Photosynthesis

Photosynthesis is the way green plants, algae, and some bacteria make their own food using sunlight. It is one of the most important processes on earth because it provides both food and oxygen for living things. The word comes from Greek roots: photo meaning 'light' and synthesis meaning 'putting together'.

Plants use their leaves to capture sunlight. Inside each leaf are tiny green parts called chloroplasts, which contain a pigment named chlorophyll. Chlorophyll gives plants their green color and helps absorb sunlight. The energy from sunlight is then used to turn water (from the soil) and carbon dioxide (from the air) into a kind of sugar called glucose. This sugar gives plants energy to grow, bloom, and produce seeds.

During photosynthesis, plants also make oxygen as a by-product. This oxygen is released into the air through small openings in the leaves called stomata. All animals, including humans, need this oxygen to breathe. So, photosynthesis not only feeds the plants but also supports nearly all life on Earth.

The process of photosynthesis happens in two main steps: the light reaction and the dark reaction. In the light reaction, sunlight energy is captured and stored in molecules. In the dark reaction, that stored energy is used to build glucose from carbon dioxide and water. Even though it is called a “dark” reaction, it can still happen during the day.

Different plants use photosynthesis in slightly different ways. For example, cactus plants in deserts use a special method to save water, while algae in oceans perform photosynthesis under water. But the goal is always the same: to make energy-rich food using light.

Without photosynthesis, there would be no green plants, no oxygen to breathe, and no animals to eat the plants. This invisible, quiet process connects all living things in a circle of life powered by the sun.