CH 4 APTER The Organization of Life CHAPTER 4 · 2008. 12. 16. · CH4APTER The Organization of Life CHAPTER 4 1 Ecosystems: Everything Is Connected 2 Evolution 3 The Diversity of

CCHHAAPPTTEERR

44 The Organization of LifeC H A P T E R 4

1 Ecosystems: Everything Is Connected

2 Evolution

3 The Diversity of LivingThings

PRE-READING ACTIVITY

LayeredBookBefore youread this

chapter, create the FoldNoteentitled “Layered Book”described in the Reading andStudy Skills section of theAppendix. Label the tabs ofthe layered book with“Ecosystem,” “Population,”“Community,” and“Habitat.” As you read thechapter, write informationyou learn about each category under theappro-priateflap.

A coral reef is an ecosystem thatcontains a wide variety of species.How many different species can youfind in this photograph?

OverviewTell students that this chapter intro-duces the concept of ecosystems. In ecosystems, the biotic (living)and abiotic (non-living) componentsinteract to form an interconnectedsystem. Species adapt to their envi-ronment through the process ofevolution by natural selection. Thesix-kingdom system of organizationhelps scientists to classify organismsand study their differences.

Using the FigureIn a coral reef ecosystem, reef-buildingcoral combine with algae to producea colony that gathers energy fromthe sun, and creates shelter for manyorganisms. Ask students to identifyways that this ecosystem is organizedand to identify some of the possibleinteractions between organisms inthe photo. (sponges grow on coral,animals hide in coral, water providesnutrients) Animals that use coralreefs include sponges, sea worms,crustaceans, mollusks, sea urchins,jellyfish, turtles, sea anemones, andmany varieties of fish. Unfortunately,coral reefs are very sensitive to chang-ing environmental conditions, andpollution, fishing, and boating candamage coral reef ecosystems.

VisualLS

98

98 Chapter 4 • The Organization of Life

For information about videosrelated to this chapter, go togo.hrw.com and type in the keyword HE8 EVOV.

GENERAL

EEnnccoouurraaggee ssttuu--ddeennttss ttoo uusseetthheeiirr FFoollddNNoottee aassaa ssttuuddyy gguuiiddee ttoo

qquuiizz tthheemmsseellvveess ffoorr aa tteesstt oonntthhee cchhaapptteerr mmaatteerriiaall.. SSttuuddeennttssmmaayy wwaanntt ttoo ccrreeaattee LLaayyeerreeddBBooookk FFoollddNNootteess ffoorr ddiiffffeerreennttttooppiiccss wwiitthhiinn tthhee cchhaapptteerr..

PRE-READING ACTIVITY

LS 4c Organisms both cooperate and compete in ecosystems. The interrela-tionships and interdependencies of these organisms may generate ecosystemsthat are stable for hundreds or thousands of years. (Section 1)

LS 3a Species evolve over time. Evolution is the consequence of the inter-actions of (1) the potential for a species to increase its numbers, (2) the geneticvariability of offspring due to mutation and recombination of genes, (3) a finitesupply of the resources required for life, and (4) the ensuing selection by theenvironment of those offspring better able to survive and leave offspring.(Section 2)

LS 3b The great diversity of organisms is the result of more than 3.5 billionyears of evolution that has filled every available niche with life forms. (Section2 and Section 3)

LS 3e Biological classifications are based on how organisms are related.Organisms are classified into a hierarchy of groups and subgroups based on

similarities which reflect their evolutionary relationships. Species is the mostfundamental unit of classification. (Section 3)

hes08TE_c04_098_CO 9/13/06 11:05 AM Page 98

Complex Systems Use the following exam-ple to illustrate the complexity and inter-connectedness of the components within anecosystem. In San Diego, California, a marshhabitat, home to two endangered bird species,was destroyed to build a freeway. To get a permit to build the freeway, the city had toagree to “rebuild” the ecosystem for the birds.After five years and $500,000, scientists andofficials found that replacing an ecosystem issomething that we do not know much about.

For example, when the endangered birds werereleased into their re-created ecosystem, theywould not nest because the marsh grass wasnot tall enough. The grass was shorterbecause a tiny predator beetle that fed onmarsh-grass-eating insects was not present inthe new ecosystem. Without the beetle to con-trol the insect population, the marsh grasscould not grow to its full height. This wasonly one of many problems that the city facedin its ecosystem re-creation project.

Chapter 4 • The Organization of Life 99

You may have heard the concept that in nature everything isconnected. What does this mean? Consider the following example.In 1995, scientists interested in controlling gypsy moths, whichkill oak trees, performed an experiment. The scientists removedmost mice, which eat young gypsy moths, from selected plots ofoak forest. The number of gypsy moth eggs and young increaseddramatically. The scientists then added acorns to the plots. Miceeat acorns. The number of mice soon increased, and the numberof gypsy moths declined as the mice ate them as well.

This result showed that large acorn crops can suppress gypsymoth outbreaks. Interestingly, the acorns also attracted deer,which carry parasitic insects called ticks. Young ticks sooninfested the mice. Wild mice carry the organism that causes Lymedisease. Ticks can pick up the organism when they bite mice.Then the ticks can bite and infect humans. This example showsthat in nature, things that we would never think are connected—mice, acorns, ticks, and a human disease—can be linked to eachother in a complex web.

Defining an EcosystemThe mice, moths, oak trees, deer, and ticks in the previous exampleare all part of the same ecosystem. An (EE koh SIS tuhm)is all of the organisms living in an area together with their physicalenvironment. An oak forest is an ecosystem. The coral reef onthe opposite page is an ecosystem. Even a vacant lot, as shownin Figure 1, is an ecosystem.

ecosystem

Objectives� Distinguish between the biotic and

abiotic factors in an ecosystem.

� Describe how a population differsfrom a species.

� Explain how habitats are impor-tant for organisms.

Key Termsecosystembiotic factorabiotic factororganismspeciespopulationcommunityhabitat

S E C T I O N 1

Ecosystems: Everything Is Connected

Figure 1 � This vacant lot is actuallya small ecosystem. It includes variousorganisms, including plants andinsects, as well as soil, air, and sunlight.

www.scilinks.orgTopic: EcosystemsCode: HE80466

OverviewBefore beginning this section,review with your students theObjectives in the Student Edition.This section will introduce studentsto the different components thatmake up an ecosystem and howpopulations and communities arestructured into ecosystems.

Ask students to think about all the things they need for survival.(Answers may vary, but shouldinclude at least food, water, oxygen,and shelter.) Ask them to thinkabout the kinds of ecosystems thatmight produce these necessities.

Activity Connections Web Draw a “con-nections web” on the board. Startwith a common animal, such as a blue jay, a raccoon, or a wasp.Write its name on the board andcircle it. Then have students nameinteractions that this animal haswith other plants or animals in itsenvironment. For instance, a bluejay eats different insects, so youcould draw a line connecting thebird to an insect. Extend the con-nections and include abiotic factors(the insect feeds on a plant, whichuses sunlight). Continue until theweb becomes complex. Introducethe idea of an ecosystem, empha-sizing that your web representsonly a fraction of the interactionsin a natural ecosystem at any given time. Visual LS

MotivateMotivate

Bellringer

FocusFocus

99

11SS EE CC TT II OO NN

GENERAL

• Lesson Plan• Active Reading• Section Quiz GENERAL

Chapter Resource File

Transparencies

TT Bellringer

CONNECTIONCONNECTIONREAL-LIFEREAL-LIFE

GENERAL

hes08TE_c04_099-102_S1 8/24/06 1:27 PM Page 99

Ecosystems Are Connected People often think of ecosystems asisolated from each other, but ecosystems do not have clearboundaries. Things move from one ecosystem into another. Soilwashes from a mountain into a lake, birds migrate from Michiganto Mexico, and pollen blows from a forest into a field.

The Components of an EcosystemIn order to survive, ecosystems need certain basic components. These are energy, mineral nutrients, carbon dioxide, water, oxy-gen, and living organisms. As shown in Figure 2, plants and soilare two of the most obvious components of most land ecosys-tems. The energy in most ecosystems comes from the sun.

To appreciate how all of the things in an ecosystem are con-nected, think about how a car works. The engine alone is madeup of hundreds of parts that all work together. If even one partbreaks, the car might not run. Likewise, if one part of an ecosys-tem is destroyed or changes, the entire system may be affected.

Biotic and Abiotic Factors An ecosystem is made up of bothliving and nonliving things. are the living and onceliving parts of an ecosystem, including all of the plants and animals.Biotic factors include dead organisms, dead parts of organisms,such as leaves, and the organisms’ waste products. (ay bieAHT ik) are the nonliving parts of the ecosystem. Abioticfactors include air, water, rocks, sand, light, and temperature.Figure 3 shows several biotic and abiotic factors in an Alaskanecosystem.

Scientists organize living things into levels. Figure 4 showshow an ecosystem fits into the organization of living things.

What is the difference between a biotic factor and

an abiotic factor? (See the Appendix for answers to Reading Checks.)��Reading Check

factorsAbiotic

Biotic factors

Figure 2 � Like all ecosystems, thiscoastal region in France contains certain basic components. Whatcomponents can you identify?

Figure 3 � This caribou is a bioticfactor in a cold, northern ecosystemin Denali National Park, Alaska.

GeofactThe Living Soil Soil, which is partof nearly all ecosystems on land, isformed in part by living organisms,which break down dead leaves andorganisms. Small, plantlike organ-isms even help break down rocks!

Demonstration Identifying EcosystemComponents Bring in some maga-zines that have photos of naturalsystems. Pick out three picturesthat represent different ecosystems.Show each picture to the class, andhave them brainstorm all the com-ponents of each ecosystem. Writethe components of each system inits own section on the board. Afterthe class is finished naming thecomponents, compare the systems.Identify the components that arecommon to all systems. Discusswhy some of the components areneeded in all ecosystems. Visual

Activity Ecosystem Connections In thisexercise, students will learn howforest and stream ecosystems arelinked. Bring in some pre-assembledwooden frames and some windowscreen. Have students staple thescreen to the frames to form aframe that will catch and holdleaves. Take these materials out toa stream area with trees next to it.(Make sure the area is somewhatisolated, so the materials are notdisturbed.) Have students tie thescreens to vegetation that is closeto the stream edge. Tell them to tryto keep the screens flat. Also havethem attach a note to the screensidentifying them as a science proj-ect. Take students out to the streamevery week to collect any materialthat has been caught in the screens.Have students bring the materialback to the classroom to identifyand weigh it. KinestheticLS

LS

TeachTeach

“When we try to pick out anything byitself, we find it hitched to everythingelse in the universe.”

—John Muir (naturalist, writer, and founder of the Sierra Club)

Ask students to explain what they thinkJohn Muir might have meant. Ask stu-dents to what extent humans are“hitched to everything else.” (Humansrely on natural systems to provide all ofthe necessities for survival.)


100

GENERAL

Notable Quotes

Diverse Temperate Forests The soil ofa temperate forest has a biological diver-sity that rivals the soil found in tropicalrain forests. In fact, invertebrates in for-est soils may be the most important factor in determining the long-term productivity of a forest. Soil arthropodsinclude beetles, centipedes, pseudoscor-pions, springtails, and mites. Have stu-dents collect several 20 cm3 soil samplesand use a microscope to examine thesamples for soil arthropods.

BRAIN FOODAAnnsswweerr ttoo RReeaaddiinngg CChheecckkBiotic factors are the living or once-living parts of an ecosystem. Abioticfactors are the nonliving parts of anecosystem.

hes08TE_c04_099-102_S1 8/28/06 12:38 PM Page 100

Self-sustaining Colonies Have groupsresearch the reasons for Biosphere II, includingits failure as a self-contained ecosystem and itscurrent use as an ecological laboratory. Oncestudents have learned something about run-ning a self-sustaining colony, have groupsdesign their own colony for Mars, Antarctica,a desert, the moon, or under the sea. Studentscan create models, scale drawings, or blue-prints on the recycling of air, water, and waste,and descriptions of how different populationswould be managed. InterpersonalLS

Linnaeus Swedish naturalist, Carolus Linnaeus(1707–1778), was the father of the binomialsystem used to identify species today. A specieshas a two-part Latin name: the first part is itsgenus, and the second part names the specificorganism. For example, the Norway rat isclassified in the genus Rattus. Its full scientificname, which is unique among all organisms, isRattus norvegicus. Have students look up thescientific name of some common plants andanimals. Also ask them to find out who namedthese species and when they were named.

