How Are Cotton Cookies - The Louis Armstrong …€¦ · How Are Cotton & Cookies ... Recycling Plasticsexplores the seven classes of plastics and their ... Paramecium species reproduce

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How AreCotton & Cookies

Connected?

How AreCotton & Cookies

Connected?

In the 1800s, the economy of the South depended heavily on cotton andtobaccotwo crops that rob the soil of nutrients, especially nitrogen. By thelate 1800s, the soil was in poor shape. A scientist named George WashingtonCarver set out to change that. He promoted the technique of crop rotationalternating soil-depleting crops such as cotton with soil-enriching crops such aspeanuts. Many farmers listened to Carver and began planting peanuts. However,there was little market for the crop. So Carver poured his energy into developinguses for peanuts. Ultimately, he came up with more than 300 products madefrom peanutseverything from soap to axle grease. He also created the firstrecipe for peanut butter cookies, which have become an American favorite.

Visit unit projects at to find project ideas and resources.Projects include: History Investigate land use in the U.S. during the past 200 years. Design flip

charts to compare, and then predict, the land use of the future. Technology Research how legumes fix nitrogen and why crop rotation

keeps farm land more productive. Model Explore peanut inventions. Design your own creative use for peanuts,

write directions, and build a prototype for a class peanut invention fair.Recycling Plastics explores the seven classes of plastics and theiruses, as well as the chemistry of plastic. Discover what it takes torecycle plastic, glass, paper, and aluminum.

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sections

1 Living Things

2 How are living things classified?

3 Cell StructureLab Comparing Cells

4 VirusesLab Comparing Light Microscopes

Virtual Lab How are living thingsclassified into groups?

Surrounded by Life!This scientist is getting a chance to seemany different living things and to studyhow they interact. Living things have somecommon characteristics. These characteris-tics are what scientists use to classify life. Byclassifying life, scientists can determine howall living things, including humans, relate toeach other.

Make a list of the living things yousee in this photo.Science Journal

Lifes Structureand Classification

LE 1.1a: Living things are composed of cells. Cells provide structure and carry on major functions tosustain life. Cells are usually microscopic in size. 1.1b: The way in which cells function is similar in allliving things. Cells grow and divide, producing more cells. Cells take in nutrients. Also covered: 1.1c,1.1d, 1.1e, 1.1f, 1.1g, 1.1h, 1.2a, 1.2j, 1.3d, 5.1a, 5.1c.

Lifes Structure and Classifica-tion Make the following Fold-able to help you understand the

vocabulary terms in this chapter. Use this Foldableto review for the chapter test.

Fold a sheet of notebook paper inhalf lengthwise.

Cut along every third line of only thetop layer to form tabs.

Turn vertically and label each tab asdescribed below.

Build Vocabulary As you read the chapter, listthe vocabulary words about the classificationand structure of life on the tabs. As you learn thedefinitions, write them under the tab for eachvocabulary word.

STEP 3

STEP 2

STEP 1

Classifying LifeLife scientists discover, describe, and namehundreds of organisms every year. Whatmethods do they use to decide if an insect ismore like a grasshopper or a beetle?

1. Observe an insectcollection or a collection of other organisms.

2. Decide which feature could be used to separate

the organisms into two groups, then sort the organisms into the two groups.

3. Continue to make new groups using dif-ferent features until each organism is in acategory by itself.

4. Think Critically List the features youwould use to classify the living thing inthe photo above. How do you think scien-tists classify living things?

Start-Up Activities

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222 CHAPTER 8 Lifes Structure and Classification

What are living things like?What does it mean to be alive? If you walked down your

street after a thunderstorm, youd probably see birds flying andclouds moving across the sky. Youd see living and nonlivingthings that are alike in some ways. For example, birds and cloudsmove. Yet clouds are nonliving things, and birds are livingthings. Any living thing is called an organism.

Organisms vary in sizefrom the microscopic bacteria inmud puddles to gigantic oak treesand are found just abouteverywhere. They have different behaviors and food require-ments. In spite of these differences, all organisms have similartraits. These traits determine what it means to be alive.

Living Things Are Organized Imagine looking at almost anypart of an organism, such as a plant leaf or your skin, under amicroscope. You would see that it is made up of small units calledcells, such as the ones pictured in Figure 1. A cell is the smallestunit of an organism that carries on the functions of life. Cellstake in materials from their surroundings and use them in com-plex ways. Some organisms are composed of just one cell whileothers are composed of many cells. Each cell has an orderlystructure and contains the instructions for cellular organizationand function in its hereditary material. All the things an organ-ism can do are possible because of what their cells can do.

How are living things organized?

Distinguish between living andnonliving things.

Identify what living things needto survive.

All living things, including you, havemany of the same traits.

Review Vocabularytrait: a feature of a living thing

New Vocabulary

organism cell homeostasis

Living Things

Figure 1 The human body isorganized into many differenttypes of cells. Two types areshown to the right.

Muscle cells

Nerve cells

Color-enhanced SEM Magnification: 2500

Color-enhanced LM Magnification: 106

LE 1.1a: Living things are composed of cells. Cells provide structure and carry on major functions to sustainlife. Cells are usually microscopic in size. Also covered: 4.3d, 5.1a, 5.1c.

Living Environment

1.1a: Define cell. Include adescription of its structure andfunction.

Living Things Grow and Develop When a puppy is born,it might be small enough to hold in one hand. After the samedog is fully grown, you might not be able to hold it at all. Howdoes this happen? Growth of a many-celled organism, such asa puppy, is mostly due to an increase in the number of cells. Inone-celled organisms, growth is due to an increase in the sizeof the cell.

Organisms change as they grow. Puppies cant see or walkwhen they are born. In eight or nine days, their eyes open, andtheir legs become strong enough to hold them up. All of thechanges that take place during the life of an organism are calleddevelopment. Figure 2 shows how four different organismschanged as they grew.

The length of time an organism is expected to live is its lifespan. Some dogs can live for 20 years. Other organisms have ashort life span. For example, mayflies live only one day. Yet,others have a much longer life span. A land tortoise can livefor more than 180 years, and some bristlecone pine trees havebeen alive for more than 4,600 years! A humans life span isabout 80 years.

SECTION 1 Living Things 223

Figure 2 Complete develop-ment of an organism can take afew days or several years.

A human

A butterflyA peaplant

A dog

Human Stages ofDevelopment Humaninfants cant take care ofthemselves at birth.Research to find out whathuman infants can do atdifferent stages of develop-ment. Make a chart thatshows changes from birthto one year of age.

Topic: Homeostasis Visit for Web links to information about homeostasis.

Activity Choose two livingthings and describe a method eachuses to maintain homeostasis.

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Living Things Respond Living things must interact withtheir surroundings. Anything that causes some change in anorganism is a stimulus (plural, stimuli). The reaction to a stim-ulus is a response. Often, that response results in movement. Anorganism must respond to stimuli to carry on its daily activityand to survive.

Living Things Maintain Homeostasis Living things alsomust respond to stimuli that occur inside them. For example,water or food levels in an organisms cells can increase ordecrease. The organism then makes internal changes to main-tain the right amounts of water and food in its cells. The regu-lation of an organisms internal, life-maintaining conditiondespite changes in its environment is called homeostasis.Homeostasis is a trait of all living things.

What is homeostasis?

Living Things Use Energy Staying organized and carryingon activities like finding food requires energy. The energy usedby most organisms comes either directly or indirectly from theSun. Plants and some other organisms can use the energy insunlight, carbon dioxide, and water to make food. You and manyother organisms cant use the energy in sunlight directly.Instead, you take in and use food as a source of energy. In orderto release the energy in food, you and many other organismsmust take in oxygen.

Some bacteria live at the bottom of the oceans and in otherareas where sunlight cannot reach. They cant use the Sunsenergy to produce food; instead, the bacteria use energy storedin some chemical compounds and carbon dioxide to make food.Unlike many other organisms, most of these bacteria do notneed oxygen to release the energy that is found in their food.

Living Things Reproduce All livingthings eventually reproduce, to make more oftheir own kind. Some bacteria reproduceevery 20 minutes, while it might take a pinetree two years to produce seeds. Figure 3shows some ways organisms reproduce.

Without reproduction, living things wouldnot exist to replace those individuals that die.An individual cat can live its entire life withoutreproducing. However, if cats never repro-duced, all cats soon would disappear.


