The common immediate source of energy for cellular activity is

Options

A. NAD
B. ATP
C. DNÁ
D. RNA

Answer

### Step-by-Step Solution:

1. **Understanding Cellular Activity**: Cells perform various activities that require energy. This energy is crucial for processes like metabolism, movement, and synthesis of molecules.

2. **Identifying the Energy Molecule**: The primary molecule that serves as an immediate source of energy for cellular activities is ATP (Adenosine Triphosphate).

3. **Structure of ATP**: ATP consists of three main components:
- A nitrogenous base called adenine.
- A pentose sugar known as ribose.
- Three phosphate groups attached to the ribose sugar.

4. **Energy Storage in ATP**: The bonds between the phosphate groups in ATP are high-energy bonds. When these bonds break, energy is released. Specifically:
- The first bond (between the second and third phosphate) releases approximately 8.15 kilocalories per mole.
- The second bond (between the first and second phosphate) releases about 6.5 kilocalories per mole.

5. **ATP to ADP Conversion**: When ATP is used for energy, it is converted to ADP (Adenosine Diphosphate) and an inorganic phosphate (P1). This conversion releases energy that the cell can utilize for its activities.

6. **Reforming ATP**: To regenerate ATP from ADP, energy must be supplied, along with an inorganic phosphate. This process allows the cell to store energy again in the form of ATP.

7. **Conclusion**: Therefore, the common immediate source of energy for cellular activity is ATP.

### Final Answer:
The common immediate source of energy for cellular activity is **ATP (Adenosine Triphosphate)**.

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