Interacting Populations

MS-LS2-4. Construct an argument supported by empirical evidence that changes to physical or biological components of an ecosystem affect populations. [Clarification Statement: Emphasis is on recognizing patterns in data and making warranted inferences about changes in populations, and on evaluating empirical evidence supporting arguments about changes to ecosystems.]

Learning Target

Construct an argument supported by empirical evidence that changes to physical or biological components of an ecosystem affect populations.

Success Criteria

Questions to Ponder

How are mice and lions similar to each other?
What is a Food Chain?
What is a Food Web?

"The Cirrrr-cle! The Circle of Life...."

Food Chains

Food Chains show a simple relationship between producers and consumers. Try the following game to learn the basics.

Click me to find out about Food Chains

Food Webs

A more detailed version of what is happening in any ecosystem is a food web. Play the following game to learn about the interactions described in a food web.

Click me for the Food Web Game

Read and Take Notes

Read the following article and take notes about food chains and food webs.
Look for the differences between Food Chains and Food Webs.

Click me for the Article

Trophic Levels

Autotrophs vs. heterotrophs

Organisms get their food in one of two ways:

Autotrophs (or producers) make their own food using light or chemical energy. Examples of autotrophs include plants, algae, and some bacteria.
Heterotrophs (or consumers) get organic molecules by eating other organisms or their by-products. Animals, fungi, and many bacteria are heterotrophs. Specialized heterotrophs, called decomposers break down dead organic material and wastes.

Each of the categories in the image to the right is called a trophic level, and it reflects how many steps separate an organism from the food chain's original energy source, such as light. However, in most ecosystems, energy flow is much more complicated than a chain. In this case, a food web can be used to represent these feeding interactions between trophic levels.
In your science notebook create a food web using the organisms in the pyramid. Draw arrows to represent the flow of energy. (arrows show the direction of energy from producer to consumer)

Food Chain and Food Web Questions

Click the Link to show your understanding of food chains and food webs. Use your notes and your experiences to answer the questions.

Click me to Demonstrate Your Understanding!

Interacting Populations

Different species in a community can have a great affect on each other. In this activity you will find a graph that charts the birth rate and death rate of two populations that live on a small island.

Complete the Interacting Populations Activity. Use the graph to answer the 5 questions.
Read this article about the Aleutian Islands, Alaska
Add the following terms to your two-column notes on Ecology*:

limiting factor
carrying capacity

Ecology

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