2.1.1 Gas exchange surfaces and Fick's Law Quiz: Pearson Edexcel Biology, Unit 2

The 20 questions

1. Which property of a gas exchange surface maximises the rate of diffusion?

   • Small surface area
   • Thick diffusion barrier
   • Equal concentrations
   • Large surface area

2. According to Fick's Law, what happens to diffusion rate if surface thickness is halved?

   • It halves
   • It quadruples
   • It doubles
   • It stays constant

3. According to Fick's Law, diffusion rate is inversely proportional to which factor?

   • Temperature
   • Surface area
   • Thickness
   • Concentration difference

4. Surface A has area 2 and thickness 0.5. Surface B has area 4 and thickness 1. How do diffusion rates compare?

   • Surface A faster
   • Surface B faster
   • Rate becomes zero
   • They are equal

5. Which structures in the human lung provide a large surface area for gas exchange?

   • Trachea
   • Alveoli
   • Bronchi
   • Bronchioles

6. Which structural feature of an alveolus ensures a short diffusion distance for gases?

   • Ciliated epithelium
   • Smooth muscle layer
   • One cell thick
   • Cartilage rings

7. What is the primary purpose of continuous blood flow through alveolar capillaries?

   • Maintain concentration gradient
   • Lower body temperature
   • Increase diffusion distance
   • Reduce surface area

8. According to Fick's Law, which adaptation increases the rate of diffusion across a membrane?

   • Increasing membrane thickness
   • Folding the membrane
   • Lowering concentration gradient
   • Decreasing temperature

9. Why can single-celled organisms rely on simple diffusion for gas exchange?

   • Thick outer membrane
   • Large SA:V ratio
   • Small SA:V ratio
   • High metabolic rate

10. According to Fick's Law, what is diffusion rate directly proportional to?

    • Concentration difference
    • Membrane thickness
    • Activation energy
    • Diffusion distance

11. Which process helps maintain a steep oxygen concentration gradient in human alveoli?

    • Continuous blood flow
    • Surfactant secretion
    • Thick alveolar walls
    • Passive expiration

12. What is the main advantage of counter-current flow in fish gills?

    • Increases surface area
    • Reduces blood pressure
    • Shortens diffusion distance
    • Maintains concentration gradient

13. Which combination of features maximises gas exchange across a respiratory surface?

    • Large area, thick
    • Small area, thick
    • Large area, thin
    • Small area, thin

14. Why must the alveolar surface remain moist for effective gas exchange?

    • Gases must dissolve
    • Thickens cell membranes
    • Prevents bacterial infection
    • Increases surface area

15. In Fick's Law equation, what is diffusion rate inversely proportional to?

    • Concentration difference
    • Temperature
    • Surface area
    • Thickness of membrane

16. If a membrane's surface area and thickness are both doubled, what happens to diffusion rate?

    • Remains unchanged
    • Quadruples
    • Halves
    • Doubles

17. How does the structure of alveolar walls adapt them for rapid gas exchange?

    • Thick cartilage rings
    • Multiple cell layers
    • Ciliated columnar cells
    • One cell thick

18. What effect does a steep oxygen concentration gradient have on gas exchange?

    • Increases diffusion rate
    • Decreases diffusion rate
    • Reduces blood flow
    • Prevents gas exchange

19. If surface area triples and membrane thickness is halved, diffusion rate increases by what factor?

    • Three
    • 1.5
    • Twelve
    • Six

20. According to Fick's Law, which change decreases the rate of diffusion across a membrane?

    • Increasing surface area
    • Increasing concentration difference
    • Increasing temperature
    • Increasing membrane thickness

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