SA:V

Question 1

What is the relationship between the size of an organism
and its SA:V?

Answer 1

Smaller organisms tend to have a higher SA:V than larger organisms

SA=length x width and then x by how many sides the shape has

Volume=length x width x depth

e.g. SA=24
volume= 8

SA:V =
3:1

Question 2

What is the relationship between SA:V and metabolic rate?

Answer 2

Rate of heat loss increases as SA:V increases
i.e. more heat lost per unit body mass in smaller animals with a high SA:V
So they need a higher metabolic rate / faster respiration
To generate enough heat to maintain a constant body temperature i.e.
replace lost heat

Question 3

Why do larger organisms require specialised surface/organ
for gas exchange?

Answer 3

They have a smaller SA:V and a long diffusion pathway
Skin is waterproof / gas tight
High demand for oxygen and need for removal of carbon dioxide