Which of these statements is correct regarding genes present on the same chromosomes ?

Options

A. Tightly linked genes on the same chromosome show very few recombinations
B. Tightly linked genes on the same chromosome show higher recombinations
C. Genes far apart on the same chromosome show very few recombinations
D. Genes loosely linked on the same chromosome show similar recombinations as the tightly linked ones.

Answer

To solve the question regarding the correct statement about genes present on the same chromosomes, we will analyze the concepts of gene linkage and recombination step by step.

### Step-by-Step Solution:

1. **Understanding Genes and Chromosomes**:
- Genes are segments of DNA that code for traits and are located on chromosomes. Chromosomes are structures within cells that contain genetic material.

2. **Gene Linkage**:
- Genes that are located close to each other on the same chromosome tend to be inherited together. This phenomenon is known as linkage.

3. **Recombination**:
- During meiosis (the process of forming gametes), chromosomes can exchange segments in a process called crossing over. This can lead to recombination, where offspring exhibit combinations of traits that differ from those of their parents.

4. **Independent Assortment**:
- Mendel's law of independent assortment states that genes for different traits can segregate independently during the formation of gametes. However, this law applies primarily to genes that are located on different chromosomes or are far apart on the same chromosome.

5. **Tightly Linked Genes**:
- If two genes are tightly linked (i.e., they are very close to each other on the same chromosome), they have a lower chance of being separated during recombination. This means that the frequency of recombination between them is low, and the parental types will be more frequently observed in the offspring.

6. **Loosely Linked Genes**:
- Conversely, if genes are loosely linked (i.e., they are farther apart on the same chromosome), they are more likely to undergo recombination, leading to a higher frequency of recombinant types.

7. **Evaluating the Statements**:
- Now, let's evaluate the provided statements:
- **Statement A**: Tightly linked genes can show very little recombination. (Correct)
- **Statement B**: Tightly linked genes show higher recombination. (Incorrect)
- **Statement C**: Genes that are far apart are not linked and show less recombination. (Incorrect)
- **Statement D**: Loosely linked genes show the same type of recombination as tightly linked genes. (Incorrect)

8. **Conclusion**:
- The correct statement regarding genes present on the same chromosomes is that tightly linked genes can show very little recombination.

### Final Answer:
The correct statement is: **Tightly linked genes can show very little recombination.**