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 answer the question regarding the chemotropic agent for the growth of the pollen tube in angiospermic plants, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Pollen Tube Growth**:
- The pollen tube grows after a pollen grain lands on the stigma of a flower. This growth is crucial for fertilization as the pollen tube transports male gametes to the ovule.

2. **Role of Embryo Sac**:
- Inside the ovary, the ovule contains the embryo sac, which is essential for fertilization. The embryo sac has two ends: the micropilar end and the chalazal end.

3. **Synergid Cells**:
- At the micropilar end of the embryo sac, there are two synergid cells and one egg cell. The synergid cells play a significant role in guiding the pollen tube towards the egg cell.

4. **Chemotropic Agents**:
- The growth of the pollen tube is influenced by specific chemicals secreted by the synergid cells. These chemicals create a chemotropic response, directing the growth of the pollen tube.

5. **Identifying the Chemotropic Agent**:
- The specific chemotropic agents secreted by the synergid cells include a complex of boron, calcium, inositol, and sugars. This combination is crucial for the proper growth and guidance of the pollen tube.

6. **Conclusion**:
- Based on the above understanding, the correct answer to the question is that the chemotropic agent for the growth of the pollen tube 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 **boron, calcium, inositol, sugar complex**.

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