The experimental system used in studies on replication of DNA is

Options

A. Escherichia coli
B. Neurospora crassa
C. Drosophila melanogaster
D. Zea mays

Answer

### Step-by-Step Solution:

1. **Understanding DNA Replication**:
- DNA replication is the process by which a cell duplicates its DNA, resulting in two identical copies. This is essential for cell division and the transmission of genetic information.

2. **Mechanism of DNA Replication**:
- During DNA replication, the double-stranded DNA unwinds, and each strand serves as a template for the synthesis of a new complementary strand. This results in two daughter DNA molecules, each containing one original (parental) strand and one newly synthesized strand.

3. **Semi-Conservative Method**:
- The method of DNA replication is known as the semi-conservative method. In this method, one strand of the original DNA molecule is conserved in each of the daughter molecules, while the other strand is newly synthesized.

4. **Key Experiment**:
- The semi-conservative nature of DNA replication was demonstrated by the experiments of Meselson and Stahl. They used a specific experimental system to prove this concept.

5. **Experimental Organism**:
- Meselson and Stahl conducted their experiments using the bacterium *Escherichia coli* (E. coli). This model organism is widely used in molecular biology due to its simple structure and rapid growth.

6. **Conclusion**:
- Therefore, the experimental system used in studies on the replication of DNA is *Escherichia coli*.

### Final Answer:
The experimental system used in studies on replication of DNA is *Escherichia coli*.

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