For keeping stomata open, besides K ions the gurad cells require a constant supply of

Options

A. ABA
B. ATP
C. Organic acids
D. Protons

Answer

To solve the question regarding what is required by guard cells, besides K ions, to keep stomata open, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Guard Cells Function**:
- Guard cells are specialized cells that control the opening and closing of stomata, which are small openings on the surfaces of leaves. This regulation is crucial for gas exchange and transpiration in plants.

2. **Role of Potassium Ions (K+)**:
- The accumulation of potassium ions (K+) in guard cells leads to an increase in their turgor pressure. This occurs because K+ ions lower the water potential in the guard cells, causing water to enter by osmosis, making the cells swell and thus opening the stomata.

3. **Energy Requirement**:
- The process of K+ ions entering the guard cells is not passive; it requires energy. This energy is provided by ATP (adenosine triphosphate), which is the primary energy currency in biological systems.

4. **Identifying the Constant Supply Needed**:
- Since the question asks for what is required in addition to K+ ions, we need to identify the energy source. The options provided are:
- A) ABA (Abscisic Acid)
- B) ATP (Adenosine Triphosphate)
- C) Organic Acids
- D) Protons

5. **Selecting the Correct Option**:
- Among the options, ATP is the only one that directly provides the energy necessary for the active transport of K+ ions into the guard cells. Therefore, the constant supply required for keeping the stomata open, besides K+ ions, is ATP.

6. **Conclusion**:
- The correct answer to the question is **B) ATP**.