🧬 Biology · Energy
Photosynthesis cheat sheet
Everything you need on one page. Print it, or switch on test-yourself mode to blur the answers and check your memory.
The equation (simplified, net)
- 6CO2 + 6H2O + light energy → C6H12O6 + 6O2
- Reactants: carbon dioxide, water, light energy
- Products: glucose, oxygen
- Each side: 6 C, 12 H, 18 O
Where
- Chloroplasts (plants and algae)
- Thylakoid membranes: chlorophyll, stage 1
- Stroma: stage 2
- Cyanobacteria: no chloroplasts; chlorophyll in sheets of membrane inside the cell
Stage 1: light-dependent reactions
- In: light, water (and ADP, NADP+ to recharge)
- Out: O2, ATP, NADPH
- Water is split here
Stage 2: Calvin cycle
- In: CO2, ATP, NADPH
- Out: sugar, ADP, NADP+
- Carbon fixation happens here
Rate limits
- Light intensity: more is faster, up to a point
- Carbon dioxide: more is faster, up to a point
- Temperature: best range, enzymes damaged when too hot
- Limiting factor: the one in shortest supply
Mix-ups
- Oxygen comes from water
- Dry mass comes mostly from CO2 and water
- Plants respire day and night
- Matter cycles, energy flows
- Algae and cyanobacteria photosynthesize too
Formulas
- Net equation (simplified): 6CO2 + 6H2O + light energy → C6H12O6 + 6O2
- Fuller bookkeeping for the oxygen: 6CO2 + 12H2O → C6H12O6 + 6O2 + 6H2O
Photosynthesis cheat sheet from HighSchoolQ.com, for personal study use.