The Biosphere of Earth: The Organization of the Living Planet

In the study of biology one of the key concepts that you must understand is what a biosphere is and how it is organized. A biosphere is the combination of air, land, and water that is found at the surface of the earth where all living organisms are. The biosphere is then broken down into smaller parts in order to classify different organisms according to where they live and how they live.

From smallest to largest, the biosphere is organized by population, community, and ecosystem. A population in a biosphere is all members of a species that are currently living in a particular area. So for example, all of the Bears that live in a specific forest would be considered a population since they are all in the same area. The next level up in classification is a community. A community shows how these populations then interact with each other. An example of this, can be seen by looking at a particular area where animals such as fish, birds, and mammals all live together. Finally and ecosystem combines the previous two categories with the physical environment. So for example if those same animals discussed in the community section were living in a particular lake that would be classified as an ecosystem, because it shows how all of these different animals and organisms are living together with the lake. Different ecosystems are found in different places depending on the climate of the biosphere. So for example, there'd be different ecosystems in places with little rain then there would in places where rainfall is heavy.

Ecosystems are characterized in two main ways: chemical cycling and energy flow. Chemical cycling shows the process in which chemicals move throughout the food chain. So for example, if a small organism is eaten by a large organism, then the larger organism will consume the chemicals that were within the smaller organism. This process continues all throughout the food chain as smaller animals are constantly the prey for larger animals. Energy flows describes how different animals receive their energy. For example, the sun shines and plant life uses that light for photosynthesis in order to produce food, or energy, for themselves. Animals that eat these plants then receive energy through the consumption of the energy that the plans had previously produced. Energy is a key part of all life and it does not cycle. Without continuous solar energy in the photosynthesis that allows to happen, larger animals would not have any chance to receive energy themselves.

Source:
Benitz, Bill. Lecture: Biology. September 7, 2009