Interpersonal LS


Organisms An is an individual living thing. You are anorganism, as is an ant crawling across the floor, an ivy plant onthe windowsill, and a bacterium in your intestines.

A is a group of organisms that can mate to producefertile offspring. All humans, for example, are members of thespecies Homo sapiens, while all black widow spiders are mem-bers of the species Latrodectus mactans. Every organism is amember of a species.

Populations Members of a species may not all live in the sameplace. Field mice in Maine and field mice in Florida will neverinteract even though they are members of the same species. Anorganism lives as part of a population. A is all themembers of the same species that live in the same place at thesame time. For example, all the field mice in a corn field makeup one population of field mice.

An important characteristic of a population is that its membersusually breed with one another rather than with members ofother populations. The bison in Figure 5 (right) will usually mate with another member of the same herd,just as the wildflowers (left) will usually bepollinated by other flowers in the same field.

population

species

organism

Figure 4 � An individual organism ispart of a population, a community,an ecosystem, and the biosphere.

Figure 5 � Two of the populationsshown here are a population of purple-flowered musk thistle (left) and a herdof bison (right).

Using the Figure Connecting Ecosystem LevelsHave students analyze Figure 4and explain the connection of each level to the preceding one.Then have students look at a series of pictures or slides, and ask them to classify the imagesusing the terms organism, popula-tion, community, ecosystem, andbiosphere. [The illustration shows a wildebeest (organism); a herd ofwildebeest (population); a closeup of several species: wildebeest, lion,giraffe, elephant, rhino and vulture(community); a scene of the Africansavanna showing many animals(ecosystem); and the Earth (biosphere)]

Visual

Group Activity Golf Course Impacts Ask stu-dents to imagine that they are on a committee that has the task ofdeciding whether a golf course canbe built without damaging theenvironment. Tell students to picka specific location in their commu-nity for their proposed golf course,and to describe the ecosystem atthat location. Take a field trip outto that location to better under-stand all the organisms that use the site. Back in the classroom,have students analyze and describeall of the possible repercussions of the golf course on the ecosystem.Finally, ask students to determine if the golf course should be built. If not, they should explain why. If they decide that the golf courseis a good idea, have them developa plan showing how the coursecould be designed so that it has lit-tle impact on the environment. If a golf-course scenario isn’t appro-priate for your region, suggest ahighway, parking garage, shoppingcenter, or other development.

Interpersonal Co-op LearningLS

LS

101

GENERAL

Transparencies

TT Levels of Ecological Organization

CONNECTIONCONNECTIONHISTORYHISTORY

GENERALGENERAL

hes08TE_c04_099-102_S1 8/24/06 2:01 PM Page 101

1. List the abiotic and biotic factors you see in thenorthern ecosystem in Figure 3.

2. Describe a population not mentioned in this section.

3. Describe which factors of an ecosystem are not partof a community.

4. Explain the difference between a population and aspecies.

CRITICAL THINKING

5. Analyzing Relationships Write your own defini-tion of the term community, using the terms biotic factors and abiotic factors.

6. Understanding Concepts Why might a scientistsay that an animal is becoming rare because ofhabitat destruction?

WRITING SKILLS

S E C T I O N 1 Review

Communities Every population is part of a a groupof various species that live in the same place and interact witheach other. A community is different from an ecosystem because acommunity is made up only of biotic components. A pond commu-nity, for example, includes all of the populations of plants, fish,and insects that live in and around the pond. All of the livingthings in an ecosystem belong to one or more communities.

Communities differ in the types and numbers of species theyhave. A land community is often characterized by the types ofplants that are dominant. These plants determine the other organ-isms that can live in this community. For example, the dominantplant in a Colorado forest might be its ponderosa pine trees. Thispine community will have animals, such as squirrels, that live inand feed on these trees.

HabitatThe squirrels mentioned above live in apine forest. All organisms live in particularplaces. The place an organism lives is calledits A howler monkey’s habitat isthe rain forest and a cactus’s habitat is adesert. The salamander shown in Figure 6 isin its natural habitat, the damp forest floor.

Every habitat has specific biotic and abi-otic factors that the organisms living thereneed to survive. A coral reef contains seawater, coral, sunlight, and a wide variety ofother organisms. If any of these factorschange, then the habitat changes.

Organisms tend to be very well suited totheir natural habitats. Indeed, animals andplants cannot usually survive for long peri-

ods of time away from their natural habitats. For example, a fishthat lives in the crevices of a coral reef will die if the coral reef isdestroyed.

Why is an organism’s habitat important for that

organism? (See the Appendix for answers to Reading Checks.)��Reading Check

habitat.

community,

Figure 6 � Salamanders, such as thisred-backed salamander, live in habi-tats that are moist and shaded.

ReteachingFinding Interactions Have students consider the followingorganisms: honeybees, sunflowers,earthworms, red-winged blackbirds,and moles. Ask students to brain-storm and draw a possible ecosys-tem using these organisms. Askthem to label at least three interac-tions. (Possible interactions include:honeybees pollinate sunflowers,which produce seeds for blackbirds;earthworms process soil for sunflow-ers; moles eat earthworms; sunflowersuse water, air, and soil.) Logical

Quiz 1. Think of your favorite animal.

What are the components of itshabitat that allow it to survive?(Answers may vary.)

2. How could soil and a mouse interact in an ecosystem? (Themouse could dig a burrow in thesoil. The soil sustains plants andfungi that provide food for themouse. When the mouse dies, itprovides food for the microbes in the soil.)

Alternative Assessment Organism Biographies Ask stu-dents to pick their favorite organ-ism and write a “biography” forthat organism that includes threechapters: one on habitat, a secondon the survival of that organism’spopulation within the community,and a third on abiotic characteris-tics that are crucial to the survivalof the organism. Invite students toinclude their “biography” in theirPortfolio. VerbalLS

LS

CloseClose

AAnnsswweerrss ttoo SSeeccttiioonn RReevviieeww 1. Biotic components include: caribou, plants

(higher plants, lichen, moss). Abiotic com-ponents include air, water, rock, and light.Students could also include soil in both thebiotic and abiotic lists.

2. Answers may vary. A population is a group of individuals of one species living in an areaat a given time.

3. The abiotic factors, including water, air, rocks,and sunlight, are not part of a community.

4. A species is a group of organisms whose mem-bers can mate to produce fertile offspring. Apopulation is a subset of a species; it consists ofmembers of the same species that also live inthe same vicinity.

5. Answers may vary. Students should understandthat only biotic factors are part of a community.

6. Each species has evolved to occupy a certaintype of habitat. If that habitat is destroyed, thespecies may become rare because its memberscannot get all the things they need to survive.


102

GENERAL

GENERAL

AAnnsswweerr ttoo RReeaaddiinngg CChheecckkA habitat is important to an organ-ism because it has the biotic and abi-otic factors the organism needs tosurvive.

hes08TE_c04_099-102_S1 8/24/06 1:28 PM Page 102

Evolution in the Fossil Record Have studentsdo research on either the fossil Archaeopteryx(thought to be the first feathered organism andthe precursor to birds) or the ancient precursorsof the horse. Both organisms are good examplesof evolution represented in the fossil record.Encourage students to include their research in their Portfolio. IntrapersonalLS


Organisms tend to be well suited to where they live and what theydo. Figure 7 shows a chameleon (kuh MEEL ee uhn) capturing aninsect. Insects are not easy to catch, so how does the chameleon doit? Chameleons can change the color and pattern of their skin, andthen blend into their backgrounds. Their eyes are raised on little,mobile turrets that enable the lizards to look around without mov-ing. An insect is unlikely to notice such an animal sitting motionlesson a branch. When the insect moves within range, the chameleonshoots out an amazingly long tongue to grab the insect.

Evolution by Natural SelectionIn 1859, English naturalist Charles Darwin observed that organ-isms in a population differ slightly from each other in form, function, and behavior. Some of these differences are hereditary(huh RED i TER ee)—that is, passed from parent to offspring.Darwin proposed that the environment exerts a strong influenceover which individuals survive to produce offspring. Some indi-viduals, because of certain traits, are more likely to survive andreproduce than other individuals. Darwin used the term

to describe the survival and reproduction of organismswith particular traits.

Darwin proposed that over many generations natural selectioncauses the characteristics of populations to change. A change inthe genetic characteristics of a population from one generation tothe next is known as

How is natural selection related to the process ofevolution?��Reading Check

evolution.

selectionnatural

Objectives� Explain the process of evolution by

natural selection.

� Explain the concept of adaptation.

� Describe the steps by which apopulation of insects becomesresistant to a pesticide.

Key Termsnatural selection evolution adaptationartificial selectionresistance

S E C T I O N 2

Evolution

GeologyConnection to

Darwin and Fossils In the1800s, fossil hunting was a popu-lar hobby. The many fossils thatpeople found started argumentsabout where fossils come from.Darwin’s theory of evolution pro-posed that fossils are the remainsof extinct species from whichmodern species evolved. When hisbook on the theory of evolutionwas first published in 1859, itbecame an immediate bestseller.

Figure 7 � A chameleon catches anunsuspecting insect that has strayedwithin range of the lizard’s long, fast-moving tongue.

www.scilinks.orgTopic: EvolutionCode: HE80546

OverviewBefore beginning this section,review with your students theObjectives in the Student Edition.In this section, students learn howorganisms become adapted to theirenvironments through the processof evolution by natural selection.

Have students look at Figure 7 andwrite down the characteristics theythink help the chameleon when ithunts. Ask them to compare theirthoughts to the information in thefirst paragraph of the section.

Group Activity Natural Variety Members of apopulation naturally vary from oneanother. Have pairs measure eachother’s shoe size in centimeters. Onthe board, create a table to recordthe data for each student. Then,have students construct a bargraph using the results. Ask stu-dents if they think a bigger orsmaller shoe size could be a moresuitable trait in a human popula-tion. Ask them to think of charac-teristics that might have beenadvantageous to the survival ofearly humans. (Sample answers:problem-solving capabilities, the abil-ity to cooperate with other humans,or the ability to recognize enemies)

InterpersonalLS

MotivateMotivate

Bellringer

FocusFocus

103


GENERAL



Transparencies

TT Bellringer

CONNECTIONCONNECTIONPALEONTOLOGYPALEONTOLOGY

AAnnsswweerr ttoo RReeaaddiinngg CChheecckkNatural selection is the survival and reproduction of organisms with particular traits. Over manygenerations, natural selection leads to a change in the genetic character-istics of a population. This change is called evolution.

hes08TE_c04_103-107_S2 8/28/06 12:36 PM Page 103

Nature Selects Darwin thought that nature selects for certaintraits, such as sharper claws or lighter feathers, because organismswith these traits are more likely to survive and reproduce. Forexample, lions that have the trait of sharper claws can kill theirprey more easily than lions with duller claws. Thus, lions withsharper claws are more likely to survive and reproduce. Over time,the lion population includes a greater and greater proportion oflions with sharper claws. As the populations of a given specieschange, so does the species. Table 1 summarizes the premises ofDarwin’s theory of evolution by natural selection. Darwin proposedhis theory after drawing a conclusion based on these premises.

Evolution by Natural Selection

Premises Conclusion

1. Individuals in a population vary in each generation.

2. Some of these variations are genetic, or inherited.

3. More individuals are produced than live to grow up andreproduce.

4. Individuals with some genes are more likely to survive and reproduce than individuals with other genes.

Table 1 �

Darwin’s Finches

Before Charles Darwin formulated

his theory of evolution, he sailed

around the coast of South America.

The plants and animals he saw had a

great effect on his thinking about

how modern organisms had origi-

nated. He was surprised by the

organisms he saw on islands because

they were often unusual species

found nowhere else.

He was particularly impressed

by the organisms in the Galápagos

Islands, an isolated group of volcanic

islands in the Pacific Ocean west of

Ecuador. The islands contain 13

unique species of birds, which have

become known as Darwin’s finches.

All the species look generally similar,

Princeton University biologists

Peter and Rosemary Grant have

spent 25 years studying Darwin’s

finches on Daphne Major, one of

the Galápagos Islands. Here, one

but different species have differently

specialized bills adapted to eating

different types of food. Some species

have large, parrotlike bills adapted to

cracking big seeds, some species

have slim bills that are used to sip

nectar from flowers, and some

species have even become insect

eaters. Darwin speculated that all

the Galápagos finches had evolved

from a single species of seed-eating

finch that found its way to the

islands from the South American

mainland. Populations of the finches

became established on the various

islands, and the finches that survived

were those able to eat what they

found on their island.

