Unit 3 - Gas Exchange

Question 1

The relationship between surface area to volume ratio and metabolic rate for a smaller organism

Answer 1

1. (Smaller so) larger surface area to volume ratio;
2. More heat loss (per gram)
3. Faster rate of respiration, releases more heat

Question 2

Explain the advantage for larger animals of having a specialised system that facilitates oxygen uptake.

Answer 2

1. Large(r)organisms have a smaller surface area:volume ratio
   Or smaller organisms have a larger surface area:volume ratio
2. Overcomes long diffusion pathway
   Or faster diffusion

Question 3

Plants - explain why stomata open due to increase in light intensity

Answer 3

Allowing carbon dioxide to enter for photosynthesis
Or for gas exchange allowing photosynthesis