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6. How does the transport system maintain the diffusion gradient?

  • Qxygenated blood is transported around the body
  • Oxygenated blood cells are removed via the capillaries
  • There is low pressure in the capillaries
  • The capillaries widen

7. How thick are the walls of the capillaries and alvioli?

  • Two cells each
  • One cell each
  • One cell between them
  • Three cells each

8. How do squamous cells aid the lungs in gas exchange?

  • They are squashed together, so more of them can fit in an alviolus.
  • They increase the distance the gases have to diffuse across
  • They decrease the distance the gases have to diffuse across.
  • They speed up gas exchange

9. How do the alvioli increase the exchange surface of the lungs?

  • They have a large surface area
  • They reduce the distance gas has to diffuse across.
  • They are numerous and folded
  • They are small and folded