Biology 9700 · AS & A Level · Movement into and out of cells

Movement into and out of cells — practice question

In the lungs, oxygen and carbon dioxide move through cell membranes by diffusion. Which row is correct?

  • Aoxygen from air: 3 membranes; carbon dioxide to air: 2 membranes
  • Boxygen from air: 3 membranes; carbon dioxide to air: 2 or 3 membranes
  • Coxygen from air: 5 membranes; carbon dioxide to air: 4 membranes
  • Doxygen from air: 5 membranes; carbon dioxide to air: 4 or 5 membranes

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