Exchange

Question 1

Describe the relationship between the size of an organism or structure and its surface area to volume ratio.

Answer 1

As an organism gets larger, its SA:V ratio decreases. This means large animals have a small surface area relative to their volume.

Question 2

Describe how gases are exchanged in single-celled organisms.

Answer 2

Gaseous exchange occurs in the cell surface membrane, where oxygen diffuses down a concentration gradient.