Beetles, like most insects, repro-duce by laying eggs.

Paramecium species reproduce by dividing into two.

Figure 3 Living things reproducethemselves in many different ways.

Color-enhanced LM Magnification: 400


Self Check1. Identify the main source of energy used by most

organisms.

2. Infer why you would expect to see cells if you looked ata section of a mushroom cap under a microscope.

3. Think Critically Why is homeostasis important toorganisms?

SummaryWhat are living things like?

An organism is any living thing. All living things are organized into cells,

which are the smallest units that carry on the functions of life.

Living things also grow and develop, respondto stimuli, maintain homeostasis, reproduce,and use energy.

What do living things need?

All living things need a place to live, a foodsource, and water to survive.

4. Compare and contrast the similarities and differences between a goldfish and the flame of a burning candle.

What do living things need?Do you have any needs that are different from those of other

living things? All living things need a place to live, water, andfood source to survive.

A Place to Live All organisms need a place to live that issuited to their unique needs. Could a cactus survive inAntarctica, or a penguin in the Sahara? A place to live also pro-vides enough space for the organism. When weeds grow in aflower bed, they crowd out the flowers, taking up the space thatthe flowers need to grow. The flower bed is no longer a suitableplace for the flower to live.

Water Water is important for all living things. All organismstake in water from their surroundings, as shown in Figure 4. Mostorganisms are composed of more that 50 percent water. You aremade up of 60 to 70 percent water. Water performs many func-tions, such as transporting materials within a cell and betweencells. Organisms also give off large amounts of water each day.Homeostasis balances the amount of water exchanged.

Food Sources Living things are made up of substances suchas proteins, fats, and sugars. Animals take in these substances aspart of the foods that they eat. Plants and some bacteria maketheir own food. When organisms die, substances in their bodiesare broken down and released into the environment. The sub-stances can then be used again by other living organisms. Someof the substances in your body might once have been part of abutterfly or an apple tree!

SECTION 1 Living Things 225

Figure 4 Most animals, includ-ing humans, drink water. They alsotake in water through the foodsthey eat, such as corn.Infer how a corn plant takes inwater.

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ClassificationPeople have grouped together similar organisms, or classified

them, for thousands of years. Many different systems were useduntil the late eighteenth century. Carolus Linnaeus, a Swedishnaturalist, developed a new system of grouping organisms thatwas accepted and used by most scientists. His classification sys-tem was based on looking for organisms with similar structures.For example, plants that had a similar flower structure weregrouped together. Linnaeus also developed a scientific namingsystem that still is used today.

Binomial Nomenclature The two-word naming system thatLinnaeus used to name various organisms is called binomialnomenclature (bi NOH mee ul NOH mun klay chur). Thistwo-word name is an organisms species. Organisms that canmate and produce fertile offspring belong to the same species.

The first word of the two-word name identifies the genus ofthe organism. A genus is a group of similar species. For example,a salamanders genus is Ambystoma. The second word of thename usually describes a feature. The Eastern tiger salamander isAmbystoma tigrinum, shown in Figure 5. Latin is the languageused for scientific names.

How are living things classified?

Describe how early scientistsclassified living things.

Explain the system of binomialnomenclature.

Demonstrate how to use adichotomous key.

Knowing how living things are clas-sified will help you understand therelationships that exist between allliving things.

Review Vocabularyhereditary: relating to the passingof traits from parent to offspring

New Vocabulary

binomial nomenclature genus phylogeny kingdom

Figure 5 An eastern tiger salamanders scientific name isAmbystoma tigrinum.Infer which trait is described in thisanimals scientific name.

226

LE 1.1h: Living things are classified by shared characteristics on the cellular and organism level. In classifying organisms, biologists consider details of internal and external structures. Biological classification systems are arranged from general (kingdom) to specific (species).

Living Environment

1.1h: Summarize how scientists classify organisms.

Kingdom Animalia

Phylum Chordata

Class Mammalia

Order Cetacea

Family Delphinidae

Genus Tursiops

Species Tursiops truncatus

Uses of Scientific Names Why use scientific names at all?Scientific names are used for four reasons. First, they help avoidmistakes. Often, common names for two different organisms arethe same, or one organism has many different common names.Scientific names help distinguish between those organisms.Second, organisms with similar evolutionary histories are classi-fied together. Because of this, you know that organisms in thesame genus are related. Third, scientific names give descriptiveinformation about the species, like the salamander mentionedearlier. Fourth, scientific names allow information about organ-isms to be organized easily and efficiently. Such informationmay be found in a book or a pamphlet that lists related organ-isms and gives their scientific names.

What are the functions of scientific names?

Modern Classification Like Linnaeus, modern scientists usesimilarities in structure to classify organisms. They also study fos-sils, hereditary information, and early stages of development.Scientists use all of this information to determine an organismsphylogeny. Phylogeny (fi LAH juh nee) is the evolutionary historyof an organism, that is, how the organism has changed over time.Today, it is the basis for the classification of many organisms.

In the classification system used today, the smallest group isa species. There are broader groups preceding species, the largestof which is a kingdom. To understand how an organism is clas-sified, look at the classification of the bottle-nosed dolphin inFigure 6. Some scientists have proposed that before organismsare grouped into kingdoms, they should be placed in largergroups called domains. One proposed system groups all organ-isms into three domains.

Figure 6 The classifica-tion of the bottle-noseddolphin shows that it is inthe order Cetacea. Thisorder includes whales andporpoises.

Communicating IdeasProcedure1. Find a magazine picture

of a piece of furniturethat can be used as a placeto sit and to lie down.

2. Show the picture to tenpeople and ask them to tellyou what word they usefor this piece of furniture.

3. Keep a record of theanswers in your ScienceJournal.

Analysis1. In your Science Journal,

infer how using commonnames can be confusing.

2. How do scientific namesmake communicationamong scientists easier?

SECTION 2 How are living things classified? 227


Self Check1. Explain the purpose of classification.

2. Identify what information a scientist would use todetermine an organisms phylogeny.

3. Think Critically Why would a field guide have commonnames as well as scientific names?

SummaryClassification

Linnaeus developed the first widely acceptedmethod of classification based on similarstructures.

Binomial nomenclature is the two-name system that scientists use today. It consists of the genus name and another identifyingname.

Scientists study fossils, hereditary informa-tion, and early stages of development todetermine classification.

Scientists use field guides and dichotomouskeys to identify organisms.

4. Classify Create a dichotomous key that identifiestypes of cars.

5. Communicate Select a field guide for trees, insects, ormammals. Select two organisms in the field guide thatclosely resemble each other. Use labeled diagrams to show how they are different.

Tools for Identifying OrganismsScientists use field guides and dichotomous (di KAH tuh mus)

keys to identify organisms. Many different field guides are avail-able. Most have descriptions and illustrations of organisms andinformation about where each organism lives.

A dichotomous key is a detailed list of identifying character-istics that includes scientific names. You can use Table 1 to findout what type of mouse is pictured to the left. Choose betweenthe pair of descriptions at each step. What is the name of thismouse according to the key?

Table 1 Mice of North America

1. Tail hair a. no tail hair; scales show plainly; house mouse, Mus musculus

b. hair on tail, go to 2

2. Ear size a. ears small and nearly hidden in fur, go to 3

b. ears large and not hidden in fur, go to 4

3. Tail length a. less than 25 mm; woodland vole, Microtus pinetorum

b. more than 25 mm; prairie vole, Microtus ochrogaster

4. Tail coloration a. sharply dark above; deer mouse, Peromyscus maniculatus

b. slightly dark above; white-footed mouse, Peromyscus leucopus



Viewing CellsFour hundred years ago, scientists did not know what cells

looked like, or that they even existed. That changed in the late1500s, when the first microscope was made by a Dutch optometrist.He put two magnifying lenses together in a tube and got an imagethat was larger than the image that was made by either lens alone.In the mid 1600s, Antonie van Leeuwenhoek, a Dutch fabric mer-chant, made a simple microscope with a tiny glass bead for a lens,as shown in Figure 7 on the next page. These microscopes eventu-ally led to the types of microscopes that scientists use today.

Development of the Cell TheoryIn the seventeenth century the microscope was improved,

which led to the discovery of cells. In 1665, Robert Hooke cut athin slice of cork and looked at it under his microscope. ToHooke, the cork seemed to be made up of empty little boxes,which he named cells.

