Organization:
* Cellular structure: Living things are made up of one or more cells, the basic unit of life.
* Hierarchy of organization: Living things show a hierarchical organization, from atoms and molecules to cells, tissues, organs, organ systems, and organisms.
Metabolism:
* Energy processing: Living things obtain and use energy to perform essential functions. They take in nutrients and convert them into usable energy, a process called metabolism.
* Anabolism: The building up of complex molecules from simpler ones.
* Catabolism: The breaking down of complex molecules into simpler ones.
Growth & Development:
* Increase in size and complexity: Living things grow and develop over time, increasing in size and complexity.
* Reproduction: Living things reproduce, creating new individuals.
Responsiveness:
* Adaptation: Living things adapt to changes in their environment. They can sense stimuli and respond appropriately.
* Homeostasis: Living things maintain a stable internal environment despite external changes.
Evolution:
* Heredity: Living things pass on their characteristics to their offspring through genes.
* Change over time: Living things evolve over time, adapting to their environment and diversifying into new species.
It's important to note:
* Viruses, for example, possess some characteristics of life (they can reproduce and evolve), but they lack others (they don't have a cellular structure, they don't metabolize on their own). This is why they are not considered to be living.
* The definition of life is constantly being refined as we learn more about the natural world.
Ultimately, the question of what makes something living is a complex one, and there is no single answer that everyone agrees on. The above properties provide a helpful framework for understanding the characteristics that define life.
