Plants convert CO2 and water into glucose and oxygen using light energy.
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Photosynthesis is the process by which plants, algae and cyanobacteria use light energy to convert carbon dioxide and water into sugar and oxygen. The overall equation is 6CO2 + 6H2O + light energy gives C6H12O6 + 6O2. It occurs in chloroplasts in two linked stages: the light-dependent reactions in the thylakoid membranes produce ATP and NADPH and release oxygen, and the light-independent Calvin cycle in the stroma uses those products to fix CO2 into sugar. The sugars produced form the base of most food webs, and the oxygen supports aerobic life. Chlorophyll and accessory pigments absorb mainly blue and red wavelengths.
Key ideas: Overall: 6CO2 plus 6H2O plus light gives C6H12O6 plus 6O2, delta G about plus 2870 kJ per mole of glucose. Occurs in chloroplasts: light reactions in thylakoids make ATP and NADPH, the Calvin cycle in stroma fixes carbon. Oxygen comes from water, not CO2, shown by O-18 labelling.
Common mistakes and connections: The big error is saying oxygen comes from CO2. Another is claiming plants do not respire; they do both. Typical efficiency is only 1 to 2 percent of incident light. C4 and CAM plants reduce photorespiration. Links to cellular respiration (reverse) and to the carbon cycle.
Absorption of chlorophylls a and b peaks in blue and red light, with a gap in the green, which is why leaves look green. The interactive lesson shows this as a live animation or chart.
Leaves look green because chlorophyll absorbs red and blue light and reflects most green light.
Plants convert CO2 and water into glucose and oxygen using light energy.
Photosynthesis is a beginner topic in Biochemistry, Environment & Industry. It needs no earlier chemistry lessons and is a good starting point.
Study these earlier topics in Biochemistry, Environment & Industry first: Glycolysis, Krebs Cycle, Oxidative Phosphorylation.
The next topics in Biochemistry, Environment & Industry are Light Reactions and Calvin Cycle.
Yes. The interactive lesson includes a self-check question on Photosynthesis, and the Biochemistry, Environment & Industry quiz draws on every topic in this area.
Photosynthesis is topic 36 of 127 in Biochemistry, Environment & Industry.
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