In the 1830s, Matthias Schleiden used a microscope to studyplant parts. He concluded that all plants are made of cells.Theodor Schwann, after observing many different animal cells,concluded that all animals also are made up of cells. Eventually,they combined their ideas and became convinced that all livingthings are made of cells.

Several years later, Rudolf Virchow hypothesized that cellsdivide to form new cells. Virchow proposed that every cell camefrom a cell that already existed. His observations and conclu-sions and those of others are summarized in the cell theory, asdescribed in Table 2.

Cell Structure

Describe the development of thecell theory.

Identify names and functions ofeach part of a cell.

Explain how important a nucleusis in a cell.

Compare tissues, organs, andorgan systems.

Humans are like other living thingsbecause we are made of cells.

Review Vocabularytheory: an explanation of eventsor circumstances based on scien-tific knowledge resulting fromrepeated observations and tests

New Vocabulary

cell theory chloroplast cell wall mitochondrion cell endoplasmic membrane reticulum

cytoplasm Golgi body ribosome tissue organelle organ nucleus organ system

Table 2 The Cell Theory

All organisms are made up of one or more cells. An organism can be one cell or many cells like most plants and animals.

The cell is the basic unit of organization in organisms. Even in complex organisms, the cell is the basic unit of structure and function.

All cells come from cells. Most cells can divide to form two new, identical cells.

SECTION 3 Cell Structure 229

LE 1.1c: Most cells have cell membranes, genetic material, and cytoplasm. Some cells have a cell walland/or chloroplasts. Many cells have a nucleus. Also covered: 1.1a, 1.1b, 1.1d, 1.1e, 1.1f, 1.1g.


Figure 7

M icroscopes give us a glimpse into a previouslyinvisible world. Improvements have vastlyincreased their range of visibility, allowingresearchers to study life at the molecular level. A selec-tion of these powerful toolsand their magnificationpoweris shown here.

VISUALIZING MICROSCOPES

BRIGHTFIELD / DARKFIELD MICROSCOPE The light microscope is often calledthe brightfield microscope because the image isviewed against a bright background. A brightfieldmicroscope is the tool most often used in labora-tories to study cells. Placing a thin metal discbeneath the stage, between the light source and the objective lenses, converts a brightfieldmicroscope to a darkfield microscope. The imageseen using a darkfield microscope is bright against

a dark background.This makes detailsmore visible than with a brightfieldmicroscope. Below are images of aParamecium as seenusing both processes.

LEEUWENHOEKMICROSCOPE Held by a modern researcher,this historic microscopeallowed Leeuwenhoek tosee clear images of tinyfreshwater organismsthat he called beasties.

FLUORESCENCE MICRO-SCOPE This type of microscope requires that thespecimen be treated with special fluorescentstains. When viewed through this microscope,certain cell structures or types of substancesglow, as seen in the image of a Parameciumabove.

Up to 2,000

Up to 250

Up to 1,500

Brightfield

Darkfield

SECTION X Section Title 231SECTION 3 Cell Structure 231

SCANNING ELECTRONMICROSCOPE An SEM sweeps a beam ofelectrons over a specimens surface, causingother electrons to be emitted from thespecimen. SEMs produce realistic, three-dimensional images, which can only beviewed as photographs or on a monitor,as in the image of the Paramecium atright. Here a researcher compares anSEM picture to a computer monitorshowing an enhanced image.

PHASE-CONTRAST MICRO-SCOPE A phase-contrast microscope emphasizesslight differences in a specimens capacity to bendlight waves, thereby enhancing light and darkregions without the use of stains. This type ofmicroscope is especially good for viewing livingcells, like the Paramecium above left. The imagesfrom a phase-contrast microscope can only be seenwhen the specimen is photographed or shown ona monitor.

TRANS-MISSION ELECTRON MICROSCOPE ATEM aims a beam of electronsthrough a specimen. Denser por-tions of the specimen allow fewerelectrons to pass through and appeardarker in the image. Organisms, suchas the Paramecium at right, can only beseen when the image is photographedor shown on a monitor. A TEM canmagnify hundreds of thousands oftimes.

Up to 1,000,000

Up to 1,500

Up to 200,000


Cellular OrganizationScientists have found that cells can be separated into two

groups. One group has membrane-bound structures inside thecell and the other group does not, as shown in Figure 8. Cellswithout membrane-bound structures are called prokaryotic (proh kayr ee AH tihk) cells. Cells with membrane-bound struc-tures are called eukaryotic (yew kayr ee AH tihk) cells. Each cellperforms specific functions; however, all cells must constantlytake in nutrients, store, produce, and breakdown substances, andtake in and use energy.

Cell Wall The cells of plants, algae, fungi, and most bacteriaare enclosed in a cell wall. Cell walls are tough, rigid outer cov-erings that protect cells and give them shape.

A plant cell wall mostly is made up of a carbohydrate calledcellulose. The long, threadlike fibers of cellulose form a thickmesh that allows water and dissolved materials to passthrough. Plant cell walls also may contain pectin and lignin.Pectin aids in cell growth, development, defense, and strength,among other functions. It is also what makes jams and jellieshave a thick texture. Lignin is a compound that makes cellwalls rigid. Plant cells responsible for support have more ligninin their walls than other plant cells.

Cell Membrane The protective layer surrounding everycell is the cell membrane, as shown in Figure 9. The cellmembrane is the outermost covering of a cell unless a cell wallis present. The cell membrane regulates interactions betweenthe cell and its environment. The cell membrane allows nutri-ents to move into the cell, while waste products leave.

Figure 9 The cell membrane ismade up of a double layer of fat-like molecules.

RibosomesOrganelles

Hereditary material

Cell membraneCell wall

Nucleus with hereditary

material

NucleolusCell membrane

Flagellum

Gel-like capsule

Ribosomes

Prokaryotic Eukaryotic

Figure 8 Examine these draw-ings of cells. Prokaryotic cells onlyare found in one-celled organisms,such as bacteria. Protists, fungi,plants and animals are made ofeukaryotic cells. Describe the differences betweenthese cells.

Cell membranes

Color-enhanced TEM Magnification: 125,000

Living Environment

1.1b: Briefly discuss the functions that all cells must perform.


Cytoplasm Cells are filled with a gelatinlike substance calledcytoplasm (SI toh pla zuhm) that constantly flows inside the cellmembrane. Most of a cells life processes occur in the cytoplasm.In prokaryotic cells, the hereditary material is found here.Throughout the cytoplasm is a framework called the cytoskele-ton, shown in Figure 10, which helps the cell maintain orchange its shape and enables some cells to move. The cytoskele-ton is made up of thin, hollow tubes of protein and thin, solidprotein fibers. Proteins are organic molecules made up of aminoacids.

How might an amoeba move using its cytoskeleton?

Manufacturing Proteins One substance that takes part innearly every cell activity is protein. Proteins are part of cellmembranes and are needed for chemical reactions that takeplace in the cytoplasm. Cells make their own proteins on smallstructures called ribosomes. All ribosomes in prokaryotic cells,and some in eukaryotic cells, are made and float freely in thecytoplasm, like the ribosomes in Figure 11. Ribosomes receivedirections from the hereditary material on how, when, and inwhat order to make specific proteins.

Figure 10 Cytoskeleton, a net-work of fibers in the cytoplasm,gives cells structure and helpsthem maintain shape.Describe what the cytoskeleton ismade of.

Figure 11 Some ribosomes, like these in this electron microscopeimage, float freely in the cytoplasm.

Modeling CytoplasmProcedure1. Add 100 mL water to a

clear container.2. Add unflavored gelatin

and stir.3. Shine a flashlight through

the solution.

Analysis1. Describe what you see.2. How does a model help

you understand what cytoplasm might be like?

Stained LM Magnification: 700

Living Environment

1.1c: List five important characteristics of cytoplasm.

Membrane-Bound Organelles Within the cytoplasm ofeukaryotic cells are structures called organelles, the largest ofwhich is usually the nucleus. Some organelles process energy andothers manufacture substances needed by the cell or other cells.Certain organelles move materials, while others act as storagesites. Most organelles are surrounded by a membrane. Ribosomesare considered organelles, but are not membrane-bound.

Nucleus All cellular activities are directed by the nucleus.Materials enter and leave the nucleus through openings in itsmembrane. The nucleus contains long, threadlike, hereditarymaterial made of DNA. DNA is the chemical that contains thecode for the cells structure and activities. A structure called anucleolus also is found in the nucleus, and is where most ribo-somes are made in a eukaryotic cell.

