Photosynthesis: How Plants Make Food
Ever wondered how plants create their own food using just sunlight, water, and carbon dioxide? Photosynthesis is an endothermic reaction that happens in the chloroplasts of plant cells. The green pigment chlorophyll acts like a solar panel, trapping light energy and converting it into chemical energy.
The equation for photosynthesis shows exactly what's happening: carbon dioxide + water → glucose + oxygen . Plants use the glucose they make in brilliant ways - for respiration to release energy, converting it to starch for storage, making cellulose to strengthen cell walls, and producing amino acids for proteins.
Limiting factors control how fast photosynthesis happens. Temperature, light intensity, carbon dioxide concentration, and chlorophyll concentration can all slow things down when they're in short supply. The inverse square law explains why moving a plant twice as far from a light source reduces light intensity by a quarter.
Top Tip: In exam questions about limiting factors, look for which one is preventing the rate from increasing further - that's your limiting factor!
Commercial greenhouses cleverly manipulate these limiting factors to maximise plant growth and profits.
