Uptake of mineral ions into xylem is controlled by

Options

A. epidermal cells
B. cortex cells
C. endodermal cells
D. xylem cells

Answer

To answer the question regarding the control of mineral ion uptake into the xylem, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding the Role of Root Cells**:
- The root system of plants is responsible for the uptake of water and minerals from the soil. This process begins at the root hair cells, which are specialized epidermal cells.

2. **Epidermal Cells and Root Hairs**:
- Root hair cells absorb minerals from the soil through specialized protein pumps. These pumps facilitate the movement of mineral ions into the cytoplasm of the epidermal cells.

3. **Function of Endodermal Cells**:
- Endodermal cells are located just inside the cortex of the root. They play a crucial role in regulating the flow of minerals from the soil into the vascular system (xylem).
- These cells contain specialized proteins that act as gatekeepers, controlling the amount of minerals that can pass into the xylem.

4. **Transport to Xylem**:
- Once minerals are absorbed by the epidermal cells, they must pass through the endodermal cells to reach the xylem. The endodermis effectively regulates this process, ensuring that only the necessary minerals are transported into the xylem for distribution throughout the plant.

5. **Conclusion**:
- Therefore, the uptake of mineral ions into the xylem is primarily controlled by the endodermal cells, which regulate the absorption and passage of these ions.

### Final Answer:
The uptake of mineral ions into the xylem is controlled by **endodermal cells**.

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