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Focus area · How life powers itself
Photosynthesis & Cellular Respiration
The biggest topic on the test. Master the equations, the locations, and how they feed each other.
🌞 Photosynthesis
Plants capture light energy and store it as glucose.
6 CO₂ + 6 H₂O + light → C₆H₁₂O₆ + 6 O₂
INPUTS
- CO₂ (air)
- H₂O (roots)
- Light
WHERE
- Chloroplast
- Thylakoid + Stroma
OUTPUTS
- Glucose (food)
- O₂ (we breathe!)
⚡ Light reactions → thylakoid. Calvin cycle → stroma.
🔥 Cellular Respiration
Every cell breaks down glucose to make ATP — usable energy.
C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O + ATP
INPUTS
- Glucose
- O₂
WHERE
- Mitochondria
- (starts in cytosol)
OUTPUTS
- CO₂
- H₂O
- ATP ⚡
Notice: respiration is photosynthesis run backwards.
🚨 #1 Trap: Plants do BOTH.
Plants photosynthesize when there's light AND they respire 24/7 (just like us). Animals only do respiration.
📍 Where each step happens (high-yield!)
Match the process to its location
Glycolysis
Krebs / Citric Acid Cycle
Electron Transport Chain
Light reactions (photo)
Calvin cycle (photo)
⚖️ Side-by-side comparison
| Photosynthesis | Respiration | |
|---|---|---|
| Inputs | CO₂, H₂O, light | Glucose, O₂ |
| Outputs | Glucose, O₂ | CO₂, H₂O, ATP |
| Where | Chloroplast (plants only) | Mitochondria (all eukaryotes) |
| Energy | Stores it (anabolic) | Releases it (catabolic) |
| When | Daylight only | 24/7 |
🧠 Quick reveals
Where is the most ATP made?▾
Electron Transport Chain on the inner mitochondrial membrane (~32 ATP). Glycolysis & Krebs make a few each.
Why do we breathe out CO₂?▾
It's a waste product of cellular respiration — broken-down carbons from glucose.
Are plants 'making energy'?▾
No — energy is converted, not created. They convert light energy into chemical energy stored in glucose bonds.
🎯 Quiz yourself
Energy · QuizQ1 / 6