GOAL:

To develop an understanding of the interdependence of all organisms and the need for conserving natural resources

Living organisms share in a variety of complex interrelationships which are based on interdependence.

Ecology H2.00 To understand that energy does not cycle within an ecosystem

2.01 define and discuss the first and second laws of thermodynamics.

2.02 explain simply the changing of light energy to chemical energy in photosynthesis by producers.

2.03 trace the energy flow from the sun through producers, consumers, and decomposers in an ecosystem.

2.04 describe ways in which energy is used, stored, and lost from the system of living things.

I. Energy changes in the ecosystem
A. First law of thermodynamics
B. Second law of thermodynamics
II. Radiant energy to chemical energy
A. Photosynthesis
1. Light phase
2. Dark phase
B. Energy conversions
III. Release of energy
A. Movement of energy to other organisms
1. Reactions to mitochondria
2. Cellular respiration
B. Power for life processes
IV. Loss of chemical energy
A. Use of energy by organisms
B. Loss of heat energy
C. Stored energy
1. Many more producers
2. Limiting numbers on a pyramid

GOAL:

To enable students to acquire scientific knowledge by applying concepts, theories, principles and laws from life/environmental, physical and earth/space sciences.

2.4 INTERACTIONS - At all levels of living and non-living systems, matter and energy act and react to determine the nature of our environment.

2.4a Interactions occur on scales ranging from elementary particles to galaxies.

BENCHMARK: All matter at every level must in some way exchange energy.

BENCHMARK: Human interaction with the biosphere is unique in environmental impact and control.

2.4b Interactions of matter and energy shape our world.

BENCHMARK: Natural resources and ecosystem dynamica are controlled by the intercanges of matter and evergy.

BENCHMARK: Nutrient cycles result from flow of energy through an ecosystem.

TIME REQUIRED:

Firstclassroom connector - one full class period plus additional time for activities, Second classroom connector - one class period plus additional time for activities and practice.

Geranium or coleus leaves, 4 small jars or beakers, 4 larger jars with lids, Bunsen burner, tripod, water bath or pan, 5 baking soda solution, iodine, alcohol (70-100), ringstand, Anacharis (Elodea), large test tube, tube clamp, short funnel, splint, handful of bean seeds, bromothymol blue, straws, model of food pyramid.

First Law of Thermodynamics, food pyramid, photosynthesis, respiration, Second Law of Thermodynamics;

This classroom connector addresses Instructional Objectives 2.01 and 2.02.

SET:

(Have all students rub their hands together hard and fast and then place their hands against their face. Students will react to the heat.) In this activity energy has not been created nor destroyed but has changed forms. In this lesson we will study the Laws of Thermodynamics and energy changes of photosynthesis.

The First Law of Thermodynamics states that energy cannot be created or destroyed but only changes forms. In the introductory activity chemical energy in our bodies was changed to mechanical energy in our arms. Friction caused some of this mechanical energy to be changed to noticeable heat energy in our hands. We also felt some of the heat move to our cooler faces.

A practical ecological consequence of this law is that all living things must have a source of energy. The ultimate source of energy for most living things is the sun.

The Second Law of Thermodynamics states that at every energy transfer some portion of the available energy is degraded to heat which moves to cooler objects. We felt the heat in our hands move to our cooler face.

As we have learned in previous lessons producers are the only organisms that are able to take the radiant energy from the sun and change it to chemical energy in food, glucose sugar. Organisms in the environment have very poor efficiency in converting the energy they receive into usable energy or into energy which is stored and eaten by the next link on a food chain.

In the process of photosynthesis producers use carbon dioxide and water, in the presence of chlorophyll and light, to make sugar and oxygen. In the "light" phase of photosynthesis energy-rich adenosine triphosphate (ATP) molecules are formed. In "dark" phase a variety of substances required to build and maintain tissues are produced. Plants may convert as much as 75 percent of the light received into chemical energy in glucose sugar.

1. Photosynthesis, to show that light and carbon dioxide are needed.

Use four healthy young growing geranium or coleus leaves. Put the stem of each leaf in water in separate small beakers or baby food jars. Place each small container with a leaf in separate larger jars which have a lid.

To jars 1 and 3, add a 5 baking soda solution outside the small jar to a depth of about one inch. This will provide the needed carbon dioxide.

Put jars 1 and 2 in a strong light source. A 100-watt bulb about two feet from the jars for 48 hours may be used. Put jars 3 and 4 in a dark cabinet for that time.

