You are studying transport of a certain type of molecules into cell. You find that transport slows down when the cells are poisoned with a chemical that inhibits energy production. Under normal circumstances the molecules you are studying is probably transported by -

Options

A. Simple diffusion
B. Osmosis
C. Active transport
D. Facilitated diffusion

Answer

To solve the question regarding the transport of molecules into a cell that slows down when energy production is inhibited, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Types of Transport**:
- There are different mechanisms through which molecules can be transported into cells: simple diffusion, facilitated diffusion, osmosis, and active transport.

2. **Identifying Energy Requirements**:
- **Simple Diffusion**: This process does not require energy. Molecules move from an area of higher concentration to an area of lower concentration until equilibrium is reached.
- **Facilitated Diffusion**: This also does not require energy but involves carrier proteins to help transport molecules across the membrane.
- **Osmosis**: A specific type of facilitated diffusion for water, which also does not require energy.
- **Active Transport**: This process requires energy (usually from ATP) to move molecules against their concentration gradient, using intrinsic proteins or carrier proteins.

3. **Analyzing the Effect of Energy Inhibition**:
- Since the question states that transport slows down when energy production is inhibited, we need to focus on the transport mechanisms that rely on energy.
- Active transport is directly affected by the lack of energy because it requires ATP to function. If energy production is inhibited, active transport will slow down or stop.

4. **Conclusion**:
- Given that facilitated diffusion and osmosis do not require energy, they would not be affected by the inhibition of energy production. Therefore, the type of transport that is most likely being used for the molecules in question is **active transport**.

### Final Answer:
Under normal circumstances, the molecules you are studying are probably transported by **active transport**.

---