9700 · 13.1
Photosynthesis as an energy transfer process
Welcome to a crucial topic in Biology: **Photosynthesis**. This isn't just about plants making food; it's the ultimate **energy transfer** process on Earth. Through photosynthesis, **autotrophs** (organisms that produce their own food) harness **light energy** from the sun and convert it into **chemical energy** stored in organic molecules like **glucose**. This transformation is literally the foundation of nearly all life, powering ecosystems and shaping our planet's atmosphere.
Need to know
What you need to know
- Photosynthesis is the process of converting light energy into chemical energy stored in organic molecules like glucose.
- The overall balanced equation is 6CO₂ + 6H₂O + Light Energy → C₆H₁₂O₆ + 6O₂.
- Photosynthesis occurs in chloroplasts. The light-dependent reactions are in the thylakoid membranes, and the light-independent reactions are in the stroma.
- Photosynthetic pigments (chlorophylls, carotenoids) absorb light energy. An absorption spectrum shows which wavelengths are absorbed, while an action spectrum shows the rate of photosynthesis at those wavelengths.
- The light-dependent stage uses light to produce ATP and reduced NADP through photophosphorylation and involves the photolysis of water.
- The light-independent stage (Calvin cycle) uses ATP and reduced NADP to fix CO₂ into triose phosphate, which is then used to make glucose and regenerate RuBP.
- Photosynthesis is fundamental to life as it forms the base of food webs and produces the atmospheric oxygen required for aerobic respiration.
Explanation
Photosynthesis as an energy transfer process
- Photosynthesis is the process of converting light energy into chemical energy stored in organic molecules like glucose.
- The overall balanced equation is 6CO₂ + 6H₂O + Light Energy → C₆H₁₂O₆ + 6O₂.
- Photosynthesis occurs in chloroplasts. The light-dependent reactions are in the thylakoid membranes, and the light-independent reactions are in the stroma.
- Photosynthetic pigments (chlorophylls, carotenoids) absorb light energy. An absorption spectrum shows which wavelengths are absorbed, while an action spectrum shows the rate of photosynthesis at those wavelengths.