� Notice the beaks in the twospecies of Darwin’s finches. Whatdo you think these finches eat?

Based on these four premises, individualswith genetic traits that make them morelikely to grow up and reproduce in theexisting environment will become morecommon in the population from onegeneration to the next.


104

MISCONCEPTION ALERT

Survival of the Fittest Ask students whatthe term “survival of the fittest” means tothem. They may say that when two organ-isms fight each other to survive, the “fittest”one will win the contest. This is not the cor-rect meaning of the term. The “fittest” indi-vidual, the one that survives to pass its geneson, is the one most adapted to its current orchanging environment. This individual maybelong to a species of birds with small bills

that can only crack small seeds. If smallerseeds become less available, and a few indi-viduals have slightly larger bills that allowthem to crack bigger seeds, those individualsare more likely to survive and pass theirgenes on to future generations. This exampleinvolves no fighting. Instead, it involves thespread of advantageous characteristicsthrough a population.

Reteaching How Evolution Occurs Ask stu-dents, “If a squirrel starts to nestunder your desk, and this allows itto survive and produce more off-spring than other squirrels in thearea, has the squirrel evolved?”(No, it has just changed its behavior;an individual cannot evolve.)

Logical

Group Activity Adaptations Worldwide Assignstudent groups to the followingareas: African Desert, SouthAmerican Tropical Rainforest,North American Prairie, AustralianOutback, Lake Baikal in Siberia,Alaskan Tundra. Have groupsbrainstorm adaptations that theythink would suit plants and ani-mals that live in their assignedregion. Initially, they do not haveto think of actual species, just thetypes of organisms and their adap-tations. Discuss the adaptations inclass. Then, ask the groups to dosome research to find representa-tive plants and animals from theirregion. Have each group create aposter with their guesses aboutadaptations on the top, and pic-tures of the real organisms withdescriptions of their adaptationsbelow the guesses. Interpersonal

Co-op LearningLS

LS

TeachTeach

Transparencies

TT The Evolution of Thicker Fur in aDeer Population

GENERAL

hes08TE_c04_103-107_S2 8/24/06 1:33 PM Page 104

Writing Skills Read a selection from Darwin’sOrigin of Species. Provide a copy of this ex-cerpt to students, and have them write a reviewof the passage. Some students may wish toread and review the entire book. Suggest thatstudents include their review in their Portfolio.

IntrapersonalLS

BUILDERSKILL


Figure 8 shows an example of evolution in which a population ofdeer become isolated in a cold area. Many die, but some have genesfor thicker, warmer fur. These deer are more likely to survive, andtheir young with thick fur are also more likely to survive to repro-duce. The deer’s thick fur is an an inherited trait thatincreases an organism’s chance of survival and reproduction in acertain environment.

adaptation,

These deer live in a warm climate. Some have thicker fur than others.

Some deer become separated from the rest of the group.

In the cold mountain climate, deer with thicker fur are more likely to survive.

As years pass, eachgeneration has agreater proportionof deer with thick fur. After many generations, most deer have thick fur.

Figure 8 � These steps show the evolution of thicker fur in a population of deer.

species, the medium ground finch,

has a short, stubby beak and eats

seeds as well as a few insects. The

ground finches have few predators.

The Grants found that the main fac-

tor that determined whether a finch

lived or died was how much food

was available. During a long

drought in 1977, many plants died

and the small seeds that the finches

food source. Second, shifts in rain-

fall determine which plants live and

die, further limiting the finches’

food sources.

The islands are strongly influ-

enced by El Niño and La Niña

weather patterns. These weather

patterns produce alternating peri-

ods of very wet and very dry

weather in a relatively short time.

The plants vary, depending on the

weather pattern, exerting different

selective pressures on the animals

that depend on the plants for food.

CRITICAL THINKING

1. Analyzing RelationshipsCould the finches that evolvedbigger beaks in this study evolvesmaller beaks some day?

eat became scarce. Only finches

that had large beaks survived. Large

beaks allowed them to eat larger

seeds from the larger plants that

had survived the drought.

The finches that survived the

drought passed their genes for

large beaks to their offspring. Two

years later, the Grants found that

the beaks of medium ground

finches on Daphne Major were

nearly 4 percent larger, on aver-

age, than they had been before

the drought. The Grants had

observed evolution occurring in

birds over a short period of time,

something that had seldom been

seen before.

Two factors make the Galápagos

Islands well suited for researching

evolution. First, there are few plant

species in the community, so the

finches have little choice in their

105

Darwin’s Finches Tell studentsthat they are going to simulatenatural selection in a changingenvironment. Divide the classinto four groups that representpopulations of a species of finchthat have four different types ofbill: thin, medium, small andpowerful, and large and power-ful. Have students write theirbill type on a nametag or indexcard. Assign a food to the foursuits in a deck of cards, andthen assign a bill type to thatfood type (e.g., if you assignednectar to spades, the correspond-ing finch would have a thin bill).Write the suits (foods) and theircorresponding bill types on theboard. Tell students that there is an abundance of two foodtypes, so you are stacking thedeck to include more of two ofthe suits. Shuffle the deck, andhave each student draw onecard. If the student draws thesuit that corresponds to her orhis bill, then that student staysin the game (i.e., passes genes on to the next generation). Infollowing rounds, have eachremaining student draw threecards for each successful matchin the previous round (successfulindividuals have three successfuloffspring each round). Keepstacking the deck to simulatepatterns of environmentalchange. At the end of the game,ask students if the surviving offspring match the most abundant food sources.

Kinesthetic

AAnnsswweerrss ttoo CCrriittiiccaall TThhiinnkkiinngg1. Yes, this population of finches

might one day evolve smallerbeaks if their environmentfavored smaller beaks for atleast several years.

Co-op LearningLS

CulturalAwarenessCulturalAwareness

Crop Origins in the New World Teosinte,a wild grass, was domesticated in Mexicomore than 7,000 years ago, and eventuallybecame our modern corn. Other importantcrops that were probably first cultivated inMexico include cotton, tomatoes, chili pep-pers, tobacco, cacao, pineapple, squash, andavocadoes. Potatoes, tomatoes, and peanutsmay have originated in Peru and werebrought to Mexico by human travelers.

hes08TE_c04_103-107_S2 8/24/06 1:33 PM Page 105

Coevolution Organisms evolve adaptations to other organisms and to their physical environment. The process of two species

evolving in response to long-term interactions with each otheris called coevolution (koh EV uh LOO shuhn). One possibleexample is shown in Figure 9. The honeycreeper’s beak islong and curved, which lets it reach the nectar at the baseof the long, curved flower. The flower has evolved struc-tures that cause the bird to get pollen on its head as it sips

the nectar. When the bird moves to another flower, some ofthe pollen rubs off. In this way, the bird helps lobelia plants

reproduce. The honeycreeper’s adaptation for obtaining morenectar is a long, curved beak. The plant has two adaptations for

greater pollination. One is sweet nectar, which attracts the birds.The other is a flower structure that forces pollen onto a bird’s headwhen the bird sips the nectar.

Evolution by Artificial SelectionMany populations of plants and animals do not live in the wildbut are cared for by humans. People control how these organismsreproduce and therefore how they evolve. The two species inFigure 10 are closely related. Over thousands of years, humansbred the ancestors of today’s wolves to produce the variety of dog breeds. The selective breeding of organisms by humans forspecific characteristics is called

The fruits, grains, and vegetables we eat were also producedby artificial selection. By selecting for traits such as size andsweetness, farmers directed the evolution of crop plants. As aresult, crops produce fruits, grains, and roots that are larger,sweeter, and easier to harvest than their wild relatives. NativeAmericans cultivated the ancestor of today’s corn from a grasslikeplant in the mountains of Mexico. Modern corn is very differentfrom the wild plant that was its ancestor.

How is artificial selection different from naturalselection?��Reading Check

artificial selection.

MATHPRACTICEPlumper PumpkinsEach year a farmer saves and plants only the seeds from his largest pumpkins. Suppose thathe starts with pumpkins that average5 kg and each year grows pumpkinsthat are 3 percent more massive, onaverage, than those he grew the yearbefore. What will be the averagemass of his pumpkins after 10 years?

Figure 10 � As a result of artificialselection, the Chihuahua on the rightlooks very different from its wolfancestor on the left.

Figure 9 � This Hawaiian honey-creeper is using its curved beak to sipnectar from a lobelia flower.

Demonstration Dog Breeds Ask students why theythink dogs were bred to appear sodifferent. (Dogs were bred to do different jobs, requiring differentsizes and personalities.) Bring in abook of dog breeds from the locallibrary, and show a few examplesof retrieving, hunting, working, andcompanion dogs. Ask students todescribe the characteristics of eachdog type that make it suitable forits work. (Sample answer: Some smallterriers were bred to catch rats, sothey are small, fast, and tenacious.)If students have a dog at home, havethem research the kind of work forwhich their dog was bred and com-pare this work with their dog’scharacteristics. Visual

Gardens and Artificial SelectionBring in some flower and vegetableseed catalogs. Have students eachpick a flower or vegetable andresearch the plant from which itoriginated. Ask them to print apicture of the original plant, if itis available, and to compare thedifferences between the artificially-selected plant and the original. Askstudents what characteristic wasselected for in each case. (It is usu-ally the size of the fruit or flower.) Asan extension, grow a few heirloomplants for students to observe dur-ing the school year. VisualLS

LS

Teach, continuedTeach, continued


106

GENERAL

English Language Learners

Wasp and Fig Coevolution Figs and tinywasps called fig wasps are thought to havecoevolved a unique relationship. Fig flowersare completely enclosed in a structure calleda syconium. Fig wasp eggs hatch in a syco-nium, the wasp eats the ovule on which the egg hatches, and the wasp matures tomate there. The male fig wasp lives and

dies within the structure, but the femalewasp chews its way out. A female, coveredwith pollen after mating, enters anothersyconium through a pore in the structure.Once inside, the female spreads pollen onsome of the flowers, lays eggs, and dies,thereby continuing the cycle.

BRAIN FOOD

AAnnsswweerrss5 kg � (1.03)10 � 6.72 kg

MATHPRACTICE

AAnnsswweerr ttoo RReeaaddiinngg CChheecckkHumans use artificial selection tobreed organisms with traits thathumans want those organisms tohave. Natural selection is not guidedby human decisions but by an organism’s chance of survival andreproduction in its environment.

hes08TE_c04_103-107_S2 8/24/06 1:34 PM Page 106


Evolution of ResistanceSometimes humans cause populations of organisms to evolveunwanted adaptations. You may have heard about insect peststhat are resistant to pesticides and about bacteria that are resist-ant to antibiotics. What is resistance, and what does it have todo with evolution?

is the ability of one or more organisms to toleratea particular chemical designed to kill it. An organism may beresistant to a chemical when it contains a gene that allows it tobreak the chemical down into harmless substances. By trying tocontrol pests and bacteria with chemicals, humans promote theevolution of resistant populations.

Pesticide Resistance Consider the evolution of pesticideresistance among corn pests, as shown in Figure 11. A pesticideis sprayed on corn to kill grasshoppers. Most of the grasshop-pers die, but a few survive. The survivors happen to have a ver-sion of a gene that protects them from the pesticide. Thesurviving insects pass on the gene to their offspring. Each timethe corn is sprayed, insects that are resistant to the pesticidewill have a greater chance of survival and reproduction. As aresult, the insect population will evolve to include more andmore resistant members.

Resistance

1. Explain what an adaptation is, and provide threeexamples.

2. Explain the process of evolution by natural selection.

3. Describe one way in which artificial selection canbenefit humans.

4. Explain how a population of insects could becomeresistant to a pesticide.

CRITICAL THINKING5. Understanding Concepts Read the description of

evolution by natural selection in this section anddescribe the role that the environment plays in thetheory.

6. Identifying Relationships A population of rabbitsevolves thicker fur in response to a colder climate. Isthis an example of coevolution? Explain your answer.

READING SKILLS


FIELD ACTIVITYFIELD ACTIVITY Artificial Selection Look aroundyour school grounds and the areaaround your home for possibleexamples of artificial selection.Observe and report on any exam-ples you can find.

