1. Atoms: The basic building blocks of all matter, including living organisms.
* Examples: Carbon, hydrogen, oxygen, nitrogen.
2. Molecules: Two or more atoms bonded together.
* Examples: Water (H₂O), glucose (C₆H₁₂O₆), proteins, DNA.
3. Organelles: Specialized structures within cells that perform specific functions.
* Examples: Mitochondria (energy production), nucleus (contains DNA), ribosomes (protein synthesis).
4. Cells: The fundamental unit of life.
* Examples: Muscle cells, nerve cells, blood cells.
5. Tissues: Groups of similar cells working together to perform a specific function.
* Examples: Muscle tissue, nervous tissue, connective tissue.
6. Organs: Structures composed of different tissues that work together for a common purpose.
* Examples: Heart, lungs, brain, stomach.
7. Organ Systems: Groups of organs that cooperate to carry out major bodily functions.
* Examples: Digestive system, circulatory system, nervous system.
8. Organisms: A complete living being made up of organ systems.
* Examples: Humans, animals, plants.
9. Populations: Groups of individuals of the same species living in the same area.
* Example: A population of deer in a forest.
10. Communities: Different populations of interacting species living in the same area.
* Example: A community of plants, animals, and fungi in a meadow.
11. Ecosystems: A community of living organisms and their physical environment.
* Example: A forest ecosystem, a desert ecosystem.
12. Biosphere: The sum of all ecosystems on Earth, encompassing all life and its physical environment.
