3.1 SA:V

Question 1

How does SA:V affect the metabolic rate?

Answer 1

The greater the surface area to volume ratio, the higher the metabolic rate.

Question 2

What is the relationship between size and the SA:V

Answer 2

The smaller the sample, the bigger the SA:V.

Question 3

Why do large organisms need adaptations for sufficient exchange?

Answer 3

They have a small SA:V, so need to compensate to make sure metabolic rates stay high.

Question 4

What things are exchanged? (2)

Answer 4

• Respiratory gases

- Nutrients (ie glucose)

Question 5

What is an exchange surface?

Answer 5

An area that is specially adapted to the transfer of molecules between an internal and external environment (ie plasma cell membrane).

Question 6

What adaptations can speed up the rate of exchange?

Answer 6

• Thin surface, for a shorter diffusion distance.
• Selectively permeable, allows only what you ‘want’ to pass through.
• Constant movement of gases, allows for a permanent conc gradient for diffusion.
• Moist, so gases can dissolve faster and more easily.