features of a specialised exchange surface

Question 1

what do large multicellular organisms have

Answer 1

evolved specialised systems for the exchange of the substances they need and the substances they need to remove

Question 2

why is an increased surface area important for exchange surfaces

Answer 2

it provides the area needed for exchange. it overcomes the limitations of the SA:V ratio of larger organisms

Question 3

how is an increased surface area achieved

Answer 3

by folding the walls and membranes for e.g. root hair cells in plants and villi in small intestine

Question 4

greater surface area = …

Answer 4

… = higher diffusion rate

Question 5

what is the root hairs at the tip of the root adaped for

Answer 5

increasing the surface area
- adapted for taking up water and mineral ions by having a large surface area to increase the rate of absorption
- contains lots of mitochondria which release energy from glucose during respiration in order to provide the energy needed for active transport

Question 6

what does the rate of diffusion also depend on

Answer 6

the difference in the concentration gradient

Question 7

what is a concentration gradient

Answer 7

difference in concentration of a substance between two areas

Question 8

steeper gradient = …

Answer 8

…. = faster rate of diffusion