GOAL:

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 C2.00 To understand that an organism's habitat is affected by abiotic and biotic factors

2.01 describe the difference between abiotic and biotic factors and the importance of each.

2.02 demonstrate that the lack or excess of specific abiotic or biotic factors imposes limits upon organisms within any ecosystem.

I. Abiotic factors in the environment
A. Light, temperature, precipitation
B. Process of soil formation
II. Biotic organization
A. Populations, communities, ecosystems
B. The biosphere
C. Autotrophic and heterotrophic nutrition
D. Symbiotic relationships
E. Producers, consumers, decomposers
F. Food chains and food webs
G. Pyramids of energy and biomass

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

Video, pictures of food chains and food webs

Abiotic factors, autotrophs, biomass, biosphere, biotic factors, carnivores, commensalism, consumers, decomposers, ecosystem, food chain, food web, herbivores, heterotrophs, latitude, omnivores, mutualism, parasitism, population, predators, producers, pyramid of energy, saprophytes, scavengers, symbiotic relationships

This classroom connector addresses Instructional Objectives 2.01 and 2.02.

What are some ways that you adapt to your environment? (Turn on heat, put on a coat, eat food, go swimming) These are things you do that enable you to survive in a particular environment. How do you get food? (Buy it, grow it in the garden, parents fix it) Living things are affected by physical conditions in the environment and the living things in an environment. We are going' to examine biotic and abiotic factors in the study of' a microhabitat.

The abiotic factors determine what types of organisms can live in a particular environment. One example of this is the desert where there is very little water, and the temperature can vary from very hot to cold on a daily basis. Only plants that are adapted to conditions such as these can survive in a desert. Other plants like corn, oak trees and roses can not live under these conditions. Plants like cactus and sagebrush can survive.

Sunlight furnishes energy for all living things on earth either directly or indirectly. The amount of sunlight striking the earth's surface varies with the latitude. The intensity, duration or length of day vary with the latitude. Some flowering plants require high intensity and long days while others grow under low intensity and short days. In many animals, migration, hibernation and reproductive behavior are triggered by length of day and night.

Aquatic conditions have varying levels of light based on the amount of light penetration through the water. The presence of light determines where the producers and consumers live in the water.

Temperature patterns on the earth vary with altitude and latitude. Mountains and oceans also affect the temperature of land nearby. The poles are the coldest areas, while mountains at the equator, if they are high enough, may be covered with snowy tops.

Annual amount of precipitation is also influenced by mountains and bodies of water. Equatorial regions are humid and have heavy rainfall throughout the year. Desert regions have almost no rain at all. Temperate regions have abundant rainfall, hot summers and cold winters.

Soil is composed of organic and inorganic materials. Rock particles are broken off from larger rocks by weathering. The freezing and thawing helps to crack and break the rocks. Bacteria, fungi, lichens and other soil-formers break down rocks. Dead plants furnish organic matter for soil.

Topsoil has organic material, leaf litter, and humus. Living organisms as well as organisms that cause decay live in this layer. Subsoil consists of rock particles mixed with mineral nutrients. The lowest deepest layer consists of fragments of the parent bedrock. Types of soil are classified according to their organic content, mineral composition, pH, and size of rock particles. Different types of plants grow best in different types of soil.

The biosphere, the part of the earth where we live is about 20 km thick. It extends from the ocean floor to the highest point in the atmosphere where life is found.

Autotrophs are organisms that can use inorganic compounds to make organic nutrients. Most carry on photosynthesis and a few carry on chemosynthesis. Heterotrophs are divided into groups depending on what they eat and how they obtain food. Herbivores eat plants. What are some examples? (Rabbits, cattle, sheep, deer) Carnivores eat other animals. Predators kill and eat their prey. Scavengers feed an dead animals. Omnivores eat both plants and animals. Where do humans fit into the picture? (Omnivores) Saprophytes break down dead plants and animals.

There are three types of symbiotic relationships that you will study in more detail later. Mutualism where both organisms benefit, commensalism where one organism benefits, and parasitism where the host may be killed by the parasite.

The producers make their own food. Consumers eat the foods produced and decomposers recycle nutrients back into the ecosystem.

In every ecosystem, there is a pathway of energy flow that always begins with the producers. Producers make organic nutrients which are transferred to consumers when the plants are eaten. Herbivores which eat plants are first level consumers. Carnivores that eat the plant eating animals are second level consumers. Many consumers have a varied diet and fit in several places in the food chain. This food chain is a series of organisms through which food energy is passed.

