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5.1 Communities and Ecosystems

By Greyson Piesco

Words to Know! Â

Species: a group of organisms that can interbreed and produce fertile offspring. Habitat: the environment in which a species normally lives or the location of a living organism. Population: a group of organisms of the same species who live in the same area at the same time. Community: a group of populations living and interacting with each other in an area. Ecosystem: a community and its abiotic environment. Ecology: the study of relationships between living organisms and between organisms and their environment. Autotroph: an organism that synthesizes its organic molecules from simple inorganic substances. Heterotroph: an organism that obtains organic molecules from other organisms. Consumer: an organism that ingests other organic matter that is living or recently killed. Detritivore: an organism that ingests non-living organic matter. Saprotroph: an organism that lives on or in non- living organic matter, secreting digestive enzymes into it and absorbing the products of digestion.

Energy Transfer Between Trophic Level: the position of an organism on a food chain or web. Ex.: Producers, Primary Consumers, Secondary Consumers, Tertiary Consumers A food chain is a tool used to visually map the flow of energy from one organism to another. Ex.: Cabbage Plant -> Mouse -> Snake -> Hawk   A -> B indicates that A is being eaten by B and therefore transferring its energy to it

A food web is a more complex version of a food chain. It maps the flow of energy within a community. It has arrows, like a food web, showing the transferring of energy and the feeding habits within a community. It has many animals. It also has multiple arrows to and from animals.

A -> B -> C B eats A and gets its energy, however only about 10% of A’s energy is transferred to B (this is true between all trophic levels). This means energy is lost between trophic levels. Energy flows in the following order: from producers, to primary consumers, to secondary consumers, to tertiary consumers. Note: Light is the initial energy source for almost all communities.

It all starts here!

Pyramids of Energy

The bottom would be the producer, the middle would be the primary consumer, and the top the secondary consumer. It is clear that only roughly 10% of the energy is transferred to the following tropic level. Â

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Topic 5.1 Piesco