Photosynthesis Process
Dr. Marcus Thompson·
PhotosynthesisPlantsChloroplastsEnergy
Photosynthesis is the process by which plants, algae, and some bacteria convert light energy into chemical energy stored in glucose.
The Equation
6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂
Two Main Stages
Light-Dependent Reactions
Occur in the thylakoid membranes:
- Photosystem II: Absorbs light, splits water molecules
- Electron Transport Chain: Generates ATP and NADPH
- Photosystem I: Further energizes electrons
Products: ATP, NADPH, O₂
Light-Independent Reactions (Calvin Cycle)
Occur in the stroma:
- Carbon fixation: CO₂ combines with RuBP
- Reduction: ATP and NADPH produce G3P
- Regeneration: RuBP is regenerated
Product: Glucose (C₆H₁₂O₆)
Key Factors Affecting Photosynthesis
- Light intensity: Increases rate up to saturation point
- Carbon dioxide concentration: Limiting factor
- Temperature: Affects enzyme activity
- Water availability: Essential reactant
Importance
- Produces oxygen for aerobic respiration
- Forms the base of most food chains
- Removes CO₂ from atmosphere
- Stores solar energy in chemical bonds
Photosynthesis is fundamental to life on Earth, supporting virtually all ecosystems.