Question

Which of the following features do all gas exchange have in common?

• A. They are enclosed within ribs.
• B. They are maintained at constant temperature.
• C. The exchange surfaces are moist.
• D. They are exposed to air.

Answer 1

The correct option is C The exchange surfaces are moist.

Gas exchange and respiration are essential if cells are to stay active, grow and divide. All the structures for gas exchange have common as follows:

• They have a large surface area relative to the volume of the organism.
  
• They are thin and so have a short diffusion pathway.
  
• They have a moist surface where gases can dissolve first before they diffuse in or out.
  
• They are able to maintain the diffusion gradient down which the gases can diffuse.
  

Therefore, the correct answer is option C.