Chapter 17: Nutrients and Digestion - mrwrightsclass.netmrwrightsclass.net/resources/old-7th-grade-text/chap17.pdf · Performance Assessment,p. 17 Chapter Review Software Computer

462B

Chapter Review, pp. 33–34Assessment, pp. 65–68Performance Assessment in the Science

Classroom (PASC)MindJogger VideoquizAlternate Assessment in the Science

ClassroomPerformance Assessment, p. 17Chapter Review SoftwareComputer Test Bank

Chapter Organizer

Standards Reproducible Resources Technology

National State/Local

National ContentStandards: UCP4,UCP5, A1, A2, B3,F1, F4

National ContentStandards: UCP3,UCP5, A1, A2, B1,C1, C3, C4

Activity Worksheets, pp. 91–92, 95Critical Thinking/Problem Solving, p. 17Enrichment, p. 48 Laboratory Manual, pp. 95–98 Multicultural Connections, pp. 33–34Reinforcement, p. 48 Study Guide, pp. 65-66

Activity Worksheets, pp. 93–94, 96Enrichment, p. 49 Laboratory Manual, pp. 99–102Reinforcement, p. 49Study Guide, pp. 67–68

Section Focus Transparency 48Glencoe Science VoyagesInteractive Videodisc—PhysicalThe Infinite Voyage SeriesGlencoe Science VoyagesInteractive CD-ROMInternet Connection, p. 471

Section Focus Transparency 49 Teaching Transparency 33Teaching Transparency 34Science Integration Transparency 17The Infinite Voyage SeriesNational Geographic Society: STVInternet Connection, p. 480

Assessment Resources

Level 1 activities should be appropriate for students with learning difficulties.

Level 2 activities should be within the ability range of all students.

Level 3 activities are designed for above-average students.

ELL activities should be within the ability range of English Language Learners.

Cooperative Learning activities are designed for small group work.

These strategies represent student products that can be placed into a best-work portfolio.

Multiple Learning Styles logos, as described on page 63T, are used throughoutto indicate strategies that address different learning styles.

P

COOP LEARN

ELL

L3

L2

L1

The following designations will help you decide which activities are appropriate for your students.

Key to Teaching Strategies

English and Spanish audiocassettes areavailable for use with each section.

Test Practice Workbooks are available foruse with each chapter.

California ScienceContent Standards:5a, 7a, 7b, 7c, 7e

California ScienceContent Standards:5a, 5b, 7a, 7c, 7d,7e

Chapter 17

462A CHAPTER 17 NUTRIENTS AND DIGESTION

Section Objectives Activities/Features

Activity MaterialsExplore Activities MiniLabs

Chapter 17 Nutrients and Digestion

Chapter Opener

17-1Nutrition

3 Sessions11⁄2 Blocks

17-2Your Digestive System

4 Sessions2 Blocks

1. List the six classes of nutrients.2. Describe the importance of each type of

nutrient.3. Explain the relationship between diet and

health.

4. Distinguish between mechanical andchemical digestion.

5. Name the organs of the digestive systemand describe what takes place in each.

6. Explain how homeostasis is maintained in digestion.

Explore Activity: Model the Digestive Tract, p. 463

Chemistry Integration, p, 465Problem Solving: Analyzing a Menu, p. 467MiniLab: Measuring the Water Content of

Food, p. 472Skill Builder: Interpreting Data, p. 473Using Computers, p. 473Activity 17-1: Identifying Vitamin C Content,

p. 474Science and Society: Antioxidants, p. 475

Chemistry Integration, p. 477Physics Integration, p. 479MiniLab: Determining How Fats Are

Emulsified, p. 481Skill Builder: Observing and Inferring, p. 483Science Journal, p. 483Activity 17-2: Protein Digestion, pp. 484–485

p. 463index cards, masking tape,meterstick, marking pens

p. 47410-mL graduated cylinder, indophenol solution, glass-marking pencil, 10 test tubes, test-tube rack, dropper, 10 dropping bottles, water, orange juice, pineapplejuice, apple juice, lemon juice, tomato juice, cranberryjuice, carrot juice, lime juice, mixed vegetable juice

pp. 484–4853 test tubes, unflavored gelatin, dropper, test-tube rack,pepsin powder, marking pen, water, dilute hydrochloricacid, beaker, timer

p. 472pan balance, 250-mL beaker,sliced celery, tray

p. 4812 glasses, large spoon, cooking oil,small spoon, liquid dishwashingdetergent, warm water

The number of recommended single-period sessions The number of recommended blocksOne session and one-half block are allowed for chapter review and assessment.

Need Materials? Contact Science Kit at 1-800-828-7777 or at www.sciencekit.com on the Internet. For alternate materials, see the activity on the listed page.

http://www.sciencekit.com

Critical Thinking/Problem Solving

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 19

NAME DATE CLASS

Chapter 19

CRITICAL THINKINGNutrients and Digestion

A recent study has found that your parentsmay have good reason to forbid sweets beforedinner. However, the study shows that specif-ic sweeteners, not sweets alone, are whateither ruin or suppress a person’s appetite.

In the study, some people were given drinkscontaining white sugar and fruit sugar oraspartame, an artificial sweetener with nocalories. Others were given plain drinkingwater. They were the control group. Later, allwere told to eat food from a buffet until theirhunger was satisfied.

Scientists discovered that the drink sweet-ened with aspartame had the same effect onappetites as a drink of water. The people who

drank water or the artificially sweeteneddrink consumed more calories worth of foodthan those who drank the beverages withsugar.

The people who drank drinks sweetenedwith white sugar and fruit sugar ate less food.The fruit sugar-sweetened drink seemed tosuppress their appetites the most. Those peo-ple ate 20 to 40 percent fewer calories thanpeople who drank water or aspartame sweet-ened drinks. They ate less even when theydrank fruit sugar-sweetened drinks 2 1/2hours before a meal. People drinking fruitsugar-sweetened drinks also chose mealslower in fat.