Dogs are one example of artifi-cial selection mentioned in thischapter, but you will probablyfind many more plant examples.Record your observations in your EcoLog.

Figure 11 � The evolution of resist-ance to a pesticide starts when thepesticide is sprayed on the corn.Most of the insects are killed, but afew resistant ones survive. After eachspraying, the insect population con-tains a larger proportion of resistantorganisms.

The survivorspass the trait forinsecticide resistanceto their offspring.

When the same insecticide is usedagain, more insects survive becausemore of them are resistant.

Insect pests are sprayed withan insecticide. Only a few resistant insects survive.

Reteaching Organize the class into groups offour or five students. Then havegroup members work together todevise a short skit, rap, song, orlimerick that uses the terms in thissection. Auditory

Quiz 1. Give two examples of organisms

that may have coevolved. (Sampleanswers: ants and aphids, beesand flowers, hummingbirds andflowers.)

2. Why did the Galápagos finchesstudied by the Grants evolve so rapidly? (When some of thesmaller food was no longer avail-able, only finches with largerbeaks could survive. Therefore,the genes for smaller beaks werelost, and the population evolvedquickly.)

Alternative Assessment Extinction Tribune Have studentgroups prepare a newspaper thatprovides information about theextinction of species and incorpo-rates the concept of naturalselection. Topics could includeextinction of dinosaurs, twentieth-century extinctions, and prehistoricmass extinctions. Each studentshould produce one major newsstory in addition to helping withother features, such as headlines,cartoons, obituaries, advertise-ments, and advice columns.

Visual Co-op LearningLS

LS

CloseClose

107

GENERAL

GENERAL

Transparencies

TT The Evolution of PesticideResistance

AAnnsswweerrss ttoo SSeeccttiioonn RReevviieeww1. An adaptation is an inherited trait that

increases an organism’s chances of survivaland reproduction, such as thick fur, sharpclaws, or a sticky tongue.

2. Organisms within populations differ in theirtraits. These differences make some organismsmore likely to survive and reproduce in theirenvironment than others in their populationare. The genetic characteristics of populationschange over time in response to these likeli-hoods, which is a process called evolution.

3. Answers may vary. Sample answer: Artificiallyselecting the most nutritious rice can helpnourish more people.

4. When a pesticide is sprayed on insects, many ofthem die. But the insects that survive have traitsthat allow them to resist the pesticide. Thoseresistant insects produce offspring that areresistant, so the population becomes resistant.

5. If the environment contains limited resources,organisms that have certain characteristics or traits may be more likely to survive and reproduce in the environment than other organisms in the same environment.

6. No. This is an adaptation to the physical environment, so it is natural selection.Coevolution involves two organisms that have evolved mutually beneficial traits.

hes08TE_c04_103-107_S2 8/24/06 1:34 PM Page 107

Life on Earth is incredibly diverse. Take a walk in a park, andyou will see trees, birds, insects, and maybe fish in a stream. Allof these organisms are living, but they are all very different fromone another.

Most scientists classify organisms into six kingdoms, asdescribed in Table 2, based on different characteristics. Membersof the six kingdoms get their food in different ways and are madeup of different types of cells, the smallest unit of biologicalorganization. The cells of animals, plants, fungi, and protists con-tain a nucleus (NOO klee uhs), which consists of a membranethat surrounds a cell’s genetic material. Bacteria, fungi, andplants all have cell walls, structures that surround their cells andprovide them with support.

Archaebacteria and EubacteriaOrganisms in the kingdoms Archaebacteria and Eubacteria sharea lot of features, even though they are not closely related. Theyare microscopic, single-celled organisms that usually have cellwalls and reproduce by dividing in half. Unlike all other organ-isms, members of Archaebacteria and Eubacteria lack nuclei.

are often found in extreme places, such as hotsprings. Eubacteria are very common and can be found in soiland animal bodies. Many types of eubacteria are commonlyreferred to as bacteria.

Archaebacteria

Objectives� Name the six kingdoms of organ-

isms and identify two characteris-tics of each.

� Explain the importance of bacteriaand fungi in the environment.

� Describe the importance of pro-tists in the ocean environment.

� Describe how angiosperms andanimals depend on each other.

� Explain why insects are such suc-cessful animals.

Key TermsArchaebacteria

Eubacteria

fungus

protist

gymnosperm

angiosperm

invertebrate

vertebrate

S E C T I O N 3

The Diversity of Living Things

The Kingdoms of Life

Kingdom Characteristics Examples

corals, sponges, worms, insects, fish, reptiles, birds, and mammals

many cells; no cell walls; ingest theirfood; live on land and in water

Animals

ferns, mosses, trees, herbs, and grassesmany cells; make their own food by photosynthesis; have cell walls

Plants

diatoms, dinoflagellates (red tide), amoebas,trypanosomes, paramecia, and Euglena

most single celled but some have manycells; most live in water

Protists

yeasts, mushrooms, molds, mildews, and rusts

absorb their food through their body sur-face; have cell walls; most live on land

Fungi

proteobacteria (common in soils and inanimal intestines) and cyanobacteria (alsocalled blue-green algae)

single celled; lack cell nuclei; reproduceby dividing in half; incredibly common

Eubacteria

methanogens (live in swamps and produce methane gas) and extreme thermophiles (live in hot springs)

single celled; lack cell nuclei; reproduceby dividing in half; often found in harsh environments

Archaebacteria

Table 2 �

OverviewBefore beginning this section,review with your students theObjectives in the Student Edition.This section describes the diversityof living organisms and the waythat scientists classify organisms.

Ask students, “Do you know howa scientist would classify you?”(Kingdom: Animalia; Phylum:Chordata; Class: Mammalia; Order:Primates; Family: Hominidae; Genus:Homo; Species: Homo sapiens.)

IdentifyingPreconceptions Extreme Organisms Ask studentsto list places where single-celledorganisms grow. Then ask if theythink that organisms grow in hotwater. They may say no, becausecommon knowledge dictates thatwashing your hands in hot waterkills germs. Explain that archae-bacteria live in extreme conditions,such as in scalding hot springs.

IntrapersonalLS

MotivateMotivate

Bellringer

FocusFocus


108




MISCONCEPTION ALERT

Classification of Life This textbook clas-sifies organisms into six kingdoms. Otherscientists use three superkingdoms: Bacteria,Archaea, and Eucarya. Still others use a five-kingdom system. Who is right? All ofthem are, in a way. Scientists use the bestdata they have to organize species in a waythat reflects how the species relate to eachother. But each classification system focuseson different characteristics. It is difficult todetermine how all organisms evolved, so it is difficult to find the “right” way to classify

them. Alternate systems enliven the debateand inspire scientists to find the closest under-lying relationships. Ask students to giveexamples of how things may be classifieddifferently but still logically. (One example isthe way grade levels are organized. One schooldistrict may divide its schools into Primary(1–6), Jr. High (7–8) and High School (9–12).Other districts may have a Middle School thatencompasses grades 6–9. Neither way is rightor wrong, and each way reflects logical rela-tionships between the grades.) LogicalLS

Transparencies

TT BellringerTT Classification of Living Things

hes08TE_c04_108-113_S3 8/24/06 1:43 PM Page 108

Ruminant Animals Bring in a diagram of acow’s digestive system. Show students how thestomachs are arranged, and tell them that eachstomach contains microbes that help the cowprocess its food. Ask students to research howthe microbes help the cow derive nutrientsfrom grass and hay. (Microbes that can breakdown cellulose, which is found in the tough cellwalls of plants, ferment grass and hay. Thisprocess releases fatty acids from the plant matterthat can be absorbed and used by the cow.)

IntrapersonalLS

Bacteria and the Environment Bacteria play manyimportant roles in the environment. Some kinds of bac-teria break down the remains and wastes of other organ-isms and return nutrients to the soil. Others recyclemineral nutrients, such as nitrogen and phosphorous.For example, certain kinds of bacteria play a veryimportant role by converting nitrogen in the air into aform that plants can use. Nitrogen is important becauseit is a main component of proteins and genetic material.

Bacteria also allow many organisms, including humans,to extract certain nutrients from their food. The bacteriain Figure 12 are Escherichia coli, or E. coli, a bacteriumfound in the intestines of humans and other animals.Here, E. coli helps digest food and release vitamins thathumans need. A different form of E. coli can causesevere food poisoning.

FungiA (plural, fungi) is an organism whose cells have nucleiand cell walls. A mushroom is the reproductive structure of a fun-gus. The rest of the fungus is an underground network of fibers.These fibers absorb food from decaying organisms in the soil.

Fungi get their food by releasing chemicals that help breakdown organic matter, and then absorbing the nutrients. The bodies of most fungi are a huge network of threads that growthrough the soil, dead wood, or other material on which thefungi are feeding. Like bacteria, fungi play an important role inthe environment by breaking down the bodies and body parts of dead organisms.

Like bacteria, some fungi cause diseases, such as athlete’sfoot. Other fungi add flavor to food. The fungus in blue cheese,shown in Figure 13, gives the cheese its strong flavor. And fungicalled yeasts produce the gas that makes bread rise.

Name one way that bacteria and fungi are similarand one way that they are different.��Reading Check

fungus

Figure 12 � The long, orangeobjects in the image above are E. colibacteria as they appear under amicroscope.

Figure 13 � A mushroom (left) is thereproductive structure of a fungusthat lives in the soil. The cheese(above) gets its taste and its bluecolor from a fungus.

Spider MapCreate the

Graphic Organizer entitled“Spider Map” described in theAppendix. Label the circle“Kingdoms.” Create a leg for eachkingdom. Then, fill in the map with detailsabout the organisms in each kingdom.

Group Activity Mushroom Walk Take your classon a walk in the woods to find thefungal structures commonly knownas mushrooms. Have students studythe fungi they find. CAUTION: Warnstudents not to eat any of the fungi,as some may be poisonous. Use amushroom identification guide,and work with students to makespore prints and identify the typesof fungi. Have students weargloves while making spore prints.Also have students identify whereeach fungus fits into its woodlandecosystem. Ask, “Does it decom-pose dead wood or attack otherfungi?” Have students draw thedifferent types of fungi and includethose drawings in their Portfolio.

Kinesthetic/VisualLS

TeachTeach

109

GENERAL

GENERAL


Humongous Fungus Theworld’s largest individualorganism is a fungus! Oneparticular honey mushroom,Armillaria ostoyae, hasbeen growing for about2,400 years and now covers2,200 acres in the MalheurNational Forest in easternOregon. That makes it3.5 miles across and as bigas 1,665 football fields. Thisgiant fungus was determinedto be one organism by aForest Service scientist,Catherine Parks, who testedits DNA at various locations.

BRAIN FOOD

GENERAL

Spider MapYYoouu mmaayy wwaanntt ttoo hhaavvee ssttuuddeennttss wwoorrkk iinn ggrroouuppss ttooccrreeaattee tthhiiss SSppiiddeerr MMaapp.. HHaavveeoonnee ssttuuddeenntt ddrraaww tthhee mmaapp aanndd ffiillll iinn tthhee iinnffoorrmmaattiioonnpprroovviiddeedd bbyy ootthheerr ssttuuddeennttssffrroomm tthhee ggrroouupp..

AAnnsswweerr ttoo RReeaaddiinngg CChheecckkBoth bacteria and fungi cause dis-eases. Bacteria do not have nuclei,while fungi do have nuclei.

hes08TE_c04_108-113_S3 8/24/06 1:44 PM Page 109

ProtistsMost people have some idea what bacteria and fungi are, but fewcould define a protist. are a diverse group of one-celledorganisms and their many-celled relatives. Some, such as amoebas,are animallike. Others, such as the kelp in Figure 14, are plantlike.

Still others are more like fungi. Most protists are one-celledmicroscopic organisms. This group includes amoebas and

diatoms (DIE uh TAHMS). Diatoms, shown in Figure 14,float on the ocean surface. The most infamous protist isPlasmodium, the one-celled organism that causes the dis-ease malaria. From an environmental standpoint, themost important protists are probably algae. Algae are

plantlike protists that can make their own food using thesun’s energy. Green pond “scum” and seaweed are exam-

ples of algae. Algae range in size from the giant kelp to theone-celled phytoplankton, which are the initial source of food inmost ocean and freshwater ecosystems.

