In a linear chromosome map, distances between 4 loci is as follows, a-b 10%, a-d 3%, b-c 4% and a-c 6%. The cross over frequency between c and d is

Options

A. 0.03
B. 0.09
C. 3 or 9%
D. 4 to 12%

Answer

To find the crossover frequency between loci C and D based on the given distances between the loci A, B, C, and D, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Given Distances**:
- The distances between the loci are given as follows:
- A-B = 10%
- A-D = 3%
- B-C = 4%
- A-C = 6%

2. **Visualize the Loci Arrangement**:
- Since the distances are given in percentages, we can visualize the arrangement of these loci on a linear chromosome.
- We know that A and D are 3% apart, and A and C are 6% apart.

3. **Determine Possible Positions**:
- Since A is the reference point, we can place A at position 0%.
- Therefore, D would be at position 3% (A-D = 3%).
- C would be at position 6% (A-C = 6%).

4. **Calculate the Distance Between C and D**:
- Now, we need to find the distance between C and D.
- Since C is at 6% and D is at 3%, the distance between C and D can be calculated as:
\[ \text{Distance (C-D)} = \text{Position of C} - \text{Position of D} = 6\% - 3\% = 3\% \]

5. **Crossover Frequency Interpretation**:
- The crossover frequency is directly related to the distance between two loci.
- Therefore, the crossover frequency between C and D is 3%.

### Final Answer:
The crossover frequency between loci C and D is **3%**.

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