Genetic map is one that :

Options

A. shows the stages during the cell division
B. shows the distribution of various species in a region
C. establishes sites of the genes on a chromosome
D. establishes the various stages in gene evolution

Explanation

**Step-by-Step Text Solution:**

1. **Understanding Genetic Mapping**: A genetic map is a representation that shows the locations of genes on a chromosome. It helps in identifying the specific locus (location) of a gene and the distances between different genes.

2. **Gene Location and Distance**: Genes are arranged in a linear sequence on chromosomes. Genetic mapping not only identifies where genes are located but also measures the distance between them. This distance is often expressed in map units, which correlate with the frequency of crossing over during meiosis.

3. **Recombination Frequency**: The distance between genes can be determined by the percentage of recombination events that occur between them. For example, 1 map unit corresponds to a 1% chance of recombination occurring between two genes.

4. **Molecular Markers**: Genetic mapping involves placing molecular markers on the genome. These markers can include genes, which are a specific type of genetic marker. Identifying these markers helps in understanding the genetic structure of an organism.

5. **Evaluating Options**: The question provides several options regarding what a genetic map represents:
- Option 1: Shows the stages during cell division - Incorrect.
- Option 2: Shows the distribution of various species in a region - Incorrect.
- Option 3: Establishes the site of genes on a chromosome - Correct.
- Option 4: Establishes the various stages in gene evolution - Incorrect.

6. **Conclusion**: Based on the explanations, the correct answer is that a genetic map establishes the site of genes on a chromosome.

**Final Answer**: A genetic map is one that establishes the site of genes on a chromosome.

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