Applying Critical Thinking Skills1. What after-school snacks would not spoil your dinner appetite?

2. Imagine that you are a person who needs to lose weight. At your doctor’s suggestion, you aretrying to exercise more and consume fewer calories each day. What might you try doing a few hours before each meal?

3. How would you expect the appetite of a person who drank a tea and sugar beverage to differ from a person who drank a glass of apple juice?

Sweeteners, Not Sweets, Spoil Your Appetite

L2

Accessibility

Resource Manager

Spanish Resources

L2

Hands-on Activities

Lab ManualActivity Worksheets


What You’ll InvestigateWhich juices contain vitamin C?

Goals• Observe differences in the vitamin C

content of juices.

Materials • indophenol solution• graduated cylinder (10-mL)

*graduated container• glass-marking pencil

*tape• test tubes (10)• test-tube rack

*paper cups• dropper• dropping bottles (10) • test substances: water, orange juice,

pineapple juice, apple juice, lemon juice,tomato juice, cranberry juice, carrot juice,lime juice, mixed vegetable juice*alternate materials

Procedure1. Make a data table like the example shown

to record your observations.

2. Label the test tubes 1 through 10.

3. Predict which juices contain vitamin C.Record your predictions in your table.

4. Measure 5 mL of indophenol into each ofthe ten test tubes. CAUTION: Wear yourgoggles and apron. Do not taste any of thejuices. Indophenol is a blue liquid thatturns colorless when vitamin C is present.The more vitamin C in a juice, the less juiceit takes to turn indophenol colorless.

5. Add 20 drops of water to test tube 1.Record your observations.

6. Begin adding orange juice, one drop at atime, to test tube 2.

7. Record the number of drops needed toturn indophenol colorless.

8. Repeat steps 6 and 7 to test the other juices.

Lab Preview1. What are vitamins? _______________________________________________________________

other nutrients.

2. Why is vitamin C necessary? _______________________________________________________

healing wounds.

Vitamin C is found in a variety of fruits and vegetables. In someplants, the concentration is high; in others, it is low. Try this activity totest various juices and find out which contains the most vitamin C.

Vitamins are essential, organic nutrients that help your body use

It is necessary for strong bones and teeth and for

NAME DATE CLASS

Chapter 19

ACTIVITY 19-1Identifying Vitamin C Content

L2Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 101

NAME DATE CLASS

Chapter 19

LABORATORY MANUALTesting for Carbohydrates 37

Carbohydrates provide energy for the body. Your body needs more carbohydrates than fats andproteins each day. Foods that contain starch and foods that contain sugar are sources of carbohydrates.

StrategyYou will test foods for starch by using iodine solution.You will test foods for sugar by using sugar test tablets.You will use your test results to determine which foods are sources of

carbohydrates.

Materials breadegg white (hard-boiled)forcepsglucose or dextrosehoneyiodine in dropping bottlelabelsmilkmolassespotato (cooked)

ProcedureCAUTION: Do not taste, eat, or drink any materials used in the lab.CAUTION: Inform your teacher if you come in contact with any chemicals.1. Label six test tubes 1 through 6. Place them in a test-tube rack.2. Fill the test tubes to about 1 cm with the following.

1—Water 4—Rice2—Starch 5—Egg white3—Bread 6—Potato

3. Add 5 drops of iodine to test tubes 1–6. CAUTION: Iodine is poisonous. Do not inhale iodinefumes. Do not allow iodine to get on your hands. Wash immediately if iodine comes in contact with yourskin. Inform your teacher. Examine the color. A blue-black color means that starch is present.Record the colors in Table 1. (See Data and Observations.)

4. Label the remaining test tubes 7 through 12. Place them in a test-tube rack.5. Fill these test tubes to a depth of about 1 cm with the following:

7—Water 10—Honey8—Glucose 11—Milk9—Syrup 12—Molasses

6. Use forceps to add one sugar test tablet each to test tubes 7–12. CAUTION: Sugar test tablets arepoisonous. DO NOT touch the tablet with your fingers. Wash hands immediately if sugar test tablets orsolution containing them come in contact with your skin. The test tubes will get hot as the tabletsdissolve. Do not remove the test tubes from the test tube rack. DO NOT TOUCH.

7. Observe the color of each of the test tubes. Green, yellow, or orange color means that sugar ispresent. Record the colors in Table 2.

rice (cooked)starch Corn starch can be usedsugar test tabletssyruptest-tube rack12 test tubes (18 � 150-mm)wateraprongogglesgloves

Clini-test tablets areavailable atpharmacies. CAUTION:They are poisonous ifingested. Do not allowstudents to handle thetablets with theirhands. They should behandled with forceps.Tes-tape or clinistixcan be used in placeof the tablets. Followthe manufacturer’sinstructions for testingurine to test the foodsin this activity.

L2

Hands-on Activities

Chapter Review

37

Part A. Vocabulary ReviewUse the clues below to complete the crossword puzzle.

