5.3 Diffusion

Question 1

Define diffusion. (4 marks)

Answer 1

The net movement of particles
from a region of higher concentration to a region of lower concentration.
It is a passive process
and continues until there is a concentration equilibrium.

Question 2

Is diffusion an active or passive process. (1 mark)

Answer 2

Passive

Question 3

Movement requires energy, but the movement of molecules in diffusion is described as passive, why? (2 marks)

Answer 3

It does not require an external energy source, it relies on the energy from the natural random movement of particles.

Question 4

Name 4 factors affecting diffusion. (4 marks)

Answer 4

Temperature
Concentration
Diffusion distance
Surface area

Question 5

Does a higher temperature increase or decrease rate of diffusion, why? (2 marks)

Answer 5

Increase, because the particles have more energy and move more rapidly.

Question 6

The ________ the difference in concentration between the two regions the ______ the rate of diffusion. (1 mark)

Answer 6

Greater/faster
Smaller/slower

Question 7

Why does a greater diffusion distance slow down diffusion? (2 marks)

Answer 7

Particles are constantly colliding, and this slows down their overall movement, the greater the distance, the more opportunity the particles have to collide.

Question 8

Does a large surface area make diffusion faster or slower? (1 mark)

Answer 8

Faster

Question 9

What is facilitated diffusion? (1 mark)

Answer 9

Diffusion through protein channels.

Question 10

How do polar molecules and ions pass through a membrane? (1 mark)

Answer 10

Facilitated diffusion.

Question 11

Why can’t ions pass through membranes? (2 marks)

Answer 11

The hydrophobic interior of the phospholipid bilayer in the membrane repels substances with a charge.