Driving force for active transport of ions across the cell membrane is

Options

A. AMP
B. ATP
C. GTP
D. ADP

Answer

### Step-by-Step Solution:

1. **Understanding Active Transport**: Active transport is the process by which ions or molecules move across a cell membrane against their concentration gradient. This process requires energy.

2. **Identifying the Energy Sources**: The question lists several molecules: AMP (Adenosine Monophosphate), ATP (Adenosine Triphosphate), GTP (Guanosine Triphosphate), and ADP (Adenosine Diphosphate). We need to determine which of these provides the necessary energy for active transport.

3. **Defining the Molecules**:
- **AMP**: Adenosine Monophosphate - a nucleotide that is not typically used for energy in active transport.
- **ATP**: Adenosine Triphosphate - the primary energy carrier in cells, used directly in active transport.
- **GTP**: Guanosine Triphosphate - can also provide energy but is less common for active transport compared to ATP.
- **ADP**: Adenosine Diphosphate - a product of ATP hydrolysis, not used directly for energy.

4. **Primary vs. Secondary Active Transport**:
- **Primary Active Transport**: Directly uses ATP to transport ions against their gradient.
- **Secondary Active Transport**: Utilizes the electrochemical gradient created by primary active transport, but does not directly use ATP.

5. **Conclusion**: Since the question asks for the driving force of active transport, and ATP is the primary molecule that provides the energy necessary for this process, the answer is ATP.

### Final Answer:
The driving force for active transport of ions across the cell membrane is **ATP (Adenosine Triphosphate)**.

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