossed with a dominant parent. This is also an example of outcrossing.

5. **Conclusion**:
- The correct answer is the option where the F1 generation is crossed with a dominant parent. Based on the analysis, the answer is **Option D**.