3.3.1 Surface area to volume ratio

Question 1

how does an organism’s size relate to their surface area to volume ratio?

Answer 1

the larger the organism, the lower the surface area to volume ratio

Question 2

how does an organism’s surface area to volume ratio relate to their metabolic rate?

Answer 2

the smaller the surface area to volume ratio, the higher the metabolic rate.

Question 3

how might a large organism adapt to compensate for its small surface area to volume ratio?

Answer 3

changes that increase surface area e.g. folding; body parts become larger e.g. elephant’s ears; elongating shape; developing a specialised gas exchange surface

Question 4

why do multicellular organisms require specialised gas exchange surfaces?

Answer 4

their smaller surface area to volume ratio means the distance that needs to be crossed is larger and substances cannot easily enter the cells as in a single-celled organism