Distance between two linked genes is measured in map units that depict

Options

A. ratio of crosing over between them
B. pecentage of crossing over between them
C. number of crossing over between them
D. none of these

Explanation

**Step-by-Step Solution:**

1. **Understanding Linked Genes**: Linked genes are genes that are located close to each other on the same chromosome. They tend to be inherited together because they are less likely to be separated during meiosis.

2. **Map Units Definition**: The distance between two linked genes is measured in map units, which are a way to quantify the distance based on the frequency of recombination (crossing over) that occurs between them during meiosis.

3. **Crossing Over and Recombination Frequency**: The frequency of crossing over between two genes is directly proportional to the distance between them. This means that the farther apart two genes are, the more likely it is that crossing over will occur between them.

4. **Centimorgan (cM)**: One map unit is equivalent to a 1% chance of crossing over occurring between two genes. This unit is referred to as a centimorgan (cM). Therefore, if there is a 1% chance of crossing over between two genes, they are said to be 1 map unit apart.

5. **Understanding Higher Percentages**: If the distance between two genes is 10% crossing over, it is termed as 10 centimorgans (10 cM). If the distance is 100% crossing over, it is referred to as 1 Morgan.

6. **Conclusion**: Thus, the distance between two linked genes, measured in map units, depicts the percentage of crossing over (or recombination frequency) between those genes.

**Final Answer**: The distance between two linked genes is measured in map units that depict the percentage of crossing over between them.

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