|Environmental Science||Habitats/Ecosystems/Biomes 4H1.00||Science In Society||Personal Needs 4.2 c|
CONTENT STANDARD: Environmental Science
CONTENT TOPIC: Habitats/Ecosystems/Biomes
CONCEPT: Living things perform specialized tasks in the environment.
CONTENT OBJECTIVE: 4H1.00 To understand the differences among producers, consumers, and decomposers
INSTRUCTIONAL OBJECTIVES: The learner will:
TN COMPONENT OF SCIENCE: Science In Society
BENCHMARK: All factors must be considered when determining solutions to problems. A solution to one problem may create other problems.
Herbivores which eat plants are first level consumers. Carnivores that eat the plant eating animals are second level consumers. Many consumers have a varied diet and fit in several places in the food chain. These are called omnivores. The food chain is a series of organisms through which food energy is passed. Eventually decomposers break down remains of dead organisms, releasing the inorganic compounds back into the environment for reuse. In short, the producers make their own food. Consumers eat the foods produced and decomposers recycle nutrients back into the ecosystem.
Many food chains are interconnected at various points so food webs are formed. Decomposers play an important role because they make use of the wastes and remains of all organisms in the system. They use the energy for their own metabolism while breaking down organic compounds into inorganic ones and making substances available for reuse in the system. Decomposers are the final consumers in every food chain or food web.
At each higher feeding level the amount of energy available in a food web decreases. Only a small fraction of the energy taken in is stored as new tissue. Much of the food is not digested or absorbed. A large part of the energy in food is used for respiration and maintenance. Much energy is lost as heat. Only about ten percent of energy taken in at any feeding level is passed upward.
The pyramid of energy is the amount of available energy in an ecosystem. The greatest amount of energy is at the base of the pyramid with the producers. The least amount of energy is present at the top of the pyramid. Energy decreases steeply so there are usually no more than four or five feeding levels in an ecosystem. As the amount of available energy decreases, so does the total mass of living organisms that can be supported at each level. The representation of this relationship is known as the pyramid of biomass. The greatest amount of biomass is found in the lowest level, the producers. The least is found in the highest level of consumers. As the amount of available energy decreases, so does the number of individuals who use the energy.
There are animals in our community that are well-populated because of the lack of predators. This lack of predators alters the life-sustaining food chains. Can you name an animal population that needs predators?
Can anyone tell me the difference between a scavenger and a predator? (pause) Scavengers are organisms that feed on refuse. Give me an example. (Buzzard, crow, rat) Predators are organisms that devour other living organisms for life-sustaining food. (Cat, wolf, human) Why are scavengers important? (They help to keep our environment clean.)
The predator-prey relationship establishes a food chain with a producer, consumer and decomposer. A food chain is really an energy chain. Energy from the sun is captured by the producers and passed on to the consumers. A producer is a green plant able to make its own food by photosynthesis. A consumer is an organism that depends on producers for its food needs. A decomposer is an organism that obtains its food from wastes and dead organisms. Let us show you an example:
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