1. Cells: The fundamental building blocks of life. These are the smallest unit that can carry out all the processes of life. Examples include muscle cells, nerve cells, and skin cells.
2. Tissues: Groups of similar cells that work together to perform a specific function. Examples include muscle tissue, nervous tissue, and epithelial tissue.
3. Organs: Structures made up of different tissues that work together to perform a specific function. Examples include the heart, lungs, stomach, and brain.
4. Organ Systems: Groups of organs that work together to perform a major bodily function. Examples include the digestive system, circulatory system, respiratory system, and nervous system.
5. Organism: A complete living being made up of multiple organ systems working together.
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