Many food chains are interconnected at various points so food webs are formed. Decomposers play an important role because they make use of the wastes and remains of all organisms in the system. They use the energy for their own metabolism while breaking down organic compounds into inorganic ones and making substances available for reuse in the system. Decomposers are the final consumers in every food chain or food web.

At each higher feeding level the amount of energy available in a food web decreases. Only a small fraction of the energy taken in is stored as new tissue. Much of the food is not digested or absorbed. A large part of the energy in food is used for respiration and maintenance. Much energy is lost as heat. Only about ten percent of energy taken in at any feeding level is passed upward.

The pyramid of energy is the amount of available energy in an ecosystem. The greatest amount of energy is at the base of the pyramid with the producers. The least amount of energy is present at the top of the pyramid. Energy decreases steeply so there are usually no more than four or five feeding levels in an ecosystem. As the amount of available energy decreases, so does the total mass of living organisms that can be supported at each level. The representation of this relationship is known as the pyramid of biomass. The greatest amount of biomass is found in the lowest level, the producers. The least is found in the highest level of consumers. As the amount of available energy decreases, so does the number of individuals who use the energy.

Now that we have discussed abiotic and biotic factors and the importance of each, let us discuss some ways these factors impose limits upon organisms in an ecosystem. What we see in nature is the outcome of interaction between a population's biotic potential and various environmental circumstances that restrict its growth rate. If you were growing a population in a laboratory under optimum conditions, the growth would be rapid. This same thing occurs in nature. If you leave one dandelion growing in the yard, soon you will have many of them. As long as the seeds are being made, other plants will grow. Until humans or predators intervene, this explosion continues.

Sunlight affects plant growth in lakes as well as on land. Suppose runoff water contains large amounts of fertilizer. This makes plants in a pond grow. They soon become crowded and deprived of nutrients and die. This produces carbon dioxide among other nutrients and takes oxygen away from fish. Soon there is not enough oxygen produced for fish and they die. All this resulting from added nutrients in the pond. Each abiotic factor greatly influences all other factors.

(This next activity lets students compare a microhabitat with a general habitat. They take one small area and analyze its contents and compare with the general area. By comparing biotic and abiotic factors students should discover their importance.)

Purpose: As a result of doing this activity the student should be able to:
1. describe a microhabitat and a general habitat.

2. list some abiotic and some biotic factors in a habitat.

3. compare the various factors found in a microhabitat with the same factors in the general habitat.

Background: A variety of organisms live in almost any habitat you could name. Each organism has its own way of life which often requires a different environment from that of other organisms. For example, some birds prefer the upper branches of a tree while others like the trunks and low shrubs near the ground. Organisms inhabit specific microhabitats within the environment of a general habitat.

This activity will help you to learn more about a given habitat by comparing microhabitat within the habitat and its organisms with the given habitat and its organisms.

Materials: 250 ml beaker, meter stick, balance, small plastic bag, oven

Procedure: The students should:


1. Work in groups of three. One person should keep a record of plants, another should be responsible for animals, and the third physical factors. Each person should keep a record of findings of the group.

2. Select a microhabitat for study in the school area. (under a rock, under a rotting log, or the bark at the base of a tree, in a ditch, under a refuse can)

3. Observe your microhabitat's location, its drainage, its exposure to wind and erosion, the nature of its sail, and the relative amount of sunlight it receives. Compare these abiotic factors with the same factors in the general habitat. Answer question one in the data section.

4. Determine the moisture content of the substrate on which organisms live in the microhabitat. Obtain a sample of the substrate--soil, rotting log, or bark of tree--and place the sample in a small plastic bag. Remember to keep the microhabitat undisturbed or you will destroy it. Determine the mass of a dry clean beaker and record in the data table. Place about 100 ml of the substrate in the beaker and weigh it again. Record. Now place the beaker and the substrate in a hot oven and leave it there until the substrate is absolutely dry. Then determine the mass of the beaker and substrate again. Record. Subtract to find the amount of water lost by heating.

