AQA GCSE Biology

Lungs & gas exchange

AQA GCSE Biology revision on Lungs & gas exchange. Aligned to the AQA GCSE Biology 8461 specification. This bank has 25 practice questions on this topic.

Sample questions (3 of 25)

  1. Question 1

    Which structural feature of the alveoli directly increases the efficiency of gas exchange?

    • A) Large total surface area
    • B) Presence of stiff cartilage
    • C) Thick basement membranes
    • D) Reduced capillary network
    Show answer

    Answer: Large total surface area

    Fick's Law of diffusion states that the rate of diffusion is proportional to the surface area. By having millions of tiny alveoli, the lungs provide a massive surface area for oxygen and carbon dioxide to exchange between the air and the blood.

  2. Question 2

    What is the primary factor that maintains a steep concentration gradient for oxygen at the alveolar surface?

    • A) Continuous blood flow
    • B) Production of mucus
    • C) Active lung ventilation
    • D) Internal gas pressure
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    Answer: Continuous blood flow

    If blood remained stagnant in the pulmonary capillaries, the concentration of oxygen in the blood would quickly equal that of the alveoli, stopping net diffusion. The circulatory system keeps the concentration gradient steep by constantly supplying deoxygenated blood and removing oxygenated blood.

  3. Question 3

    During inhalation, what is the movement of the diaphragm?

    • A) It relaxes and domes up
    • B) It contracts and flattens
    • C) It moves toward the neck
    • D) It stays in fixed position
    Show answer

    Answer: It contracts and flattens

    When the diaphragm contracts, it moves downward, increasing the volume of the chest cavity. This increase in volume results in a decrease in pressure inside the lungs, causing air to be drawn in from the atmosphere.

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