All genes located on the same chromosome.

Options

A. Form different groups depending upon their relative distance
B. Form one linkage group
C. will not form any linkage groups
D. Form interactive groups that affect the phenotype

Answer

### Step-by-Step Solution:

1. **Understanding Chromosomes**:
- Chromosomes are structures within cells that contain DNA and genes. Each chromosome can carry multiple genes.

2. **Genes on the Same Chromosome**:
- When genes are located on the same chromosome, they are physically linked together. This means they are inherited together during cell division.

3. **Linkage Group**:
- The term used to describe a group of genes that are located on the same chromosome and tend to be inherited together is called a "linkage group."

4. **Behavior During Cell Division**:
- During cell division (meiosis), these genes do not separate independently. Instead, they are passed on as a single unit unless crossing over occurs.

5. **Crossing Over**:
- Crossing over is a process that can occur during meiosis where homologous chromosomes exchange segments. This can lead to the separation of linked genes, but only if they are not too close to each other on the chromosome.

6. **Conclusion**:
- Therefore, all genes located on the same chromosome form one linkage group, which means they are inherited together as a single entity during the process of cell division.

### Final Answer:
All genes located on the same chromosome comprise one linkage group.

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