Alaska Science
Key Element A9

A student who meets the content standard should understand the transfers and transformations of matter and energy that link living things and their physical environment from molecules to ecosystems (Flow of Matter and Energy).

Performance Standard Level 3, Ages 11–14

Students create an ecosystem and explain physical and chemical changes that take place as energy flows and matter cycles within that ecosystem.

 

Sample Assessment Ideas

• Students use role play to demonstrate a food web that consists of at least five organisms; discuss interrelationships and how each organism contributes to the survival of the others.

Expanded Sample Assessment Idea

• Students create a model biosphere and explain the physical and chemical changes taking place within each component.

Procedure

Students will:

1. Create a total living environment that includes producers, consumers, and decomposers. (Bottle Biology describes several terrestrial and aquatic biospheres made with recycled soda-pop plastic bottles.)

2. Record observations made with naked eye, hand lens, and microscope, as appropriate.

3. Create a visual display (such as a poster, 3-D model, computer graphic, or computer simulation) that describes the cycling of matter and flow of energy in their biosphere.

Reflection and Revision

How would the biosphere have been affected if you started it with twice as many producers? Predict the effect of removing one of the organisms. Predict the effect of damaging one of the components? What would change if the model biosphere was located inside a spaceship?

Levels of Performance

Standards Cross-References
( Alaska Department of Education & Early Development Standards)

National Science Education Standards

Populations of organisms can be categorized by the function they serve in an ecosystem. Plants and some microorganisms are producers–they make their own food. All animals, including humans, are consumers, which obtain food by eating other organisms. Decomposers, primarily bacteria and fungi, are consumers that use waste materials and dead organisms for food. Food webs identify the relationships among producers, consumers, and decomposers in an ecosystem. (Page 157)

For ecosystems, the major source of energy is sunlight. Energy entering ecosystems as sunlight is transferred by producers into chemical energy through photosynthesis. That energy then passes from organism to organism in food webs. (Page 158)

The number of organisms an ecosystem can support depends on the resources available and abiotic factors, such as quantity of light and water, range of temperatures, and soil composition. Given adequate biotic and abiotic resources and no disease or predators, populations (including humans) increase at rapid rates. Lack of resources and other factors, such as predation and climate, limit the growth of populations in specific niches in the ecosystem. (Page 158)

Benchmarks

Food provides molecules that serve as the fuel and the building material for all organisms. Plants use the energy from light to make sugars from carbon dioxide and water. This food can be used immediately or stored for later use. Organisms that eat plants break down the plant structures to produce the materials and energy they need to survive. (Page 120)

Over a long time, matter is transferred from one organism to another repeatedly and between organisms and their physical environment. As in all material systems, the total amount of matter remains constant, even though its form and location change. (Page 120)

Energy can change from one form to another in living things. Animals get energy from oxidizing their food, releasing some of its energy as heat. Almost all food energy comes originally from sunlight. (Page 120)