NAME DATE CLASS

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

Nutrients and Digestion

Chapter 19

CHAPTER REVIEW

4/19:2

5/19:2

4/19:2

F A T S M

M I N E RV NI F O O D G R O U P T A A C M

C H Y M E C D I G E SI A D C N U T R I E N T S H S B A

P R O T E I N S N H I Y C H E M I C AD A R L A T

P E R I S T A L S IS

S A A L S I V A A T I O N T I O V X I I L D L A I N T S S

1 2 3

4

87

13

11

15

16

14

12

109

5

6

F A T S

M M I N E R

V NI F O O D G R O U P T A A C M




S A A L S I V A T I O N V I L L I S

1 2 3

4

7

13

10

14

15

12

11

98

5

6

F A T S

M M I N E R

V NI F O O D G R O U P T A A C M




S A A L S I V A A T I O N T I O V X I I L D L A I N T S S

1 2 3

4

87

13

11

15

16

14

12

109

5

6

Across1. nutrients that help store vitamins and form

a cushioning layer 2/19:1

4. inorganic nutrients that regulate the body’schemical reactions 2/19:1

6. name given to a group of foods that containthe same nutrients 3/19:1

8. food in thin, watery liquid form that isabsorbed by the body 5/19:2

10. the process that breaks food down intosmall molecules so they can be absorbed

11. substances in foods that provide energyand materials for cell development, growth,and repair 1/19:1

12. nutrients that repair and replace cells 2/19:1

14. type of digestion that breaks down foodinto molecules that can be absorbed 4/19:2

15. contractions that move food 5/19:2

Down2. twenty subunits of protein 2/19:1

3. enzyme-containing fluid in the mouth

5. essential, organic nutrients that help thebody use other nutrients 2/19:1

7. type of digestion when food is chewed

9. main source of energy for the body; sugarsand starches 2/19:1

13. tiny, fingerlike projections that cover thefolds of your small intestine 5/19:2

L2

Performance Assessment


Are you a label reader?The United States Food and Drug Administration requires that all food labels list the name, net

weight, and standard serving size, as well as a list of ingredients. They also must include the amountof saturated fat and dietary fiber in the product. Most product labels also list nutritional informationand the name and address of the manufacturer. Ingredients must be listed in the order of the amountby weight that the product contains. For example, if sugar is listed first in an ingredient list, thatmeans that there is more sugar than any other ingredient, by weight, in the product.

A column headed % Daily Value is included with the nutrients on a food label. The number listed inthis column shows the percentage of the listed nutrient that is contained in one serving of the product,compared to what a person needs each day for good health. For example, if the % Daily Value numberfor a vitamin is 35% on a food label, then one serving of the food provides 35 percent of the amount ofthat vitamin that is needed by a person each day.

If evidence shows a connection between a product and a health benefit, the label is allowed to claimthat the product “may” or “might” reduce the risk of the disease. They must not overstate the benefitand must state that other factors play a role. A product that is low in saturated fat and cholesterol mayclaim that items low in saturated fat and cholesterol may, with exercise, help prevent heart disease.

Obtain labels from three similar food products, such as three different cereals, and answer the follow-ing questions.

1. Make a table that compares product calories, protein, carbohydrates, fat, cholesterol, and sodi-um.

2. If your doctor tells you that you should limit your sodium intake, which item should you buy?

3. Which ingredient is in the largest amount in each product?

4. If a person is trying to lose weight while maintaining proper nutrition, which product should he orshe buy?

5. Compare the % Daily Values on the products, and decide which product is the most nutritious.

NAME DATE CLASS

Chapter 19

SKILL ASSESSMENT Using Food Labels

L2

Assessment Extending ContentExtending Content

Accessibility

Multicultural ConnectionsTest Practice WorkbookAssessment


I. Testing ConceptsMatch the description in the first column with the item in the second column by writing the correct letter in the spaceprovided. Some items in the second column may not be used.

_____ 1. main sources of energy; starches and sugars 2/19:1

_____ 2. nutrients that repair and replace body cells 2/19:1

_____ 3. subunits of proteins 2/19:1

_____ 4. inorganic nutrients that regulate the body’s chemical reactions 2/19:1

_____ 5. physical breakdown of food, as in chewing 5/19:2

_____ 6. breakdown of large molecules of food for absorption 5/19:2

_____ 7. enzyme-containing fluid in the mouth 5/19:2

_____ 8. muscular contractions that move food 5/19:2

_____ 9. fingerlike projections in the small intestine 5/19:2

For each of the following, write the letter of the term or phrase that best completes each sentence.

_____10. Unlike inorganic nutrients, organic nutrients contain _____ . 1/19:1a. carbon b. hydrogen c. nitrogen d. oxygen

_____ 11. Starches are in foods such as potatoes and _____ . 1/19:1a. eggs b. fruits c. grains d. leafy green vegetables

_____12. Milk, cheese, and _____ contain ALL the essential amino acids. 1/19:1a. eggs b. nuts c. poultry d. red meats

_____13. Throughout history, many cultures have used _____ to meet their needs for protein aswell as carbohydrates. 2/19:1a. whole grains b. green vegetables c. yellow fruit d. yellow vegetables

_____14. _____ are nutrients that help store some vitamins and form a cushioning tissue. 2/19:1a. Carbohydrates b. Fats c. Minerals d. Proteins

_____15. Saturated fats, found in _____, are believed to contribute to high cholesterol and heartdisease. 3/19:1a. corn b. fish c. poultry d. red meats

_____16. _____ are essential, organic nutrients that help your body use other nutrients. 2/19:1a. Carbohydrates b. Minerals c. Proteins d. Vitamins

_____17. Scurvy is a disease caused by a lack of _____ . 3/19:1a. calcium b. iron c. phosphorus d. vitamin C

NAME DATE CLASS

Chapter 19

CHAPTER TEST Nutrients and Digestion

a. amino acids

b. chyme

c. carbohydrates

d. chemical digestion

e. fats

f. mechanical digestion

g. minerals

h. peristalsis

i. proteins

j. saliva

k. villi

l. vitamins

c

i

a

g

f

d

j

h

k

a

c

a

a

b

d

d

d

L2 L2Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

37

Introducing young people to the mysteries ofthe land was one reason why, in 1995, thetribal council of the San Juan Pueblo in NewMexico decided to turn 200 acres of barrenland into a piece of agricultural paradise.

Working TogetherToday, the innovative experiment is produc-

ing results. Where the land was once unusedsuch traditional Native American crops asgreen chili, corn, native tobacco, and tomatoesnow grow. Other crops include melons, alfal-fa, and hay. And cattle peacefully graze on theland not actually being harvested.

