how living things interact t -...

Chapter

How Living ThingsInteract

The two tree swallows in the photo are clearlycommunicating. Communication between twomembers of a species is just one way that living things

interact. Perhaps the birds are "arguing" over which one of themgets the nesting box. Providing nesting boxes is a way thathumans, a different species, interact with tree swallows. InChapter 3, you will learn about different ways that living thingsinteract in ecosystems. You will also find out how theseinteractions can cause changes in ecosystems.

Organize Your Thoughts

Speciesinteractions

• Competition• Cooperation• Symbiosis

Interactions

Ecology Energy

• Food web• Energy pyramid

Goals for Learning

To define ecology and identify biotic and abiotic factors

To describe the parts of an ecosystem

To identify the roles of producers, consumers, anddecomposers

To describe food chains and food webs

To define niche, habitat, and predator-prey relationships

To explain succession and how ecosystems changeover time

Lesson Everything Is Connected

Objectives

After reading thislesson, you shouldbe able to

+ define ecology

+ describe howbiotic and abioticfactors interact

BanTo forbid by law

Ecology

The interactions among

living things anil thenonliving things in

their environment

EcologistA scientist whostudies ecology

In the 1960s, scientists noticed that the numbers of peregrinefalcons were declining. After years of research, they discoveredthe cause: a chemical pesticide called DDT. DDT helpedfarmers by killing the insects that fed on their crops. However,when birds ate dead insects that contained DDT, the chemicalpoisoned them. When peregrine falcons ate these poisonedbirds, they got even more DDT. DDT did not kill adult falcons.Instead, DDT caused females to lay eggs with weak shells. Theweight of the parent crushed the eggs, and the chicks died.

Eventually, DDT was banned, and peregrine falcon populationsstarted to recover. It turned out that DDT hurt many livingthings, including honeybees, bald eagles, and even people. Ittook scientists years to discover the connections between DDTand the problems it caused. This is because it is often difficult toknow how different environmental factors interact.

The Study of InteractionsThe word ecology was first used by a German biologist in1869. It comes from two Greek words: eco, meaning house, andlogy, meaning study. Ecology, then, is the study of interactionsbetween organisms and their "house"—their environment.By studying these interactions, ecologists can learn whatorganisms need to survive. They can also learn how organismsaffect other living things and the environment.

Technology and Society

Scientists can reduce the need for pesticides by changingthe DMA of some crops. For example, corn containing genesfrom the bacterium Bacillus thuringiensis has been created in alab. This corn, called Bt corn, produces a chemical that kills acommon pest called the corn borer.

82 Chapter 3 How Living Things Interact

Biotic factorA living part ofthe environment

Abiotic factorA nonliving part of

the environment

MicroorganismAn organism too smallto be seen without being

magnified

DomainThe highest level ofclassification ofliving things

KingdomThe second level of

classification ofliving things

Rnvi ronn ien ta l s i - i c i u c is one b r a n c h of ecology. Environmentalscientists focus mostly on the interactions between humans andthe environment. They study what humans need to survive andtheir effects on their environment.

For example, when farmers used DDT, they did not know itharmed more than pests. Scientific studies were needed to discoverwhat other damage DDT was causing. That is one of the reasonsenvironmental science is so important. It helps people learn howto prevent harmful changes to the environment.

Biotic FactorsGeologists divide everything that makes up the earth into bioticfactors and abiotic factors. The living parts of the earth arecalled the biotic factors. These include all the different typesof life, such as animals, plants, fungi, and microorganisms.Microorganisms are living things too small to be seen withoutbeing magnified. The biotic factors in an environment alsoinclude the wastes organisms produce.

All of these types of living things are made up of cells. Someorganisms, like yeast, are made up of a single cell. Otherorganisms, like humans, can be made up of trillions of cells.

Biotic factors are divided into a number of categories,beginning with domains and kingdoms. A domain is thehighest level of classification, or organi/ation, of living things.The three domains are Bacteria, Archaea, and Eukarya. Akingdom is the second level of classification. Most living thingsare included in Kingdom Protista, Kingdom Fungi, KingdomPlantae, or Kingdom Animalia. These kingdoms arc locatedwithin Domain Eukarya.

After being placed in a kingdom, organisms are organizedby phylum (for animals) or division (for plants and fungi).The next levels of classification are class, order, family, genus,and species. Assigning organisms to these different levels ofclassification is one way to identify them. This is important formany types of scientific research.

How Living Things Interact (Chapter 3 83

MineralAn element orcombination of dementsfound in the earth

Researchand Write

Identify oneorganism fromeach domain oflife. Then usethe Internet tofind out in whichkingdom theseorganisms areclassified. For eachorganism, write thedomain name, thekingdom name,and the organismname.

Abiotic FactorsThe nonliving parts of an ecosystem are called abiotic factors.These include rocks, minerals, water, air, sunlight, wind,and temperature. A mineral is an element or combination ofelements found in the earth. These examples of abiotic factorscontain no living material. Some abiotic factors were once alive,like leather or wood used for building. They still contain cellsthat are no longer alive.

Living things depend on the nonliving parts of the environment.They also depend on other living things. Every time you takea breath, you are interacting with the atmosphere. When youeat an apple, you are interacting with plants. When you take adrink, you are interacting with water systems. These are just afew examples of how biotic and abiotic factors are connected.

Express Lab 3

Materials*• aquarium with fish

* pencil* paper

Procedure1. Observe the fish tank in

your classroom.

2. Draw all the parts of thefish's environment.

3. Label each item as bioticor abiotic.

Analysis1. What are some ways that

the abiotic factors in thefish's environment affectthe biotic factors?

2. Describe the environmentof the fish in terms of theatmosphere, lithosphere,and hydrosphere.


Lesson 7 R E V I E W

Word Bankabiotic

biotic

ecology

On a sheet of paper, write the word from the Word Bank thatcompletes each sentence correctly.

1. Environmental science is one branch of .

2. Leather and wood are _____ factors that have cells.

3. The different kinds of life are part of the factors inan environment.

On a sheet of paper, write the letter of the answer thatcompletes each sentence correctly.

4. is a pesticide that caused serious problems for birds,insects, and people.

A DDT B Carbon C Iron D Chlorophyll

5. Examples of biotic factors in an ecosystem include .

A butterflies and rocks C squirrels and fungiB water and sunlight D weather and grass

6. Examples of abiotic factors in an ecosystem include .

A sunlight and minerals C flowers and leavesB microorganisms and soil D rocks and moss

Critical ThinkingOn a sheet of paper, write the answers to the followingquestions. Use complete sentences.

