The physical association of the two genes on chromosome is called

Options

A. linkage
B. recombination
C. crossing over
D. segration

Answer

To answer the question, "The physical association of the two genes on chromosome is called," we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the term that describes the physical association of two genes located on the same chromosome.

2. **Identifying Key Terms**: The options provided are linkage, recombination, crossing over, and segregation. We need to analyze each term to determine which one fits the definition of physical association.

3. **Defining Linkage**: Linkage refers to the close association of genes or DNA sequences on the same chromosome. When genes are linked, they tend to be inherited together during the process of cell division.

4. **Evaluating Other Options**:
- **Recombination**: This term refers to the mixing or reshuffling of genetic material, often between different chromosomes or organisms, and does not specifically describe the physical association of genes on the same chromosome.
- **Crossing Over**: This is a process that occurs during meiosis where homologous chromosomes exchange segments. While it involves genes on chromosomes, it does not define their physical association.
- **Segregation**: This term describes the separation of alleles during gamete formation, which is a different concept from physical association.

5. **Conclusion**: Based on the definitions and explanations, the correct answer to the question is "linkage." This term specifically describes the physical association of two genes on the same chromosome.

### Final Answer:
The physical association of the two genes on chromosome is called **linkage**.

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