4.2 Diffusion

Question 1

What is diffusion

Answer 1

The net movement of molecules or ions from a region where they are more highly concentrated to one where their concentration is lower until they are evenly distributed

Question 2

What is facilitated diffusion

Answer 2

Helping molecules move across a membrane using carrier and channel proteins

Question 3

How do carrier proteins work

Answer 3

• Have receptors of which are complimentary to the molecules
• This causes the carrier protein to change shape
• The molecule binds to the receptor which causes a conformational change to push the molecule through

Question 4

How do protein channels work?

Answer 4

• Form water-filled hydrophilic channels across the membrane
• They allow specific water-soluble ions to pass through.
• The channels are selective, each opening in the presence of a specific ion.

Question 5

What are the factors affecting the rate of diffusion

Answer 5

Temperature
Concentration gradient
Surface area
Diffusion pathway

Question 6

How does temperature affect the rate of diffusion

Answer 6

As the temp increases the rate of diffusion also increases as the molecules gain kinetic energy.
Therefore more successful collisions occur.

Question 7

how does the concentration gradient increase the rate of diffusion

Answer 7

As the concentration increases the rate of diffusion increases too.
This is because more molecules result in more collisions

Question 8

How does the surface area affect the rate of diffusion

Answer 8

As the SA increases the rate of diffusion increases too as more molecules can diffuse into or out of the membrane at the same time

Question 9

How does the diffusion pathway affect the rate of diffusion

Answer 9

A smaller diffusion pathway increases the rate of diffusion