Which of the following is NOT a characteristic of an efficient respiratory surface?

  • A. It is dry and thick
  • B. It is thin
  • C. It is kept moist
  • D. It has a large surface area

Explanation

Gases must dissolve before diffusing, and distance must be tiny, so efficiency demands a moist, thin, extensive surface. A dry thick barrier would stop diffusion, which is exactly why land animals keep their lungs internal.

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