Every inch of the land at the San JuanAgricultural Cooperative is being used, andmany people are reaping the benefits. Forstarters, each of the 40 families who donatedtheir unused land to the cooperative gets apiece of the profits from the sale of the crops.Then there are the jobs that are created byplanting and harvesting the crops—jobs thatgo almost exclusively to Native Americans.The senior citizens benefit because their mealsare prepared daily from the produce grownon the land.

The cooperative has also started a mail-orderbusiness. Its first product is dried green chilistew, which is also available in stores through-out New Mexico. A new and bigger food dry-ing facility is currently being built in hopes ofpreparing enough of the stew to feed peoplearound the country. The former dryingmethod of simply allowing produce to dry inthe sun is too lengthy for mass productionand distribution.

The recipe testers for the mail-order chiliwere the Pueblo’s senior citizens. They havebeen called “the best research and develop-ment team around,” with a wealth of recipesthey’re ready to share with the world.

The Perils of FarmingEven though the cooperative is enjoying its

first tastes of success—and even a littlefame—there have been plenty of challengesalong the way. New Mexico’s high altitudeand harsh climate have made farming diffi-cult. And it is always a struggle to convincepeople that farming can be financially reward-ing. Like much of the country, farming in theSouthwest has been in decline since World

War II. During this period, members of thetribe started flocking to the nearby cities ofSanta Fe and Albuquerque in search of jobs inindustry. But the San Juan Pueblo, a commu-nity of about 1600 Native Americans, decidedon a different course of action.

In 1992, the tribal council approved the for-mation of the San Juan AgriculturalCooperative. Now, the project has grown toinclude an experimental solar dehydrator todry food crops. The dehydrator functions likea giant greenhouse. As the greenhouse warmsup, the air is blown from it by huge fans intoan adjacent food drying chamber. Extrapropane-powered heaters are used at nightand on days when there is a lot of cloudcover.

The project is also now testing a solar heatedoven at the senior citizen’s center. The oven, alarge bowl-shaped structure with built-inreflecting panels, is capable of reaching about180 degrees Celsius. The people of the Puebloare enjoying the traditional dishes coming outof the alternate-energy apparatus. It’s evenpassed the bread test: producing bread that’scrunchy on the outside but soft on the inside,just as the adobe ovens used to do.

Keeping Tradition AliveThe San Juan Agricultural Cooperative was

started with money from outside sources butis now close to becoming self-supporting. Thelarger drying facility will help increase profits.

Chapter 19

MULTICULTURAL CONNECTIONSSan Juan Agricultural Cooperative

NAME DATE CLASS

A Native American surveys crops growing on theSan Juan Agricultural Cooperative’s 200-acre farmin New Mexico.

L2

462D

Meeting Different Ability Levels

Transparencies

Chapter 17 Chapter 17 Nutrients and Digestion

Enrichment WorksheetsReinforcementStudy Guide

for Content Mastery

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Name Date

CHAPTER 19 Study Guide for Content Mastery

Overview Nutrients and DigestionDirections: Use the following terms to complete the concept map below. Some terms

are used more than once.

mechanical duodenum mouth enzymes muscles

digestion

enzymesfrom

pancreasduodenum by the

action of

enzymesstomach by theaction of

occursin the

salivamouth by theaction of

chemical

bileduodenum by theaction of

musclesstomach by theaction of

occursin the

teethmouth by theaction of

mechanical

BASICCopyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.52

NAME DATE CLASS

Chapter 19

REINFORCEMENT

Use with Section 1

NutritionName the six nutrients available in food and briefly describe each:

1. ______________________ __________________________________________________________

__________________________________________________________

2. ______________________ __________________________________________________________

__________________________________________________________

3. ______________________ __________________________________________________________

__________________________________________________________

4. ______________________ __________________________________________________________

__________________________________________________________

5. ______________________ __________________________________________________________

__________________________________________________________

6. ______________________ __________________________________________________________

__________________________________________________________

Answer the following questions.

7. What foods supply saturated fats and unsaturated fats? _________________________________

saturated fats and plant foods supply unsaturated fats. Poultry, fish, and nuts also

supply some unsaturated fats.

8. How much of a human body is water? ________________________________________________

9. What are the six food groups? ________________________________________________________

the bread group, the meat group, and the fat group

10. Which food group is represented by pizza? ____________________________________________

combination.

Use the tables in your textbook to answer the following questions.

11. Which minerals help make strong bones? ______________________________________________

12. Which vitamin is essential for good eyesight? __________________________________________

13. In what way do we lose the most water? ______________________________________________

14. Where is most of the body’s water located? ____________________________________________

15. What food sources provide vitamin C? ________________________________________________

16. How does a person get iodine? _______________________________________________________

carbohydrates

proteins

fats

vitamins

minerals

water

Red meats supply

about 60 percent

the milk group, the fruit group, the vegetable group,

Pizza is an example of a food group

calcium and phosphorus

vitamin A

through the excretory system

in and around cells in tissues

citrus fruits, tomatoes, green leafy vegetables

by eating seafood and iodized salt

These nutrients contain C, H, and O atoms. Carbohydrates

are the main source of energy.

Proteins are made up of amino acids. Proteins are used for

growth, replacement, and repair.

Fats provide energy and help the body store some

vitamins.

Vitamins are essential, organic nutrients that help the body

use other nutrients.

Minerals are inorganic nutrients that regulate many chemi-

cal reactions in the body.

Water enables the chemical reactions to take place in the

body and removes waste products from the cells.

AT LEVELCopyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.52

Nutrition

Use with Section 1

NAME DATE CLASS

Chapter 19

ENRICHMENT

Procedure1. Look at the nutritional information on the package. The amount of fat is usually listed in

grams per serving. Fat content may be divided into saturated fat and unsaturated fat. To findthe total amount of fat in a serving, add these two types of fat together.

