GRADE: Fourth

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:

1.01 define a producer, a consumer, and a decomposer.
1.02 give examples of producers, consumers, and decomposers.
1.03 define food chain/food web
1.04 explain how the success and survival of one living thing in an environment can depend on the success and survival of one or many living things

I. Terms
A. Producer
B. Consumer
C. Decomposer
II. Examples
III. Food Chains/Webs
A. Host
B. Parasite
C. Predator
D. Prey

TN COMPONENT OF SCIENCE: Science In Society

TN GOAL:

To enable students to demonstrate attitudes toward science in solving problems and making personal decisions about issues affecting the individual, society, and the environment.

4.2 PERSONAL NEEDS - The application of science may be used to change the quality of life for the individual

4.2c - Science solves practical problems but may create new problems and needs for an individual.

BENCHMARK: All factors must be considered when determining solutions to problems. A solution to one problem may create other problems.

TIME REQUIRED:

Two class periods

Video, pictures of food chains and food webs

For an ecosystem to be stable and self-sustaining certain conditions must exist. There must be a constant source of energy. Almost all earth ecosystems get their energy from the light of the sun. There must be organisms in the system that can use the incoming light from the sun to make organic compounds. Green plants and producers fill this role in an ecosystem. There must be a cycle of materials between living organisms in the ecosystem and the environment. Producers take inorganic compounds from the environment and make organic compounds which can pass through the food chain or food web. In every ecosystem, there is a pathway of energy flow that always begins with the producers. Producers make organic nutrients which are transferred to consumers when the plants are eaten.

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:

Plants and/or animals die resulting in dead organisms.
Decomposers, such as bacteria, then break down the dead organisms into simple compounds ready for use by plants and the cycle starts over.

Now you think of a food chain that contains at least a producer, a herbivore, and a carnivore and write it for one food which you had for breakfast. Example: eggs
Sun; Grass (grain); Chicken ( eggs); You

This is the time this file has been accessed since 07/01/97.

The University of Tennessee at Martin is not responsible for the information or views expressed here.

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