Facilitated diffusion

Options

A. Is uphill transport
B. Requires ATP energy
C. Highly selective
D. Does not requier pastenis

Answer

To solve the question regarding facilitated diffusion, let's analyze the options one by one:

1. **Understanding Facilitated Diffusion**:
- Facilitated diffusion is a type of passive transport that allows substances to cross membranes with the assistance of special proteins. It occurs down the concentration gradient, meaning that molecules move from an area of higher concentration to an area of lower concentration.

2. **Analyzing the Options**:
- **Option a: Uphill transport**: This is incorrect because facilitated diffusion does not involve moving substances against their concentration gradient (uphill). Instead, it moves substances down their gradient (downhill).
- **Option b: Requires ATP energy**: This is also incorrect. Facilitated diffusion is a passive process and does not require ATP or any energy input. Energy is only required for active transport.
- **Option c: Highly selective**: This is correct. Facilitated diffusion is selective because it uses specific carrier proteins or channels that allow only certain molecules to pass through the membrane.
- **Option d: Does not require proteins**: This is incorrect. Facilitated diffusion specifically requires proteins (either channel proteins or carrier proteins) to assist in the transport of molecules across the membrane.

3. **Conclusion**:
- Based on the analysis, the correct answer is **option c: Highly selective**.

### Step-by-Step Solution:
1. Define facilitated diffusion as a type of passive transport.
2. Explain that it occurs down the concentration gradient.
3. Analyze each option:
- a: Incorrect (not uphill transport).
- b: Incorrect (does not require ATP).
- c: Correct (it is highly selective).
- d: Incorrect (requires proteins).
4. Conclude that the correct answer is option c.