Organelles That Process Energy Cellsrequire a continuous supply of energy to

process food, make new substances, eliminate wastes, and com-municate with each other. In plant cells, food is made in greenorganelles in the cytoplasm called chloroplasts (KLOR uh plasts),shown in Figure 12. Chloroplasts contain the green pigmentchlorophyll, which gives many leaves and stems their color.Chlorophyll captures light energy that is used to make a sugarcalled glucose. This light energy is changed and stored in glucoseas chemical energy. Many cells do not have chloroplasts for mak-ing food and must get food from their environment.

The energy in food usually is released by mitochondria.Mitochondria (mi tuh KAHN dree uh) (singular, mitochondrion),also shown in Figure 12, are organelles where energy is releasedwhen food is broken down into carbon dioxide and water. Sometypes of cells, such as muscle cells, are more active than other cellsand have larger numbers of mitochondria. Both chloroplasts andmitochondria contain ribosomes and hereditary material. Bothplant and animal cell structures can be found in Figure 13.

Figure 12 These organellestransform energy for the cell.Compare and contrast chloroplasts and mitochondria.

Chloroplasts are organelles inorganisms, such as plants, that uselight to make sugar from carbondioxide and water.

Mitochondria are knownas the powerhouses of thecell because they releaseenergy that is needed bythe cell.



Color-enhanced SEM Magnification: 48,000

Living Environment

1.1c, 1.1h: Design a chart tocompare the organelles of plantcells to animal cells. Identify theorganelles that are specific toplant cells.

Ribosome

Smooth endoplasmicreticulum (SER)

Nucleus

Nucleolus

Mitochondrion

Rough endoplasmicreticulum (RER)

Cell membraneCell wall

Cell wall of adjacent cell

Golgi bodies

Central vacuoleChloroplast

Free ribosome

Plant Cell

Nucleus

Nucleolus

Ribosome

Smooth endoplasmicreticulum (SER)

Cell membrane Cytoskeleton

Mitochondrion

Rough endoplasmicreticulum (RER)

LysosomeGolgi bodies

Free ribosome

Animal Cell

Figure 13 Refer tothese diagrams of atypical animal cell(top) and plant cell(bottom) as you readabout cell structuresand their functions.


Organelles That Process, Transport, and StoreFigure 14 shows the endoplasmic reticulum (en duh PLAZ mihk rih TIHK yuh lum), also called the ER. The endoplasmicreticulum is a series of folded membranes in which materialscan be processed and moved around inside of the cell. It extendsfrom the nucleus to the cell membrane and takes up a consider-able amount of space in some cells.

The ER may be rough or smooth. Ribosomes are attached toareas on the rough ER. There they carry out their job of making pro-teins that are moved out of the cell or used within the cell. ER thatdoes not have attached ribosomes is called smooth ER. This type ofER processes cellular substances such as lipids that store energy.

What is the difference between rough ER andsmooth ER?

After proteins are made in a cell, they are transferred toanother type of cell organelle called the Golgi (GAWL jee) bod-ies. The Golgi bodies, shown in Figure 15, are stacked, flattened

membranes. The Golgi bodies sort proteins andother cellular substances and package them intomembrane-bound structures called vesicles. Thevesicles deliver cellular substances to areas insidethe cell, and carry cellular substances to the cellmembrane where they are released to the outsideof the cell.

Cells also have membrane-bound spacescalled vacuoles for the temporary storage ofmaterials. A vacuole can store water, waste prod-ucts, food, and other cellular materials. In plantcells, the vacuole may make up most of the cellsvolume.

Figure 15 Golgi bodies packagematerials.Infer why some materials areremoved from the cell.

Figure 14 Endoplasmic reticulum (ER) is a complex series of membranes in thecytoplasm of the cell. Describe smooth ER.



CELL SURFACE AREA AND VOLUME You can find the surface area and volume of a cell in the same way you find the surface area and volume of a cube, if you assume that a cell is like a cube with six equal sides.Find the ratio of surface area to volume for a cell that is 4 cm high.

Solution

Organelles That Recycle Active cells break down and recy-cle substances. Organelles called lysosomes (LI suh sohmz) con-tain digestive chemicals that help break down food molecules,cell wastes, worn-out cell parts, and viruses and bacteria thatenter a cell. Chemicals can be released into vacuoles whenneeded to break down its contents. The lysosomes membraneprevents the digestive chemicals inside from leaking into thecytoplasm and destroying the cell.

When a cell dies, the lysosomes membrane disintegrates,releasing digestive chemicals that allow the quick breakdown ofthe cells contents. This is what happens when a frog tadpolebecomes an adult. The lysosomes digest the cells in the tadpolestail. These cellular molecules then are used to make other cells,such as those in the legs of the frog.

Find a Ratio

1. Calculate the ratio of surface area to volume for a cell that is 2 cm high. What happens tothis ratio as the size of the cell decreases?

2. If a 4-cm cell doubled just one of its dimensionslength, width, or heightwhat wouldhappen to the ratio of surface area to volume?

For more practice, visit glencoe.com

This is what you know:

This is what you want to find out:

This is the procedure youneed to use:

Check your answer: Multiply 1.5 cm2/cm3 64 cm3. You should get 96 cm2.

Use the following equations:surface area (A) width length 6volume (V) length width height R A/V

Substitute in known values and solve.A 4 cm 4 cm 6 96 cm2

V 4 cm 4 cm 4 cm 64 cm3

R 96 cm3/64 cm2 1.5 cm2/cm3

What is the ratio (R) of surface area to volume for each cell?

A cell has six equal sides of4 cm 4 cm

Recycle Just like a cell, youcan recycle materials.Paper, plastic, aluminum,and glass can be recycledinto usable items. Manyother countries requirerecycling because of a lackof space for landfills.Research recycling in othercountries and make a bargraph that compares recy-cling rates in other coun-tries to the rate in theUnited States.

4 cm

4 cm4 cm


Hot Words Hot Topics: Bk 1 pp. 274, 330, 335


Many-Celled OrganismsCells in a many-celled organism do not work alone.

Each cell carries on its own life functions while dependingin some way on other cells in the organism. Many one-celled organisms, however, perform all life functions ontheir own.

In Figure 16, you can see cardiac muscle cells groupedtogether to form a tissue. A tissue is a group of similarcells that work together to do one job. Each cell in a tissuedoes its part to keep the tissue alive.

Tissues are organized into organs. An organ is astructure made up of two or more different types of tis-sues that work together. Your heart is an organ made upof nerve, blood, and cardiac muscle tissues. The cardiacmuscle tissue contracts, making the heart pump. Thenerve tissue brings messages that tell the heart how fastto beat. The blood tissue is carried from the heart toother organs of the body.

A group of organs working together to perform a cer-tain function is an organ system. Your heart, arteries,veins, and capillaries make up your cardiovascular system.Organ systems work together to make up a many-celledorganism.


Self Check1. Describe the events leading to the discovery of the cell

theory.

2. Identify the role of the nucleus in the life of a cell.

3. Compare and contrast the differences between plantand animal cells.

4. Explain how a cell is like your school or town. What isthe nucleus of your town? The mitochondria?

5. Think Critically How is the cell of a one-celled organ-ism different from the cells in many-celled organisms?

SummaryViewing Cells and the Cell Theory

Cells could be seen after the invention of themicroscope by van Leeuwenhoek.

The cell theory states that all organisms aremade up of cells, the cell is the basic unit oforganization, and all cells come from other cells.

Cellular Organization

Cells are prokaryotic or eukaryotic. All cells have a cell membrane, cytoplasm,

and ribosomes. Some have a cell wall.

All eukaryotic cells have membrane-boundorganelles to carry out life processes.

Many-Celled Organisms

Cells in many-celled organisms cannot functionalone. Cells group together to form tissues, tis-sues form organs, organs form organ systems,and organ systems form an organism.

6. Solve One-Step Equations The magnification of alight microscope can be found by multiplying thepower of the eyepiece by the power of the objectivelens. Calculate the magnifications of a microscope that has an 8 eyepiece, and 10 and 40 objectives.

Organ system

Organ

Organism

Tissue

Cell

Figure 16 In a many-celled organism,cells are organized into tissues, tissuesinto organs, organs into systems, andsystems into an organism.

