A-LevelBiologyGas exchangeMay/June 2024Paper 1 Q321 Mark
What maintains the steep concentration gradients needed for successful gas exchange in the lungs? 1 Air flow in the alveoli is in the opposite direction to blood flow in the capillaries. 2 Blood arrives in the lungs with a lower oxygen concentration and a higher carbon dioxide concentration than the air in the alveoli. 3 Blood is constantly flowing through and out of the lungs, bringing a fresh supply of red blood cells.
A1, 2 and 3
B1 and 2 only
C1 and 3 only
D2 and 3 only
✓ Correct Answer
The correct answer is D. This question tests the candidate's understanding of gas exchange within the Biologysyllabus. The examiner's mark scheme requires...
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
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