Topic 1b - transport in cells ( 1. diffusion )

Question 1

what is diffusion?

Answer 1

diffusion is the spreading out of particles from an area of higher concentration to an area of lower concentration.

Question 2

what substances does diffusion occur in?

Answer 2

solutions and gases as the particles are free to move around.

Question 3

what do cell membranes do in diffusion?

Answer 3

they hold the cell together and let stuff in and out. dissolved substances can move into and out of cells through diffusion.

Question 4

examples of molecules that can and cannot diffuse through cell membranes

Answer 4

small molecules can diffuse through such as oxygen, glucose, amino acids and water
large molecules cannot such as starch and protein.

Question 5

name 3 ways the rate of diffusion can be affected

Answer 5

the concentration gradient
the temperature
the surface area

Question 6

what is the concentration gradient

Answer 6

the difference in concentration of the particles. the bigger the concentration gradient the faster the diffusions. as the net movement from one side is greater.

Question 7

how does the temperature affect the rate of diffusion

Answer 7

the higher the temperature, the faster the rate of diffusion. as particles have more energy and move faster.

Question 8

how does surface area affect the diffusion rate?

Answer 8

the larger the surface area the faster the rate of diffusion. as more particles can pass through at once.