Diffusion

Definition of Diffusion

• Net movement of particles from an area of higher concentration to an area of lower concentration.

• Overall spreading out of particles due to random motion.

Characteristics of Diffusion

• Occurs in gases and liquids.

• Process is passive; does not require energy from cells.

• Particles can move randomly but tend to spread out over time.

Diffusion Through Cell Membranes

• Membranes are partially permeable; only small molecules can diffuse (e.g., water, glucose, amino acids).

• Larger molecules (e.g., proteins, starch) cannot pass through.

Factors Affecting Rate of Diffusion

1. Concentration Gradient
      - Difference in concentration between two areas.
      - Larger gradient results in higher diffusion rate.

2. Temperature
      - Higher temperatures increase particle energy and movement.
      - Higher temperature yields a higher rate of diffusion.

3. Surface Area
      - Larger surface area allows more particles to diffuse at once.
      - Increased surface area correlates with a higher rate of diffusion.