19 papers, 2017–2025 · Unit 5, Unit 1, Unit 6, Unit 4
Every Biology IAL past paper in the collection that assesses gas exchange.
By unit: all units (19) · Unit 1 (11) · Unit 4 (1) · Unit 5 (6) · Unit 6 (1)
These papers were matched to gas exchange automatically, by keyword patterns in their questions and mark schemes. A hand-check of 65 randomly chosen matches, read against the source question papers, found 53 that genuinely assess the topic and 12 that do not — 81.5% (95% confidence interval 70.4–89.1%). That is a good way to find practice on a topic, not proof a paper covers it, and a paper missing from this list may still assess it. A separate check found real papers that assess a topic without being tagged for it.