PlantsPlants are many-celled organisms that have cell walls and thatmake their own food using the sun’s energy. Most plants live onland, where the resources a plant needs are separated between theair and the soil. Sunlight, oxygen, and carbon dioxide are in theair, and minerals and water are in the soil. Plants have roots thataccess water and nutrients in the soil and leaves that collect lightand gases in the air. Leaves and roots are connected by vasculartissue, a system of tubes that carries water and food. Vascular tis-sue has thick cell walls, so a wheat plant or a tree is like a build-ing supported by its plumbing.

Lower Plants The first land plants had no vascular tissue, andthey also had swimming sperm. As a result, these early plantscould not grow very large and had to live in damp places. Theirdescendants alive today are small plants such as mosses. Fernsand club mosses were the first vascular plants. Some of the firstferns were as large as small trees. Tree ferns still live in the trop-ics and in New Zealand today. Some examples of lower plantsare shown in Figure 15.

Protists

BiologyConnection to

Cell Size Every cell mustexchange substances with itsenvironment across its surface.The larger the cell, the smaller itssurface is compared with its vol-ume. So the larger the cell, themore slowly substances movefrom outside the cell to itsinterior. This relationship limitsmost cells to microscopic sizes.

Figure 14 � Kelp (left) are hugeprotists with many cells that liveattached to the ocean floor. Themicroscopic diatoms (right) are protists that live in the plankton.

Figure 15 � Lower plants, such asthese mosses and ferns, live in dampplaces because they need water toreproduce.

Activity Pond Protists Gather 2 or 3 plastic lab bottles with lids, somemicroscopes, glass slides, coverslips, medicine droppers, and abook on protist identification.Then visit a local pond where it is easy to get a water sample. Have students fill the bottles withpond water. Back in class have stu-dents prepare slides using drops ofpond water. Have students lookfor protists and other organismsunder the microscope. Ask stu-dents to draw what they see and to include those drawings in their Portfolio.

Kinesthetic

Teaching Tip Pond Creatures The followingprotists are likely to be found inpond water: diatoms: one-celledorganisms with geometric shapes,they are made of silica and are usu-ally yellow-brown in color; amoe-bas: one-celled organisms that“ooze” or travel by cytoplasmicmovement; ciliates: single-celledprotozoans with hair-like structures(cilia) around their entire cell mar-gin; volvox: colonial green algaethat look like spiky golfballs; eugle-nas: single-celled protozoans with atail called a flagellum; dinoflagel-lates: tiny algae with two flagella,one extending like a tail and onerunning in a groove around thecenter of the organism; other typesof green algae: these can be variousshapes and sizes.

LS


Horton Hears a Who Check out the Dr. Seussbook Horton Hears a Who from the locallibrary. Many of your students may have readthis book as small children. Tell students that,even though this is a children’s book, it hasmany ideas that relate to the ecological con-cepts in this chapter. Ask for some volunteersto read the story out loud. After students haveread the story, ask them to discuss how itrelates to species diversityand ecosystems. VerbalLS


110


GENERAL

GENERAL

CONNECTIONCONNECTIONLANGUAGE ARTSLANGUAGE ARTS

CONNECTIONCONNECTIONARTSARTS


Diatoms—Jewels of the Pond Diatoms aretruly beautiful organisms. Since they are madeof silica, they look like small glass boxes. If youfind a good assortment of diatoms in a pondwater sample, have students sketch what theysee looking through a microscope. If you can’tfind a good array, have students find photos ofdiatoms on the Internet to sketch. Some uni-versities have Web sites with Scanning ElectronMicroscope (SEM) galleries that include imagesof diatoms. Ask students to include the sketchesin their Portfolio.

VisualLSEnglish Language

Learners

hes08TE_c04_108-113_S3 8/24/06 1:44 PM Page 110

Vocabulary Gymnosperms and angiospermsshare the base -sperm, derived from the Greeksperma, or “seed.” Since gymnosperms haveseeds that are not covered by fruit, their seedsare gymnos, which is Greek for “naked.” Anangiosperm has a seed covered by an angion,or “vessel,” which is the fruit. For extra credit,ask students if they can figure out the generic(genus) name for the ground squirrel. Givethem the hint that it is a “seed lover.” (spermophilus) VerbalLS

BUILDERSKILL Teaching Tip Transport of Materials in Plants The vascular tissue of higher plants is made up of phloem, which transports sugars (food)throughout the plant and xylem, which trans-ports water. Xylem usually has larger cells and is located closer to the center of the stem.Lower plants, such as moss, lack xylem butcontain elongated conducting cells that movewater through the plant. Food-conducting cells exist in some mosses, to take the place of phloem.


Gymnosperms Pine trees and other evergreens with needle-likeleaves are gymnosperms (JIM noh SPUHRMZ). arewoody plants that produce seeds, but their seeds are not enclosedin fruits. Gymnosperms such as pine trees are also called conifersbecause their seeds are inside cones, as shown in Figure 16.

Gymnosperms have several adaptations that allow them to livein drier conditions than lower plants can. Gymnosperms producepollen, which protects and moves sperm between plants. Theseplants also produce seeds, which protect developing plants fromdrying out. And a conifer’s needle-like leaves lose little water.Much of our lumber and paper comes from gymnosperms.

Angiosperms Most land plants today are (AN jeeoh SPUHRMZ), flowering plants that produce seeds in fruit. All ofthe plants in Figure 17 are angiosperms. The flower is the repro-ductive structure of the plant. Some angiosperms, such as grasses,have small flowers that produce pollen that is carried by thewind. Other angiosperms have large flowers that attract insectsor birds to carry their pollen to other plants. Many floweringplants depend on animals to disperse their seeds and carry theirpollen. For example, a bird that eats a fruit will drop the seedselsewhere, where they may grow into new plants.

Most land animals could not survive without floweringplants. Most of the food we eat, such as wheat, rice, beans,oranges, and lettuce, comes from flowering plants. Building mate-rials and fibers, such as oak and cotton, also come from flower-ing plants.

How do angiosperms depend on animals, and how

do animals depend on angiosperms?��Reading Check

angiosperms

Gymnosperms

Figure 16 � This gymnosperm hasmale and female reproductive struc-tures called cones.

Figure 17 � This meadow contains awide array of angiosperms, includinggrasses, trees, and wildflowers.

QuickLABPollen andFlower DiversityProcedure

1. Use a cotton swab to collectpollen from a common flower-ing plant.

2. Tap the cotton swab on amicroscope slide and cover theslide with a cover slip.

3. Examine the slide under amicroscope, and draw thepollen grains in your EcoLog.

4. Repeat this exercise with agrass plant in bloom.

Analysis

1. Based on the structure of theflower and the pollen grains,explain which plant is pollinatedby insects and which is polli-nated by wind.

Group Activity Angiosperms in the ClassroomPlace students in groups of three or four. Give them three minutes to write down everything that is a product of an angiosperm. Thenask each group to name theirobjects. Disqualify any objects thatare not produced from a floweringplant. Award small prizes made ofangiosperm products to the win-ning group. Prizes could includedried fruit, nuts, pencils made ofbirch or maple, and somethingmade of cotton. Intrapersonal

Discussion Do All Fruiting Trees Flower?Some trees, such as magnolias andplums, have fragrant flowers thatare hard to miss. But what aboutmaple or birch trees? Have studentsthink about the types of flowersthey might have seen on trees thatare not well known for their flowers.Bring in a tree identification guidefor your area, and show studentsthe different flowers. If it is spring,tell them to watch for these flow-ers, and report back to the classwhen they see each tree blooming.

IntrapersonalLS

LS

111

GENERAL

GENERAL

QuickLABSkills Acquired:• Classifying• Identifying and Recognizing

Patterns

AAnnsswweerrss1. Pollen grains that are spread by

the wind need to be very light.Pollen grains spread by insectsneed to be sticky.

GENERAL

AAnnsswweerr ttoo RReeaaddiinngg CChheecckkAngiosperms depend on animals forpollination and dispersal of seeds.Animals depend on angiosperms forfood, building materials, and fibers.

hes08TE_c04_108-113_S3 8/24/06 1:45 PM Page 111

AnimalsAnimals cannot make their own food like plants can. They haveto take in food from their environment. In addition, animal cellshave no cell walls, so animals’ bodies are soft and flexible. Someanimals have evolved hard skeletons against which their musclescan pull to move their bodies. As a result, animals are much moremobile than plants and all animals move around in their environ-ments during at least one stage in their lives.

Invertebrates Animals that lack backbones are(in VUHR tuh brits). Many invertebrates live attached to hardsurfaces in the ocean and filter their food out of the water. Theseorganisms move around only when they are larvae (juveniles). Atthis early stage of life, they are part of the ocean’s floating plank-ton. Filter feeders include corals, various worms, and molluskssuch as clams and oysters. Figure 18 shows a variety of inverte-brates. Other invertebrates, including squid in the ocean andinsects on land, move around actively in search of food.

More insects exist on Earth than any other type of animal.Insects have a waterproof external skeleton that keeps them fromlosing water in dry environments. Insects move quickly and theyreproduce quickly. Also, most insects can fly. Their small sizeallows them to live on little food and to hide from enemies insmall spaces, such as a seed or in the hair of a mammal.

Many insects and plants have evolved together and depend oneach other to survive. Insects carry pollen from male parts of flowersto female parts of flowers to fertilize a plant’s egg, which developsinto a fruit. Without insect pollinators, we would not have toma-toes, cucumbers, apples, and many other crops. Insects also eatother insects that we consider to be pests. But, humans and insectsare often enemies. Bloodsucking insects transmit human diseases,such as malaria, sleeping sickness, and West Nile virus. Insectsprobably do more damage indirectly, however, by eating our crops.

invertebrates

MATHPRACTICEInsect Survival Most invertebrates produce large numbers of offspring. Most ofthese offspring die before reachingadulthood. Suppose an insect lays80 eggs on a plant. If 70 percentof the eggs hatch and 80 percentof those that hatch die beforereaching adulthood, how manyinsects will reach adulthood?

Figure 18 � Examples of inverte-brates include the banana slug (left), the leaf-footed bug (middle), and the cuttlefish (right).

www.scilinks.orgTopic: InvertebratesCode: HE80812

Group Activity Pollinator Game Organize theclass into two groups, and give eachgroup a pile of blank index cards.Have students conduct research tofind names of specific plants thathave insect pollinators. Ask thegroups to write the name of eachplant on one side of each card andthat of the pollinator on the other.Tell the groups not to share infor-mation. After the groups have eachcreated six pollination pairs, haveeach group take turns trying toidentify the pollinator associatedwith the plants the other group hasresearched. The group that iden-tifies the most correct pairs winsthe game. (You may want to giveflowers as a prize.) Interpersonal

Writing Ask students to write anessay about their favorite animal.Have them include informationabout where the animal lives, whatit eats, if it is a vertebrate or inver-tebrate, how it reproduces, if it issolitary or social, and informationon its other traits. Ask students to include information about howthe animal may have adapted to itscurrent environment. VerbalLS

BUILDERSKILL

LS


112

GENERAL

GENERAL

AAnnsswweerrss80 eggs � 0.7 � 56 hatchlings56 � (1 � 0.8) � 11 survive toreach adulthood

MATHPRACTICE


StrategiesStrategiesINCLUSIONINCLUSION

Ask students to create a chart to compare in-vertebrates and vertebrates. Ask students tofold a piece of lined paper in half vertically.Have students label one half “Invertebrates”and the other half “Vertebrates.” Studentscan fill in the characteristics of these animalsusing the textbook as a reference. Have stu-dents list at least three examples for eachtype of animal. The charts can be displayedor presented to groups of students.

••LLeeaarrnniinngg DDiissaabblleedd••DDeevveellooppmmeennttaallllyy DDeellaayyeedd••AAtttteennttiioonn DDeeffiicciitt DDiissoorrddeerr

hes08TE_c04_108-113_S3 8/24/06 1:45 PM Page 112

4. Fungi and some bacteria break down theremains of organisms and return the nutrientsfrom the remains to the soil. Some bacteria alsoconvert nitrogen to a form plants can use.

5. Many insects have evolved together withangiosperms. The success of angiospermsspurred the success of insects.

6. Angiosperms produce flowers as reproductivestructures, while gymnosperms called conifersproduce cones. Unlike the seeds of gym-nosperms, the seeds of angiosperms areenclosed in fruit.


