2.1.6 - Diffusion & Facilitated Diffusion

Question 1

Describe Diffusion
(3 Points)

Answer 1

~ Net movement of a substance from a region of its higher concentration to a region of its lower concentration.

~ Molecules move down a concentration gradient.

~ Passive process, as it does not require energy.

Question 2

Describe Simple Diffusion
(2 Points)

Answer 2

~ When molecules are able to diffuse directly between the phospholipids of a membrane.

~ These molecules tend to be small and non-polar, as small molecules can fit between the phospholipids and non-polar molecules can interact with the non-polar tails.

Question 3

What Are Factors Affecting The Rate Of Diffusion?
(4 Points)

Answer 3

~ Steepness of the concentration gradient.

~ Temperature.

~ SA.

~ Properties of molecules or ions.

Question 4

How Does ‘Steepness Of The Concentration Gradient’ Affect The Rate Of Diffusion?
(3 Points)

Answer 4

~ There are more molecules on one side of a membrane than the other.

~ More molecules could randomly move across the membrane.

~ A greater difference in concentration, increases the rate of diffusion.

Question 5

Describe Facilitated Diffusion
(3 Points)

Answer 5

~ Use of transport proteins to move large molecules (Amino acids and glucose) and polar molecules (ions).

~ Moves particles down a concentration gradient from a higher to lower concentration.

~ Passive process, as it does not require energy.

Question 6

What Are The 2 Transport Proteins Which Enable Facilitated Diffusion?

Answer 6

~ Channel proteins.

~ Carrier proteins.

Question 7

Describe Channel Proteins
(2 Points)

Answer 7

~ Pores in the membrane for charged particles to diffuse through down their concentration gradient.

~ Highly specific, they only allow one type of molecule or ion to pass through.

Question 8

Describe Carrier Proteins
(5 Points)

Answer 8

~ Move large molecules into or out of the cell down their concentration gradient.

~ They can switch between two shapes.

~ Causing the binding site to be open on one side and closed on the other. Vice versa.

~ The direction of movement of the molecules diffusing across depends on their relative concentration on each side of the membrane.

~ Highly specific, they only allow one type of molecule or ion to pass through.