Characteristics of Life
Ever wondered what makes something "alive"? Living things share seven key characteristics: organization, homeostasis, metabolism, reproduction, growth and development, response to stimuli, and evolution in populations.
Biology organizes life into different levels, from smallest to largest. At the microscopic level, we have cells (the smallest living unit), which form tissues, which form organs, which work together as organ systems within an organism. Remember: cells only come from pre-existing cells!
The levels continue outward: organisms of the same species form a population, different populations create a community, and communities plus their environment form an ecosystem. All ecosystems together make up the entire biosphere - everything living on Earth!
Cool Fact: You're made of trillions of cells, but each one contains the complete instruction manual for your entire body!



































