Taylor and his colleagues proved the semi - conservative model of replication by performing experiments on ………(a) …………. Using (b) ……….

Options

A. `{:((a),"(b)"),("Bacteriophage","radioactive thymidine"):}`
B. `{:((a),"(b)"),("E. coli","radioactive nitrogen "):}`
C. `{:((a),"(b)"),("Vicia faba","radioactive thymidine "):}`
D. `{:((a),"(b)"),("E. coli","heavy nitrogen "):}`

Answer

To solve the question regarding Taylor and his colleagues' experiments that proved the semi-conservative model of DNA replication, we can break it down into a few steps:

### Step-by-Step Solution:

1. **Identify the Organism Used in the Experiment:**
- The experiments were conducted on a specific plant organism. In this case, the correct organism is **Vicia faba**, commonly known as the broad bean.

2. **Identify the Substance Used for Labeling:**
- To demonstrate the semi-conservative model of DNA replication, Taylor and his colleagues used a radioactive substance. The correct substance used for labeling in their experiments was **radioactive thymidine**.

3. **Understanding the Semi-Conservative Model:**
- The semi-conservative model of replication suggests that when DNA replicates, each of the two resulting DNA molecules contains one original strand and one newly synthesized strand. Taylor's experiments provided evidence for this model by showing how the labeled thymidine incorporated into the DNA during replication.

4. **Conclusion:**
- Therefore, the correct answer to the question is:
- (a) Vicia faba
- (b) Radioactive thymidine

### Final Answer:
Taylor and his colleagues proved the semi-conservative model of replication by performing experiments on **(a) Vicia faba** using **(b) radioactive thymidine**.

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