Chemotropic agent for the growth of pollen tube in angiospermic plants is

Options

A. Citric acid
B. Malic acid
C. `K^(+)` and protein
D. `B^(-)` Ca-inositol sugar complex

Answer

To determine the chemotropic agent for the growth of the pollen tube in angiospermic plants, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Chemotropic Agents**: Chemotropic agents are substances that promote the growth of pollen tubes in flowering plants. They play a crucial role in guiding the pollen tube towards the ovule for fertilization.

2. **Identify Common Chemotropic Agents**: Some well-known chemotropic agents that facilitate pollen tube growth include:
- Calcium
- Boron
- Inositol
- Sugars (which may form complexes with the above agents)

3. **Analyze the Options**: The question provides several options, including:
- Citric Acid
- Malic Acid
- Potassium
- Boron-Calcium-Inositol-Sugar complex

4. **Evaluate Each Option**:
- **Citric Acid**: Part of the Krebs cycle, not a chemotropic agent for pollen tubes.
- **Malic Acid**: Also part of the Krebs cycle, not directly involved in pollen tube growth.
- **Potassium**: While important for plant growth, it is not specifically a chemotropic agent for pollen tubes.
- **Boron-Calcium-Inositol-Sugar complex**: This combination is known to facilitate the growth of pollen tubes.

5. **Select the Correct Answer**: Based on the analysis, the correct chemotropic agent for the growth of pollen tubes in angiospermic plants is the **Boron-Calcium-Inositol-Sugar complex**.

### Final Answer:
The chemotropic agent for the growth of pollen tube in angiospermic plants is the **Boron-Calcium-Inositol-Sugar complex**.

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