Neutral solutes may move across the membrane by

Options

A. acitve process
B. diffusion
C. against gradient
D. uphill movement

Answer

### Step-by-Step Solution:

1. **Understanding Transport Mechanisms**:
- There are two main types of transport mechanisms for moving substances across cell membranes: **active transport** and **passive transport**.

2. **Active Transport**:
- Active transport involves the movement of substances against their concentration gradient, meaning from an area of lower concentration to an area of higher concentration.
- This process requires energy, typically in the form of ATP, and is often referred to as "uphill" transport.

3. **Passive Transport**:
- Passive transport, on the other hand, allows substances to move along their concentration gradient, from an area of higher concentration to an area of lower concentration.
- This process does not require energy and is often referred to as "downhill" transport.

4. **Types of Passive Transport**:
- **Simple Diffusion**: This is when molecules move directly across the membrane without the assistance of proteins. Neutral solutes can move this way.
- **Facilitated Diffusion**: This involves the use of specific proteins in the membrane to help transport substances that cannot directly diffuse through the lipid bilayer.

5. **Neutral Solutes Movement**:
- Neutral solutes typically move across the membrane through **simple diffusion** as they can pass through the lipid bilayer without the need for energy or special proteins.

6. **Conclusion**:
- Therefore, the correct process by which neutral solutes may move across the membrane is **diffusion**, which is a type of passive transport.

### Final Answer:
Neutral solutes may move across the membrane by **diffusion**.