7. Give an example of how organisms depend on nonlivingparts of an ecosystem.

8. Explain how DDT caused the numbers of peregrinefalcons to decline. What caused their numbers torise again?

9. Describe how ecology can help protect organisms andtheir environments.

10. List three abiotic factors and three biotic factors in anecosystem where you live.

How Living Things Interact Chapter 3 85

Lesson Components of an Ecosystem

Objectives

After reading thislesson, you shouldbe able to+ name the

five levels ofinteraction in theenvironment

+ describe howenergy istransferredbetween livingthings andecosystems

+ explain howecosystemsreuse matter

All biotic and abiotic factors are part of an ecosystem. They areconnected by the flow of energy and nutrients in an ecosystem.A coral reef, desert, forest, grassland, and rotting log are allexamples of ecosystems. Together, these and other ecosystemsmake up the biosphere, the parts of the earth where life can exist.

Levels of Interaction in the EnvironmentFigure 3.2.1 shows the different levels of interaction in theenvironment. At the bottom level are individual organisms,such as a single-celled fungus or lowland gorilla. Individualsof the same species often interact with each other. If you lookaround you outside, you might see examples of members of aspecies interacting. You might see two squirrels mating, raisingtheir young, searching for food, or chasing away a threat.You might also see individuals from two different speciesinteracting, such as a robin eating a worm. Individuals interactwith their own species and other species in many different ways.

Figure 3.2.1 There are fivelevels of interaction in theenvironment.

Biosphere

Ecosystem

86 Chapter J How Living Things Interact

PopulationA group of organismsof the same species that

live in the same area

The next level of interaction is a population. A populationincludes all the members of one species living in the samearea. Blue crabs in the Chesapeake Bay and black bears inYellowstone National Park are examples of populations.Members of a population interact when they compete for food,water, and shelter. The males and females also interact whenthey mate.

The word population can refer to a group of species in general,such as a population of pandas. It can also refer to a number,such as the population of your city. The population of theworld is the total number of people on all continents.

Map Skills: Population Density

When scientists study populations, they usually make maps thatshow the locations of the populations. The area of the mapmight cover an entire region or a small plot of land. Scientists

often want to know the density of apopulation. Population density measureshow many individuals are in a unitof area, such as a square meter. Theformula for density is:density - number of individuals/area.

The map to the left shows populationsof three different kinds of wildflowers.Use the map to answer the questions.

1. Which type of flower do you thinkfavors a wet ground environment?

2. Describe how clover and dandelionsdiffer in how they are grouped inthis area.

3. What is the total area shown onthis map?

4. Which type of flower in this area hasthe largest population?

5. What is the density of eachpopulation of wildflowers?

UXMNI)

Violet I

Dandelion O

Clover JZ


CommunityA group of differentspecies that live in the

same area

MatterAnything that has mass

and takes up space

ReproductionThe process by which

living things produceoffspring

The third level of interaction in the environment is acommunity. A community is a group of different populationsthat live and interact in the same area. A forest communityincludes the trees, birds, squirrels, and other organisms that livein the forest. A beach community might include shorebirds,dune crickets, ghost crabs, and beach grass.

The next level of interaction is an ecosystem. An ecosystem ismade up of living and nonliving things and how they interact.A beach ecosystem would not only include living things, butalso the sand, the tides, and sunlight.

The highest level of interaction is the biosphere, which is madeup of all of Earth's ecosystems. It is the part of earth whereorganisms can live and the organisms that live there. Eventhough it includes a lot, the biosphere is only a small part of theearth. That is why it is so important to protect it.

Energy TransferThough each ecosystem is unique, they all perform twoimportant processes. First of all, they transfer energy from oneorganism to another. Second, they deal with matter. Matter isanything that has mass and takes up space. Ecosystems work tomove different types of matter through different cycles. Thesetwo processes link living and nonliving things.

Sunlight is the source of energy for almost all ecosystems onEarth. Energy is transferred from the sun to green plants, thento animals. In a few ecosystems, energy is transferred fromchemicals to bacteria, then to animals. Energy from chemicals,in the form of nutrients, and energy from the sun fuel livingcells. This energy supports growth, movement, and otheractivities. One of these activities is reproduction, the process bywhich living things create offspring.


CellularrespirationThe process cells use to

release energy from food

MoleculeThe smallest part of asubstance that has the

same properties ofthe substance

RecycleTo reuse the samematter in different forms

Living things get the energy they need for these activitiesthrough a process called cellular respiration. Every time oneorganism eats another organism, a transfer of energy takesplace. Think about the last meal you ate. Once the food enteredyour stomach, it was broken into smaller bits called molecules.The blood carried these molecules to your cells along withoxygen and water. Inside your cells, the food molecules werecombined with oxygen. In this chemical reaction, carbondioxide, water, and energy were released. This process happensevery time you eat. It gives you the energy you need to live.Every time you run, walk, read, dance, or think, you use energy.

Nutrient RecyclingThe second job of ecosystems of every size is to cycle matter. InChapter 2, you learned about the cycles of different elements.Ecosystems can use carbon, oxygen, and other elements manytimes. These elements are being recycled. To recycle means touse the same matter in different forms. Ecosystems can alsohelp the elements move from one form to another. The carbonin a tree can be recycled to become the carbon in a humanbody. The oxygen a fish absorbed could become the oxygenneeded for a fire to burn.

Energy transfer and nutrient recycling arc linked processes.Without energy, the different elements could not be recycledinto new forms. Without elements like carbon, oxygen, andhydrogen, energy could not be stored or released from food.Cycling matter and transferring energy depend on theinteract ion of biotic and abiotic factors.

Chemistry

The chemical reaction for cellular respiration is:oxygen + glucose > energy + carbon dioxide + water.

How Living Things Interne! Chapter 3 89

lesson 2 R E V I E W

Word Bankcellular respiration

community

ecosystem

sun

On a sheet of paper, write the word or words from the WordBank that complete each sentence correctly.

1. The is the source of almost all of Earth's energy.

2. Cells use the process of _ to get energy from food.

3. Different species that live in the same area form a(n)

4. Plants, animals, and other living things in a(n) areconnected by the cycles of energy and nutrients.


5. A _ _ includes all the members of one species that livein the same area.

A communityB niche

6. Examples of __and grasslands.

A communitiesB ecosystems

C populationD kingdom

include coral reefs, deserts, forests,

C populationsD species


7. Why is the biosphere considered the highest level ofinteraction in the environment?

8. What are the two major processes that occur in anecosystem and how do they support each other?

9. Do you think that different foods give you differentamounts of energy? Explain your answer.

10. Draw a picture that shows how these words are related:population, community, biosphere, ecosystem, organism.Write a caption that explains your drawing.


