[Campbell Biology P.989] Which of the following statements accurately describes a key charac... | Practice Question

Which of the following statements accurately describes a key characteristic of effective respiratory surfaces in animals?

  • A: They must be thin, moist, and possess a large surface area relative to the diffusion path.
  • B: They are always internal organs, such as lungs, to prevent dehydration.
  • C: Gas exchange primarily occurs when cells are not in direct contact with an aqueous solution.
  • D: The rate of net diffusion is inversely proportional to the surface area across which it occurs.
  • E: While an animal's general body surface often suffices for gas exchange, specialized organs are rare.

Explanation

Effective respiratory surfaces are characterized by being thin and moist to allow gases to dissolve and diffuse easily. A large surface area shortens the diffusion path and increases the rate of net diffusion, which is proportional to surface area and inversely proportional to the square of the distance. Option B is incorrect because many animals use external or semi-external structures. Option C is incorrect as contact with an aqueous solution is essential for gas exchange. Option D contradicts the text stating net diffusion rate is proportional to surface area. Option E is incorrect as specialized organs like gills, tracheae, and lungs are common solutions for most animals.