How Plants Make Food

All living things need energy to survive. Animals get energy by eating food, but plants have an amazing ability — they can make their own food using sunlight. This process is called photosynthesis, which comes from Greek words meaning "light" and "putting together." Photosynthesis is one of the most important chemical processes on Earth because it produces the oxygen we breathe and the food that almost every living thing depends on.

Photosynthesis takes place inside tiny structures called chloroplasts, which are found in the cells of leaves and other green parts of a plant. Chloroplasts contain a green pigment called chlorophyll, which captures energy from sunlight. Using that light energy, plants combine water (absorbed through their roots) and carbon dioxide (a gas taken in through tiny pores called stomata) to produce glucose — a sugar that the plant uses for energy and growth. Oxygen is released as a byproduct through the stomata, which is why plants are essential for maintaining breathable air on our planet.

The overall equation for photosynthesis is: 6CO₂ + 6H₂O + Light Energy → C₆H₁₂O₆ + 6O₂. In plain language, six molecules of carbon dioxide and six molecules of water, powered by light, produce one molecule of glucose and six molecules of oxygen. The more sunlight a plant receives, and the more carbon dioxide available, the faster photosynthesis can occur — up to a point. Without enough water, the stomata close to prevent the plant from drying out, which also stops carbon dioxide from entering and slows the process significantly.