Lesson Producers, Consumers, and Decomposers

Objectives

After reading thislesson, you shouldbe able to

+ describe theprocess ofphotosynthesis

+ explain howcarnivores andomnivores getenergy

+ describe the roleof decomposers

ProducerAn organism that makesits own food

PhotosynthesisA process plants use tochange energy from thesun into stored sugars

PigmentA chemical that absorbs

certain kinds of lightenergy

ChlorophyllA green pigment inplants that absorbssunlight

ChloroplastA structure in a cell thatharvests energy from

the sun

All living things get the energy they need from food. Differentorganisms have different food sources. Some make their ownfood. Some eat other living things. Some eat dead organisms.Depending on how they get their food, organisms are dividedinto one of three groups.

ProducersEvery time you eat fruits or vegetables, you are eating producers.Producers, such as lettuce, broccoli, and apple trees, areorganisms that make their own food.

Most producers are green plants and algae. They make foodusing a process called photosynthesis. Photosynthesis comesfrom two Greek words that mean "putting together with light."Carbohydrates, which are food for plants and many animals,are created during photosynthesis.

There are four things that green plants and algae need forphotosynthesis to take place. First, they need a source of energy,which is sunlight. Second, they need water. Third, they needcarbon dioxide. Fourth and last is a special green pigmentcalled chlorophyll. A pigment is a chemical that can absorbcertain kinds of light. Chlorophyll, which is stored in special cellstructures called chloroplasts, absorbs sunlight.

During photosynthesis, chlorophyll absorbs light energy fromsunlight. This breaks water molecules into hydrogen and oxygen.The oxygen is given off as waste. The hydrogen combines withcarbon dioxide to create a simple sugar called glucose.

Science Myth

Myth: Animals get energy through cellular respiration, but plantsget energy through photosynthesis.

Fact: Both plants and animals get energy through cellularrespiration. Plants also change energy from the sun into storedchemical energy through photosynthesis.


ChemosynthesisA process bacteria and

other life forms useto create energy fromchemicals

InorganicNot containing carbon

ConsumerAn organism that feedson other organisms

HerbivoreAn animal that eatsonly plants

CarnivoreAn animal that eatsother animals

Green plants and algae can change glucose into other sugars,as well as starch. They can also create more complex moleculessuch as proteins and fats. These molecules provide energy thathelps plants grow. Plants also store some of the sugar and starchin their roots. Root vegetables such as potatoes and carrots aremade this way.

Humans and other animals rely on producers for more thanjust food. They also rely on the oxygen that producers give offas waste during photosynthesis. The oxygen in the atmospherecomes from plants and algae. More than 50 percent of thatoxygen comes from green plants in the ocean.

Some deep ocean and cave ecosystems do not rely on sunlightfor energy. Instead, they get their nutrients from chemicalsformed inside the earth. Chemosynthesis is a process in whichbacteria and other life forms use chemicals to create nutrients.These organisms are also producers. They use hydrogen sulfideand other inorganic molecules to make their own food.Inorganic molecules do not contain carbon atoms.

ConsumersWhat do people, deer, and sharks have in common? They areall consumers. Consumers are organisms that depend onproducers for food. All animals are consumers. Unlike greenplants and algae, they cannot make their own food.

Some animals feed directly on producers. These consumers arecalled plant eaters, or herbivores. Cows, rabbits, deer, sheep,and grasshoppers are all herbivores.

Other animals, such as wolves and eagles, are carnivores.Carnivores feed on herbivores or other carnivores. For example,frogs are carnivores because they eat insects and small fish.Snakes are also carnivores. Some snakes eat other carnivores,such as frogs. Others eat herbivores, such as mice and rats.


CarrionA dead animal orrotten meat

ScavengerAn animal that feedson dead animals

OmnivoreAn animal that eatsboth plants and animals

DecomposerAn organism that breaksdown dead organismsand other organic waste

OrganicLiving or once-livingmaterial containingcarbon

Cultures

An animal that canonly eat plants iscalled an herbivore.However, peoplethat choose notto eat otheranimals are calledvegetarians. Peoplemay choose thisdiet for ethical,environmental,religious,nutritional, orpolitical reasons.

Some carnivores do not feed on living things. Instead, they eatdead animals that they find. Rotting meat is called carrion.Carnivores that feed on carrion are called scavengers. Carrionbeetles, lobsters, shrimp, vultures, coyotes, and gulls are allscavengers. Some scavengers, such as gulls, eat living things aswell. They eat live animals some of the time and are scavengersat other times.

Some consumers eat both animals and plants. Theseconsumers, including people, bears, pigs, and raccoons, arecalled omnivores. Many omnivores eat a large variety offoods. Raccoons, for example, eat eggs, fish, frogs, berries, andwhatever else they can find.

Eating a variety of foods can be an advantage in the wild. Itmeans an animal can use many food sources at different timesof the year. Bears often eat fish and berries in the summer. Theywill also eat roots and other plants when fish and berries arenot available.

Some animals also eat different things during different stagesof life. Caterpillars of monarch butterflies feed on milkweedleaves. When the caterpillars change into butterflies, the adultsget their food from flowers instead.

DecomposersSome consumers get the energy they need by breaking downdead organisms. These consumers are called decomposers.Without decomposers, dead animals and plant material wouldpile up everywhere. Fungi and bacteria are some of the mostcommon decomposers. Both get nutrients from dead animalsand organic matter, such as fallen leaves and tree trunks.Organic matter is material containing carbon that is alive orwas once alive.


Language ArtsThe wordscarnivore, herbivore,and omnivore areeach formed fromtwo Latin words.The verb vorare,"to eat," is partof all three words.Carnivore includescaro, which means"meat." Herbivoreincludes herba,which means"vegetation."Omnivore includesomnis, whichmeans "all."

Decomposers play an important role in ecosystems. Forexample, fungi break down leaves and dead animals. Someof the nutrients are absorbed by the fungus. Others arerecycled, often in a simple form that plants can use. In this way,decomposers make sure matter passed from plants to animals isrecycled again. This is the ongoing cycle of matter.

• * * • # « • * * • # • • * • • * » • # * • # * • # » • # » • * * •

Science in Your Life

Consumer Choices:Home Composting Bins

Many people use special binsto turn grass, leaves, and otherorganic waste into a materialcalled compost. Compost isrich in nutrients and can beadded to soil. Compostinghelps the environment in twoways. First, it gets rid of yardwaste that would otherwisebe thrown out with the trash.Second, it provides a free,organic fertilizer which canreplace chemical fertilizers.Chemical fertilizers can causehealth and pollution problems.

Composting requires moisture, air, yard and food wastes, andtime. The fungi and bacteria in the air and wastes decomposethe dead plant material and recycle the nutrients. All you have todo is add water regularly and turn the yard waste. Turning allowsair and moisture to reach all the material so the decomposerscan do their work. You can buy a compost bin or you can alsomake your own.

1. What type of organisms work in a compost bin?

2. What is necessary for composting to take place?

3. What are some benefits of composting?


Word Bank


chlorophyll

consumer

omnivore

photosynthesis

On a sheet of paper, write the word from the Word Bank thatcompletes each sentence correctly.

