How many linkage groups are present in Drosophila melanogaster?

Answer

To determine the number of linkage groups present in Drosophila melanogaster, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Linkage Groups**:
- A linkage group is essentially a group of genes that are located on the same chromosome and tend to be inherited together. Each chromosome represents one linkage group.

2. **Determine the Chromosome Number**:
- The number of linkage groups in an organism is generally equal to its haploid chromosome number. The haploid number is half the total number of chromosomes (diploid number).

3. **Identify the Diploid Number for Drosophila melanogaster**:
- For Drosophila melanogaster, the diploid chromosome number (2n) is 8.

4. **Calculate the Haploid Number**:
- To find the haploid number (n), divide the diploid number by 2:
\[ n = \frac{2n}{2} = \frac{8}{2} = 4 \]

5. **Conclude the Number of Linkage Groups**:
- Since each chromosome corresponds to one linkage group, Drosophila melanogaster has 4 linkage groups.

### Final Answer:
Drosophila melanogaster has **4 linkage groups**.

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