Movement by diffusion is _________

Explanation

**Step-by-Step Solution:**

1. **Understanding the Concept of Diffusion**:
- Diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration. This movement occurs until there is an equal concentration of molecules in both areas.

2. **Types of Transport in Biology**:
- In biological systems, transport of molecules can occur through two main processes: active transport and passive transport.

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