[Campbell Biology P.971] The text discusses two basic adaptations that permit efficient exch... | Practice Question

The text discusses two basic adaptations that permit efficient exchange for all of an animal's cells. Which of the following statements correctly describes one of these adaptations?

  • A: Unicellular organisms rely on a complex circulatory system for material exchange with the external environment.
  • B: Animals with a simple body plan, like cnidarians and flatworms, place many or all cells in direct contact with the environment.
  • C: Multicellular organisms primarily use diffusion over long distances to exchange materials with their environment.
  • D: Circulatory systems allow exchange with the environment and body tissues to occur over very long distances.

Explanation

The text states: 'One adaptation for efficient exchange is a simple body plan that places many or all cells in direct contact with the environment. Each cell can thus exchange materials directly with the surrounding medium. Such an arrangement is characteristic of certain invertebrates, including cnidarians and flatworms.' Option B accurately reflects this adaptation.