Poisons like cyanide inhibit `Na^(+)` influx during cellular transport. This inhibitory effect is reversed by an injection of ATP. This demonstrates that

Options

A. ATP is the carrier protein in the transport system
B. Energy for `Na^(+)-K^(+)` exchange pump comes from ATP
C. ATP is hydrolysed by ATPase to release energy
D. `Na^(+)-K^(+)` exchange pump operates in the cell

Answer

To solve the question regarding the effect of cyanide on sodium influx during cellular transport and the role of ATP, we can break down the solution into the following steps:

### Step-by-Step Solution:

1. **Understanding Cyanide's Mechanism**:
- Cyanide is a potent poison that inhibits the electron transport chain by binding to cytochrome c oxidase (Complex IV). This binding prevents the normal function of the electron transport chain, leading to a decrease in ATP production.

**Hint**: Remember that cyanide affects cellular respiration by targeting a specific component of the electron transport chain.

2. **Impact on ATP Production**:
- Due to the inhibition of the electron transport chain, ATP synthesis is significantly reduced. ATP is crucial for various cellular processes, including active transport mechanisms.

**Hint**: Consider the relationship between ATP production and cellular functions that require energy.

3. **Role of the Sodium-Potassium Pump**:
- The sodium-potassium pump (Na+/K+ ATPase) is an active transport mechanism that requires ATP to function. It pumps sodium ions out of the cell and potassium ions into the cell, maintaining the resting membrane potential.

**Hint**: Recall how active transport differs from passive transport and the energy requirements involved.

4. **Cyanide's Effect on Sodium Influx**:
- With cyanide present, ATP levels drop, leading to the failure of the sodium-potassium pump. This results in inhibited sodium influx because the pump cannot operate without sufficient ATP.

**Hint**: Think about how the absence of ATP affects the transport of ions across the cell membrane.

5. **Reversal by ATP Injection**:
- When ATP is injected, it provides the necessary energy for the sodium-potassium pump to resume its function. This reverses the inhibitory effect of cyanide on sodium influx, demonstrating that the pump requires ATP for its activity.

**Hint**: Consider how external sources of ATP can compensate for the lack of ATP production due to cyanide.

6. **Conclusion**:
- The statement in the question demonstrates that the sodium-potassium pump requires ATP for its function, and the injection of ATP can reverse the inhibitory effects of cyanide on sodium influx. Therefore, the correct conclusion is that energy for the sodium-potassium exchange pump comes from ATP.

**Hint**: Summarize the key points about the relationship between ATP, the sodium-potassium pump, and the effects of cyanide.

### Final Answer:
The correct conclusion is that the energy for the sodium-potassium exchange pump comes from ATP. The inhibition of sodium influx by cyanide can be reversed by the injection of ATP, highlighting the importance of ATP in active transport mechanisms.