5. Determine the dimensions of the microhabitat and record data.

6. Now study the biotic factors in the microhabitat. Count the number of plants in a 100 cm square area. From the number of plants in the sample area calculate or estimate the total number of plants in the microhabitat. Record. Observe the kinds of plants present--like mosses, ferns, grasses, weeds, vines, shrubs. ) Record. Compare the kinds and numbers of plants in the microhabitat with the kinds and estimated number in the general habitat. Record.

7. Observe the substrate surface for animals such as insect larvae, worms, spiders, sow bugs, or tadpoles. If you can not name the animal, make a drawing of the animal and label it with the letter A, using consecutive letters of the alphabet. After identifying the animals in the microhabitat, observe the general habitat and record similar information.

Data:

1. Describe the microhabitat--location, exposure to wind, moisture, sunlight.

2. Find the mass of:


a. clean beaker
b. beaker and unheated substrate
c. beaker and dry substrate
d. water lost

3. Dimensions of microhabitat

4. Number of plants estimated in microhabitat

5. Kinds of plants in microhabitat

6. Most abundant plants in microhabitat and most abundant plants in general habitat

7. Animals in microhabitat (Number and drawings of unidentified animals)

8. Animals the same or similar to animals in general habitat

Conclusions:

1. How was the general habitat different from the microhabitat?

2. What amount of the substrate was water? How does this compare to general habitat? more less about the same?

3. Were the numbers and kinds of plants in the microhabitat and the general habitat about the same or different?

4. Do you think the kinds of plants and height of plants in the microhabitat are related to the environment?

5. Were the animals you found similar to animals in the general habitat? How do you explain their distribution?

6. From what you observed, which factor was most important in determining the kind and number of plants and animals in the microhabitat--moisture, temperature, abundance of food, shelter from wind and rain, protection from enemies, or amount of sunlight? Explain you response.

1. Study the living organisms in the test site. Select a suitable size for a study plot (100 cm square), then count the numbers and kinds of organisms within the ground to a depth of several centimeters. Study soil organisms from several different depths. Correlate the kinds and numbers of organisms with your data about the abiotic factors of your site.

2. Study the change in temperature of soil with increasing depth. Use a wooden dowel and a hammer to make a hole. Attach a string to the thermometer to lower it into the hole in the soil. Make a graph of the soil temperature change. Does the temperature continue to decrease or does it eventually level off? Compare your findings with the class.

3. Make posters of food chains, food webs, pyramid of energy, pyramid of biomass.

4. Choose an abiotic factor and write a paragraph about what would happen to you without it.

Now that we have completed these activities and discussion, who can list a biotic factor? (Any living organism) Who can list an abiotic factor? (Water, oxygen, light, temperature, soil) Can you list biotic and abiotic factors and tell the importance of each? (pause, then call on several students for responses) What theory was supported by the data collected on our study plots? (that mirciohabitats are as diverse as general habitats) What kind of questions and generalizations were we able to make about the habitats based on our data collected? (answer should be related to conclusion questions listed above)

abiotic factors - nonliving factors, including water, oxygen, light, temperature, soil, and inorganic and organic nutrients

autotrophs - organisms that can make all the organic nutrients they need from inorganic compounds

biomass - mass of organisms

biosphere - the portion of the earth in which living things exist

biotic factors - living factors including all the living organisms in the environment and their effects, both direct and indirect, on other living things

carnivores - animals that feed only on other animals

commensalism - one organism benefits from a symbiotic relationship and the other is not affected

consumers - heterotrophs that must obtain nutrients from other organisms

decomposers - break down the remains of plants and animals, releasing substances that can be used by other members of the ecosystem

ecosystem - includes a community and its physical environment

food chain - a series of organisms through which food energy is passed

food web - food chains interconnected at various points forming a food web

herbivores - animals that feed only on plants

heterotrophs - organisms that cannot make their own nutrients

latitude - distance north or south of the equator

omnivores - animals that feed an both plants and animals

mutualism - both organisms benefit from their association

parasitism - one organism benefits from a symbiotic relationship while the other is harmed

population - all individuals of a particular species within a certain area

predators - attach and kill their prey and feed on their bodies

producers - autotrophs that can produce their own nutrients from inorganic compounds

pyramid of energy - amount of available energy in an ecosystem

saprophytes - organisms that obtain nutrients by breaking down remains of dead plants and animal

scavengers - feed on dead animals they find

symbiotic relationships - two organisms living in close association and benefit at least one of them

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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Last Modified Thursday, 31-Oct-2002 14:56:34 CST