Vertebrates Animals that have backbones are calledMembers of three vertebrate groups are shown in Figure 19. Thefirst vertebrates were fish, but today most vertebrates live on land.Amphibians, which include toads, frogs, and salamanders, arepartially aquatic. Nearly all amphibians must return to water tolay their eggs.

The first vertebrates to complete their entire life cycle on landwere the reptiles, which today include turtles, lizards, snakes, andcrocodiles. These animals have an almost waterproof egg, whichallows the egg to hatch on land, away from predators in the water.

Birds are warm-blooded vertebrates with feathers. Bird eggshave hard shells. Adult birds keep their eggs and young warm untilthey develop insulating layers of fat and feathers. Mammals arewarm-blooded vertebrates that have fur and feed their young milk.The ability to maintain a high body temperature allows birds andmammals to live in cold areas, where other animals cannot survive.

vertebrates.

1. Describe how animals and angiosperms depend oneach other. Write a short paragraph to explain youranswer.

2. Describe the importance of protists in the ocean.

3. Name the six kingdoms of life, and give two charac-teristics of each.

4. Explain the importance of bacteria and fungi in theenvironment.

CRITICAL THINKING

5. Analyzing Relationships Explain how the largenumber and wide distribution of angiosperm speciesis related to the success of insects.

6. Understanding Concepts Write a short paragraphthat compares the reproductive structures of gym-nosperms and angiosperms. WRITING SKILLS

WRITING SKILLS


EcofactConserving Water Arthropodsand vertebrates are the only twogroups of animals that have adap-tations that prevent dehydration soeffectively that some of them canmove about freely on land on adry, sunny day.

Figure 19 � Examples of vertebratesinclude the toco toucan (left), theblue-spotted stingray (middle), andthe snow leopard (right).

Reteaching Different Kingdoms Ask studentsto think about the major differencesbetween organisms in each kingdom.Have each student write an essayoutlining these differences andabout the advantages or disadvan-tages of each of the major charac-teristics of the six groups.

Intrapersonal

Quiz 1. What are the differences between

archaebacteria and eubacteria?(Archaebacteria are found mostlyin harsh environments, such as hotsprings. Eubacteria are commonthroughout terrestrial and aquaticenvironments.)

2. How might seeds of an angiospermbe spread? (some are carried bythe wind; some are spread by ani-mals that eat fruit and pass theseeds through their digestive sys-tem; some are spread by animalsthat hide seeds and forget wherethey are)

Alternative Assessment Kingdoms and EcosystemsHave students create an “ecosystembrochure.” Suggest that studentsgive the brochure an exciting coverthat clearly identifies the chosenecosystem. Inside the brochure,students could show pictures ofrepresentative plants, animals, pro-tists, fungi, and bacteria. The habi-tat for each organism should beincluded as well. Students shouldalso show pictures of relevant abi-otic factors, such as minerals,water, and rocks. Students shouldexplain the role of the abiotic fac-tors in the ecosystem. VisualLS

LS

CloseClose

113

GENERAL

GENERAL

AAnnsswweerrss ttoo SSeeccttiioonn RReevviieeww1. Many animals use the components of

angiosperms for food. Many angiospermsdepend on animals to pollinate them and to spread their seeds.

2. Algae make their own food using the sun’senergy and in turn are the initial source offood for most ocean animals.

3. Archaebacteria: single-celled, lack nuclei, livein extreme environments; eubacteria: single-celled, lack nuclei; fungi: have cell walls,absorb food through body surface; protists:mostly single-celled, most live in water; plants:multi-celled, photosynthesize food, have cellwalls; animals: multi-celled, ingest their food

hes08TE_c04_108-113_S3 8/24/06 1:46 PM Page 113

HighlightsCCHHAAPPTTEERR

44 HighlightsC H A P T E R 4

1 Ecosystems: Everything IsConnected

2 Evolution

3 The Diversity of Living Things

Key Termsecosystem, 99biotic factor, 100abiotic factor, 100organism, 101species, 101population, 101community, 102habitat, 102

Main Ideas� Ecosystems are composed of many intercon-nected parts that often interact in complex ways.

� An ecosystem is all the different organismsliving in an area as well as the physical environment.

� Organisms live as populations of one speciesin communities with other species. Each specieshas its own habitat, or type of place that it lives.

natural selection, 103evolution, 103adaptation, 105artificial selection,

106resistance, 107

� The naturalist Charles Darwin used the termnatural selection to describe the survival andreproduction of organisms with particulartraits.

� Darwin proposed that natural selection isresponsible for evolution—a change in thegenetic characteristics of a population fromone generation to the next.

� By selecting which domesticated animals andplants breed, humans cause evolution by artifi-cial selection.

� We have unintentionally selected for peststhat are resistant to pesticides and for bacteriathat are resistant to antibiotics.

archaebacteria, 108eubacteria, 108fungus, 109protist, 110gymnosperm, 111angiosperm, 111invertebrate, 112vertebrate, 113

� Organisms can be divided into six kingdoms,which are distinguished by the types of cellsthey possess and how they obtain their food.

� Bacteria and fungi play the important envi-ronmental roles of breaking down dead organ-isms and recycling nutrients.

� Gymnosperms, which include the conifers,are the earliest plants with seeds. Angiospermsare flowering plants.

� Insects, invertebrates that are the most suc-cessful animals on Earth, affect humans in bothpositive and negative ways.

� Vertebrates, or animals with backbones,include fish, amphibians, reptiles, birds, andmammals.

Alternative AssessmentEcosystem Alterations Ask stu-dents to think of three organismsfrom each of the six kingdoms of life. Have them connect all theorganisms so that they operate asan ecosystem. Students may repre-sent this ecosystem as a drawing or as words arranged in a web-likechart. Ask students to eliminatetwo species and to rearrange theecosystem to represent that loss.Finally, have students triple thepopulation of one of the species.Ask them to document how theecosystem changes. Visual

Clarifying Natural SelectionLamarck was a famous scientistwho suggested (incorrectly) thatthe neck of the giraffe becamelonger because it was stretching toreach high leaves. Ask students todiscuss why Lamarck was wrong.(If the parents lengthened their necksslightly by reaching for food, the off-spring would still start with the samelength neck as their parents. Neckswould not lengthen over generationswithout a genetic basis.) Have stu-dents use Darwin’s theory of evolu-tion by natural selection to devise a possible explanation for thegiraffe’s long neck. (Giraffe ances-tors with slightly longer necks wereable to reach more food and wereable to survive and reproduce betterthan their counterparts with shorternecks. Generations of longer-neckedanimals survived and reproduced more than others did, causing theevolution of long-necked giraffes.)

LogicalLS

LS


114

GENERAL

• Chapter Test• Chapter Test• Concept Review• Critical Thinking• Test Item Listing• Math/Graphing Lab• Observation Lab• CBL™ Probeware Lab• Consumer Lab• Long-Term Project

GENERAL

GENERAL

GENERAL

Chapter Resource FileStrategiesStrategiesINCLUSIONINCLUSION

Using Figure 4 as a model, ask students todesign and draw an ecosystem from a dif-ferent environment such as a forest, ocean,or desert. Have students label the organism,population, community, and ecosystem.Students can use pictures from magazinesor their original drawings to show theirunderstanding of the ecosystem.

••LLeeaarrnniinngg DDiissaabblleedd••DDeevveellooppmmeennttaallllyy DDeellaayyeedd

hes08TE_c04_114-117_HCR 8/24/06 2:02 PM Page 114

ReviewUsing Key TermsUse each of the following terms in a separatesentence.

1. adaptation2. invertebrate3. abiotic factor4. habitat5. species

For each pair of terms, explain how the meaningsof the terms differ.

6. community and population7. evolution and natural selection8. gymnosperm and angiosperm9. bacteria and protists

Understanding Key Ideas10. Which of the following pairs of organisms

belong to the same population?a. a dog and a catb. a marigold and a geraniumc. a human mother and her childd. a spider and a cockroach

11. Which of these phrases does not describepart of the process of evolution by naturalselection?a. the environment contains limited resources b. organisms produce more offspring than

will survive to reproducec. communities include populations of several

speciesd. organisms in a population differ in their

traits

12. Which of the following components of anecosystem are not abiotic factors?a. windb. small rocksc. sunlightd. tree branches

13. Some snakes produce a powerful poison thatparalyzes their prey. This poison is an exam-ple ofa. resistance.b. an adaptation.c. a reptile.d. an abiotic factor.

14. Angiosperms called roses come in a varietyof shapes and colors as a result ofa. natural selection.b. coevolution.c. different ecosystems.d. artificial selection.

15. Single-celled organisms that live in swampsand produce methane gas area. protists.b. archaebacteria.c. fungi.d. eubacteria.

16. Which of the following statements aboutprotists is not true?a. Most of them live in water.b. Some of them cause diseases in humans.c. They contain genetic material.d. Their cells have no nucleus.

17. Which of the following statements aboutplants is not true?a. They make their food from oxygen and

water through photosynthesis.b. Land plants have cell walls that help hold

their stems upright.c. They have adaptations that help prevent

water loss.d. Plants absorb nutrients through their roots.

C H A P T E R 4

Make an Outline After reading each section,summarize the main ideas into a short outline,leaving space between each entry. Then writethe key terms under the subsection in whichthey are introduced, followed by a short defini-tion for each.

STUDY TIP

ANSWERS

UUssiinngg KKeeyy TTeerrmmss1. Sample answer: Thick fur is an

adaptation that helps deer sur-vive in cold weather.

2. Sample answer: An invertebratedoes not have a backbone.

3. Sample answer: Water, rocks,light, temperature, and air are allabiotic factors in an ecosystem.

4. Sample answer: A habitat is theplace where an organism lives.

5. Sample answer: A species is agroup of organisms that areclosely related and can breed toproduce fertile offspring.

6. A community is a group of vari-ous species that live in the sameplace and interact with eachother. A population is an inter-breeding group of individuals ofthe same species in a given area.

7. Evolution is the change in the genetic characteristics of a popu-lation from one generation to the next. Natural selection is a process that drives evolution innature.

8. A gymnosperm is a plant whoseseeds are not enclosed in fruit.An angiosperm is a plant that produces flowers and seedsenclosed in fruit.

9. Bacteria are single-celled organ-isms that lack nuclei. Protists canbe multi-celled, and their cellscontain nuclei.

UUnnddeerrssttaannddiinngg KKeeyy IIddeeaass10. c11. c12. d13. b14. d15. b16. d17. a


115

ReviewCCHHAAPPTTEERR

44

Section Questions1 3–6, 10, 12, 18, 19, 25, 312 1, 7, 11, 13, 14, 20, 21, 23, 24, 26,

28–30, 34, 353 2, 8, 9, 15–17, 22, 27, 31–33

Assignment Guide


May June July August0

100

200

300

400

500

600

Ap

hid

po

pul

atio

n

Spraying 2

Spraying 3

Spraying 1

ReviewShort Answer18. List the five components that an ecosystem

must contain to survive indefinitely.19. What is the difference between biotic and

abiotic factors in an ecosystem?20. What is the difference between adaptation

and evolution?21. Describe the three steps by which a population

of insects becomes resistant to a pesticide.22. List the six kingdoms of organisms and the

characteristics of each kingdom.

Interpreting GraphicsBelow is a graph that shows the number ofaphids on a rose bush during one summer. Theroses were sprayed with a pesticide three times,as shown. Use the graph to answer questions 23and 24.23. What evidence is there that the pesticide

killed aphids?24. Aphids have a generation time of about 10

days. Is there any evidence that the aphidsevolved resistance to the pesticide during thesummer? Explain your answer.

Concept Mapping25. Use the following terms to create a concept

map: ecosystem, abiotic factor, biotic factor,population, species, community, and habitat.

Critical Thinking26. Analyzing Ideas Can a person evolve? Read

the description of evolution in this chapterand explain why or why not.

27. Making Inferences A scientist applies astrong fungicide, a chemical that kills fungi,to an area of forest soil every week duringOctober and November. How might thisarea look different from the surroundingground at the end of the experiment?

28. Drawing Conclusions In what building inyour community do you think bacteria areevolving resistance to antibiotics most rap-idly? Explain your answer.

29. Evaluating Assumptions Many peopleassume that the human population is nolonger evolving. Do you think these peopleare right? Explain your answer.

Cross-Disciplinary Connection30. Geography Find out how the isolation of

populations on islands has affected theirevolution. Research a well-known example,such as the animals and plants of Madagascar,the Galápagos Islands, or the HawaiianIslands. Write a short report on your find-ings.

