Select an incorrect statement for facilitated diffusion and active transport

Options

A. Transport rate reaches a maximum when all the protein transporters are saturated
B. Proteins transporters are sensitive to inhibitors that react with protein side chains.
C. Proteins transporters use energy to carry substances across the cell membrane.
D. Both follow saturation kinetics

Answer

### Step-by-Step Solution:

1. **Understand the Concepts**:
- **Facilitated Diffusion**: This is a type of passive transport where substances move across a cell membrane through protein channels or carriers, following the concentration gradient (from high to low concentration) without the use of energy.
- **Active Transport**: This process requires energy (usually from ATP) to move substances against their concentration gradient (from low to high concentration).

2. **Identify Key Characteristics**:
- **Energy Requirement**: Facilitated diffusion does not require energy, while active transport does.
- **Direction of Movement**: Facilitated diffusion moves substances along the concentration gradient, whereas active transport moves substances against it.
- **Role of Transport Proteins**: Both processes involve specific membrane proteins, but their function differs based on the energy requirement.

3. **Assess the Statements**:
- **Statement 1**: "Transport rate reaches a maximum when all transporters are saturated."
- This is true for both facilitated diffusion and active transport.
- **Statement 2**: "Transport proteins are sensitive to inhibitors."
- This is also true for both types of transport.
- **Statement 3**: "Protein transporters use energy to carry substances across the cell membrane."
- This statement is incorrect for facilitated diffusion, as it does not require energy.

4. **Conclusion**:
- The incorrect statement regarding facilitated diffusion and active transport is the third statement: "Protein transporters use energy to carry substances across the cell membrane." This is true only for active transport, not for facilitated diffusion.

### Final Answer:
The incorrect statement is: "Protein transporters use energy to carry substances across the cell membrane."

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