Hot Words Hot Topics: Bk 1 p. 90



SECTION # Section Title 239

Real-World QuestionIf you compared a goldfish to a rose, you wouldfind them unlike each other. Are their individ-ual cells also different? Try this lab to compareplant and animal cells. How do human cheekcells and plant cells compare?

Goals Compare and contrast an animal and a

plant cell.

Materialsmicroscope droppermicroscope slide Elodea plantcoverslip prepared slide of humanforceps cheek cellstap water

Safety Precautions

Procedure1. Copy the data table in your Science Journal.

Check off the cell parts as you observe them.

2. Using forceps, make a wet-mount slide of ayoung leaf from the tip of an Elodea plant.

3. Observe the leaf on low power. Focus on thetop layer of cells.

4. Switch to high power and focus on one cell.In the center of the cell is a membrane-bound organelle called the central vacuole.Observe the chloroplaststhe green, disk-shaped objects moving around the centralvacuole. Try to find the cell nucleus. It lookslike a clear ball.

5. Draw the Elodea cell. Label the cell wall,cytoplasm, chloroplasts, central vacuole, andnucleus. Return to low power and removethe slide. Properly dispose of the slide.

6. Observe the prepared slide of cheek cellsunder low power.

7. Switch to high power and observe the cellnucleus. Draw and label the cell membrane,cytoplasm, and nucleus. Return to low powerand remove the slide. Properly dispose of theslide.

Conclude and Apply1. Compare and contrast the shapes of the

cheek cell and the Elodea cell.

2. What can you conclude about the differencesbetween plant and animal cells?

Cell Observations

Cell Part Cheek Elodea

Cytoplasm

Nucleus

Chloroplasts

Cell wall

Cell membrane

Comparing Cells

Draw the two kinds of cells on one sheet of paper. Use a green pencil to label theorganelles found only in plants, a red pencil to label the organelles found only in animals, and a blue pencil to label theorganelles found in both.

LAB 239

Do not write in this book.


Viruses

Virus

Host cell

Nucleus

Viral hereditarymaterial

ViralproteinsThe viruss hereditary

material enters the host cell.

New viruses are released as the host cell bursts open and is destroyed.

The virus attaches to a specific host cell.

New viruses forminside of the host cell.

The viruss hereditary materialcauses the cell to make viral hereditary material and proteins.

Figure 17 An activevirus multiplies anddestroys the host cell.

What are viruses?Cold sores, measles, chicken pox, colds, the flu, and AIDS are

diseases caused by nonliving particles called viruses. A virus is astrand of hereditary material surrounded by a protein coating.A virus multiplies by making copies of itself with the help of aliving cell called a host cell. Viruses dont have a nucleus, otherorganelles, or a cell membrane. They have a variety of shapesand are too small to be seen with a light microscope. They werediscovered only after the electron microscope was invented.Before that time, scientists only hypothesized about viruses.

Active Viruses When a virus enters a cell and is active, itcauses the host cell to make new viruses. This process destroysthe host cell. Follow the steps in Figure 17 to see one way that anactive virus functions inside a cell.

Explain how a virus makescopies of itself.

Identify the benefits of vaccines. Investigate some uses of viruses.

Viruses can infect nearly all organ-isms, including humans.

Review Vocabularybacteria: a prokaryotic, one-celled organism

New Vocabulary

virus host cell

LE 1.2a: Each system is composed of organs and tissues which perform specific functions and interact witheach other. 1.2j: Disease breaks down the structures or functions of an organism. Specialized cells protect thebody from infectious disease.

Latent Viruses Some viruses can be inactive, and are calledlatent. This means that after the virus enters a cell, its hereditarymaterial becomes part of the cells hereditary material. It doesnot immediately make new viruses or destroy the cell. As thehost cell reproduces, the hereditary material of the virus iscopied. A virus can be latent for many years. Then, at any time,certain conditions, either inside or outside the body, can activatethe virus.

If you have had a cold sore on your lip, a latent virus in yourbody has become active. The cold sore is a sign that the virus isactive and destroying cells in your lip. When the cold sore disap-pears, the virus has become latent again. The virus, however, isstill in your bodys cells.

How do viruses affect organisms?Viruses can infect animals, plants, fungi, protists, and all

bacteria. Most viruses can infect only specific kinds of cells.For instance, many viruses, such as the potato leafroll virus inFigure 18, are limited to one host species or to one type of tis-sue within a species. A few viruses affect a broad range of hosts.An example of this is the rabies virus. Rabies can infect humansand many other animal hosts.

A virus cannot move by itself, but it can reach a hosts bodyin several ways. For example, it can be carried onto a plants sur-face by the wind or it can be inhaled by an animal. In a viralinfection, the virus first attaches to the surface of the host cell.The virus and the place where it attaches must fit togetherexactly, also shown in Figure 18, which is why most virusesattack only one kind of host cell. Viruses that infect bacteria arecalled bacteriophages (bak TIHR ee uh fay juhz).

SECTION 4 Viruses 241

Cell membrane

VirusThe potato leafroll virus, PLRV, damages potato cropsworldwide, and is specific to only potatoes.

Figure 18 Viruses and theattachment sites of the host cellmust match exactly, like a puzzle.Thats why most viruses infect onlyone kind of host cell.

Topic: Latent Viruses Visit for Web links to information about viruses.

Activity Name three environ-mental stimuli that may activate a latent virus.

glencoe.com

Magnification: unknown

Living Environment

1.2j: Create a flowchart to showthe sequence of how a virusattacks a host cell.



Treating and Preventing Viral Diseases Antibiotics are used to treat bacterial infections, but they do

not work against viral diseases. Antiviral drugs can be given toinfected patients to help fight a virus; however, they are notwidely used because of adverse side effects. Prevention is thebest way to fight the diseases, because treatment is very difficult.

Public health measures for preventing viral diseases includevaccinating people, improving sanitary conditions, separatingpatients with diseases, and controlling animals that spread thedisease. Yellow fever was wiped out completely in the UnitedStates through mosquito-control programs. Annual rabies vac-cinations protect humans by keeping pets and farm animals freefrom infection.

What are some methods used to prevent viralinfections?

Natural Immunity One way your body can stop viral infec-tions is by making interferons. Interferons are proteins thatprotect cells from viruses. These proteins are produced rap-idly by infected cells and move to noninfected cells in thehost. They cause the noninfected cells to produce protectivesubstances.

Vaccines Vaccinations, like the one the child is receiving inFigure 19, are used to prevent disease. A vaccine is made fromweakened virus particles that cause your body to produce inter-ferons to fight the infection. Vaccines have been made to prevent

many diseases, includ-ing measles, mumps,smallpox, chicken pox,polio, and rabies.Edward Jenner is cred-ited with developing thefirst vaccine in 1796. Heinjected a weakenedform of the cowpoxvirus into healthy peo-ple, which protectedthem from smallpox.Jenner did not knowhow his virus worked,or that smallpox andcowpox were relatedviruses.

Figure 19 A child is getting vac-cinated before entering school.Describe how a vaccine works.

Living Environment

1.2a: Compare and contrastthe treatment and prevention of viral diseases to bacterialinfections.

Self Check1. List the steps an active virus follows when attacking

a cell.

2. Compare and contrast a latent virus and an activevirus. Give an example of each.

3. Explain how vaccines prevent infection.

4. Infer how some viruses might be helpful.

5. Think Critically Explain why a doctor might not giveyou any medication if you have a viral disease.

SummaryWhat are viruses?

A virus is a strand of hereditary material surrounded by a protein coating, which multiplies by making copies of itself using a host cell.

Almost every living thing can be infected by a virus.

Fighting Viruses

Viruses can be prevented by vaccines, antiviraldrugs, improving sanitary conditions, separat-ing infected patients, and controlling animalsthat spread disease.

Your body produces interferons to naturallyprotect itself.

6. Interpret Scientific Illustrations Using Figure 18,explain why most viruses infect one species.

7. Research Information Find one precaution your community uses to prevent viral disease.

Research with VirusesYou might think viruses are always harmful.

However, scientists are discovering helpful uses forsome viruses through research. One use, called genetherapy, is being tried on cells with defective hereditarymaterial. Normal hereditary material is enclosed inviruses. The viruses then infect defective cells, takingthe new hereditary material into the cells to replace thedefective material. Using gene therapy, scientists hopeto help people with genetic disorders and find a curefor cancer.

How does gene therapy work?

