The biosphere is the part of the Earth in which life exists. It is 20 km thick, from the bottom of the ocean to the lower atmosphere. It consists of three layers: the lithosphere, which is the land on the surface of the Earth; the hydrosphere, which comprises the water on Earth as well as water vapor in the air; and the atmosphere, which is made up of the air that surrounds the Earth.
The living organisms in the biosphere interact and affect each other in many ways. This is called a biotic factor. Similarly, non-living elements have an effect on living organisms, which are considered abiotic factors. Examples of abiotic factors include air, temperature, water, soil, light, and minerals.
In a biosphere, organisms live in special groupings. For instance, a population consists of all individuals of a species living in a general area. A community is a population located in a certain area living among different species. An ecosystem is yet a larger conglomeration of a population, a community, and abiotic factors. Ecosystems can be aquatic or terrestrial.
The Earth’s aquatic ecosystem makes up about 75% of the Earth’s surface. This aquatic environment is divided into marine and freshwater environments. The Earth’s terrestrial ecosystem is mainly made up of forests and deserts, which make up 25% of the Earth’s surface. The role or function of an organism in a community is that organism’s niche. An organism’s niche is an area chosen by that organism based on physical factors such as temperature, light, oxygen, and carbon dioxide content, as well as biological factors such as food, competition for resources, and predators.
This niche provides an organism with a place to live. A habitat remains consistent with an organism’s niche and provides a place for reproduction. Organisms may have the same habitat but different niches. There are three types of relationships involving interactions between organisms: mutualism, commensalism, and parasitism.
Mutualism is a relationship where both organisms benefit from their interaction with each other. An example is the honey bee and a flowering plant. Commensalism benefits only one organism, but the other organism is not affected. Parasitism benefits only one organism and harms the other organism, which most of the time is the host.
In the ecosystem, matter and nutrients are cycled via biogeochemical cycles such as water, carbon dioxide, nitrogen, and phosphorus. The burning of fossil fuels contributes to the industrial cycle of carbon dioxide in the atmosphere, which contributes to the greenhouse effect and global warming. Nitrogen is found in the atmosphere and makes up about 78% of the Earth’s air mixture.
Oxygen makes up about 22% of the Earth’s air mixture, and pollutants make up about 1%. Nitrogen is important in the development of organisms on Earth as they make compounds such as proteins and amino acids. These compounds are crucial to the formation and sustenance of life, including DNA and other important compounds. Changes in an ecosystem are brought about by various factors, such as ecological succession, which replaces one community with another.
In other instances, organisms that colonize an area with no community present are considered pioneer organisms. A climax community is the final stage of development of organisms and can be disrupted by a major catastrophe, such as a volcanic eruption.
