Diffusion

Question 1

Define diffusion

Answer 1

Particles will move randomly from where they are at a high concentration to where they are at a lower concentration until they are evenly spaced.
Happens down a concentration gradient.

Question 2

3 Factors which affect rate of diffusion

Answer 2

Difference in concentrations
Surface Area
Distance to travel

Question 3

How does a difference in concentrations affect the rate of diffusion?

Answer 3

The greater the difference between concentration values, the faster the rate of diffusion.

Question 4

How does surface area affect the rate of diffusion?

Answer 4

The greater the surface area, the faster the rate of diffusion.
Because more particles can diffuse across a cell membrane a once.

Question 5

How does the distance to travel affect the rate of diffusion

Answer 5

The shorter the diffusion distance, the faster the rate of diffusion.

Question 6

Which law is used to measure the rate of diffusion?

Answer 6

Fick’s Law

Question 7

Why is facilitated diffusion sometimes required?

Answer 7

If charged particles or large molecules need to move across the membrane.

They are less/in-soluble in lipids, so they must move through protein lined pores.

Question 8

What increases the rate of facilitated diffusion?

Answer 8

Increased number of protein lined pores.

Question 9

Which two proteins are involved in facilitated diffusion?

Answer 9

Channel Proteins
Carrier proteins

Question 10

What is the role of channel proteins in facilitated diffusion?

Answer 10

They line the water filled pores in the membrane so water soluble molecules can pass.
They are selective.

Question 11

What is the role of carrier proteins

Answer 11

They combine with the substance, the protein changes shape which carries the substance through the membrane.
These proteins are specific for a particular substance.