GOALS:

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

The area where an organism lives must provide it with its basic life requirements.

Ecology C3.00 To understand the similarities that exist within systems from the lowest to the highest level of organization

3.01 identify various ways producers and consumers, and the spatial and nutritional factors of the environment can be upset.

I. Factors that upset an ecosystem
A. Pesticides
B. Wastes
C. Overcrowding
II. Comparison of tundra and swamp ecosystems

COMPONENT OF SCIENCE: Process of Science

GOAL:

To enable students to demonstrate the processes of science by posing questions and investigating phenomena through language, methods and instruments of science.

1.5 EXPLAINING - Phenomena and related information are made understandable through discussion that culminates in a higher level of learning.

1.5a Tables and graphs may be used to interpret the meaning and significance of data.

BENCHMARK: Data in maps, charts and graphs may be used to answer questions.

1.5b Nonmathematical language may be used to interpret the relationships presented in mathematical form.

BENCHMARK: Formulation of appropriate generalizations is warranted by the relationships found among data.

1.5c Information should be related to prior knowledge.

BENCHMARK: When interpreting results of new experiments the results are generalized to a scientific theory.

TIME REQUIRED:

Two 50 minute class periods

Reference books, graph paper

Cycles, pesticides, producer

This classroom connector addresses Instructional Objective 3.01.

Have you ever wondered why communities change? (response) Have you heard your parents talk about where they lived when they were your age? (response) Did the house seem big to them and then when you returned with them years later, it seemed small? (response) People change, places change, ecosystems change. From the highest to the lowest levels changes are taking place. Space and nutrients are required by every living thing. We will study how these factors can be upset.

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. A few ecosystems are based on chemosynthesis, deriving energy for synthesis of organic nutrients from chemical reactions with various inorganic compounds. 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. Eventually decomposers break down remains of dead organisms, releasing the inorganic compounds back into the environment for reuse.

Overcrowding is one spatial factor. When the number of organisms increases so there is not enough food, weaker organisms die. Finally enough die or move elsewhere so that numbers again balance. In cases where there are no predators, other problems are created. If there are no natural enemies, then there are breaks in the Food chain.

Wastes and pesticides create problems for populations. Living things such as insects sometimes interfere with our plans. Termites might attack our house or a virus might kill our tomatoes in the garden. We immediately search for a pesticide to kill the insect or a fungicide to get rid of the tomato virus. One of the serious considerations is how does this pesticide affect our environment? (pause)

Mass spraying of large areas with pesticides can destroy an entire ecosystem. Larger insects that prey on smaller ones may also be killed. So humans make the problem worse. Insects become immune to pesticides and some generations of insects may develop immunity to them. Some pesticides remain in the food chain and their effects become magnified. (Active Participation: Surviving Pelican Game)

In nature, certain kinds of plants grow best in certain areas. A given area can support a certain amount of plant life because of space and nutrients needed by the plants. One limiting factor is the amount of water and minerals in the ground. Another factor is space available for plants to grow and flourish. Another factor is the amount of light that reaches the plant for photosynthesis to occur. If plants in an area become too great in number or too large, some of the plants may die. Others will live but will not be as healthy as they should be.

Factors necessary for plant life are present in limited amounts in any area. Plants must compete with one another for those factors. Plants that survive are adapted for that environment. Others might be better able to survive in a different kind of environment. (Active Participation: Plant Competition)

We have studied how pesticides and competition affect the numbers and kinds of organisms. In the next activity we will compare a tundra and a swamp to see if the same relationships exist in basic and advanced systems of the biosphere. By comparing abiotic and biotic factors in each system, we should find some similarities and differences. (Active Participation: Comparison of Tundra and Swamp Ecosystems)

Purpose: This game will show you how harmful chemicals can remain in a food chain in a freshwater ecosystem.

Materials: deck of cards, pencil or pen

Procedure:


1. Each student draws a pelican to use in the game.

2. Discard the jokers from a deck of cards. Label 30 cards as algae, 15 cards as little fish, 7 as big fish. (Disregard the numbers and suits of the cards, or make your own cards from poster board.)

3. Shuffle the deck and place it face down in the middle of the players. Four is a good number for a group.

4. The game is played according to who eats whom. Algae eat nothing. Little fish eat algae. Big fish eat little fish. Pelicans eat only big fish.

5. First player draws a card and turns it over. If the card is algae or little fish, it remains in front of the player. If it happens to be a big fish, the next player will not draw a card, but will use his turn by having his pelican eat the big fish (take it) and remove it from the gams. (Put the big fish card aside.)

6. The next player turns over a card (if his pelican did not eat). If a little fish is drawn, it must take all untaken algae which has been drawn. Stack the algae cards with the little fish on top in front of the players.

