organisms exchange substances with their environment

Question 1

what surface area: volume do small organisms have?

Answer 1

-large surface area: volume, to allow efficient exchange across the body surface

Question 2

what surface area: volume do large organisms have?

Answer 2

-small surface area: volume, to allow efficient exchange across the body surface

Question 3

how do you calculate the surface area and volume?

Answer 3

surface area=
-area of one side x amount of sides
volume=
-length x width x height

Question 4

what are the features of specialised exchange surfaces? (3)

Answer 4

-large surface area: volume, which increases the rate of exchange
-very thin, providing a short diffusion pathway
-selectively permeable, allows selected materials to cross

Question 5

how does aerobic respiration increase gas exchange in insects?

Answer 5

1. anaerobic respiration in muscles produce lactate
2. lactate in the muscles decrease water potential
3. water moves from the tracheoles into the muscle by osmosis
4. this decreases the volume of tracheoles
5. this draws air into the tracheoles, therefore increasing gas exchange

Question 6

what are the structures in insects relating to gas exchange? (3)

Answer 6

tracheoles=
-thin, providing a short diffusion pathway
-highly branched, large surface area
exoskeleton=
-prevents water loss
spiracles=
-hairs, preventing water loss
-holes on the surface that can open and close, preventing water loss
-allows oxygen to diffuse into tracheae

Question 7

what are the structures of the gills in fish relating to gas exchange?

Answer 7

gill filaments=
-contain gill lamellae
gill lamellae=
-many of them, large surface area
-very thin, providing a short diffusion pathway

Question 8

what is counter current flow?

Answer 8

-flow of water over the gill lamellae and the flow of blood travel in opposite directions
-diffusion gradient is maintained throughout the whole gill filament
-if they both flowed in the same direction, far less gas exchange would take place