1. A(n) is an animal that eats a variety of plant andanimal material.

2. In ., plants use sunlight, water, and carbon dioxide toproduce food and oxygen.

3. A green pigment in plants that absorbs sunlight is

4. A(n) _ cannot make its own food and must feed onother organisms.


5. Cows, deer, rabbits, and sheep are .

A producers C omnivoresB herbivores D decomposers

6. are needed for photosynthesis to occur.

A Sunlight and carbon dioxideB Salt water and oxygenC Sunlight and oxygenD Salt water and carbon dioxide

7. is a waste product of photosynthesis.

A Carbon dioxide B Oxygen C Fat D Energy


8. What is the nutrient source for producers that live in thedark, deep ocean?

9. Are you a carnivore, an herbivore, or an omnivore? Explainyour answer by describing the types of food you eat.

10. How are decomposers important to an ecosystem?

How lAving Things Interact Chapter 3 95

Lesson Energy Flow in Ecosystems

Objectives

After reading thislesson, you shouldbe able to+ explain how

energy istransferred in afood chain

41 explain how afood web differsfrom a food chain

^ identify thedifferent roles ina food chain orfood web

Food chainThe feeding order

of organisms in a

community

When an animal eats a plant, energy is transferred from theplant to the animal. The same thing happens when an animaleats another animal. The energy stored in one organism istransferred to the organism that eats it. The transfer of energythrough an ecosystem can be traced. This helps scientists seehow organisms are connected by feeding relationships. Usingthis information, scientists can also calculate how much energyis transferred.

Food ChainsA food chain shows how organisms in an ecosystem get theirfood. Each organism is a link in the chain, and provides foodfor the next link. A food chain always starts with a producer andends with a consumer. A simple food chain in the grasslands ofAfrica would start with acacia trees. As producers, they maketheir own food using sunlight. Giraffes eat the leaves and getsome of the energy stored in the leaves. Finally, lions feed onthe giraffes, and get the energy stored in the giraffe's cells. Thisexample demonstrates how energy moves in a food chain fromone link to the next. Another example of a food chain can beseen in Figure 3.4.1.

Bird

Small fish

\e fishWater plant

Figure 3.4.1 A food chain shows the sequence of organismsthat feed on each other.


Food webAll the food chains ina community that arelinked together

Mice

Food WebsThere are millions of food chains in nature. Each of themdemonstrates one way that organisms are linked together inan ecosystem. In most ecosystems, however, energy transfer ismuch more complicated. That is because most organisms arepart of more than one food chain. In a meadow, for example,grasshoppers feed on many different kinds of plants. A varietyof birds, amphibians, and reptiles feed on grasshoppers. Theseanimals are in turn eaten by raccoons, bears, hawks, and othercreatures. This network of feeding relationships is called a foodweb. A food web shows many different feeding relationships inan ecosystem. Figure 3.4.2 is an example of a food web.

Eating many different foods can help a consumer makesure it can find enough food. A few species feed on only onething. If something happens to their food source, they coulddie out. Australian koalas, for example, feed on the leaves ofeucalyptus trees. When land is cleared for new houses, many

of these trees are destroyed. If all eucalyptustrees disappear, koalas will have to

find new sources of food andshelter. If they cannot, their

populations will decline.When that happens, otherparts of their ecosystem'sfood web can also bedisturbed.

Figure 3.4.2 A food webshows the different foodchains an organism is partof in a community.

Hawks

Birds

Decayingmaterials

Plants withseeds


Trophic levelA link in a food chain

PrimaryconsumerAn herbivore that feedson plants

SecondaryconsumerA carnivore or omnivorethat feeds on herbivores

TertiaryconsumerA carnivore or omnivorethat feeds on other

consumers

Energy pyramidA diagram comparingthe amounts of energyavailable to populationsat different trophiclevels

Trophic LevelsBeyond food webs, you can see how energy is transferred bylooking at feeding relationships. A trophic level is a feedinglevel in a food chain or web. In most ecosystems, producerssuch as green plants make up the first trophic level. In agrassland ecosystem, this level would include grasses and otherplants. In an ocean ecosystem, algae forms the first trophic level.In a few ecosystems, bacteria form the first level.

The second trophic level is made up of herbivores, which arealso called primary consumers. Giraffes in the African plainsand squirrels in North American forests are primary consumers.Secondary consumers make up the third trophic level. Lions,eagles, and snapping turtles are all secondary consumersbecause they feed on primary consumers.

In some food chains there is a fourth or fifth level of consumersthat eat other consumers. These carnivores or omnivores arecalled tertiary consumers.

Most consumers eat several types of food and feed at more thanone trophic level. A bear is a primary consumer when it feeds onberries. It can also be a secondary consumer when it eats fish.

Energy PyramidsHow do the numbers of species in each trophic level compare?Would you expect there to be more producers or carnivores? Ifyou guessed more producers, you are right.

You can use an energy pyramid to picture how trophic levelsrelate to each other. Look at the energy pyramid in Figure 3.4.3on page 99. Producers form the bottom of the pyramid. Trophiclevels form a pyramid because there are many more producersthan primary consumers. There are also more primaryconsumers than there are secondary or tertiary consumers.Think about it this way. A field of grass can only support acertain number of rabbits. The number of rabbits can supporta smaller number of bobcats. The bobcats can only support aneven smaller number of cougars.


An energy pyramid shows more than the relative numbers ofspecies. It also shows the amount of energy available at eachtrophic level. Each time energy is transferred from one level tothe next, about 90 percent is lost. Some of that energy is lost asheat and escapes into the atmosphere. An animal uses most ofthe energy it receives to live. That means only 10 percent of theenergy gets stored in the animal. This is the energy availableto the consumer that eats the animal. As you move up thepyramid, there is less food energy available. Scientists call thisthe 10 percent rule, even though the amount of energy lostvaries between ecosystems.

0.1% of energy

1% of energy

10% of energy

100% of energy

Figure 3.4.3 The energy pyramid represents the percentageof energy transferred from one trophic level to another.


Math Tip

To figure out theamount of energyin the next level ofan energy pyramid,multiply theprevious amount

byjo-

Look back at the energy pyramid on page 99. You can see thatthe first trophic level is the largest. This level has the mostenergy and the most species. Each level above it has less energyand fewer species. The top level of tertiary consumers has thesmallest amount of energy There is about 1,000 times moreenergy in the first trophic level than at the top. This is why thereare more small animals than large animals in an ecosystem. It isalso why most food chains do not have more than four or fivelinks. There is not enough energy at the top level to supportanother level of consumers.

Energy pyramids, food chains, and food webs all showhow energy travels from one organism to another. In everyinteraction illustrated in a food chain or web, energy istransferred. An ecosystem depends on this transfer of energy tomaintain all forms of life.

