What is true about the crossing over between linked genes ?

Options

A. No crossing over at all
B. High percentage of crossing over
C. Hardly any crossing over
D. none of these

Explanation

To answer the question "What is true about the crossing over between linked genes?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Linked Genes**:
- Linked genes are genes that are located close to each other on the same chromosome. Because of their proximity, they tend to be inherited together during cell division.

2. **Crossing Over**:
- Crossing over is a process that occurs during meiosis where homologous chromosomes exchange segments of genetic material. This can lead to genetic variation.

3. **Effect of Linkage on Crossing Over**:
- In the case of linked genes, the likelihood of crossing over occurring between them is reduced. This is because they are physically close together on the chromosome, making it less likely that a crossover event will occur between them.

4. **Recombinant vs. Parental Types**:
- When crossing over occurs, it can produce recombinant types of offspring (those that have a combination of traits different from either parent). However, with linked genes, the parental combinations are more frequently observed because crossing over is less common.

5. **Evaluating the Options**:
- **Option A**: "No crossing over at all" - This is incorrect because crossing over can occur, but it is rare.
- **Option B**: "High percentage of crossing over" - This is also incorrect as linked genes do not have a high percentage of crossing over.
- **Option C**: "Hardly any crossing over" - This is correct; linked genes show hardly any crossing over.
- **Option D**: "None of these" - This is incorrect since option C is true.

6. **Conclusion**:
- The correct answer is **Option C: hardly any crossing over** occurs between linked genes.