Biology 9700 · AS & A Level · The gas exchange system

The gas exchange system — practice question

The photomicrograph displays a cross-section of a bronchus. What functions do tissues X and Y carry out?

  • AX: secrete mucus; Y: prevent collapse of the airway
  • BX: support the airway; Y: dilate airway
  • CX: trap dust and dirt; Y: secrete mucus
  • DX: waft dust and dirt upwards; Y: constrict airway

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