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

Movement into and out of cells — practice question

The diagram illustrates the Bohr shift in actively respiring cells. What is responsible for the shift from L to M?

  • ACarbonic acid dissociates to release protons that bind to oxyhaemoglobin, affecting the conformation of haemoglobin to reduce its affinity for oxygen.
  • BHydrogencarbonate ions produced by carbonic anhydrase alter the charge of oxyhaemoglobin, reducing its ability to bind oxygen.
  • CHydrogen ions combine with chloride ions in tissue fluid to produce hydrochloric acid, distorting oxyhaemoglobin and causing it to lose bound oxygen.
  • DA low concentration of oxygen in actively respiring cells causes oxyhaemoglobin to release oxygen more quickly down the concentration gradient.

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