Notes on Biogeochemical Cycles and Ecology.pdf

you had Biology 101, this should be review; if you had Geology 101, this is new stuff.Either way, it is pretty basic and you shouldn't have much trouble reading thismaterial or the associated material in the text.Roles of OrganismsOrganisms can be either producers or consumers in terms of energy flow through anecosystem. Producers convert energy from the environment into carbon bonds, suchas those found in the sugar glucose. Plants are the most obvious examples ofproducers; plants take energy from sunlight and use it to convert carbon dioxide intoglucose (or other sugars). Algae and cyanobacteria are also photosynthetic producers,like plants. Other producers include bacteria living around deep-sea vents. Thesebacteria take energy from chemicals coming from the Earth's interior and use it tomake sugars. Other bacteria living deep underground can also produce sugars fromsuch inorganic sources. Another word for producers is autotrophs.Consumers get their energy from the carbon bonds made by the producers. Anotherword for a consumer is a heterotroph. Based on what they eat, we can distinguishbetween 4 types of heterotrophs:consumer trophic level food sourceHerbivores primary plantsCarnivores secondary or higher animalsOmnivores all levels plants & animalsDetritivores --------------- detritusA trophic level refers to the organisms position in the food chain. Autotrophs are atthe base. Organisms that eat autotrophs are called herbivores or primary consumers.An organism that eats herbivores is a carnivore and a secondary consumer. Acarnivore which eats a carnivore which eats a herbivore is a tertiary consumer, and soon. It is important to note that many animals do not specialize in theirdiets. Omnivores (such as humans) eat both animals and plants. Further, except forsome specialists, most carnivores don't limit their diet to organisms of only onetrophic level. Frogs, for instance, don't discriminate between herbivorous andcarnivorous bugs in their diet. If it's the right size, and moving at the right distance,chances are the frog will eat it. It's not as if the frog has brain cells to waste wonderingif it's going to mess up the food chain by being a secondary consumer one minute anda quaternary consumer the next.