Portfolio Project31. Study an Ecosystem Observe an ecosystem

near you, such as a pond or a field. Identifybiotic and abiotic factors and as many popu-lations of organisms as you can. Do not tryto identify the organisms precisely. Just listthem, for example, as spiders, ants, grass,not as a specific type. Make a poster show-ing the different populations. Put the organ-isms into columns to show which of thekingdoms they belong to.

WRITING SKILLS

READING SKILLS

C H A P T E R 4?

? ?

Aphid Population Changes Over Multiple Pesticide Sprayings

SShhoorrtt AAnnsswweerr18. Energy, mineral nutrients, water,

oxygen, and living organismsare all necessary to maintain anecosystem.

19. Biotic factors are the living oronce-living factors, and abioticfactors are the non-living factors.

20. An adaptation is an inheritedtrait that increases an organism’schance of survival. Evolution is achange in the genetic characteris-tics of a population from onegeneration to the next. Popula-tions evolve adaptations.

21. Step 1: The pesticide kills mostof the insects, but some are notkilled; Step 2: The survivinginsects pass the trait for resist-ance to their offspring; Step 3:Each time the pesticide is used,the resistant insects become alarger portion of the population,which is evolution.

22. Archaebacteria are single-celled,lack nuclei, and live in extreme environments. Eubacteria are single-celled, lack nuclei, and livein everyday environments. Fungiabsorb food through their sur-faces and have cell walls. Protistsare mostly single-celled, and mostlive in water. Plants are multi-celled, produce food through photosynthesis, and have cellwalls. Animals are multi-celledand ingest their food.

IInntteerrpprreettiinngg GGrraapphhiiccss23. The population dropped in size

after each spraying.24. Yes. The population still alive after

each spraying steadily increasedduring the summer indicatingthat a larger and larger propor-tion of the population is resistant.


116

CCoonncceepptt MMaappppiinngg25. Answers to the concept mapping questions

are on pages pp. 715–720.

CCrriittiiccaall TThhiinnkkiinngg26. No, individual people cannot evolve.

Individuals with different traits can repro-duce, and the traits that are best suited to theenvironment may become more common inthe population. In this way, the geneticmakeup of any population can graduallychange.

27. Answers may vary. Leaf litter may accumu-late because fungi are not there to help breakit down. Plants that have fungal associationsmay not grow there.

28. Answers may vary. Many antibiotics are usedin a hospital, so hospitals could be an areawhere bacteria evolve antibiotic resistance.

29. Answers may vary. Natural selection may not be taking place in most modern humanpopulations because we are protected frommost environmental factors.

CCrroossss--DDiisscciipplliinnaarryy CCoonnnneeccttiioonn30. Answers may vary.

ReviewCCHHAAPPTTEERR

44


Read the passage below, and then answerthe questions that follow.

Some Central American acacia trees, calledant acacias, have a mutually beneficial rela-tionship with ants that live on them. The treeshave several structures that benefit the ants.The trees have hollow thorns in which theants live, glands that produce sugary nectar,and swollen leaf tips, which the ants removeand feed to their larvae.

The ants reduce the damage that otherorganisms do to the tree. They remove dust,fungus spores, and spider webs. They destroyseedlings of other plants that sprout under thetree, so that the tree can obtain water andnutrients without competition from otherplants. The ants sting animals that try to eatthe tree.

Proof that the ants are valuable to the aca-cia tree comes from studies in which the antsare removed. Fungi invade the tree, it is eatenby herbivores, and it grows more slowly.When ants are removed from the tree, it usu-ally dies in a few months.

1. According to the passage, which of thefollowing statements is not true?a. Ants and ant acacias have evolved a

relationship beneficial to both of them.b. The ants prevent fungi from growing

on the acacia.c. The tree would benefit from not

having ants.d. The ants benefit from living on

the tree.

2. What is the advantage to an acacia ofnot having other plants grow nearby?a. Ants cannot crawl onto the acacia

from the other plants.b. The acacia keeps more ants for itself.c. This reduces competition for water

and nutrients.d. This reduces competition for fungi.

MATH SKILLS

Use the graph below to answer questions 32–33.

32. Analyzing Data The graph below shows themass of different types of organisms found ina meadow. How much greater is the mass ofthe plants than that of the animals?

33. Analyzing Data What is the ratio of the massof the bacteria to the mass of the fungi?

WRITING SKILLS

34. Communicating Main Ideas Why is evolu-tion considered to be such an important ideain biology?

35. Outlining Topics Outline the essentialsteps in the evolution of pesticide resistancein insects.

0

1,000

2,000

3,000

4,000

5,000

Bacteria Plants Fungi Animals Protists

Mass of Organisms in a Meadow

Kilo

gra

ms

READING SKILLS

PPoorrttffoolliioo PPrroojjeecctt31. Answers may vary.

MMaatthh SSkkiillllss32. Total plant mass is 2500 kg and

total animal mass is approxi-mately 500 kg. Therefore, themass of the plants is about 5 times the mass of the animals.

33. 4,100 � 1,700 � 2.4; The ratioof bacteria to fungi is about 2.4to 1.

WWrriittiinngg SSkkiillllss 34. Answers may vary. Evolution

provides a simple mechanism(natural selection) that explainswhy organisms are well suited totheir environments, why popula-tions change over time, and whyand how new species develop.

35. Answers may vary. Insects aretreated with a pesticide; mostdie, but some are not harmed;over generations, insects that cansurvive the pesticide become adominant part of the population;the pesticide eventually becomesineffective because the insectpopulation has evolved to beresistant to it.

RReeaaddiinngg SSkkiillllss1. c2. c


117


CC H A P T E R 4 Standardized Test PrepUnderstanding ConceptsDirections (1–4): For each question, write on aseparate sheet of paper the letter of the correctanswer.

1 What is the term for the area where organisms live together with their physicalenvironment?A. biomeB. biosphereC. ecosystemD. population

2 Which of the following describes the theoryof natural selection?F. Organisms with desired traits are selected

for reproduction.G. Heredity determines which organisms

will survive in their environment.H. Traits are developed in organisms in

response to interaction with other organisms.

I. Organisms with strong survival traits are more likely to pass on the traits inreproduction.

3 What inherited trait increases an organism’schance of survival and reproduction in acertain environment?A. adaptationB. characteristicC. evolutionD. natural selection

4 What are the six kingdoms of life?F. Archaebacteria, Eubacteria, Fungi,

Protists, Plants, AnimalsG. Eubacteria, Fungi, Protists, Plants, Land

Animals, Marine AnimalsH. Archaebacteria, Fungi, Plantlike Protists,

Animal-like Protists, Plants, AnimalsI. Bacteria, Fungi, Protists, Flowering

Plants, Non-flowering Plants, Animals

Directions (5–6): For each question, write a shortresponse.

5 Everything in nature is connected. Use theconcept of interdependence to analyze howan ecosystem works.

6 Describe one of the important roles of bacteria.

Reading SkillsDirections (7–9): Read the passage below. Thenanswer the questions.

Ecosystems are composed of many intercon-nected parts that often interact in complexways. People often think of ecosystems as iso-lated from each other, but ecosystems do nothave clear boundaries. Things move from oneecosystem into another.

Ecosystems are made up of both living andnonliving things. Biotic factors are the livingand once-living parts of an ecosystem, including all the plants and animals. Biotic factors include dead organisms, dead parts oforganisms, such as leaves, and the organisms’waste products. The biotic parts of an ecosys-tem interact with the abiotic factors, the non-living parts of the ecosystem. There aredifferent levels in the ecological organization,from the individual organism to the biosphere.

7 What is one example of an abiotic factor?A. armadilloB. carnationC. robin D. rock

8 Why would it be incorrect to describeecosystems as being isolated from eachother?F. All ecosystems have different species.G. Things can move from one ecosystem

into another because ecosystems do nothave clear boundaries.

H. Ecosystems have biotic and abiotic factors.

I. Both ecosystems and communities havebiotic and abiotic factors.

9 State the kinds of biotic factors that wouldbe found in an ocean ecosystem.

Interpreting Graphics

A.B.C.D.

F.G.H.

I.

A.

B.

C.

D.

118

Estimated TimeTo give students practice undermore realistic testing conditions,allow them 30 minutes to answerall of the questions in this practicetest.

118 Chapter 4 • Standardized Test Prep

Standardized Test Prep

10. D11. H12. D

AAnnsswweerrss1. C2. I3. A4. F5. Answers will vary. See Test Doctor for detailed

scoring rubric.6. Answers will vary. See Test Doctor for detailed

scoring rubric.7. D8. G9. Answers will vary. See Test Doctor for detailed

scoring rubric.

Question 5 Full-credit answersshould include the followingpoints:

• every organism affects all otherorganisms in its ecosystem eitherdirectly, by eating or being eatenby other organisms, or indirectlyby competing for resources

• every organism is dependent onevery other organism, so anychange to one organism affectsthe entire ecosystem

Question 6 Full-credit answersshould include one of the follow-ing points:

• bacteria help to decompose deadorganisms

• bacteria return nutrients to thesoil

• bacteria recycle mineral nutri-ents

• some bacteria convert nitrogeninto a form plants can use

Question 9 Full-credit answersshould include the followingpoints:

The biotic factors would include

• all of the living organisms, suchas fish, plants, algae

• all of the dead organisms• all of the waste products, such

as dead leaves

hes08TE_c04_118-119_STP 8/24/06 2:12 PM Page 118

TestAllow a few minutesat the end of the test-taking period to checkfor mistakes made inmarking answers.

Interpreting GraphicsDirections (10–12): For each question below, record the correct answer ona separate sheet of paper.

The map below shows changes in forest cover in Costa Rica over 40 years.Use this map to answer questions 10 through 12.

Forest Cover in Costa Rica

0 Approximately what percentage of Costa Rica was covered by forestin 1947?A. 25%B. 33%C. 50%D. 75%

q What conclusion can be drawn about the forest cover of Costa Rica?F. Most of the remaining forests are near cities.G. The remaining forests are concentrated along the western coast.H. Costa Rica lost more than half of its forest cover in less than

50 years.I. Deforestation has accounted for little change in Costa Rica’s

environment.

w What can be inferred about organisms adapted to living in trees inCosta Rica?A. Organisms that are adapted for living in trees will continue to

thrive across the country.B. Organisms that are adapted for living in trees will be eliminated

from the country’s environment.C. Organisms that are adapted for living in trees will continue to

thrive in areas that used to have forest.D. Organisms that are adapted for living in trees will thrive in forested

areas but struggle in areas that no longer have trees.119

Standardized Test Prep

Chapter 4 • Standardized Test Prep 119

Question 11 Answer H is correct.Answer F is incorrect because mostremaining forests are far fromcities. Answer G is incorrectbecause the remaining forests arespread out around the country.Answer I is incorrect becausewide-scale deforestation can haveaffects on local and global envi-ronments.

Question 12 Answer D is correct.Students struggling with this typeof question may benefit fromimagining probable consequencesof habitat change for a smallerpopulation. For example, have stu-dents imagine three communitiesof tree-dwelling monkeys. In onearea, the forests are left as theyarea. In another, the forests arecleared completely. And in a thirdarea, half of the trees are cut down.Ask students to write out a quickdescription of how each popula-tion will probably change in theyear following the habitat change.This specific population can beused to more concretely under-stand the more general descriptionasked about in the question.

hes08TE_c04_118-119_STP 8/24/06 2:12 PM Page 119

CCHHAAPPTTEERR

44How Do Brine Shrimp Select a Habitat?Different organisms are adapted for life in different habitats. Forexample, brine shrimp are small crustaceans that live in saltwaterlakes. Organisms select habitats that provide the conditions, suchas a specific temperature range and amount of light, to whichthey are best adapted. In this investigation, you will explore habi-tat selection by brine shrimp and determine which environmentalconditions they prefer.

ProcedureEstablish a Control Group

1. To make a test chamber and to establish a control group,divide a piece of plastic tubing into four sections by makinga mark at 10 cm, 20 cm, and 30 cm from one end. Label thesections "1", "2", "3", and "4".

2. Place a cork in one end of the tubing. Then transfer 50 mLof brine shrimp culture to the tubing. Place a cork in theother end of the tubing. Set the tube aside, and let the brineshrimp move about the tube for 30 min.

