Diffusion - Biology

Define diffusion

The net movement of particles from an area of higher concentration to an area of lower concentration (until equilibrium is achieved)

Is energy required for diffusion

No it is passive

In which states can diffusion occur

Gas and liquid

What is meant by ‘net movement’

Overall movement: particles can move in any direction but most particles are moving in one particular direction, hence ‘net’ movement

State the three factors that affect the rate of diffusion

Concentration gradient, short diffusion pathway, surface area (could also include temperature)

How does concentration difference affect the rate of diffusion

Higher/steeper concentration gradient means faster diffusion

Explain why a higher temperature will increase the rate of diffusion

Particles will have more kinetic energy; will move around faster

Explain why a larger surface are will increase the rate of diffusion

More surface for the particles to diffuse through at the same amount of time so movement of particles is faster

Name useful substances that diffuses into our cells

Oxygen, glucose

Name waste substances that diffuse out of our cells

Carbon dioxide, urea