Chapter 2.2 Flow of Energy in an Ecosystem Notes
Energy in an Ecosystem The ______is the original source of energy for EVERY SINGLE organism on this planet
One way to study an ______is to follow the energy that flows through the ecosystem • Organisms differ in how they obtain energy. The two ways to obtain energy are to be an ______or to be a ______. o Autotroph: organisms that produce their own food. Green plants, algae and some bacteria are autotrophs because they make their own food. There are two ways to be an autotroph- through ______or ______. Chemosysnthesis: the process of using inorganic substances to make ______for the cell. • Some bacteria, like those found in deep sea vents, that do not have access to sunlight do this process Photosynthesis: the process of using the Sun’s energy to make ______, an energy source for the cell. • Plants, algae, and some bacteria do this process
o Heterotroph: an organism that meets its energy requirements by consuming other organisms. There are 6 basic types of heterotrophs ______: a heterotroph that eats only plants or algae ______: a heterotroph that preys on other heterotrophs ______: a heterotroph that eats other heterotrophs and autotrophs ______: a heterotroph that feeds on dead organisms. Think hyaenas and vultures. ______: heterotrophs that consume fragments of dead organisms AND return nutrients to the soil, air, and water where they can be reused by organisms. • Examples include worms and aquatic insects that live on stream bottoms ______: heterotrophs that consume dead organisms AND return nutrients to the soil, air, and water where they can be reused mostly by ______. They do this by releasing digestive enzymes and absorbing what they have broken down. • Examples are mostly limited to bacteria and fungi
Why are detritivores and decomposers important to an ecosystem? 1.
2.
Models of Energy Flow
Ecologists use ______and ______to model the energy flow through an ecosystem. Like any model, food chains and food webs are simplified representations of the flow or energy. • Food chain: a simple model that shows how energy flows through an ecosystem. o The ______in a food chain represent the one-way energy flow, which typically starts with autotrophs and moves to heterotrophs. o Each organism uses a portion of the energy it obtains from the organism it eats for cellular process (to build new cells, maintain or repair existing cells). o The remaining energy is released into the surrounding environment as heat or wastes, and is no longer available to these organisms • Food webs: a model representing the many interconnected food chains and pathways in which energy flows through a group of organisms. o Feeding relationships are usually more complex than a single food chain because most organisms feed on more than one species.
• ______: another model ecologists use to show how energy flows through ecosystems. There are three types o ______: each level represents the amount of energy that is available at the next trophic level. With each step up, there is an energy loss of ______. This means that only ______of the available energy is passed to the next level. The numbers in this pyramid never change-they are the same for ALL ecosystems o ______: each level represents the amount of biomass consumed by the level above it. ______: the total mass of living matter at each trophic level. Biomass decreases at each trophic level because there is ______available to support organisms The numbers in this pyramid can change depending on the size and type of ecosystem it is modeled after o ______: each level represents the number of individual organisms consumed by the level above it. The numbers in this pyramid can change depending on the size and type of ecosystem it is modeled after The number of organisms decreases at each trophic level because there is ______available to support organisms
• ______: each step in a food chain or food web. o Autotrophs make up the first level in all ecosystems, and therefore all food chains and food webs. o Heterotrophs make up the remaining levels o With the exception of the first trophic level, organisms at each trophic level get their energy from the trophic level before it. Where does the first trophic get its energy from?