A.V-4 A Y •< A Y •< A Y •< A Y A Y -« A A Y •< A Y

Science at Work

Animal Caretaker

Do you have an interest in wild animals?Then you might want to explore a careeras an animal caretaker. Zoos, aquariums,and other wildlife organizations are themain employers of animal caretakers.Handling the large number and variety ofwild animals reguires skilled and trainedprofessionals.

Animal caretakers are responsible forthe daily well-being of the animals intheir care. Caretakers maintain feedingand grooming programs for the animalsand are responsible for keeping theirenvironment clean. Caretakers mustbecome very familiar with the appearanceand behavior of their animals as well.

The caretaker isresponsible forrecognizing healthproblems andalerting the medicalstaff. They alsokeep records onhow the animalsbehave and theirfeeding habits.

To become a caretaker, you must showresponsibility in dealing with animals.Some zoos require a college degreein biology or animal science. Othersmay require a high school diploma andcompletion of a certified training program.



Word Bankenergy

food chain

food web

producers


1. In a(n) , energy is passed along from a producer to aconsumer, and then sometimes to another consumer.

2. A(n) shows many feeding relationships inan ecosystem.

3. The first trophic level in an ecosystem includes .

4. An energy pyramid shows the number of species and theamount of available at each trophic level.


5. A(n) __ _ is considered a secondary consumer.

A tree B mouse C eagle D fungus

6. Each time energy is transferred from one trophic level tothe next, energy .

A increases by 10 percentB is lost

C stays about the sameD doubles


7. How can a bear be a primary and a secondary consumer?

8. Draw and label a food chain you would find in a lakeor stream.

9. Why do ecosystems constantly need new energy?

10. Would it make sense to use another shape other than apyramid to show energy changes at each trophic level?Explain your answer.


I N V E S T I G A T I O N 3

Materials

data table

pencil

$300 of play money

calculator

The Energy PyramidAn energy pyramid shows how the amount of availableenergy decreases as it moves through trophic levels.In this lab, you will track this energy. You will usemoney to represent the energy as it moves betweentrophic levels.

Procedure1. Form a group of four students. Choose someone

to be the sun bank, the grass bank, the rabbit bank,and the fox bank.

2. Make a data table like the one on the next page.

3. The grass bank represents 300 grass plants. Eachplant makes $1 a day through photosynthesis.Have the sun bank pay $300 to the grass bank.Record this amount in your data table under the"Amount earned." The grass bank does not losemoney in this transfer, since no energy is "spent."Record the same amount under "Amount saved."


4. Have the grass bank pay the rabbitbank the money it has saved. Recordthis in the data table under "Amountearned." According to the 10 percentrule, the rabbit bank "spends" 90percent of this money right away.Record this amount in your table.Then calculate and record the totalamount that is saved.

5. A rabbit needs $2 a day to survive.Calculate how many rabbits can besupported by the amount of moneysaved in the rabbit bank. Recordthis number in your data table.

6. Have the rabbit bank pay the foxbank the money it has saved. Recordthis amount, the amount that isspent (remember the 10 percentrule), and how much is saved.

7. A fox needs $3 a day to survive.Calculate how many foxes can besupported by the amount of moneysaved in the fox bank. Record thisnumber in your data table.

Cleanup/DisposalPut away the materials and make sureyour lab area is clean.

Analysis1. How much money is remaining at

the end of this lab?

2. What does the money that wasspent represent?

Conclusions1. What happened to the grass plants

that provided energy for therabbits? How will this affect theenergy available the next day?

2. Tf the rabbit population grew verylarge, how would other organismsbe affected?

Explore FurtherCalculate how many more grass plantsand rabbits would be needed to support10 more foxes.

Trophiclevel

Crass

Rabbits

Foxes

Amountearned

Amountspent

Amountsaved

Number oforganisms


/.ess on Relationships Within Ecosystems

Objectives

After reading thislesson, you shouldbe able to+ define habitat

and niche anddescribe how theyare related

^ explain howcompetitionaffectscommunities

+ describe therelationshipbetweenpredators andprey

+ explain two waysthat prey avoidpredators

NicheThe role an organism

plays in an ecosystem;an organism's way of life

Every living thing lives somewhere. Earthworms liveunderground. Fleas live on cats, dogs, and squirrels. Cactilive in the desert. An organism's habitat can be large, like thegrasslands in Africa. Habitats can be small, like the inside of asheep's nostril. The size depends on how big the organism is andhow much space it needs. Inside this space, the organism mustfind the food, shelter, water, and other things it needs to survive.

There can be many different habitats within every ecosystem.That is because one part of an ecosystem can have very differentconditions from another part. Species living in the deep oceanare used to colder and darker conditions than those near thesurface. Species living inside a sheep's nostrils experiencedifferent conditions than those that cling to its hair.

The Perfect NicheEvery organism has special ways to survive within its habitat.It needs to find food, find a mate, and reproduce. It also needsto avoid dangers and find the water and minerals it needs. Theunique role that an organism plays in its ecosystem is calledits niche. A niche includes where a species lives and how itinteracts with other species. It also includes what conditionsit depends on for survival. You can think of a habitat as anorganism's address. Then its niche is its job. In other words, aniche is everything an organism does in its habitat to survive.

One way to see different niches is to watch what a species eats.Red-tailed hawks and kestrels can both live in the same field.Red-tailed hawks feed on mice and snakes. Kestrels feed oninsects, lizards, and other small creatures. Even species thateat the same type of food have different niches. Cardinals andindigo buntings both feed on seeds. They have different nichesbecause cardinals eat bigger seeds than indigo buntings. Theyalso depend on different plants to survive.


CompetitionA relationship in which

different individuals

or populations try touse the same limited

resources

Researchand Write

Some organismswork together tosurvive. Find anexample of twoorganisms thatwork together toobtain resources.Make a collage thatshows how theorganisms benefitfrom each other.

No two species in the same habitat have exactly the same niche.It might look like they do, but there are many differences.Different species have very different life cycles and ways ofreproducing. They are also eaten by different creatures and havedifferent methods of defending themselves.

For example, monarch butterflies, honeybees, and ruby-throatedhummingbirds all feed on nectar. Yet each species has its ownway of getting nectar and prefers different flowers. They alsohave different ways of avoiding predators. Hummingbirds can flythe fastest of the three. Honeybees have a poisonous sting thatcan hurt an attacker. Monarch butterflies are poisonous to manywould-be predators.

Competing for a NicheSometimes, two species compete for the same niche. Thespecies that is best suited to the niche usually wins. The speciesthat loses either moves, adapts to a new niche, or dies out.In the late 1800s, a bird lover imported birds called starlingsfrom England. He released them in Central Park in New YorkCity. The starlings competed with native birds in the area fornesting sites. Today there are millions of starlings all over NorthAmerica. They fill niches that belonged to other birds beforethe starlings forced them out.

