What do all living things need to live? They need energy! Where do plants get their ENERGY from?

The flow of energy starts with the sun. It moves next to plants (The PRODUCERS.)

Producers

Plants use the energy of the Sun to make their own food. This process is called PHOTOSYNTHESIS. During photosynthesis they produce starch. Starch is food and is now available for animals to eat. Energy has moved from the Sun to plants and animals.The energy in plants and animals is now in the form of chemical energy(food). Producers (plants) photosynthesize and produce their own food.

Energy moves from producers to animals (CONSUMERS.)

Animals such as squirrels, leaf eating insects and butterflies all eat plants they are called HERBIVORES. They are consuming (eating) the plants we call them PRIMARY CONSUMERS. Animals which eat other animals are called CARNIVORES. We call these animals SECONDARY CONSUMERS.

The plants and animals die. Their stored energy remains.
  In millions of years they become fossil fuels which we use - Coal - Petroleum - Natural Gas

Energy in an ecosystem flows in a food chain.  Producers (plants) get their energy from the sun.  Primary consumers eat the plants.  Secondary consumers eat the primary consumers. As these organisms die DECOMPOSERS (bacteria, fungi) make soil for new plants(producers.)

For example:
   ^{* sun tree leaves  caterpillar  bird cat}

    ^{* sun  wheat  mouse   snake hawk}

    ^{* sun  grass   gazelle   lion   bacteria}

But look how complicated life can be!
 

This is an example of a FOOD WEB

Each ecosystem has its own unique set of animals and plants. The most important thing to remember about food chains and webs is that energy flows from the producers and through each consumer.
 
 
 

Energy enters an ecosystem from the Sun and exits after everyone has taken as much as they need. When organisms are done with the energy, they release it back into the biosphere as heat.

http://www.kapili.com/biology4kids/eco/cycle.html
 

FOR THE GEPA:
A STUDENT SHOULD KNOW THAT:

A. PERSONAL AND SOCIETAL ACTIVITIES IMPACE THE ENVIRONMENT
    1. Natural systems are affected by human activity.
    2. Human activities cause lasting effects in the environment upon which all life depends.
    3. Some human activities have led to extinction of numerous species of plants and animals, primarily through habitat destruction.

B. HUMAN PRACTICE AFFECTS THE USE AND MANAGEMENT OF NATURAL RESOURCES.
    1. Through increased awareness of ecological interactions, humans have attempted to prevent continued disruption of the environment and to counteract the results of many of their past negative practices.

C. INDIVIDUALS AND GROUPS MAY HAVE DIFFERING POINTS OF VIEW ON ENVIRONMENTAL ISSUES.

D. IN AN ECOSYSTEM, LIVING COMMUNITIES AND THEIR PHYSICAL ENVIRONMENT FUNCTION TOGETHER AS AN INTERDEPENDENT AND RELATIVELY STABLE SYSTEM.
    1. Living organisms interact with each other and their environment to form an ecosystem.
    2. An ecosystem includes relationships that cycle and recycle materials between organisms and their environment.  *
    3. An ecosystem must contain a constant supply of energy which is available to all organisms within the ecosystem.  The energy must flow from organism to organism through a food web.  *
    4. Ecosystems are systems that are constantly changing resulting in changes to the makeup of the community.  *
        a. Lake recession, e.g., lakes naturally fill in with silt over time eventually resulting in a forest.
        b. Old field succession, e.g., a series of changes that goes from grass to forest.

THE STUDENT SHOULD BE ABLE TO:

Explain how organisms are affected by different components and changes in an ecosystem.
Predict the effect of a particular pollutant on a given component of an ecosystem.
Infer possible causes of environmental damage.
 

Links:
http://edu.leeds.ac.uk/~edu/technology/epb97/forest/azfoodcw.htm
http://www.brainpop.com/science/ecology/foodchains/