In resting condition, the concentration gradient is maintained by

Options

A. Sodium-potassium pump
B. Active transport of ions
C. Utilisation of ATP energy
D. All of the above

Explanation

To answer the question, "In resting condition, the concentration gradient is maintained by?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Resting Condition**:
- In a resting state, neurons and other cells maintain a specific concentration of ions across their membranes. This is crucial for the proper functioning of the nervous system.

2. **Identifying Key Mechanisms**:
- The primary mechanism for maintaining the concentration gradient of sodium (Na⁺) and potassium (K⁺) ions is the sodium-potassium pump (Na⁺/K⁺ ATPase).

3. **Role of Sodium-Potassium Pump**:
- The sodium-potassium pump actively transports Na⁺ ions out of the cell and K⁺ ions into the cell. This process requires energy in the form of ATP, as it moves ions against their concentration gradients.

4. **Active Transport**:
- The process of moving ions against their concentration gradient is known as active transport. This is a critical function of the sodium-potassium pump.

5. **Utilization of ATP**:
- ATP is essential for the functioning of the sodium-potassium pump. The energy derived from ATP hydrolysis is used to drive the pump's action.

6. **Conclusion**:
- Since the sodium-potassium pump, active transport of ions, and the utilization of ATP all contribute to maintaining the concentration gradient in resting conditions, the correct answer is "all of the above".

### Final Answer:
The concentration gradient in resting condition is maintained by **all of the above** (sodium-potassium pump, active transport of ions, and utilization of ATP).

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