For all living things, competition is a normal part of life.Competition happens when two species compete for the sameresources. Competition can occur between individuals, suchas two lions competing over a mate. It can also occur betweendifferent populations. A population of gulls may compete forthe same food as a flock of crows.


CoexistIndividual members compete with each other. When prayingmantis young hatch, they all compete for the same food. Somewill even eat each other to stay alive. Some species that competefind ways to coexist in the same space. In some marshy areas,bats and dragonflies both feed on mosquitoes. They competewith each other, but they have different niches. Bats hunt atnight. Dragonflies hunt during the day. People also competewith other species. When people fish for salmon, they maycompete with bears and eagles for the same food. People alsocompete with wildlife for space to build their homes. This oftenforces species to move, adapt, or die.

Predators and PreyWhen a fly is caught in a spider web, the spider feels it shakethe web. The spider wraps the insect in a silklike case. Whenit is hungry, the spider will suck out the insect's liquids to getnourishment. A spider feeding on a fly is an example of apredator in action. A predator is an organism that hunts andfeeds on another organism. The animal that a predator eats iscalled its prey. This kind of interaction between species is calledpredation. Road runners, sea otters, rattlesnakes, and lizards areall examples of predators.

************************* ******** «****** »** * *

To exist at the sametime, in the same place

NourishmentFood

PredatorAn organism that huntsand feeds on otherconsumers

PreyA consumer that iseaten by anotherorganism

PredationA relationship in whichone species eats anotherspecies

Achievements in Science

Learning by Observing

What is the best way to learn aboutchimpanzees? Watch them at a zoo? Reada book about them? Jane Goodall thoughtthe best way was to watch them in thewild. In 1960, she started living with apopulation of chimpanzees in East Africa.

When Dr. Goodall first started her studies,the chimpanzees would run from her.Then they slowly accepted her. Dr. Goodallbecame a member of their community.She gave the chimpanzees names and gotto know their different personalities.

By observing their daily life, Dr. Goodallwas able to make important discoveries.For example, she discovered thatchimpanzees use tools. One such tool isa stick used to "fish" termites out of theground. She learned that chimpanzeesact as small family groups. She evenwitnessed a four-year war betweenchimpanzee tribes.

jane Goodall's work has been an examplefor other scientists. Much of what is nowknown about animals comes from observingthem in their natural environments.


Boom-bust cycleA cycle in whichpredators increase asprey increases, andpredators decrease asprey decreases

CamouflageColors, patterns, orbehaviors that helporganisms hide in theirsurroundings

Predator and prey populations are linked. More prey cansupport more predators. If the number of prey decreases, thenthe number of predators will shrink too. If a new predator joinsan ecosystem, there might be less prey for native species. Insome ecosystems, top predators, such as tigers or jaguars, areoverhunted or face other threats. This can lead to an increase inprey species and cause changes in the ecosystem.

Many populations go through boom-bust cycles. In thesecycles, the number of prey can affect the number of predators.When the population of prey grows, the population ofpredators grows. This is a population boom. Over time, thenumber of predators becomes too high for the prey to support.Predators begin to starve and die. This is a population bust.When the number of predators goes down, the number of preyincreases. Then the cycle starts again.

Staying AliveOver time, many preyspecies have found ways todefend themselves againstpredators. One way speciesprotect themselves is withcamouflage. Camouflagehelps a species hide orlook like something it isnot, like the thorn mimictreehopper in Figure 3.5.1.Some frogs and insects lookjust like leaves or tree bark.Some caterpillars look liketwigs or bird droppings.

Figure 3.5.1 The thorn mimic treehopper avoids being eatenbecause it looks like a sharp thorn.


WarningcolorationThe bright colors or

patterns on animalsthat scare off predators

MimicryA method of defense inwhich a species looks,sounds, or acts like amore dangerous species

The shinglebacklizard's tail andhead are the sameshape and size.Because of this,predators oftenattack the wrongend. This increasesthe lizard's chancesof survival. Anattack on thelizard's tail doesnot injure it asmuch as an attackon its head.

Some species contain toxic chemicals that harm predators.Many of these animals have bright colors called warningcoloration. These bright colors warn predators to stay away.Poison dart frogs, coral snakes, skunks, wasps, bees, andmonarch butterflies all have warning coloration.

Species also use mimicry to protect themselves. In mimicry,one species looks, sounds, or acts like a more dangerous species.For example, several species of snake copy the bright colorsof a coral snake. The viceroy butterfly has the same colors andpatterns as a monarch butterfly.

Predators may also be camouflaged. This lets them hide fromprey and have a better chance of catching them. Crab spiderscan change color to match the color of the flowers where theyhide. When prey passes by, it may not see the camouflagedspider. The spider then easily captures its prey. Camouflage,warning coloration, and mimicry help both predator and preyspecies survive.

Technology and Society

Humans have copied the way animals use camouflage. Themilitary uses camouflage patterns on tanks, uniforms, andother equipment. A new technology allows soldiers to becomealmost invisible while wearing special reflective clothing. Aphotographic image of their surroundings is projected onto thesoldiers. Optical camouflage creates the illusion that the soldiersare part of their surroundings.



Word Bankboom-bust cycle

camouflage

niche

predator


1. The unique role that an organism plays in its environmentis called its _ .

2. In a , the numbers of predators and prey rise and falldepending on each other.

3. An animal that actively hunts and kills its prey is called

4. A caterpillar disguised as a bird dropping is an exampleof .


5. A snake feeding on a mouse and a frog eating a fly are twoexamples of

C camouflageD mutualism

A competitionB predation

6. The of a species can be called its address inan ecosystem.

A home B trophic level C niche D habitat


7. Describe an example of warning coloration.

8. Explain how predator and prey populations are linked.

9. Name three things that animals or plants might competefor in an ecosystem.

10. Describe the niche of an animal in your area.


DISCOVERY I N V E S T I G A T I O N 3

Materials

variety of plastic utensils

tweezers

toothpicks

chopsticks

watch, stopwatch,

or timer

multicolored pasta

Predator-Prey InteractionsAll predators and prey have ways to be successful intheir environments. Hawks, for example, have sharpbeaks and talons to help them catch prey. Rabbits movequickly to escape capture. Some predators and prey usecamouflage to survive. In this lab, you will explore howthese factors benefit predators and prey.

Procedure1. Your teacher will lead you to an outdoor site. Note

the environmental conditions around you. SafetyAlert: Be careful around plants and animals. Letyour teacher know if you are bitten, scratched,or stung.

2. The colored pasta represents the prey. Your teacherwill provide a selection of tools to "capture" prey.Examine these tools.

3. Work in pairs. With your partner, write ahypothesis that describes how successful a"predator" will be at capturing the pasta "prev"Your hypothesis can include information on thetype of pasta, the environment, or the tools used.

