Which of the following statements is not true for retroviruses?

Options

A. The genetic material in mature retroviruses is RNA
B. Retroviruses are causative agents for certain kinds of cancer in man
C. DNA is not present at any stage in the life cycle of retroviruses
D. Retroviruses carry gene for RNA-dependent DNA polymerase

Answer

To determine which statement is not true for retroviruses, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understand the Characteristics of Retroviruses**:
- Retroviruses are a type of virus that primarily contain RNA as their genetic material. They are known for their ability to convert their RNA into DNA upon infecting a host cell.

2. **Evaluate Each Statement**:
- **Statement 1**: "The genetic material in mature retroviruses is RNA."
- This statement is true. Retroviruses indeed have RNA as their genetic material.

- **Statement 2**: "Retroviruses are causative agents for certain kinds of cancers in man."
- This statement is also true. Retroviruses can lead to various cancers, including some forms of leukemia and lymphoma.

- **Statement 3**: "DNA is not present at any stage in the life cycle of retroviruses."
- This statement is false. During the life cycle of retroviruses, the RNA is reverse transcribed into DNA by the enzyme reverse transcriptase. Therefore, DNA is present at a stage in their life cycle.

- **Statement 4**: "Retroviruses carry genes for RNA independent DNA polymerase."
- This statement is misleading. Retroviruses carry genes for reverse transcriptase, which is an RNA-dependent DNA polymerase, not an RNA-independent one. However, it does not directly contradict the nature of retroviruses.

3. **Identify the Incorrect Statement**:
- The statement that is not true for retroviruses is: "DNA is not present at any stage in the life cycle of retroviruses." This is incorrect because DNA is indeed produced during the retroviral life cycle.

### Conclusion:
The correct answer is that the statement "DNA is not present at any stage in the life cycle of retroviruses" is not true.

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