Photosynthesis Basics
Ever wonder how plants create their own food whilst you're stuck making sandwiches? Photosynthesis is nature's ultimate food-making process, and it only happens in green plants and algae because they contain chlorophyll.
The equation you absolutely must remember is: carbon dioxide + water → glucose + oxygen (using light energy). This is an endothermic reaction, meaning it needs energy input to work. The process starts when leaves absorb CO₂ and roots take up water, then chlorophyll captures light energy to convert these ingredients into glucose.
Leaves are perfectly designed for photosynthesis with several clever adaptations. They're broad and flat to maximise surface area for light absorption, thin for short diffusion paths, and packed with chlorophyll-containing cells. Guard cells control the stomata (tiny pores) to let gases flow in and out, whilst veins transport water in and glucose out.
Quick Tip: Remember that some glucose gets converted into insoluble starch for storage - this prevents it from messing up the plant's water balance through osmosis.
Several factors can slow down photosynthesis and act as limiting factors. Lack of light means no energy for glucose production, cold temperatures make enzymes work poorly, and insufficient CO₂ starves the reaction of raw materials. Plants cleverly use their glucose for respiration, making cellulose for cell walls, creating fats and oils for storage, and producing proteins (when combined with nitrate ions from soil).