2. Find the number of calories from fat per serving. Multiply total grams of fat by 9 calories.3. Find the total number of calories per serving on the label. Divide the number of calories from

fat by the total number of calories. Multiply this number by 100 to get the percentage of calo-ries from fat.

4. Record your answers in the table below.

Conclude and Apply1. Which of your favorite foods were high in fat? ___________________________________________

chips or cheese.

2. How can you make sure you aren’t eating too much fat? __________________________________

amounts of high-fat foods and eat plenty of foods high in carbohydrates.

Fat (grams)per serving

2.3

13.0

1.12

5.5

1.12

Calories per serving

120

230

170

140

100

Percentageof calories

from fat

17.0

51.0

5.9

8.5

10.0

Vegetable Soup

Chili

Light Salad Dressing

Oatmeal

Milk

Carbohydrates, proteins, fats, vitamins, andminerals are nutrients that are important togood health and growth. To maintain health,you need to eat lots of carbohydrates. Proteinsand fats are needed in smaller amounts.

Most people don’t realize that fats are impor-tant to your health. Doctors recommend that30 percent of the calories you eat come fromfat. However, many people eat too many fattyfoods. In most Americans’ diets, 40 percent ofthe calories come from fat. Many people like

the way high-fat foods taste. One gram of fatcontains 9 calories. On the other hand, 1 gramof carbohydrate or protein contains only 4 calories. So, you can eat less fat than carbo-hydrate, but the total calories from fat couldbe higher.

Are you eating too much fat? Find out howmany calories come from fat in five of yourfavorite foods. Nutritional information can befound on the labels of packaged foods or innutrition or diet books at the library.

Do you eat too much fat?

Food 1

Food 2

Food 3

Food 4

Food 5

Answers will vary, but may include potato

Choose low-fat snacks or eat small

CHALLENGE

Meeting Different Ability Levels

Section Focus Transparencies

Teaching TransparenciesScience Integration

Transparencies

Copyright©Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 48

48

IDENTIFYING THE NUTRIENTS IN FOODSYou eat foods for two reasons. First, the energy you need to carry out your

life functions and other activities is provided by the foods you eat. Second,the foods you eat supply your body with nutrients. Nutrients are substancesin foods that provide your body with the materials it needs for growth,maintenance, and repair. Descriptions of some of the nutrients your bodyneeds appear in the table shown.

1. What kinds of foods do you think are rich in sugars? In starches?

2. What kinds of foods do you think are rich in proteins? Give three examples.

3. Of the following, which foods do you think are rich in fats—butter,apples, beef, asparagus, lard? Explain.

SECTION FOCUS TRANSPARENCYSection 17-1

NutrientType

Characteristics of Nutrient Source(Plants or Animals)

Proteins Used by the body for growth; are madeof large molecules containing carbon,hydrogen, oxygen, and nitrogen

Animals and Plants

Sugars Taste sweet; provide the body withenergy

Plants

Starches Often have a pasty or mushy texture;provide the body with energy

Plants

Cellulose Cannot be digested by the body;have fibrous texture

Plants

Fats Have a greasy or oily feel; observed insome foods after cooking as a layer ofoil; provide the body with energy

Plants and Animals

L2Copyright©Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 49

49

MEETING YOUR ENERGY NEEDSThink of all the ways you use energy each day. You use the energy provid-

ed by your body to think, walk, play sports, and even to sleep. You also useenergy generated from Earth’s energy resources when you ride a bus, play aradio, watch television, or cook your dinner.

1. What are some of the ways you use energy (electricity) in your everydaylife? Where does this energy come from?

2. Why does your body need energy? Where does it get the energy it needs?

3. How is the way in which your body gets energy similar to the way inwhich energy is provided to a community by a power plant?

SECTION FOCUS TRANSPARENCYSection 17-2

L2

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

SCIENCE INTEGRATION TRANSPARENCY

Enzyme Catalysts at Work

Gall bladder

Energy NeededWithout Enzyme

Energy NeededWith Enzyme

Ene

rgy

leve

l

Ene

rgy

leve

l

Reaction

Products

Reaction

Products

Fat Digestion inSmall Intestine

Fatty acids to lymph

Fatglobule

Bile saltsrecycled

Enzymes frompancreas

Enzyme (lipase)

Substrate(lipid)

Fattyacids

Bile salt

Gall bladder

Energy NeededWithout Enzyme

Energy NeededWith Enzyme

Ene

rgy

leve

l

Ene

rgy

leve

l

Reaction

Products

Reaction

Products

Fat Digestion inSmall Intestine

Fatty acids to lymph

Fatglobule

Bile saltsrecycled

Enzymes frompancreas

Enzyme (lipase)

Substrate(lipid)

Fattyacids

Bile salt

17

L2Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

33. HUMAN DIGESTIVE SYSTEM

L2Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

34.D

IGE

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L1 L2 L3

462C CHAPTER 17 NUTRIENTS AND DIGESTION

possible without thework of specialized pro-teins—the enzymes—that serve as catalystsfor chemical reactions.These compounds oftenrequire precise environ-mental conditions suchas the proper tempera-ture, pH, and substrate to be active. As an exam-ple, the enzyme pepsin, which is found in thestomach, is only active in a medium having apH 1.5 to 2.2 and only digests proteins.

Absorption (Section 17-2)

The small intestine is an ideally constructedorgan for absorption. Its 6-meter length and in-terior surface of numerous tiny projections pro-vide an incredible amount of surface area for theabsorption of digested materials. The tiny, fin-gerlike projections called villi consist of singlelayers of epithelial cells with cores of connectivetissue in which beds of blood capillaries and alymph capillary are located. Nutrients are ab-sorbed by the blood capillaries. Water and ionsof sodium and potassium are absorbed by thelymph capillaries.

Other Organs (Section 17-2)

The pancreas, a flat, triangular-shaped organ onthe underside of the stomach, secretes digestivejuices that aid in digestion. The liver is a large,reddish-brown organ. It lies under the di-aphragm and produces bile, which causes fatsand oils to separate into small droplets.