4. Test your hypothesis. Spread out the pastawhile one partner is not looking. The "predator"should choose a tool and capture as much "prey"as possible.

5. Stop the predator after 30 seconds. Count thenumber of prey captured successfully.

6. Repeat the process five times. Vary the tool usedand the test site. Record your data.


Cleanup/DisposalBefore returning to the classroom,clean up your materials. Wash yourhands afterward.

Analysis1. What was your hypothesis?

2. Was your hypothesis supportedby the data you collected? Explainyour answer.

Conclusions1. How did the tools of the "predator'

affect its success at predation?

2. How did the color of the "prey"affect success?

3. How did the environment affectsuccess?

Explore FurtherChoose a different type of prey anddifferent tools. Write a hypothesis withthese new factors and test it.


Lesson Ecosystems and Change

Objectives

After reading thislesson, you shouldbe able to+ describe how

primary andsecondarysuccession differ

+ give examples ofspecies found indifferent stages ofsuccession

+ describe howclimax communitiescan change

SuccessionThe process of ecologicalchange in a communityover time

Ecosystems are always changing. Some of the changes canhappen quickly. Hurricanes, volcanoes, floods, and fires canchange a habitat overnight. Change also happens on a smallerscale. In a forest, conditions might change if a tree gets hitby lightning and falls. Sunlight can now reach the forestfloor. Seeds that have been buried in the soil can grow. Smallflowering plants and shrubs soon appear. This creates a newlayer of plants on the forest floor. Over time, the bigger plantswill block sunlight from the species below them. Finally, shrubsand flowering plants will be replaced by trees. This process cantake many years.

Some changes in ecosystems can take hundreds or eventhousands of years. What is a forest today might have been aswamp. A field might once have been a forest that was destroyedby a fire.

Communities of life are not created overnight. They form overtime, through several different stages. This process of ecologicalchange in a community over time is called succession. In manyecosystems, one community of life is replaced by another.Succession usually refers to how the plant life changes. Still,each stage in succession also has its own animals and otherorganisms. Succession can also happen in water environments.

Primary SuccessionOn November 14,1963, a volcano erupted underwater off thecoast of Iceland. The eruption pushed a new island out of thewater. The island was named Surtsey, after a Norse god of fire. Atfirst, Surtsey was just a lifeless black rock. Over the next few years,the eruptions continued. The island grew to about 2.6 squarekilometers and rose more than 171 meters above sea level.


LichenAn organism made

up of a fungus, u

green alga, and acyanobacterium

PrimarysuccessionSuccession in a lifeless

environment that

creates a community

ErodeTo break apart or

wear away

Pioneer speciesThe first species to

arrive in an urea

The first signs of life on the island were bacteria and fungi. Soonmosses and lichens began to colonize the island. Seeds carriedby birds, the wind, or the sea started to sprout. Three years afterthe eruption, birds started nesting on the island. Insects andother small creatures arrived, along with new plants.

Today, there are about 60 kinds of plants growing on the island.Ten different kinds of birds nest there, including puffins andgulls. There arc also thousands of insects and other smallorganisms. Seals now live on the island. The rocks are coveredwith algae and starfish.

Primary succession is the process of succession in what wasonce a lifeless environment. Recently exposed rock or newlyformed sand dunes are two examples of lifeless environments.Primary succession also happens after a volcano leaves anarea almost without soil. Primary succession usually follows apattern. First, new soil is formed when rocks erode, breakinginto smaller pieces. This is caused by wind, water, and frost. Inmost areas, soil forms with the help of lichens. Lichens are tinyorganisms made up of fungi, algae, and cyanobacteria livingtogether. Unlike many producers, lichens can live on bare rock.The algae create their own food through photosynthesis. Thefungi absorb water and nutrients from rocks. Together theymake and give off acids that can break down rocks. These plants,which are often the first to arrive, are called pioneer species.

Science Myth

Myth: Lichens harm trees.

Fact: Lichens live on a tree's bark without interacting withthe tree. Often green or gray-colored, lichens are sensitive topollutants such as sulfur dioxide. This means that the presence oflichens can signal clean air and a healthy environment.

How Living Things interact Chapter 3 113

ClimaxcommunityThe last step in thesuccession of anecosystem

DistributionThe location of speciesin a community

SecondarysuccessionSuccession in anenvironment that wasdisturbed by humans ornatural causes

Once soil starts to form, small plants like mosses and grassesbegin to grow. Seeds and spores are carried in by animals orthe wind. Insects, small mammals, and other creatures startto arrive. As the soil gets deeper, shrubs with longer roots cangrow. These larger plants will crowd out the grasses. The shrubswill eventually be replaced by trees.

The last step in the succession of an ecosystem is called a climaxcommunity. Scientists once thought each climax communitywas stable. They now realize that these communities alsoexperience change. Over time, a climax community typically hasthe same kinds of species. Yet the numbers and distribution, orlocation of species in a community, can change. Different speciesmake up climax communities in different areas of the world.

Secondary SuccessionSecondary succession is the process of change in communitiesthat have been disturbed. Human activities, fires, floods, andother events can all lead to secondary succession.

Secondary succession is similar to the later stages of primarysuccession. When farmland is abandoned, grasses andwildflowers are the first plants to grow. They are followed bylarger shrubs and then fast-growing trees, such as pines.Slow-growing trees, such as maples, oaks, and beeches,eventually outcompete the pines and smaller shrubs. Overtime, a climax community forms. It may resemble the forestthat was originally cleared to create the farm.

During succession, animal species change along with the plantspecies. Some species might be found in all stages. Other specieswill enter or leave a community as it moves through differentstages. In a field, you would find species that depend on grasses,wildflowers, and small shrubs. As it becomes a forest, finches,squirrels, and other species would join the community.


Old-growthforestA forest containing trees

that can be hundreds orthousands of years old

DiverseVaried

Protecting Species and SpacesOver hundreds of years, an abandoned farm can become aforest through succession. However, the new forest might neverrecover the species and relationships the original one had.Many people are concerned about how fast ecosystems arechanging. Farming, road building, and other human activitiescause changes that can affect the species of an area.

Many people are working to protect natural communities thathave not been changed by humans. One example of this typeof community is an old-growth forest. An old-growth forestcontains trees that are hundreds or thousands of years old.Certain species of animals need these ecosystems to find foodand a place to live.

Natural communities such as old-growth forests are someof the most diverse that exist today. A diverse area has manydifferent plants and animals. If these ecosystems are disturbed,it can take them hundreds or thousands of years to recover. Insome cases, the original forest will never recover.

Earth Science

Rocks and soil made from volcanic lava are especially rich inminerals and nutrients. That is one reason why crops grow sowell on the volcanic Hawaiian Islands.



Word Bankold-growth forest

pioneer species

succession


1. Primary and secondary _ _ are two kinds of change inan ecosystem over time.

2. The first organisms to move into a lifeless area arecalled .

3. A(n) can have trees that are hundreds of years old.

On a sheet of paper, write the letter of the correct answer.

