surface area and exchange

Question 1

exchange of many substances between an organism and its environment relies on _________

Answer 1

exchange of many substances between an organism and its environment relies on diffusion

Question 2

how do single cell organisms exchange substances?

Answer 2

single celled organisms have a large surface area to volume ratio

this provides a short diffusion pathway to all parts of the cell

this satisfies gas exchange requirements for small organisms and ensures removal of heat

Question 3

how do multicellular organisms exchange substances?

Answer 3

as the size of organisms increases, the surface area to volume ratio decreases

to overcome this problem, larger organisms have developed specialised exchange structures such as the lungs and gills to maintain adequate rates of gaseous exchange

to help maintain a constant body temperature, changes in body shape or specialised structures have evolved

Question 4

how do elephants control their body temperature?

Answer 4

elephants are the largest land animals and have a small surface area to volume ratio

as they are mammals they maintain a constant body temperature

the large volume of body cells releases a lot of heat from metabolic processes, mainly respiration

large ears are an adaptation to increase the overall surface area for this heat loss

Question 5

how do mice control their body temperature?

Answer 5

a mouse has a large surface area to volume ratio and therefore loses a large amount of heat relative to its mass

due to this large heat loss, mice have to respire at a high rate to help maintain a constant body temperature (respiration releases heat)

this means they have a high uptake of oxygen relative to their mass

they also have to consume a lot of food, relative to their mass