Minerals (Section 17-1)

Inorganic compounds called minerals are an essential part of a healthy diet. Some mineralssuch as calcium, phosphorus, sodium, potas-sium, chlorine, sulfur, and magnesium are usedin relatively large amounts by the body for cellular functions. Other minerals used inminute amounts also play an important part inreactions within the body.

Trace Element Function

iron red blood cell formation, oxy-gen transport

manganese in enzymes, normal function-ing of nervous system

copper hemoglobin synthesis, enzymeproduction

iodine thyroid compound synthesis

cobalt enzyme synthesis

zinc in enzymes, liver metabolism,healthy skin

Digestion (Section 17-2)

The process of transforming foods into usablenutrients is called digestion. This extracellularprocess takes place in the digestive system,specifically in the stomach and small intestine.The process has three phases. First, food is me-chanically broken down; second, it is turnedfrom an insoluble to a soluble form; and third,the food is changed chemically to a form thatcells can use. The digestive process would not be

462F

For current events or science in the news,access the Glencoe Science Web Site atwww.glencoe.com/sec/science/ca

ontent Background

ontent Background

CC

Teacher to TeacherTeacher to Teacher“To illustrate how owl pellets are formed, put one or two paper

sugar packets and 100 mL of water in a self-sealing sandwich bag

(the stomach) and seal it. Knead the bag with your fingers until the

packages break up. Make a pellet out of the large sugar pieces.”

Janet Doughty, Teacher

H. J. MacDonald Middle School

New Bern, NC

Chapter 17

462E CHAPTER 17 NUTRIENTS AND DIGESTION

Nutrition (Section 17-1)

The energy requirements for body activities aresupplied by the foods we eat. The rate at whichour body consumes energy when at rest istermed our basal metabolic rate. Our basalmetabolic rate and our physical activity meta-bolic rate are two major factors that determinethe number of Calories required each day. Thetable below provides an overview of the numberof Calories needed for various daily activities.

Physical Activity Number of Calories Needed

desk job 2000–2500

housework 2000–2300

moderate work 2800–3500

active work 3500–4500

strenuous work 6000–7000

Among the other factors that determine thenumber of Calories required each day are age,weight, size, sex, endocrine gland activity, alti-tude, and external temperature. A lumberjackworking in winter requires a great deal moreCalories than a student sitting in a theaterwatching a movie.

Calories are supplied by the nutrients in thefoods we eat. Carbohydrates and proteins sup-ply about 4 Calories per gram, and fats supplyabout 9 Calories per gram. Excess sugar isstored in the liver and muscles in the form ofglycogen. When required for energy, a series of

activities involving a section of the brain,nerves, and the adrenal glands brings about theconversion of glycogen to glucose. The aminoacids of protein can be converted into carbohy-drates and these can consequently be utilizedfor energy production. Excess fat is deposited invarious body areas, but chiefly in the neck, ab-dominal wall, and in the fold of tissue over thestomach. Fats can oxidize and supply energywith a great deal of heat being produced as awaste product.

Vitamins (Section 17-1)

The role of vitamins as nutrients was not for-mally recognized until the early 1900s. Duringthe early years of research, each new vitaminthat was identified was given a letter designa-tion. This method proved to be inadequate tocorrectly classify the substances. The namingwas changed to use their chemical names.Niacin is one example of such a vitamin.

Products Available from GlencoeTo order the following products for use with this chap-ter, call Glencoe at 1-800-334-7344:

CD-ROMNGS PictureShow: Human Body 2Curriculum KitGeoKit: Human Body 1Transparency SetNGS PicturePack: Human Body 2VideodiscSTV: Human Body

Products Available from NationalGeographic SocietyTo order the following products for use with this chapter,call National Geographic Society at 1-800-368-2728:

VideosBacteriaDigestive System (The Human Body Series)Incredible Human MachineNutrition: Eating Well

Teacher’s Corner

Chapter 17 Nutrients and Digestion

CD-ROMGlencoe Science Voyages Interactive CD-ROM

Chapter SummariesUse the Chapter Summary to introduce, teach,or review chapter material.

Helping You Prepare

http://www.glencoe.com/sec/science/ca

1. Use index cards to make labelsfor all of the organs listed below.Each card should include thename of the structure, its length,and the time it takes for food topass through that structure.Mouth (8 cm, 5–30 s), Pharynxand Esophagus (26 cm, 10 s),Stomach (16 cm, 2–3 h), SmallIntestine (4.75 m, 3 h), and LargeIntestine (1.25 m, 2 days).

2. Working with a partner, place apiece of masking tape 6.5 m longon the classroom floor.

3. Beginning at one end of the tape,measure off and mark the lengthsfor each section of the digestivetract. Place each label next to itsproper section.

Explore Activity

What does a paper fan have in common with your stom-ach? Both the fan and the wall of your stomach, as

shown in the photograph, are made of folds. Because of thefolds and its elastic wall, the stomach can expand to holdabout 2 L of food or liquid. In the stomach, one part of theprocess that releases energy from food occurs. How long doyou think it takes for the food to go through this process?

Model the Digestive Tract

In your Science Journal,record what factorsmight alter the amountof time digestion takes.Suggest reasons whythere is such variation inthe time food spends ineach of the structures.

463

463

Explore ActivityPurpose

Visual-Spatial Use theExplore Activity to in-

troduce students to the diges-tive system.

PreparationFind an area that will allow

the masking tape not to bedisturbed during the activity.

Materialsindex cards, marking pens,masking tape, meterstick ormeasuring tape

Teaching Strategies• Discuss with students the

fact that the length of timefood spends in the diges-tive tract varies among in-dividuals and can dependon health conditions.

• Once the complete lengthof the digestive system hasbeen marked off, encour-age students to infer howsomething that long can fitinside their bodies.

