Improvement of qualities of F, hybrid when two unrelated individuals are crossed is called :

Options

A. Dominance
B. Inbreeding depression
C. Heterosis
D. Selection

Answer

To solve the question regarding the improvement of qualities of F1 hybrids when two unrelated individuals are crossed, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Terms**:
- Familiarize yourself with the terms 'F1 hybrid', 'dominance', 'inbreeding depression', and 'heterosis'.
- F1 hybrid refers to the first generation offspring resulting from a cross between two different parental lines.

2. **Identify the Process**:
- The question specifically asks about the improvement of qualities in F1 hybrids when two unrelated individuals are crossed.
- This process is related to the genetic advantages gained from combining different genetic backgrounds.

3. **Evaluate the Options**:
- **Dominance**: This refers to the phenomenon where one allele masks the effect of another allele at the same locus. This does not specifically relate to the improvement of F1 hybrids from unrelated individuals.
- **Inbreeding Depression**: This occurs when closely related individuals breed, leading to a decrease in biological fitness. This is the opposite of what happens when unrelated individuals are crossed.
- **Heterosis**: Also known as hybrid vigor, this refers to the improved or increased function of any biological quality in a hybrid offspring. It occurs when two unrelated individuals are crossed, resulting in offspring that exhibit superior qualities.

4. **Conclude the Answer**:
- Based on the definitions and evaluations, the correct answer to the question is **Heterosis**. This term specifically describes the improvement of qualities in F1 hybrids resulting from the crossing of unrelated individuals.

### Final Answer:
The improvement of qualities of F1 hybrid when two unrelated individuals are crossed is called **Heterosis**.

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