Select an incorrect statement for facilitated diffusion

Options

A. Substances soluble in lipids diffuse through the membrane faster.
B. Creates concentration gradient
C. Special proteins help in movement substances across membranes without expenditure of ATP energy
D. Transport rate reaches a maximum when all of the protein transporters are being used

Answer

**Step-by-Step Solution:**

1. **Understanding Facilitated Diffusion:**
- Facilitated diffusion is a type of passive transport where molecules move from an area of higher concentration to an area of lower concentration through a membrane. This process does not require energy (ATP) because it occurs along the concentration gradient.

2. **Analyzing the Statements:**
- We need to evaluate each statement provided in the question to identify which one is incorrect regarding facilitated diffusion.

3. **Statement 1: "Substances soluble in liquid lipids diffuse through the membrane faster."**
- This statement is correct. Lipid-soluble substances can easily pass through the lipid bilayer of the membrane.

4. **Statement 2: "Creates concentration gradient."**
- This statement is incorrect. Facilitated diffusion does not create a concentration gradient; rather, it utilizes an existing concentration gradient to allow molecules to move from high to low concentration.

5. **Statement 3: "Special proteins help in movement of substances across the membrane without expenditure of ATP energy."**
- This statement is correct. Facilitated diffusion involves specific transport proteins that assist in moving substances across the membrane without using energy.

6. **Statement 4: "Transport rate reaches a maximum when all the protein transporters are being used."**
- This statement is also correct. When all available transport proteins are saturated, the rate of transport cannot increase further, reaching a maximum.

7. **Conclusion:**
- After analyzing all statements, the incorrect statement regarding facilitated diffusion is: "Creates concentration gradient."

**Final Answer:**
The incorrect statement for facilitated diffusion is: "Creates concentration gradient."

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