An active area of viral research is HIV/AIDSresearch. HIV stands for human immuno-deficiencyvirus, a virus that attacks the immune system. Theimmune system is the system that protects your body from dis-ease. Eventually, this virus leads to Acquired Immune DeficiencySyndrome, or AIDS. A weak immune system allows the body tobe attacked by other diseases and infections, like pneumoniaand certain types of cancer. AIDS occurs worldwide, with 95 percent of the cases in developing countries. Table 3 showssome recent calculations of infected individuals. Currently,there is no known cure for AIDS. The research will hopefullylead to better treatments, a vaccine, and eventually a cure.

SECTION 4 Viruses 243More Section Review glencoe.com


Design Your OwnDesign Your Own

244 CHAPTER 8

Real-World QuestionYoure a technician in a police forensic laboratory. You use a stereomi-croscope, which uses two eyepieces to see larger objects in threedimensions, and a compoundlight microscope to see asmaller specimen. A detectivejust returned from a crimescene with bags of evidence.You must examine each piece ofevidence under a microscope.How do you decide whichmicroscope is the best tool touse? Will all of the evidencethat youve collected be view-able through both microscopes?

Form a HypothesisForm a hypothesis to predict which items in an actual police labora-tory, such as blood and dirt samples, would be viewed under a com-pound light microscope. A stereomicroscope? What qualificationswould the technician use to decide?

Goals Learn how to correctly

use a stereomicroscopeand a compound lightmicroscope.

Compare the uses ofthe stereomicroscopeand compound lightmicroscope.

Possible Materialscompound light

microscopestereomicroscopeitems from the

classroominclude some living or once-living items (8)

microscope slides andcoverslips

plastic petri dishesdistilled waterdropper

Safety Precautions

Comparing Light Microscopes

Test Your HypothesisMake a Plan1. As a group, decide how you will test your hypothesis.

2. Describe how you will carry out this experiment using a series of specific steps.Make sure the steps are in a logical order. Remember that you must place anitem in the bottom of a plastic petri dish to examine it under the stereomicro-scope, and you must make a wet mount of any item to be examined under thecompound light microscope. For more help, see the Reference Handbook.

3. If you need a data table or an observation table, design one in your ScienceJournal.

Follow Your Plan1. Make sure your teacher approves the objects youll examine, your plan, and

your data table before you start.

2. Carry out the experiment.

3. While doing the experiment, record your observations and complete the datatable.

Analyze Your Data1. Compare the items you examined with those of your classmates.

2. Based on this experiment, classify the eight items you observed.

Conclude and Apply1. Were you correct in your original hypothesis about the correct

microscope to use? For which objects would you reconsider themicroscope used?

2. Infer which microscope a scientist might use toexamine a blood sample, fibers, and live snails.

3. List five careers that require people to use astereomicroscope. List five careers that requirepeople to use a compound light microscope.Enter the lists in your Science Journal.

4. Describe If you examined an item under acompound light microscope and a stereomi-croscope, how would the images differ?

5. Name the microscope that was better forlooking at large or possibly live items.

LAB 245

In your Science Journal, write a shortdescription of an imaginary crime scene andthe evidence found there. Sort the evidenceinto two listsitems to be examinedunder a stereomicroscope and items to beexamined under a compound lightmicroscope.

Jewel Plummer Cobb is a cell biologist whodid important background research on theuse of drugs against cancer. She removedcells from cancerous tumors and cultured themin the lab. Then, in a controlled study, she tried aseries of different drugs against batches of thesame cells. Her goal was to find the right drug to

cure each patients par-ticular cancer. Cobbnever met that goal,but her research laidthe groundwork formodern chemother-apythe use of chemi-cals to treat peoplewith cancer.

JewelPlummer Cobbalso has influ-enced sciencesas dean or

president of several universities. She was ableto promote equal opportunity for students ofall backgrounds, especially in the sciences.She retired in 1990 from her post as presidentof California State University at Fullerton, andcontinues to be active in the sciences.

Light Up a CureBuilding on Cobbs work, Professor Julia Levy

and her research team at the University of BritishColumbia actually go inside cells, and evenorganelles, to work against cancer. One techniquethey are pioneering is the use of light to guidecancer drugs to the right cells. First, the patientis given a chemotherapy drug that reacts to light.Next, a fiber optic tube is inserted into the tumor.Finally, laser light is passed through the tube.The light activates the light-sensitive drugbutonly in the tumor itself. This technique keepshealthy cells healthy while killing sick cells.

SCIENCEANDHISTORY

SCIENCECAN CHANGE THE COURSE OF HISTORY!

CobbCobbAgainst

Cancer

Write Report on Cobbs experiments on cancer cells. What wereher dependent and independent variables? What would she haveused as a control? What sources of error did she have to guardagainst? Answer the same questions about Levys work.

For more information, visitglencoe.com

This colored scanningelectron micrograph

(SEM) shows two breastcancer cells in the final

stage of cell division.

AgainstCancer


Copy and complete the following concept map of the basic units of life.

Living Things

1. Organisms are made of cells, use energy,reproduce, respond, maintain homeostasis,grow, and develop.

2. Organisms need a food source, water, and aplace to live.

How are living thingsclassified?

1. Scientists today use phylogeny to grouporganisms into six kingdoms.

2. All organisms are given a two-word scien-tific name using a system called binomialnomenclature.

Cell Structure

1. The invention of the microscope led to thecell theory.

2. Cells without membrane-bound structuresare prokaryotic cells. Cells with membrane-bound structures are eukaryotic cells.

3. Most many-celled organisms are organizedinto tissues, organs, and organ systems.

Viruses

1. A virus is a nonliving structure containinghereditary material surrounded by a pro-tein coating. It can only make copies ofitself when inside a living host cell.

2. Viruses cause diseases in organisms.

CHAPTER STUDY GUIDE 247

CellOrganelles

have different functions

Transport and storage

movesmaterial

around cells

packages cellular

substances

Energyprocessing

Lysosomes Ribosomes

captures energy

releases energy

containsdigestivechemicals

makesproteins

Interactive Tutor glencoe.com

Golgi bodies Endoplasmicreticulum

Mitochondria Chloroplasts

Recycling Manufacturing


Write the correct vocabulary word for each phrase.

1. the smallest unit of life

2. maintaining proper internal conditions

3. similar structures

4. Homo sapiens

5. directs all cell activities

6. plant-cell organelle that processes energy

7. powerhouse of a cell

8. a structure that surrounds every cell

9. made up of cells

10. contains only hereditary material

Choose the word or phrase that best answers thequestion.

11. What category of organisms can mate andproduce fertile offspring?A) family C) genusB) class D) species

12. What is the closest relative of Canis lupus?A) Quercus alba C) Felis tigrisB) Equus zebra D) Canis familiaris

13. What is the source of energy for plants?A) the Sun C) waterB) carbon dioxide D) oxygen

14. What is the length of time an organism isexpected to live?A) life span C) homeostasisB) stimulus D) theory

15. What is the first word in a two-word nameof an organism?A) kingdom C) phylumB) species D) genus

Use the following photo to answer question 16.

16. Identify the folded membranes that movematerials around the cell, pictured above.A) nucleusB) cytoplasmC) Golgi bodyD) endoplasmic reticulum

17. What are the structures in the cytoplasmof a eukaryotic cell called?A) organs C) organ systemsB) organelles D) tissues

18. Groups of different organ systems formwhich of the following?A) organ C) organ systemB) organelle D) organism

19. According to the cell theory, what is thebasic unit of life?A) the Sun C) a cellB) a tissue D) a chloroplast

20. Where does a virus multiply?A) in the ground C) a host cellB) in water D) in the air

binomialnomenclature p. 226

cell p. 222cell membrane p. 232cell theory p. 229cell wall p. 232chloroplast p. 234cytoplasm p. 233endoplasmic

reticulum p. 236genus p. 226Golgi body p. 236homeostasis p. 224

host cell p. 240kingdom p. 227mitochondrion p. 234nucleus p. 234organ p. 238organelle p. 234organism p. 222organ system p. 238phylogeny p. 227ribosome p. 233tissue p. 238virus p. 240

248 CHAPTER REVIEW Vocabulary Puzzlemaker glencoe.com


21. Draw Conclusions Using a bird as an exam-ple, explain how it has the traits of livingthings.

22. Explain what binomial nomenclature is andwhy it is important.

23. Infer what Lathyrus odoratus, the name for a sweet pea, tells you about one of itscharacteristics.

24. Determine why it is difficult to treat a viraldisease.

25. Predict what would happen to a plant cellthat suddenly lost its chloroplasts.

26. Concept Map Make an events-chain conceptmap of the following from simple to com-plex: small intestine, circular muscle cell,human, and digestive system.