S t u d e n t sshould ob-serve that

the amount of digestiontime may depend on thetype of food. Some foodsundergo several differentchemical processes as theyare digested.

Process Have students pre-dict what symptoms mightoccur in an infant if a birthdefect causes constriction of aportion of the digestive tract.Use Performance Assess-ment in the Science Class-room, p. 17.

COOP LEARNL2

Assessment

PortfolioRefer to p. 487 for suggested items that stu-dents might select for their portfolios.Performance AssessmentSee p. 487 for additional Performance Assessment options.Skill Builder, p. 483MiniLab, pp. 472, 481Activity 17-1, p. 474; 17-2, pp. 484–485

Content AssessmentSection Assessment, pp. 473, 483Chapter Assessment, pp. 488–489Proficiency Prep, pp. 473, 482

Assessment Planner

CHAPTER 17Nutrients

and DigestionNutrients

and Digestion

462 CHAPTER 17 NUTRIENTS AND DIGESTION

Nutrients andDigestionNutrients andDigestion

✔Reading Check

17

As you skim this chapter,

choose five illustrations. With-

out reading the captions,

write what they tell you about

nutrients or digestion.

C H A P T E R

462

Chapter Preview

Section 17-1Nutrition

Section 17-2Your Digestive Sys-tem

Skills Preview

Skill Builders• Compare and Contrast

• Observe and Infer

Activities • Experiment

• Collect Data

MiniLabs • Measure in SI

• Make a Model

CHAPTER OVERVIEWSection 17-1 This section fo-cuses on the nutrients re-quired by the body to carryon the activities of life. Thesix classes of nutrients andtheir functions within thebody are also described.Section 17-2 The process ofdigestion is introduced in thissection. Each of the major or-gans of the digestive systemis described and its specificfunction is detailed.

Chapter Vocabularynutrient enzymecarbohydrate mechanicalprotein digestionamino acid chemicalfat digestionvitamin salivamineral peristalsisfood group chymedigestion villi

Theme ConnectionEnergy Energy is a majortheme in this chapter. Nutri-ents contain chemical energy.Complex food compoundsbecome simpler compoundsthat the body cells can use formetabolism. Chemical energyis transformed into thermaland mechanical energy.

If time does not permit

teaching the entire chap-

ter, use Reviewing Main

Ideas on p. 486.

OUT OF

TIME?MultipleLearning

Styles

Look for the following logos for strategies that emphasize different learning modalities.

Linguistic Activity, p. 466; Using Sci-ence Words, p. 469; Discussion,

pp. 469, 478; Science Journal, p. 469; Preview, p. 486

Logical-Mathematical Across theCurriculum, p. 467; MiniLab, p. 472;

Correcting Misconceptions, p. 479; Activity,pp. 484–485

Visual-Spatial Explore Activity, p. 463;Across the Curriculum, p. 472; Reteach,

pp. 471, 482, 486; Assessement, p. 473; Ac-tivity, p. 474, MiniLab, p. 481

Auditory-Musical Out of Time, p. 486Kinesthetic Enrichment, p. 470;Making a Model, p. 482Interpersonal Across the Curriculum,p. 466; Discussion, p. 467; Review,

p. 486

Classes of NutrientsSix kinds of nutrients are available in food: carbohydrates,

proteins, fats, vitamins, minerals, and water. Carbohydrates,proteins, vitamins, and fats all contain carbon. Nutrients thatcontain carbon are called organic nutrients. In contrast, min-erals and water are inorganic. These nutrients do not containcarbon. Foods containing carbohydrates, fats, and proteinsare usually too complex to be absorbed right away by yourbody. These substances need to be broken down into simplermolecules before the body can use them. In contrast, mineralsand water can be absorbed directly into your bloodstream.They don’t require digestion or need to be broken down.

CarbohydratesStudy the panels on several boxes of cereal. You’ll notice

that the number of grams of carbohydrates found in a typi-cal serving is usually higher than the amounts of the othernutrients. That means that the major nutrient in the cereal isin the form of carbohydrates. Carbohydrates (kar boh HIdrayts) are the main sources of energy for your body. Theycontain carbon, hydrogen, and oxygen atoms. During cellu-lar respiration, energy is released when molecules of carbo-hydrates break down in your cells.

Types of CarbohydratesThe three types of carbohydrates—sugar, starch, and

cellulose—are shown in Figure 17-2. Sugars are simplecarbohydrates. There are many types of sugars. You’re prob-ably most familiar with one called table sugar. Fruits, honey,and milk also are sources of sugar. Your cells use sugar in theform of glucose. Starch and cellulose are complex carbohy-drates. Starch is in foods such as potatoes and those madefrom grains such as pasta. Cellulose occurs in plant cellwalls.

17 1 NUTRITION 465

CHEMISTRY INTEGRATION

17-1 NUTRITION 465

2 TeachDiscussion

Are you what you eat? Havestudents consider this questionbefore studying this section.Reconsider the question aftercompleting this section.

Caption AnswerFigure 17-1A calcium and phosphorus

L2

When cells need energy, they oxidize fuels such as carbohy-drates and fats. This process results in the formation of carbondioxide and water, the sameproducts that are formed when a fuel such as gasoline is burnedin an engine. Energy is releasedin this reaction.

VideodiscGlencoe Science VoyagesInteractive Videodisc—PhysicalSide 2, Lesson 5 Carbohydratesand Hydrocarbons

!75O%.á}"1844Refer to Videodisc TeacherGuide for additional bar codes.

Quick DemoBurn a Brazil nut, pecan, or whole peanut

to illustrate the energy liberated due to itsfat content. Insert the sharp end of a needleinto the nut. Push the eye end of a needleinto a cork. Stand the entire apparatus in ametal pan. Ignite the nut and observe thelength of time it takes to burn. Compare thefood energy of several different kinds ofnuts. Follow safety precautions for sharpobjects, flame, eye safety, and clothing protection.

