3.1.1 a and b efficient exchange surfaces

Question 1

features of a good exchange surface

Answer 1

thin, large surface area, good blood supply, large concentration gradient so diffusion can happen

Question 2

how can exchange take place?

Answer 2

actively where energy is required and passively where no energy from respiration is required

Question 3

surface area to volume ratio

Answer 3

surface area of the organism must be large compared with it’s volume for exchange to be effective

Question 4

what is the surface area to volume ratio for small and large organisms?

Answer 4

small organisms have a large surface area to volume ratio
large organisms have a small surface area to volume ratio

Question 5

why are specialised exchange systems needed?

Answer 5

single-celled organisms have a large surface area to volume ratio and their metabolic activity is low so diffusion is enough for substances to be transported.
for larger organisms the surface area to volume ratio is smaller and they have a higher metabolic activity so their need for oxygen is greater so they need to have a specialised exchange system to cope with demands.
distance between cells where oxygen is needed is too far for diffusion to be effective.

Question 6

what is Fick’s law?

Answer 6

rate of diffusion is directly proportional to (surface area x concentration gradient) divided by thickness of membrane