B1.6 diffusion

Question 1

what is diffusion

Answer 1

the spreading out of particles resulting in a net movement from an area of higher concentration to an area of lower concentration.

Question 2

where does diffusion happen and why

Answer 2

diffusion happens in substances in solutions and gases because the particles are free to move about

Question 3

why does temperature increase, increase the rate of diffusion

Answer 3

the particles move around quicker ( they have more kinetic energy)

Question 4

how does temperature increase affect diffusion

Answer 4

increases diffusion

Question 5

how does an increase in concentration gradient (difference in concentration) affect diffusion

Answer 5

increases diffusion

Question 6

why does an increase in conc gradient affect diffusion

Answer 6

many particles will move towards the area of low concentration

Question 7

how does an increase in surface area affect the rate of diffusion

Answer 7

increases diffusion

Question 8

how does an increase in surface area increase the rate of diffusion

Answer 8

the area over which diffusion can take place is increased

Question 9

how does an increase in thickness of exchange surface affect the rate of diffusion

Answer 9

decreases it

Question 10

why does an increase in the thickness of exchange surface decrease diffusion

Answer 10

the diffusion pathway (distance) is longer

Question 11

what are the substances that move in and out of cells accross the cell membrane by diffusion?

Answer 11

glucose
oxygen
carbon dioxide
urea

Question 12

what is gas exchange

Answer 12

the diffusion of oxygen and carbon dioxide in opposite directions in the lungs

Question 13

why have many cells adapted for diffusion by having folded membranes

Answer 13

it increases the surface are of the cell membrane which increases the rate of diffusion
e.g. microvilli