27. Interpret Scientific Illustrations Use the illustra-tions in Figure 1 to describe how the shapeof a cell is related to its function.

28. Compare and Contrast Copy and complete thefollowing table to compare and contrastthe structures of a prokaryotic cell tothose of a eukaryotic cell.

29. Describe how you would decide if a cell wasanimal, plant, or prokaryotic.

30. Make a Time Line Make and illustrate atime line to show the development ofthe cell theory. Begin with the develop-ment of the microscope and end withVirchow. Include the contributions ofLeeuwenhoek, Hooke, Schleiden, andSchwann.

31. Make a Model Use materials that resemblecell parts or that represent their functionsto make a model of a plant cell or an ani-mal cell. Make a key to the cell parts toexplain your model.

32. Make a Brochure Research the types of vacci-nations required in your community andat what ages they are usually administered.Contact your local Health Department forcurrent information. Prepare a brochurefor new mothers.

Use the table below to answer questions 33 and 34.

33. Temperature Dependence Use a computer tomake a line graph of the above data.

34. Number of Viruses From the line graph youhave just made, determine the number ofviruses at 37.3C

Temperature v. Number of Viruses

Temperature Number of Viruses

37C 1.0 million 37.5C 0.5 million 37.8C 0.25 million 38.3C 0.1 million 38.9C 0.05 million

CHAPTER REVIEW 249

Cell Structure

Structure Prokaryotic Eukaryotic

Cell Cell

Cell Membrane Yes

Cytoplasm Yes

Nucleus Yes

Endoplasmic Reticulum

Golgi Bodies

Hot Words Hot Topics: Bk 1 pp. 195, 283-284

Chapter Review glencoe.com

Yes

Yes

No

No Yes

No Yes


Intermediate-LevelScience Examination PracticeIntermediate-LevelScience Examination Practice

Record your answers on the answer sheetprovided by your teacher or on a sheet of paper.

Use the photo below to answer question 1.

1 The puffball above is releasing millions ofspores. What characteristic of living thingsis represented by this picture?(1) reproduction (3) organization(2) development (4) use of energy

2 Which of the following is the best exampleof homeostasis?(1) the ability of plants to use the Suns

energy, carbon dioxide and water tomake food

(2) the movement of a cat toward food(3) the ability of some organisms to keep

their temperature within a certain range(4) the production of eggs by most insects

3 What plant cell structure is made up mostlyof cellulose?(1) cell wall (3) cell membrane(2) chloroplast (4) mitochondrion

4 Which one of the following structures isfound in prokaryotic cells?(1) chloroplast (3) mitochondrion(2) Golgi bodies (4) ribosomes

5 Which of the following is the evolutionaryhistory of an organism?(1) phylogeny (3) nomenclature(2) classification (4) dichotomy

6 What is the two-word system used to namevarious species?(1) binomial species(2) binomial nomenclature (3) dichotomous key(4) modern classification

Use the illustration below to answer questions 7 and 8.

7 Which letter corresponds to the nucleus?(1) F (3) H(2) G (4) I

8 Which part is used by plant cells to makefood?(1) F (3) H(2) G (4) I

9 What are the smallest units that make upyour body called?(1) cells (3) organisms(2) tissues (4) organs

G

I

FH

250 INTERMEDIATE-LEVEL SCIENCE EXAMINATION PRACTICE

Intermediate-LevelScience Examination PracticeIntermediate-LevelScience Examination Practice

Record your answers on the answer sheet provided by your teacher or on a sheet of paper.

10 Explain why your heart would be called an organ and not a tissue.

11 List three different organisms whose cells are enclosed in cell walls.

12 Explain why water is important to living things.

13 A scientist observes a cell under a microscope and notices that the cells cytoplasmis almost completely full of rough endoplasmic reticulum. What would youhypothesize these cells are making in large amounts? Explain your answer.

14 List the groups in the biological classification system from largest to smallest.

15 What are four reasons scientific names are used to describe organisms rather thancommon names?

16 Draw diagrams of a prokaryotic cell and of a eukaryotic cell. Label the parts to showthe differences between the two cell types.

17 Explain how DNA is related to the chromosomes found in the nucleus of a cell.What is the importance of DNA in the nucleus?

18 The nucleus of a cell directs all the activities of a cell. But bacteria, which areprokaryotic cells, do not have nuclei. Explain how bacterial cells can function with-out a nucleus.

Use the photo below to answer questions 19 and 20.

19 Both of these organisms use energy. Describe the difference between their sourcesof energy. What are the common ways that these organisms use energy?

20 How are the needs of the two organisms alike? Explain why the plant fulfills a needfor the beetle. When the beetle dies, how could it fill a need for the plant?

251Science Examination glencoe.com


Glencoe Science: New York Science Grade 6Contents in BriefTable of ContentsUnit 1: Simple and Complex/Compound MachinesChapter 1: The Nature of ScienceSection 1: What is science?Section 2: Science in ActionSection 3: Models in ScienceSection 4: Evaluating Scientific ExplanationLab: What is the right answer?Lab: Identifying Parts of an Investigation

Chapter 2: Energy and Energy ResourcesSection 1: What is energy?Section 2: Energy TransformationsLab: Hearing with Your Jaw

Section 3: Sources of EnergyLab: Use the Internet: Energy to Power Your Life

Chapter 3: Work and Simple MachinesSection 1: Work and PowerLab: Building the Pyramids

Section 2: Using MachinesSection 3: Simple MachinesLab: Pulley Power

Unit 2: The Atmosphere, Hydrosphere, and LithosphereChapter 4: States of MatterSection 1: MatterSection 2: Changes of StateLab: The Water Cycle

Section 3: Behavior of FluidsLab: Design Your Own: Design Your Own Ship

Chapter 5: Thermal EnergySection 1: Temperature and Thermal EnergySection 2: HeatLab: Heating Up and Cooling Down

Section 3: Engines and RefrigeratorsLab: Design Your Own: Comparing Thermal Insulators

Chapter 6: AtmosphereSection 1: Earth's AtmosphereLab: Evaluating Sunscreens

Section 2: Energy Transfer in the AtmosphereSection 3: Air MovementLab: Design Your Own: The Heat is On

Chapter 7: WeatherSection 1: What is weather?Section 2: Weather PatternsSection 3: Weather ForecastsLab: Reading a Weather MapLab: Model and Invent: Measuring Wind Speed

Unit 3: BiodiversityChapter 8: Life's Structure and ClassificationSection 1: Living ThingsSection 2: How are living things classified?Section 3: Cell StructureLab: Comparing Cells

Section 4: VirusesLab: Design Your Own: Comparing Light Microscopes

Chapter 9: Interactions of LifeSection 1: Living EarthSection 2: PopulationsSection 3: Interactions Within CommunitiesLab: Feeding Habits of PlanariaLab: Design Your Own: Population Growth in Fruit Flies

Unit 4: InterdependenceChapter 10: The Nonliving EnvironmentSection 1: Abiotic FactorsLab: Humus Farm

Section 2: Cycles in NatureSection 3: Energy FlowLab: Where does the mass of a plant come from?

