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

Movement into and out of cells — practice question

How many times does an oxygen molecule have to cross a cell surface membrane to move from the air in the alveolus to the haemoglobin in a red blood cell? (Assume there are no pores between the cells through which the oxygen molecule has to travel.)

  • A2
  • B3
  • C4
  • D5

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