Which of the following means of transmembrane transport involves expenditure of energy by the cell and can move materials up a concentration gradient?

Options

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

Explanation

To solve the question regarding which means of transmembrane transport involves expenditure of energy by the cell and can move materials up a concentration gradient, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Types of Transport Mechanisms**:
- There are various mechanisms by which substances can move across cell membranes, including osmosis, facilitated diffusion, simple diffusion, and active transport.

2. **Define Osmosis**:
- Osmosis is the movement of solvent (usually water) across a semi-permeable membrane towards a higher concentration of solute. This process does not require energy and occurs along a concentration gradient.

3. **Define Facilitated Diffusion**:
- Facilitated diffusion is the passive movement of molecules across a membrane through specific transport proteins. It also occurs along the concentration gradient and does not require energy.

4. **Define Simple Diffusion**:
- Simple diffusion is the process where solute particles move directly across the semi-permeable membrane from an area of higher concentration to an area of lower concentration. This process is also passive and does not require energy.

5. **Define Active Transport**:
- Active transport is the process of moving molecules across a cell membrane from an area of lower concentration to an area of higher concentration, which is against the concentration gradient. This process requires energy, typically in the form of ATP.

6. **Identify the Correct Answer**:
- Given the definitions, the only transport mechanism that involves the expenditure of energy by the cell and can move materials up a concentration gradient is **Active Transport**.

### Final Answer:
The correct answer is **Active Transport**.

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