◈ Oracle PrepSign Up Free
A-LevelBiologyGas exchange9700/12 · May/June 2021 · Q301 Mark

What is the main reaction occurring in blood capillaries at the gas exchange surface in a human lung?

ACarbonic acid dissociates into carbon dioxide and hydrogen ions.
BCarbonic anhydrase converts carbon dioxide into hydrogencarbonate ions.
CCarbon dioxide combines with haemoglobin to form carbaminohaemoglobin.
DCarbon dioxide is produced from hydrogencarbonate ions by carbonic anhydrase.

✓ Correct answer

D: Carbon dioxide is produced from hydrogencarbonate ions by carbonic anhydrase.

Practise more questions on this topic

Oracle Prep sorts past-paper questions by topic, so you can drill Gas exchange and see which topics are most likely to come up next.

Sign up free →

About this question

Topic
Gas exchange, A-Level Biology (syllabus 9700). Multiple choice, 1 mark.
Source
A-Level Biology, May/June 2021 Paper 1 Variant 2, question 30.

Questions and mark schemes are from past examination papers and remain the copyright of the exam board. How Oracle Prep builds its content

Related Biology questions

Gas exchangeFeb/Mar 20181m

What can combine with the haem group of a haemoglobin molecule? 1 oxygen 2 carbon dioxide 3 carbon monoxide

Gas exchangeFeb/Mar 20181m

Chronic obstructive pulmonary disease (COPD) includes bronchitis and emphysema. Which symptom is specific to emphysema?

Gas exchangeFeb/Mar 20191m

Which statements about the formation of haemoglobinic acid are correct? 1 It is linked to the action of carbonic anhy…

Genetic technologyFeb/Mar 20228m

Factor VIII can be made as a recombinant human protein.

Biodiversity and conservationFeb/Mar 20228m

Describe the biological species concept.

Cell structureFeb/Mar 20231m

A student calibrated an eyepiece graticule using a stage micrometer. • Each division of the stage micrometer was 0.01…

← Browse all past-paper questions

© 2026 Oracle Prep