All living things, from the tiniest bacteria to the largest whale, are made of cells. Cells are the basic units of life. Some organisms, like bacteria, are made of just one cell! Others, like humans and plants, have trillions.
In multicellular organisms, cells form tissues, tissues form organs, and organs work together in systems (like the respiratory or digestive system). This organization makes complex life possible.
Understanding cells helps doctors treat diseases, farmers grow better crops, and scientists develop new medicines.
Plant cells have a rigid cell wall and chloroplasts for photosynthesis.
Human blood contains red blood cells that carry oxygen.
Cells are the basic units of life, organizing into tissues and organs to make living systems function.