Biology HL
Follow energy and matter through enzyme-controlled pathways, ATP production in respiration, and carbon fixation in photosynthesis—from active-site collisions to chemiosmotic membranes.
3 simulation entries
Compare productive collisions with activation-energy profiles, then test how temperature, pH and substrate concentration change pathway rate.
Appears in: 2.1 Enzymes and Metabolic Pathways, 2.2 Enzyme Inhibition and Pathway Control
Molecular control bench
Relative pathway rate
66%
Route one glucose through aerobic or anaerobic conditions and inspect carbon, ATP and reduced-carrier totals at each stage.
Appears in: 2.3 Cell Respiration, ATP and Anaerobic Pathways, 2.4 Redox Reactions and Glycolysis, 2.5 Aerobic Respiration and Chemiosmosis
Carbon · carriers · ATP
ATP / glucose
30
Pathway
aerobic
Pyruvate enters mitochondria; oxygen accepts electrons at the end of the chain.
Scan wavelength across chlorophyll a, chlorophyll b and carotenoids; compare combined absorption with predicted photosynthetic action.
Appears in: 2.6 Photosynthesis, Light and Pigments, 2.7 Measuring Photosynthesis and Limiting Factors, 2.8 Light-dependent Reactions and the Calvin Cycle
Photon → electron → carbon
Combined pigment absorption
100%
Action follows combined absorption because only absorbed photons can excite photosystem pigments.