After 48 hours dip each leaf separately into boiling water then put each leaf into a beaker of alcohol heated in a water bath or pan of hot water. (DO NOT heat the alcohol directly). Continue heating each leaf until it is colorless. Dry each leaf with a paper towel and cover it with iodine to test for starch. (The leaf with carbon dioxide and light should show the most positive results).

2. To show that oxygen is given off in photosynthesis.

Put a bunch of Anacharis (Elodea) or other water plant in a large container of water. Cover the plants with a short inverted funnel. Cover the spout of the funnel with an inverted test tube full of water. Set the experiment in a well lighted place and observe for several days. Watch for bubbles or gas displacing the water in the tube. When enough oxygen has been collected, test with a glowing splint.]

[Have students write the answers to the following questions.
1. Can energy be created or destroyed? (No)

2. This is a statement of what law? (First Law of Thermodynamics)

3. Which living things are able to convert radiant or solar energy into usable chemical energy? (Producers or plants)

4. As food moves through an ecosystem is all the energy converted into usable energy? (No)

5. This is a statement of what law? (Second Law of Thermodynamics)]

(Have students write reports or make posters about photosynthesis.)

This classroom connector addresses Instructional Objectives 2.03 and 2.04.

(Have all students look at models of food pyramids built during activities under the first Content Objective of this Strand H. Have students write the answers to these questions.)
1. What happens to the size as you move to the upper layers of the pyramid? (Each layer is smaller)

2. What happens to the numbers on the side of the pyramid as you move up from one level to the next? (They decrease by a factor of 10.)

In this classroom connector we will see how energy is used, released, and stored as food passes through an ecosystem.

Energy moves through the ecosystem as consumers eat and as decomposers decay other organisms. The energy stored in glucose may be released when organisms burn food in their cells during respiration. (Emphasize that respiration occurs in the cells of producers, consumers, and decomposers.)

These energy releasing reactions usually occur in the cell mitochondria. Oxygen is combined with glucose forming water and carbon dioxide with the release of energy. This is just opposite of the photosynthesis reaction.

The energy released by respiration is used to power the life processes of organisms including movement, growth, chemical synthesis, movement of materials in the organism, reproduction, and others. Much of the energy released in respiration is lost to the environment as heat.

1. Have students breathe on a cold glass plate or mirror. They should be able to see the water vapor from respiration condense on the cold object.

2. Have students breath through a straw into a bromothymol blue solution. The color change from blue to green or yellow indicates the presence of carbon dioxide which was produced by respiration.

3. Have students exercise vigorously for a few minutes. Observe the rapid breathing, increased heart rate, skin changes, and other evidence of increased respiration.

4. Soak a hand full of bean seeds in water over night. Place them in a large jar with a top. Put a baby food jar containing bromothymol blue beside the beans in the larger jar and close the lid. You should have a moist paper towel in the bottom of the large jar. Observe any color changes for a few days.)

As we have learned, much of the energy in the glucose which the producer made was used for its own metabolic activities. Much of this energy is also lost to the environment as heat. The energy remaining in chemicals in the producers' cells may be used by the consumers which eat them. However, only about 10 of the food energy in the plants will show up in the first level consumers, the herbivores, which eat the plants.

The rabbit, a herbivore, may eat the plant. Much of the energy in its food is converted into energy of motion; large amounts of energy are lost to the environment as heat. Some of the energy in food is never assimilated and is lost in wastes. Much of the energy is used in the rabbit's other metabolic activities. Again only about 10 of the energy received by the rabbit will be available to the second level consumer which eats it. This is only one tenth (10) of one tenth (10) which is one hundredth (01) of the plants energy.

The numbers on our food pyramid show that each successive level has only about one tenth of the energy of the previous level. Thus the higher an organism is on a food pyramid the less useful energy is available to it. Therefore there must be many more producers and very few high level consumers in any ecosystem. This loss of energy limits the number of links possible in a food chain or layers on a food pyramid.

1. What happens to the amount of energy available as you move to higher levels on a food pyramid? (It decreases)

2. On the average, it decreases how many times as you move up one level? (10)

3. How many times would the energy decrease if you moved up two levels? (100), three levels? (100), four levels? (10,000)]

[Have students show their pyramids and explain how many pounds of organisms would be necessary to provide energy for organisms at other higher levels. Use various examples: Producer-second level consumer (100), producer-third level consumer (1000), first level consumer-second level consumer (10), first level consumer-third level consumer (1000, producer-fourth level consumer (10,000), second level consumer-third level consumer (10).]

This is the time this file has been accessed since 11/16/96.

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