Increased vigour of hybrid , over the parents resulting from the crossing of genetically unlike organisms is called

Options

A. Mutant
B. heterosis
C. Polypoid
D. Superiors

Answer

To solve the question regarding the term that describes the increased vigor of a hybrid over its parent organisms resulting from the crossing of genetically unlike organisms, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the term that describes the phenomenon where a hybrid exhibits greater vigor than its parent organisms. This is a common concept in genetics and plant breeding.

2. **Identifying Key Terms**: The key terms in the question are "increased vigor," "hybrid," and "crossing of genetically unlike organisms." These terms suggest that we are looking for a specific genetic concept.

3. **Evaluating the Options**:
- **Mutant**: This term refers to an organism or gene that has undergone mutation. It does not relate to hybrid vigor.
- **Heterosis**: This term refers to the phenomenon where hybrids exhibit greater biological performance than their parents. This is often referred to as "hybrid vigor."
- **Polyploid**: This term describes organisms that have more than two sets of chromosomes. It does not relate to hybrid vigor.
- **Superior**: This term generally refers to having better qualities but does not specifically denote the increased vigor seen in hybrids.

4. **Selecting the Correct Answer**: Based on the definitions and explanations of the terms, the correct answer is **heterosis**. Heterosis is specifically defined as the increased vigor of hybrids over their parents, resulting from the combination of genetically diverse parent organisms.

5. **Conclusion**: Therefore, the answer to the question is **heterosis**.

### Final Answer:
The increased vigor of hybrid over the parents resulting from the crossing of genetically unlike organisms is called **heterosis**.