Select an incorrect statement for active transport

Options

A. Active transport uses energy to pump molecules against a concentration gradient.
B. Active transport is carried out by membrane-proteins
C. Proteins transporters use energy to carry substances across the cell membrane.
D. Substances are transported from a high concentration to a low concentration

Answer

To determine the incorrect statement regarding active transport, we can analyze the provided statements one by one.

### Step-by-Step Solution:

1. **Understanding Active Transport**:
- Active transport is a process that requires energy to move molecules against their concentration gradient. This means that substances move from an area of lower concentration to an area of higher concentration.

2. **Analyzing the Statements**:
- **Statement 1**: "Active transport uses energy to pump molecules against a concentration gradient."
- This statement is **correct** because active transport indeed requires energy (usually in the form of ATP) to move substances against their concentration gradient.

- **Statement 2**: "Active transport is carried out by membrane proteins."
- This statement is also **correct**. Active transport relies on specific membrane proteins (such as pumps) that facilitate the transport of molecules across the cell membrane.

- **Statement 3**: "For active transport, energy is required."
- This statement is **correct** as well. Energy is essential for active transport to function, as it involves moving substances against their natural tendency to move from high to low concentration.

- **Statement 4**: "Substances are transported from a high to low concentration."
- This statement is **incorrect**. In active transport, substances are transported from a low concentration to a high concentration, which is the opposite of what this statement claims.

3. **Conclusion**:
- The incorrect statement regarding active transport is **Statement 4**: "Substances are transported from a high to low concentration."

### Final Answer:
The incorrect statement for active transport is: **"Substances are transported from a high to low concentration."**

---