7. If a player turns over a big fish, it must eat all the little fish in front of the other players as well as the algae the little fish ate.

8. After a big fish has eaten, the next person's pelican must eat whatever fish are showing, including little fish and algae. These cards are taken from in front of the players and kept aside out of the game, by the student whose pelican ate them.

9. After all cards are played and taken, each person counts how many doses of pesticide (how many cards) his pelican has eaten. The pelican who has eaten the most has to drop out of the game. Surviving pelicans shuffle the cards and play as many rounds as needed until there is a final survivor.

10. Each group plays for a final survivor. Play-offs can be held with the pelicans until one survivor is found.

Questions:

1. How does chance play a part in this game?

2. How may chance play a part in the real world?

3. If algae absorb one unit of a chemical, than how much does each little fish take in? How much does each big fish take in? How much does each pelican take in?

Purpose: How do plants compete?

Materials: mowed lawn containing plantains or dandelions, ball of string, meter stick, dandelion digger

Procedure:


1. Choose an area within a mowed lawn that contains a healthy dandelion or plantain. Place a piece of string to form a circle that is just large enough to include all the plant's leaves, around the plant.

2. Without moving the string, carefully use the dandelion digger to remove the dandelion. Do not disturb the grasses. Describe the appearance of the lawn where you removed the dandelion. (question 1 - data)

3. After you remove the plant, count the number of grass plants remaining within the circle of string. One plant includes clump of leaves on one stem. Record the number in data chart under weed 1.

4. Pick up the string and measure its length with a meter stick. Record the length, or measure the circumference of the circle and record.

5. Repeat these procedures for five other weeds and record data.

6. Determine the average number of grass plants in each circle. Determine the average circumference of the circles formed around the plants. Record data in the average column.

7. On a small grassy area that contains no dandelions or plantains, use the string to lay out a circle with the average circumference you calculated. Count the number of grass plants in this circle. Record in question three.

Data:

l. What did the lawn look like where you removed the plant?

2.

Weed 1

Weed 2

Weed 3

Weed 4

Weed 5

Weed 6

Average

Number of grass plants

Circumference

3. In the grassy area where there were no plantains or dandelions, how many grass plants did you count inside the circle?

Conclusions:

1. How can you explain the appearance of the lawn in places where you removed?

2. Would you consider plantains or dandelions to be weeds in a lawn?

3. Do you think the dandelions were in competition in the areas you studied? Why?

4. Do you think grasses would grow in an area occupied by dandelions if dandelions were not there? Explain.

5. Considering the factors necessary for plant life - water, air, minerals, and light, which was the main factor involved in the competition between dandelions and grasses? Why?

6. What structural factors do dandelions and plantains have that helps them compete successfully with grasses?

7. Makers of weed killers for broad-leaved weeds say that the weeds should be moist before being treated. Why do you think this moisture helps to kill the weeds?

8. Why do you think some people prefer to use a weed killer rather than pulling the weeds by hand?

Enrichment:

1. Observe a weed patch along a road, in a ditch, or along an alley. What weeds seem to be the most successful?

What structural characteristics enable them to compete successfully?

2. Observe a lawn on a sunny side of a building and on the shady side of a building. Compare the types of weeds on the shady side with the weeds on the sunny side. Are the same types of weeds growing in both shady and sunny areas?

Purpose: To compare the biotic and abiotic factors of a tundra and swamp.

Materials: reference books, magazine articles (National Geographic)

Procedure:


1. Make a chart listing the factors you will need to find.

2. Using references, find and record data.

3. Compare data recorded to find how plants and animals are suited to each ecosystem.

Data:

Tundra

Swamp

Abiotic Factors
water

oxygen

light

temperature

soil

nutrients

Biotic Factors
plants

animals

protists

Choose a specific tundra and specific swamp if you are using reference books or articles and it will help in the research.

Conclusions:

1. What similarities did you notice in the swamp and tundra?

2. What differences did you notice?

3. What factors do you think cause these differences?

Enrichment:

1. Graph data showing average rainfall monthly in the tundra of Soviet Union and the Everglades of Florida.

2. Graph data comparing temperature of a tundra and swamp monthly.

3. Graph data comparing nutrients.

Now that we have completed three activities, based on our charts and data what factors have we studied that can upset an ecosystem? (Pesticides - staying in the food chain, overcrowding - in the dandelion count, lack of abundance of abiotic factors in swamp or tundra ecosystem) Do communities change? (response) What factors can you list that cause change? (Water, temperature, nutrients)

cycles - recurring of events in a regular pattern

pesticides - chemical agent used to destroy pests

producer - organisms which produce their own organic compounds

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

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

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