photosynthesis

Photosynthesis is the process by which green plants and algae use sunlight to make their own food from carbon dioxide and water.

• What goes in: sunlight (energy), carbon dioxide from air/water, and water.
• What comes out: a sugar called glucose (food/energy stored by the organism) and oxygen released into the surroundings.
• Where it happens: in tiny cell parts called chloroplasts, which contain chlorophyll—the green pigment that traps sunlight.
• Why microalgae are so important: because they are extremely numerous in oceans and lakes, their photosynthesis adds a huge amount of oxygen to Earth’s atmosphere and supports aquatic food chains.
• Everyday analogy: think of chlorophyll like a solar panel—it captures sunlight and uses that energy to “build” food from simple raw materials.
• Small but key idea: photosynthesis doesn’t just “make oxygen”; its main job is making food, and oxygen is a useful by-product for many living things (including us).