Unit Overview
Food Chain
A food chain shows how each living thing gets its food. They are a link of relationships between predators and prey within a certain ecosystem or habitat. Food chains serve as a method for ecologists, and people in general, to understand the interactions of species they observe in nature. The food chain shows the transfer of energy from one living thing to another. These living things need energy in order to survive and most find it in the form of food while others can survive just from the energy they receive from the sun. Every food chain begins with the sun. Solar Energy The base of the chain/web, there is solar energy. Organisms that produce their own food utilize the solar energy. These organisms are called autotrophs. The process autotrophs use to make their own food is called photosynthesis. This process converts carbon dioxide into sugars or organic compounds that can be used as food. Energy from the sun flows from each organism to the next, and at each level some energy is lost. Autotrophs Autotrophs are the organisms that produce their own food using photosynthesis and are also called producers. If there were no autotrophs, there would be no life on this planet. Examples of autotrophs are algae and plants. Heterotrophs Heterotrophs are organisms that cannot make their own food and are also known as consumers. In order to survive, heterotrophs must consume other animals to get energy. Examples of heterotrophs are deer, bears and dogs. Heterotrophs are further divided into four groups based upon what they eat. These groups are: decomposers, herbivores, omnivores, and carnivores. Herbivores are organisms that are primary consumers and feed on only plants. Carnivores only feed on other animals. Omnivores feed on both plants and other animals. Decomposers are bacteria and fungi that feed on decaying matter. These decomposers speed up the decaying process that releases mineral salts back into the food chain for absorption by plants as nutrients. Trophic Levels Trophic levels are the steps in the transfer of energy in the food chain and web. The main trophic levels are heterotrophs and autotrophs, or producers, consumers and decomposers. The first trophic level is the producer. The producers get most of their energy from the sun and make their own food so it can be provide energy for another organism that consumes it. The next trophic level is then the consumers, or the organisms that eat the producers. Lastly there are the decomposers. The decomposers feed on any dead material and break it down into nutrients or fertilizers for the soil. Conservation of Energy One very important thing about the food chain is that the energy is constantly “recycled” and never lost. This is called the principle of conservation of energy, which simply states that energy cannot be created or destroyed. Energy is constantly being transferred from one organism to another. Interdependence Since the food chain is a cycle, each organism involved depends greatly on another organism for their source of energy because without it they will die. If there were no producers, then every consumer would die off. If there are no more consumers, then the decomposers have nowhere to get energy either so they all die too. If there are no decomposers, there are no nutrients given back to the soil so the producers cannot grow. Everything on the food chain is dependent on something else and that is called interdependence. Food Webs Most organisms, similar to humans, do not get their energy from just one food source. Humans eat both chicken and beef so their food chain is more complex. That is when we use a food web. A food web displays an organism getting its energy from multiple organisms and those organisms getting their energy from multiple organisms as well. |
Common Core Reading 6th:
Determine a central idea of a text and analyze its development over the course of the text, including how it emerges and is shaped and refined by specific details; provide an objective summary of the text.
Science Standards 6th:
6.1a Energy flows through ecosystems in one direction, usually from the Sun, through producers to consumers and then to decomposers. This process may be visualized with food chains or energy pyramids.
6.1b Food webs identify feeding relationships among producers, consumers, and decomposers in an ecosystem.
6.1c Matter is transferred from one organism to another and between organisms and their physical environment. Water, nitrogen, carbon dioxide, and oxygen are examples of substances cycled between the living and nonliving environment.
Determine a central idea of a text and analyze its development over the course of the text, including how it emerges and is shaped and refined by specific details; provide an objective summary of the text.
Science Standards 6th:
6.1a Energy flows through ecosystems in one direction, usually from the Sun, through producers to consumers and then to decomposers. This process may be visualized with food chains or energy pyramids.
6.1b Food webs identify feeding relationships among producers, consumers, and decomposers in an ecosystem.
6.1c Matter is transferred from one organism to another and between organisms and their physical environment. Water, nitrogen, carbon dioxide, and oxygen are examples of substances cycled between the living and nonliving environment.