Chapter 11: EcosystemsSection 1: How Ecosystems ChangeSection 2: BiomesLab: Studying a Land Ecosystem

Section 3: Aquatic EcosystemsLab: Use the Internet: Exploring Wetlands

Feature ContentsCross-Curricular ReadingsNational GeographicTIME Science in SocietyTIME Science and HistoryOops! Accidents in ScienceScience and Language ArtsScience Stats

LABSLaunch LABMiniLABMiniLAB Try at HomeOne-Page LabsTwo-Page LabsDesign Your Own LabsModel and Invent LabsUse the Internet Labs

ActivitiesApplying MathApplying ScienceIntegrateScience OnlineIntermediate-Level Science Examination Practice

Student ResourcesScience Skill HandbookScientific MethodsSafety SymbolsSafety in the Science Laboratory

Extra Try at Home LabsTechnology Skill HandbookComputer Skills

Math Skill HandbookMath ReviewScience Applications

Reference HandbooksUse and Care of a MicroscopeTopographic Map SymbolsWeather Map SymbolsDiversity of Life: Classification of Living OrganismsPeriodic Table of Elements

English/Spanish GlossaryIndexCredits

Student WorkbooksThe Nature of ScienceHands-On ActivitiesMiniLAB: Try at Home: Classifying Parts of a SystemMiniLAB: Try at Home: Forming a HypothesisMiniLab: Thinking Like a ScientistLab: What is the right answer?Lab: Identifying Parts of an InvestigationLaboratory Activity 1: Solving a Problem with a Scientific MethodLaboratory Activity 2: Modeling the WeatherFoldables: Reading and Study Skills

Meeting Individual Needs: Extension and InterventionDirected Reading for Content MasteryDirected Reading for Content Mastery in SpanishReinforcementEnrichmentNote-taking Worksheet

AssessmentChapter Review

Transparency ActivitiesSection Focus Transparency ActivitiesTeaching Transparency ActivityAssessment Transparency Activity

Energy and Energy ResourcesHands-On ActivitiesMiniLAB: Try at Home: Analyzing Energy TransformationsMiniLAB: Building a Solar CollectorLab: Hearing with Your JawLab: Use the Internet: Energy to Power Your LifeLaboratory Activity 1: Energy TransformationsLaboratory Activity 2: Hydroelectric GeneratorFoldables: Reading and Study Skills




Work and Simple MachinesHands-On ActivitiesMiniLAB: Try at Home: Work and PowerMiniLAB: Observing PulleysLab: Building the PyramidsLab: Design Your Own: Pulley PowerLaboratory Activity 1: Calculating Work and PowerLaboratory Activity 2: The BicycleFoldables: Reading and Study Skills




States of MatterHands-On ActivitiesMiniLAB: Observing VaporizationMiniLAB: Try at Home: Predicting a WaterfallLab: The Water CycleLab: Design Your Own: Design Your Own ShipLaboratory Activity 1: States of MatterLaboratory Activity 2: Crystal FormationFoldables: Reading and Study Skills




Thermal EnergyHands-On-ActivitiesMiniLAB: Try at Home: Comparing Rates of MeltingMiniLAB: Observing ConvectionLab: Heating Up and Cooling DownLab: Design Your Own: Comparing Thermal InsulatorsLaboratory Activity 1: The Effect of Temperature on Diffusion and ExpansionLaboratory Activity 2: Observing RadiationFoldables: Reading and Study Skills




AtmosphereHands-On ActivitiesMiniLAB: Determining If Air Has MassMiniLAB: Try at Home: Modeling Heat TransferLab: Evaluating SunscreensLab: Design Your Own: The Heat is OnLaboratory Activity 1: Air Volume and PressureLaboratory Activity 2: Temperature of the AirFoldables: Reading and Study Skills




WeatherHands-On ActivitiesMiniLAB: Determining Dew PointMiniLAB: Try at Home: Measuring RainLab: Reading a Weather MapLab: Model and Invent: Measuring Wind SpeedLaboratory Activity 1: Effect of Temperature on Cloud FormationLaboratory Activity 2: Wind PowerFoldables: Reading and Study Skills




Life's Structure and ClassificationHands-On ActivitiesMiniLAB: Try at Home: Communicating IdeasMiniLAB: Modeling CytoplasmLab: Comparing CellsLab: Design Your Own: Comparing Light MicroscopesLaboratory Activity 1: The MicroscopeLaboratory Activity 2: ClassificationFoldables: Reading and Study Skills




Interactions of LifeHands-On ActivitiesMiniLAB: Try at Home: Observing Seedling CompetitionMiniLAB: Comparing Biotic PotentialLab: Feeding Habits of PlanariaLab: Design Your Own: Population Growth in Fruit FliesLaboratory Activity 1: CommunitiesLaboratory Activity 2: Changes in Predator and Prey PopulationsFoldables: Reading and Study Skills




The Nonliving EnvironmentHands-On ActivitiesMiniLAB: Try at Home: Determining Soil MakeupMiniLAB: Comparing FertilizersLab: Humus FarmLab: Where does the mass of a plant come from?Laboratory Activity 1: The Rain Shadow EffectLaboratory Activity 2: Carbon Dioxide and Earth's TemperaturesFoldables: Reading and Study Skills




EcosystemsHands-On ActivitiesMiniLAB: Try at Home: Modeling Rain Forest LeavesMiniLAB: Modeling Freshwater EnvironmentsLab: Studying a Land EcosystemLab: Use the Internet: Exploring WetlandsLaboratory Activity 1: Succession Communities and GrassesLaboratory Activity 2: Exploring Life in Pond WaterFoldables: Reading and Study Skills




NY Reading Essentials Grade 6 Student EditionTo the StudentChapter 1: The Nature of ScienceChapter 2: Energy and Energy ResourcesChapter 3: Work and Simple MachinesChapter 4: States of MatterChapter 5: Thermal EnergyChapter 6: AtmosphereChapter 7: WeatherChapter 8: Life's Structure and ClassificationChapter 9: Interactions of LifeChapter 10: The Nonliving EnvironmentChapter 11: Ecosystems

NY Science Notebook Grade 6 Student EditionNote-Taking TipsUsing Your Science NotebookChapter 1: The Nature of ScienceChapter PreviewSection 1-1Section 1-2Section 1-3Section 1-4Wrap-Up

Chapter 2: Energy and Energy ResourcesChapter PreviewSection 2-1Section 2-2Section 2-3Wrap-Up

Chapter 3: Work and Simple MachinesChapter PreviewSection 3-1Section 3-2Section 3-3Wrap-Up

Chapter 4: States of MatterChapter PreviewSection 4-1Section 4-2Section 4-3Wrap-Up

Chapter 5: Thermal EnergyChapter PreviewSection 5-1Section 5-2Section 5-3Wrap-Up

Chapter 6: AtmosphereChapter PreviewSection 6-1Section 6-2Section 6-3Wrap-Up

Chapter 7: WeatherChapter PreviewSection 7-1Section 7-2Section 7-3Wrap-Up

Chapter 8: Life's Structure and ClassificationChapter PreviewSection 8-1Section 8-2Section 8-3Section 8-4Wrap-Up

Chapter 9: Interactions of LifeChapter PreviewSection 9-1Section 9-2Section 9-3Wrap-Up

Chapter 10: The Nonliving EnvironmentChapter PreviewSection 10-1Section 10-2Section 10-3Wrap-Up

Chapter 11: EcosystemsChapter PreviewSection 11-1Section 11-2Section 11-3Wrap-Up

Probeware Labs, Student EditionTo the StudentGetting Started with ProbewareSafety in the LabSafety SymbolsLife Science LabsLab 1: Size Limits of CellsLab 2: Exercise and Heart RateLab 3: Cooking with BacteriaLab 4: Sweat is CoolLab 5: Biodiversity and Ecosystems

Earth Science LabsLab 6: The Effect of Acid Rain on LimestoneLab 7: The Formation of CavesLab 8: Measuring EarthquakesLab 9: Predicting the WeatherLab 10: How are distance and light intensity related?

Physical Science LabsLab 11: How fast do you walk?Lab 12: Transforming EnergyLab 13: Endothermic and Exothermic ProcessesLab 14: Thermal ConductivityLab 15: Let the Races Begin!

Appendix A: Using the TI-73 to Create a HistogramAppendix B: Using the TI-83 Plus to Create a HistogramAppendix C: Using the TI-73 to Create a Box Plot and Display StatisticsAppendix D: Using the TI-83 Plus to Create a Box Plot and Display StatisticsAppendix E: Using the TI-73 to Create a Circle Graph

Math Skills Activities, Student EditionActivity 1Activity 2Activity 3Activity 4Activity 5Activity 6Activity 7Activity 8Activity 9Activity 10Activity 11Activity 12Activity 13Activity 14Activity 15Activity 16Activity 17Activity 18Activity 19Activity 20Activity 21Activity 22Activity 23Activity 24Activity 25Activity 26

Reading and Writing Skill Activities, Student EditionActivity 1Activity 2Activity 3Activity 4Activity 5Activity 6Activity 7Activity 8Activity 9Activity 10Activity 11Activity 12Activity 13Activity 14Activity 15Activity 16Activity 17Activity 18Activity 19Activity 20Activity 21Activity 22Activity 23Activity 24Activity 25Activity 26

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