* Tissues: A group of similar cells that work together to perform a specific function. Examples include muscle tissue, nervous tissue, and connective tissue.
* Organs: A structure made up of different tissues that work together to perform a more complex function. Examples include the heart, lungs, and stomach.
* Organ Systems: A group of organs that work together to carry out major bodily functions. Examples include the digestive system, circulatory system, and nervous system.
* Organisms: A complete living being made up of multiple organ systems working together. This could be a plant, animal, or even a single-celled organism like bacteria.
This hierarchical organization allows for increasingly complex and specialized functions within living things.