3. After 30 min, divide the tubing into four sections by placinga screw clamp at each mark on the tubing. While someone inyour group holds the corks firmly in place, tighten the mid-dle clamp at 20 cm and then tighten the other two clamps.

4. Remove the cork from the end of section 1 and pour the con-tents of section 1 into a test tube labeled "1." Repeat thisstep for the other sections by loosening the screw clamps andpouring the contents of each section into their correspondingtest tubes.

5. To get an accurate count for the number of brine shrimp ineach test tube, place a stopper on test tube 1, and invert thetube gently to distribute the shrimp. Use a pipet to transfer a 1mL sample of the culture to a Petri dish. Add a few drops ofDetain™ to the sample so that the brine shrimp move slower.Count and record the number of brine shrimp in the Petri dish.

Objectives� Observe

the behavior of brine shrimp.� Identify a

variable, and design an experimentto test the effect of the variable onhabitat selection by brine shrimp.

Materialsaluminum foilbrine shrimp culturecorks sized to fit tubingDetain™ or methyl cellulosefluorescent lamp or grow lightfunnelgraduated cylinder or beakerhot-water bagice bagmetric rulerPetri dishpipetplastic tubing, 40cm � 1cm,

clear, flexiblescreen, piecesscrew clampstapetest-tube racktest tubes with stoppers

USING SCIENTIFIC METHODS

USING SCIENTIFIC METHODS

Inquiry Lab: DESIGN YOUR OWNC H A P T E R 4

� Making a Test Chamber Use ascrew clamp to divide one section oftubing from another.

HOW DO BRINE SHRIMPSELECT A HABITAT?

Teacher’s Notes

Time Required two 45-minute class periods

Lab Ratings

TEACHER PREPARATION

STUDENT SETUP

CONCEPT LEVEL

CLEANUP

Skills Acquired• Designing Experiments• Experimenting• Communicating

Scientific MethodsIn this lab, students will:• Make Observations• Ask Questions• Test the Hypothesis• Analyze the Results• Draw Conclusions• Communicate the Results

MaterialsMaterials listed are enough forgroups of 3 to 4 students. After thelab, return the brine shrimp to anaquarium or a pet supply store.

E A S Y H A R D

Tips and TricksStudents are asked to design the conditionsfor the brine shrimp themselves. Possible vari-ables for this experiment include temperatureand light. To test temperature, students canplace a section of tubing on a hot water bag,place a section on an ice bag, and leave twosections at room temperature. (Caution: Donot use water with a temperature higher than70°C.) Each of the room temperature sectionsshould be right next to the cold or hot sectionso that shrimp don’t have to migrate througha habitat they do not like to get to one they

prefer. To test light, shine a grow light on onesection and cover another section with alu-minum foil. Again leave two sections in natu-ral light and put those on either side of theextremes. Be sure that students include a control in their experiment. Students shouldmake sure other factors besides the one theyare testing are not different across the testtube. If students do not keep all other factorsthe same, they will not be able to tell whichenvironmental factors the brine shrimpselected.

120


Inquiry LabDesign Your Own

hes08TE_c04_120-121_Lab 8/24/06 2:13 PM Page 120


6. Empty the Petri dish, and take two more 1 mL samples ofbrine shrimp from test tube 1. Calculate the average of thethree samples recorded for test tube 1.

7. Repeat steps 5 and 6 for each of the remaining test tubes tocount the number of brine shrimp in each section of tubing.

Ask a Question

8. Write a question you would like to explore about brineshrimp habitat selection. For example, you can explorehow temperature or light affects brine shrimp. Toexplore the question, design an experiment that uses thematerials listed for this lab.

9. Write a procedure and a list of safety precautions foryour group’s experiment. Have your teacher approve yourprocedure and precautions before you begin the experiment.

10. Set up and conduct your group’s experiment.

Analysis 1. Constructing Graphs Make a bar graph of your data. Plot

the environmental variable on the x-axis and the number ofbrine shrimp on the y-axis.

2. Evaluating Results How did the brine shrimp react tochanges in the environment?

3. Evaluating Methods Why did you have to have a control inyour experiment?

4. Evaluating Methods Why did you record the average ofthree samples to count the number of brine shrimp in eachtest tube in steps 6 and 7?

Conclusions5. Drawing Conclusions What can you conclude from your

results about the types of habitat that brine shrimp prefer?

1. Formulating Hypotheses Now that you have observedbrine shrimp, write a hypothesis about how brine shrimpselect a habitat that could be explored with anotherexperiment, other than the one you performed in this lab.Formulate a prediction based on your hypothesis.

2. Evaluating Hypotheses Conduct an experiment to test yourprediction. Write a short explanation of your results. Didyour results support your prediction? Explain your answer.

Extension

� Brine Shrimp These crustaceanshave specific habitat preferences.

AAnnsswweerrss ttoo AAnnaallyyssiiss1. Answers may vary.2. Answers may vary. Have students

compare results so they can under-stand how brine shrimp reacted todifferent variables.

3. A control is there to show whathappens to the organisms during“normal,” non-experimental cir-cumstances. It shows how muchof a difference there is betweentreated and untreated organisms.

4. If you sample several times asopposed to once, it is more likelythat any differences you see willbe due to the factor you are test-ing, not because of a random sam-pling error or natural variation inthe brine shrimp population.

AAnnsswweerrss ttoo CCoonncclluussiioonnss5. Answers may vary depending on

students’ results.

AAnnsswweerrss ttoo EExxtteennssiioonn1. Answers may vary. If one of the

factors appears to influence habi-tat selection, students could testthat factor in conjunction withanother factor. This kind of experi-ment could help determine if envi-ronmental factors interact witheach other to change behavior.

2. Answers may vary.

121

Tammie NiffenegerPort Washington

High School Port Washington, Wisconsin

TEACHER

TESTED& APPRO

VED

• Datasheets for In-Text Labs• Lab Notes and Answers


Holt Lab Generator CD-ROM

Search for any lab by topic, standard, difficulty level, or time.Edit any lab to fit your needs, orcreate your own labs. Use the LabMaterials Quicklist software tocustomize your lab materials list.

hes08TE_c04_120-121_Lab 8/28/06 12:51 PM Page 121

BUTTERFLY ECOLOGIST Imagine millions of butterfliesswirling through the air like autumnleaves, clinging in tightly packedmasses to tree trunks and branches,and covering low-lying forest veg-etation like a luxurious, movingcarpet. According to AlfonsoAlonso-Mejía, this is quite a sightto see.

Every winter Alfonso climbs upto the few remote sites in centralMexico where about 150 millionmonarch butterflies spend the winter.He is researching the monarchsbecause he wants to help preservetheir habitat and the butterfliesthemselves. His work helped himearn a Ph.D. in ecology from theUniversity of Florida.

Monarchs are famous for theirlong-distance migration. The butter-flies that eventually find their wayto Mexico come from as far awayas the northeastern United Statesand southern Canada. Some of

them travel an amazing 3,200 kmbefore reaching central Mexico.

Wintering Habitat at RiskUnfortunately, the habitat that themonarchs travel long distances toreach is increasingly threatened byillegal logging and other humanactivities. Logging reduced the sizeof the wintering region by approxi-mately 90 percent over a 30-yearperiod, from about 1970 to 2000.Mexico has set aside five of theknown butterfly sites as sanctuar-ies, but even these are endangeredby people who cut down fir treesfor fuel or money.

Alfonso’s work is helpingMexican conservationists betterunderstand and protect monarchbutterflies. Especially important isAlfonso’s discovery that the mon-archs depend on bushlike vegeta-tion, called understory vegetation,that grows beneath the fir trees.

Keeping WarmAlfonso’s research showed that whenthe temperature falls below freezing,as it often does in the mountainswhere the monarchs winter, under-story vegetation can mean the differ-ence between life and death for somemonarchs. These conditions are lifethreatening to the monarchs becauselow temperatures (–1°C to 4°C, or30°F to 40°F) limit their movement.In fact, the butterflies are not evenable to fly at such low temperatures.They can only crawl. At even coldertemperatures (–7°C to –1°C, or 20°Fto 30°F), monarchs resting on theforest floor may freeze to death. Butif the forest has understory vege-tation, the monarchs can slowlyclimb the vegetation until they are atleast 10 cm above the ground, whereit is warmer. This tiny difference inelevation can provide a microclimatethat is warm enough to ensure themonarchs’ survival.

� Butterfly Man Alfonso exam-ines a monarch as part of

his efforts to under-stand its ecology.

BUTTERFLY ECOLOGIST

DiscussionAnnual Life Cycle of a MonarchThere are four generations of mon-archs in the United States each year.First generation butterflies emergefrom eggs laid by females thatoverwintered in Mexico. Four daysafter they emerge, the first genera-tion migrates north, laying eggs asit migrates. Eggs from this genera-tion are only found in the southernUnited States. The second genera-tion is then spread throughout theUnited States. When this secondgeneration emerges, it migrates far-ther north to avoid hot tempera-tures. Females lay eggs as theymigrate. Individuals of the thirdgeneration that emerge during thesummer then lay eggs. Individualsin the third generation that emerge during early fall, as well as all ofthe fourth generation, migrate toMexico. This generation of mon-archs does not reproduce rightaway. They slip into a stage calleddiapause, which is a stage ofdelayed maturity. In March, gen-erations three and four move intothe southern United States to layeggs, and the first generation of the next year emerges.


122

GENERAL

Making a DifferenceMaking a Difference

hes08TE_c04_122-123_MD 8/24/06 2:15 PM Page 122

AAnnsswweerrss ttoo WWhhaatt DDoo YYoouu TThhiinnkk??Animals that migrate between two countries needthe habitat that exists in both countries to sur-vive. If countries do not cooperate to understandand protect the animals, one of the countries maydestroy critical habitat. Even if necessary habitatis ample in one country, a loss of habitat in theother country may cause the animal’s populationto decline or disappear. Therefore, cooperationbetween governments is essential when managingthreatened or endangered migratory species.


What Do You Think?As a migrating species, mon-archs spend part of their livesin the United States and partin Mexico. Should the U.S.and Mexico cooperate in theirefforts to understand andmanage the monarch? Shouldnations set up panels to man-age other migrating species,such as many songbirds?

The importance of understoryvegetation was not known beforeAlfonso did his research. Now,thanks to Alfonso’s work, Mexicanconservationists will better protectthe understory vegetation. And theMexican government has passed anew decree that protects monarchsin areas the butterflies are knownto use.

The Need for ConservationAlthough the monarchs continueto enjoy the forests where theyoverwinter, those forests are stillthreatened. There is little forest leftin this area, and the need forwood increases each year. Alfonsohopes his efforts will help protectthe monarch both now and in thefuture.

Now that he has completed hisPh.D., Alfonso is devoting himselfto preserving monarchs and otherorganisms. He works as director forconservation and development forthe Smithsonian Institutions

Monitoring and Assessment ofBiodiversity (MAB) program.

Information...If you are interested in learningmore about monarchs, includingtheir spectacular migration, visitthe Website for Monarch Watch.Monarch Watch is an organizationbased at the University of Kansasthat is dedicated to educating peo-ple about the monarch and pro-moting its conservation.

� Monarch Sanctuaries Monarchbutterflies spend the winter at forested sites just above Mexico City.

� A Sea of Orange At their over-wintering sites in Mexico, millions ofmonarchs cover trees and bushes in afluttering carpet of orange and black.

123

CONNECTIONCONNECTION

BIOLOGYBIOLOGYGENERAL

Becoming a Butterfly The yel-low and black monarch caterpillar, or larva, is an eating machine, constantly feeding on milkweed.After passing through five moltsof skin as a caterpillar, the larvabecomes a pupa. The pupa stageinvolves 10–14 days in a chrysalis,and allows the monarch to developinto a butterfly. This butterfly willbecome a reproducing adult in fourdays or eight months, dependingon its generation.

Adaptive Delay The migra-tory generations of monarchsare developmentally delayeddue to the environmental con-ditions when they were cater-pillars. Shorter days and coolnights keep the monarchs ina juvenile state, which allowsthem to delay reproductionuntil winter is over and foodis available for the nextgeneration.

BRAIN FOOD

hes08TE_c04_122-123_MD 8/24/06 2:15 PM Page 123

Documents

CH 4 APTER The Organization of Life CHAPTER 4 · 2008. 12. 16. · CH4APTER The Organization of Life CHAPTER 4 1 Ecosystems: Everything Is Connected 2 Evolution 3 The Diversity of