4. Which of the following is an example of primary succession?

A lichens, mosses, grasses, shrubs, then treesB forests, shrubs, weeds, algae, then flowering plantsC forests, fields, rocks, soil, then desertsD fields, wetlands, bare rock, then grasses

5. On the island of Surtsey, happened after thevolcano erupted.

A nothing C secondary successionB primary succession D distribution

6. Secondary succession would probably occur after .

A abandoning a farm C a comet hits EarthB a volcanic eruption D a nuclear explosion


7. What is special about lichens?

8. Why is it important to preserve old-growth forests?

9. Describe how a human activity can cause secondarysuccession.

10. In primary succession, what happens after plants appear?


ENVIRONMENTAL ISSUES INTHE WORLD

Integrated Pest ManagementFor many years, farmers have dependedon chemical pesticides to keep cropssafe. However, these pesticides cancause health problems in humans andother animals. Now, many agriculturalscientists advise using several differentmethods to defeat weed and insect pests.This approach is called Integrated PestManagement (IPM).

IPM does not try to replace pesticides.Instead, its goal is to help people useless of them.

IPM begins by looking at each crop andthe pest that is threatening it. Once theproblems are identified, IPM scientistslook for many different solutions. Often,natural predators can be introducedto fight a problem insect or weed. Forexample, some farmers add ladybugs totheir crops. The ladybugs eat the insectpests, but do not damage the crops.Another method is to rotate crops fromyear to year. Crops that are not affectedby particular pests and diseases replacethose that are.

An IPM program may include usingsmall amounts of pesticides. However,they are used only when and where theyare necessary.

Combining these different tools worksbetter than chemicals alone. At the sametime, it reduces pollution from pesticides.IPM also improves the effectiveness of thechemical pesticides that are used. Whenfarmers use fewer chemicals, the pestshave less exposure to them. This meansthey cannot become resistant to thechemicals as easily. Finally, when farmersuse fewer chemicals, the cost to producecrops is lowered.

1. What does IPM include?

2. How does IPM actually improve theability of chemicals to reduce pests?

3. Describe two advantages of using IPM.


Chapter 3 S U M M A R Y

The environment is made up of living,or biotic, factors and nonliving, orabiotic, factors that interact.

Ecosystems transfer energy from thesun to green plants to animals.

Ecosystems recycle matter. This allowsatoms of carbon, oxygen, and otherelements to be used over and over.

The environment is organized intofive levels: organisms, populations,communities, ecosystems, and biosphere.

Living things can be divided into threegroups depending on how they get theirfood. Producers make their own food.Consumers eat other living things.Decomposers break down waste.

Consumers can be divided intothree groups. Herbivores eat plants.Carnivores eat animals. Omnivores eatboth plants and animals.

Food chains and food webs show thefeeding relationships in an ecosystem.

Energy pyramids show the amount ofenergy transferred from one trophiclevel to the next.

Species compete for resources,including food, shelter, water, andliving space.

Predators are species that feed onprey. Camouflage, warning coloration,mimicry, and defensive behaviors helpprotect prey from predators.

Ecosystems follow a pattern of changeover time called succession. Primarysuccession happens in areas that wereonce lifeless. Secondary successionoccurs in areas that were onceinhabited by living things.

Vocabulary

abiotic factor, 83ban, 82biotic factor, 83boom-bust cycle, 107camouflage, 107carnivore, 92carrion, 93cellular respiration, 89chemosynthesis, 92chlorophyll, 91chloroplast, 91climax community, 114coexist, 106community, 88competition, 1 05

consumer, 92decomposer, 93distribution, 114diverse, 115domain, 83ecologist, 82ecology, 82energy pyramid, 98erode, 113food chain, 96food web, 97herbivore, 92inorganic, 92kingdom, 83lichen, 113

matter, 88microorganism, 83mimicry, 1 08mineral, 84molecule, 89niche, 104nourishment, 106old-growth forest, 115omnivore, 93organic, 93photosynthesis, 91pigment, 91pioneer species, 113population, 87predation, 106

predator, 106prey, 1 06primary consumer, 98primary succession, 1 1 3producer, 91recycle, 89reproduction, 88scavenger, 93secondary consumer, 98secondary succession,

114succession, 1 12tertiary consumer, 98trophic level, 98warning coloration, 108


Chapter 3 R E V I E W

Word Bankabiotic factors

chemosynthesis

competition

consumers

decomposers

ecology

energy pyramid

food web

niche

photosynthesis

population

predators

prey

producer

scavenger

succession

trophic level

Vocabulary ReviewOn a sheet of paper, write the word or words from the WordBank that complete each sentence correctly.

1. The process of ecological change in a community overtime is .

2. The study of how living things interact with each other iscalled

3. Through a process calledthe sun to make food.

4. When predators eat

., plants use energy from

., it is known as predation.

5. A{n) is a group of organisms of the same speciesthat live in the same area.

6. A(n) _ , such as a gull or vulture, feeds on carrion.

7. Every _ is made up of food chains that are connected.

8. When resources such as food, shelter, and water arelimited, „ _ occurs between living things.

9. Wind, water, temperature, and minerals are among thethat are part of the environment.

10. When there is no sunlight available, some organisms makefood using .

11. Some _ _ feed directly on producers. Others feed onanimals that feed on producers.

12. Without _ __, the world would be full of plant andanimal waste.

13. Every food chain begins with a(n) _ .

14. Scientists use a(n) to show the amount of energy ateach trophic level in an ecosystem.

Continued on next page


Chapter 3 R E V I E W - continued

15. Cats, lions, hawks, and praying mantises are called ..because they actively hunt and eat other animals.

16. A(n) __ _ is a layer of a feeding relationship and a link ina food chain.

17. Each organism's role in an ecosystem, or ,is different.

Concept ReviewChoose the answer that best completes each sentence.Write the letter of the answer on your paper.

18. The numbers and of species can change in aclimax community.

A colors B types C habitats D distribution

19. A ( n ) would eat both fish and lettuce.

A carnivore C omnivoreB herbivore D producer

20. An example of is lichens and mosses growing onbare rock after a volcanic eruption.

A competition C primary successionB population D secondary succession

21. Trophic levels describe _ _ in a community.

A the energy availableB successionC predator-prey relationshipsD competition

22. Most of the energy that fuels ecosystems on Earth comesfrom .

A chemicals B water C sunlight D bacteria


^^ "̂


23. Is a decomposer a predator or prey? Explain your answer.

24. Draw a local food web or use the example from the book.Are there more producers or consumers? Why?

25. List the levels of interaction in the environment and giveexamples of each level.

Restate the test directions in your own words. Tell yourselfwhat you are expected to do.


how living things interact t -...

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