Captioning is on. Turn off by clicking the CC button at bottom right! Follow us on Twitter (@AmoebaSisters) or Facebook! If I asked you to describe the biological levels of organization, could you do it? What would those levels be? Actually, what would be the point about caring about it in the first place? Biological systems are composed of many levels. We care about them because when these levels are analyzed, it’s possible to relate the levels not only to each other, but the whole system. All of our videos tend to focus on one or more of these levels which is why we have chosen to make this our first video in our biology playlist. The first level that we are going to start with is the most basic, living level that makes up all of life. It is…the cell. Can something be smaller than a cell? Sure. For the cells that contain organelles, the organelles are obviously smaller than the cell they are contained in. Biomolecules are smaller than cells. We learn about biomolecules as they are major, nonliving components within cells. Atoms are smaller than a cell. You can even get smaller than atoms when considering subatomic particles. But for this video, we’re going to start at the cellular level, a basic living unit. It doesn’t matter whether you’re a bacterium, arcaheon, fungus, protist, plant, or animal---if you’re alive, you are made up of cells. When you have a lot of cells that work together for a combined function, you end up with the next level: tissues. An example of tissue includes cardiac muscle tissue, which would be made up many cardiac muscle cells. Tissues make up organs, which is our third level. You have a lot of organs in your body. An example of an organ would include your heart. When you have multiple organs working together in a body, you end up with an organ system. Consider the digestive system. It includes your stomach, the small intestine, the large intestine, liver, etc…these particular organs work together to help you digest your food and use food for the energy you need for all kinds of cell processes. The digestive system is just one example of an organ system. But tie in all of the organ systems and what do you get? An individual. An organism. Like you! Or, this platypus. He’s got organ systems too. Put many platypus together…what’s the plural of platypus…according to dictionary.com, you can say platypi which sounds especially fancy…and you have a population. This population of platypi can breed with each other. They’re all the same species. It’s a platypi population. That’s a great YouTube channel name right there. But include other populations such as fish, algae, and plants along with the platypi and now you have a community. A community includes many populations, but it does not include abiotic features. Abiotic features are features that are nonliving. Like rocks. Abiotic factors are NOT considered in the community level, just biotic factors. Biotic factors, on the other hand, are living. When abiotic factors are considered, such as the rocks, the temperature of this environment, the water, and the biotic factors such as all the organisms we mentioned before, now we have an ecosystem. Well it turns out that many ecosystems can be found in different regions on the globe. If talking about this collectively, you are at the level of biome. An example is a desert biome or a rainforest biome. You will find desert ecosystems or rainforest ecosystems in multiple places on the globe. When talking about a desert biome or rainforest biome, you are considering these ecosystems. What happens when you put all the biomes together? You are now considering our planet, the Earth---which talking about the level of biosphere. The biosphere is the sum of all of these biomes---all the areas where organisms live. We’re finished with our tour of the biological levels of organization, but this is just an overview. The more biology you learn, the more you will discover how these levels relate to each other…and the whole system. That’s it for the Amoeba Sisters and we remind you to stay curious!