Surface Area

Question 1

What happens as an organism gets larger?

Answer 1

The organism requires more oxygen in order to fulfil its metabolic needs so more exchange must take place.

Question 2

What happens as SA:V ratio decreases?

Answer 2

Diffusion and the efficiency of gas exchange, via diffusion, decreases.

Question 3

What must happen to an organism in order for SA:V ratio to decrease?

Answer 3

The size of the organism/cell must increase.

Question 4

Why must the rate of diffusion be rapid within the body?

Answer 4

Because the body’s demand for oxygen is enormous.

Question 5

What three things does the rate of diffusion rely on?

Answer 5

1. SA: the greater the SA, the greater the rate of diffusion
2. CG: the greater the difference in concentration (greater CG), the greater the rate of diffusion.
3. Thickness of exchange surface: The thicker the gas exchange surface, the slower the rate of diffusion.

Question 6

What is Fick’s Law?

Answer 6

Surface Area x difference in concentration / thickness of gas exchange surface.