Lesson 16 - Diffusion Flashcards
1
Q
Diffusion
A
Net movement of particles from a region of higher concentration to a region of lower concentration until there is a concentration equilibrium between the two areas.
2
Q
Why diffusion occurs:
A
- Particles in a gas or liquid have kinetic energy.
- Movement is random.
- An unequal distribution of particles becomes equal.
- Particles move at high speeds and are constantly colliding, slowing their overall movement. –> short distance diffusion is fast, long distance diffusion is slow.
3
Q
Factors affecting rate of diffusion:
A
- Temperature –> high = higher rate of diffusion as particles have more kinetic energy and move at higher speeds.
- Concentration difference –> greater the difference in concentration between two regions, faster the rate of diffusion.
4
Q
Diffusion in absence of a barrier / membrane?
A
Simple diffusion
5
Q
Diffusion across membranes:
A
- Hydrophobic interior repels substances with positive / negative charge (ions)
- Water (polar) can diffuse at a slow rate.
- Small polar molecules can diffuse more easily.
6
Q
Affects on rate of diffusion across membranes:
A
- Surface area (larger –> higher rate of diffusion)
- Thickness of membrane (thinner –> higher rate of diffusion)
7
Q
Facilitated diffusion
A
- Diffusion across membranes with channel / carrier proteins.
8
Q
Membranes with cannel proteins are …
A
selectively permeable
9
Q
Membranes are
A
partially permeable
