surface area: volume ratio

Question 1

how is diffusion different in organisms differently sized

Answer 1

small organisms= diffusion alone is sufficient and meets the needs of the organism

large organisms= diffusion is insufficient, have different body shapes and specialised exchange systems to inc SA:Vol ratio

Question 2

what are the general features of exchange surface (5)

Answer 2

• selectively permeable
• thin-> short diffusion distance
• large SA:Vol ratio
• moist
• maintain concentration gradient

Question 3

what is the trend between organism size and sa: vol ratio

Answer 3

as organism size increases, sa:vol ratio decreases

small organisms - high SA:Vol
large organisms - low SA:Vol

Question 4

factors a high SA:Vol ratio has an affect on

Answer 4

high rate of diffusion
high rate of heat transfer
high rate of exchange of nutrients

Question 5

equation for Fick’s Law

Answer 5

rate of diffusion= SA x conc gradient/ diffusion distance

Question 6

3 properties of a good exchange surface

Answer 6

large surface area
large concentration gradient
thin exchange surface