A mitogen of animal origin is

Options

A. Cyanide
B. Azide
C. Chalone
D. Platelet derived growth factor.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for a mitogen of animal origin. A mitogen is a substance that stimulates or induces mitosis (cell division).

2. **Reviewing the Options**: The options provided are:
- A) Cyanide
- B) Azide
- C) Kalon
- D) Platelet-derived growth factor

3. **Analyzing Each Option**:
- **Cyanide**: This is a potent antimitogen, meaning it inhibits cell division. It is a poison that binds to cytochrome c and disrupts oxidative phosphorylation, thus blocking the cell cycle. Therefore, this option is incorrect.

- **Azide**: Similar to cyanide, azide is also a poison that inhibits cell division by blocking various proteins and signaling molecules necessary for the cell cycle. Hence, this option is also incorrect.

- **Kalon**: These are water-soluble molecules that inhibit mitosis by interfering with cell signaling and the cell cycle. Thus, this option is incorrect as well.

- **Platelet-derived growth factor (PDGF)**: This is a known potent mitogen that induces mitosis. It is released by activated blood platelets and other cells such as smooth muscle cells and macrophages. This makes it the correct answer as it is of animal origin and functions to stimulate cell division.

4. **Conclusion**: The correct answer is **D) Platelet-derived growth factor**.

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