‹ Biology simulationsBiology · A Level 9700 · 12 Energy and respirationEight 3D simulations covering Topic 12.1 Energy and 12.2 Respiration. Spend ATP, calculate RQ, run a respirometer, explore a mitochondrion, follow carbon atoms round the Krebs cycle, pump protons, compare anaerobic pathways and time methylene blue.
Living things need energy for active transport, movement and anabolic reactions. ATP hydrolysis releases energy in small, usable amounts. Spend some ATP.
Different substrates release different amounts of energy and use different amounts of oxygen. RQ = CO₂ produced ÷ O₂ taken in.
Germinating seeds take in oxygen and give out carbon dioxide. Potassium hydroxide absorbs the carbon dioxide, so the coloured liquid shows oxygen uptake. Measure, then calculate the RQ.
Aerobic respiration has four stages: glycolysis in the cytoplasm, then the link reaction and Krebs cycle in the matrix, and oxidative phosphorylation on the inner membrane. Click the structures.
Follow the carbon atoms of one glucose molecule. Each sphere is a carbon atom. Watch the tally of ATP, reduced NAD, reduced FAD and carbon dioxide.
Reduced NAD and FAD deliver hydrogen to the inner membrane. Electrons pass along the electron transport chain, protons are pumped, and ATP synthase makes ATP. Then take away the oxygen.
Without oxygen, reduced NAD must be reoxidised another way so glycolysis can continue. Compare the pathways and the energy yield, then see how rice copes with flooded roots.
Methylene blue (or DCPIP) accepts hydrogen from respiring yeast and is decolourised. The faster it loses its colour, the faster the rate of respiration.
| tube | temperature | time to decolourise |
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Eight interactive 3D simulations for Cambridge A Level Biology 9700 topic 12 Energy and respiration: ATP as the energy currency for active transport, movement and anabolic reactions, respiratory substrates and RQ from equations, a respirometer to find the RQ of seeds and larvae, the structure of the mitochondrion, glycolysis, the link reaction and the Krebs cycle with carbon atoms and coenzymes, oxidative phosphorylation with chemiosmosis, lactate and ethanol fermentation and rice in flooded fields, and redox indicators to measure yeast respiration.
Eight 3D simulations covering Topic 12.1 Energy and 12.2 Respiration. Spend ATP, calculate RQ, run a respirometer, explore a mitochondrion, follow carbon atoms round the Krebs cycle, pump protons, compare anaerobic pathways and time methylene blue.
Energy and respiration is a free, browser-based simulation for Cambridge International AS & A Level Biology 9700 (topic 12 Energy and respiration). The course is assessed in Paper 1 (Multiple choice), Paper 2 (AS structured), Paper 3 (Advanced practical), Paper 4 (A Level structured), Paper 5 (Planning, analysis, evaluation). Syllabus for examination in 2025-2027. There are 8 tabs, each a self-contained experiment with its own controls and live readings, and nothing to install: it runs on a laptop, tablet or classroom projector.
Full syllabus map: A Level Biology 9700 topic 12.
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