History The extraction of sugar fromsugar cane is an ancient practice. Sugar canegrass was first discovered in the South Pacificor India. It most likely spread to Europe viathe Chinese and Arabs. Early explorersbrought sugar cane to the New World. Find-ing that beets were a source of sugar wasfirst discovered by Andreas S. Marggraf inBerlin in the mid-eighteenth century.

Across the CurriculumAcross the Curriculum

NutritionWhy do you eat?

What to have for breakfast? You may base your decisionon taste and amount of time available. A better factor mightbe the nutritional value of the food you choose. A chocolate-iced donut might be tasty and quick to eat, but it providesfew of the nutrients your body needs to carry out your morning activities. Nutrients (NEW tree unts) are sub-stances in foods that provide energy and materials for celldevelopment, growth, and repair, as shown in Figure 17-1.

17 1

The six classes of nutrientsThe importance of each typeof nutrientThe relationship between dietand health

Vocabularynutrient fatcarbohydrate vitaminprotein mineralamino acid food group

Learning about nutrients willhelp you plan well-balancedmeals and ensure goodhealth.

Why What You'll Learn

It's Important

You'll Learn

It's Important It's Important


It's Important

You'll Learn

It's Important

You'll Learn


Figure 17-1 Just as a racecar runs best with high-grade fuel,your body can best grow, maintain,and heal when you provide it withproper nutrients.

A To repair an injury, your body requires certainnutrients. What nutrients do you think areneeded to repair a broken bone?

B Your body gets the nutri-ents it needs to grow fromthe food you eat.


Prepare

PreplanningRefer to the Chapter Orga-nizer on pp. 462A–B.

1 Motivate

Tying to PreviousKnowledge

Have students discuss whatis meant by a balanced diet.

SECTION 17•1

Bellringer

Before presenting the lesson,display Section Focus Transparency 48 on the

overhead projector. Use the accompanying Focus Activityworksheet. ELLL2

Copyright©Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

48

48

IDENTIFYING THE NUTRIENTS IN FOODS

You eat foods for two reasons. First, the energy you need to carry out your

life functions and other activities is provided by the foods you eat. Second,

the foods you eat supply your body with nutrients. Nutrients are substances

in foods that provide your body with the materials it needs for growth,

maintenance, and repair. Descriptions of some of the nutrients your body

needs appear in the table shown.

1. What kinds of foods do you think are rich in sugars? In starches?

2. What kinds of foods do you think are rich in proteins? Give three examples.

3. Of the following, which foods do you think are rich in fats—butter,

apples, beef, asparagus, lard? Explain.

SECTION FOCUS TRANSPARENCY

Section 17-1

Nutrient

Type

Characteristics of NutrientSource

(Plants or Animals)

Proteins Used by the body for growth; are made

of large molecules containing carbon,

hydrogen, oxygen, and nitrogen

Animals and Plants

Sugars Taste sweet; provide the body with

energy

Plants

Starches Often have a pasty or mushy texture;

provide the body with energy

Plants

Cellulose Cannot be digested by the body;

have fibrous texture

Plants

Fats Have a greasy or oily feel; observed in

some foods after cooking as a layer of

oil; provide the body with energy

Plants and Animals

Refer to Nutri-tion, Vitamins, and Miner-als on pp. 462E–F.

ontent Background

ontent Background

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The following Teacher Classroom Resources can be used with Section 17-1:

Reproducible Masters

Activity Worksheets, pp. 91–92, 95

Critical Thinking/Problem Solving, p. 17

Enrichment, p. 48

Laboratory Manual, pp. 95–98

Multicultural Connections, pp. 33–34

Reinforcement, p. 48

Study Guide, pp. 65-66 ELLL1

L2

L2

L2

L3

L2

L2

Resource Manager

Twelve of these amino acids can bemade in your cells. The eightremaining amino acids are calledessential amino acids. Your body doesn’t have geneticinstructions to construct these. They must be suppliedthrough the food you eat. Eggs, milk, and cheese contain allthe essential amino acids. Beef, pork, fish, and chicken sup-ply most of them. You might be surprised to know thatwhole grains such as wheat, rice, and soybeans supply manyneeded amino acids in addition to supplying carbo-hydrates. In order to get their full complement ofamino acids, vegetarians need to eat a wide varietyof vegetables that are good sources of protein.

Analyzing a Menu

Blanca is a long-distance runner. She plans to run inthe Boston Marathon on Patriot’s Day. This world-famous race is more than 42 km long. Like most run-ners, Blanca is conscious about eating food that willprovide the nutrients needed for endurance. The nightbefore the marathon, Blanca must choose what to eatfor dinner. She wants a meal with lots of carbohy-drates.

Study the menu. Then, select a suitable dinner forBlanca. Keep in mind that Blanca will run in amarathon the next morning and needs foods rich incarbohydrates.

Think Critically1. List all the foods on this menu that contain

carbohydrates.

2. Why does Blanca want to eat carbohydrates beforethe marathon?

3. What foods on this menu are rich in complex car-bohydrates?

17-1 NUTRITION 467

APPETIZER

ENTREE

VEGETABLES

DESSERT

DRINKS

Potato Skins...............................................$4Caesar Salad...............................................$3Sizzling Rice Soup.....................................$2Vegetable Salad..........................................$3

Baked Chicken............................................$6Shrimp with Lobster Sauce........................$8Grilled Pork Chop.......................................$7Grilled Steak..............................................$9

Mashed Potatoes........................................$2Baked Potato.............................................$2Boiled Rice.................................................$2Green Beans...............................................$2

Fresh Fruit.................................................$3Ice Cream....................................................$2Chocolate Cake...........................................$3

Milk............................................................$1Water..........................................................$1Orange Juice................................................$1

Figure 17-3 Meats, poultry,eggs, fish, peas, beans, and nutsare all rich in protein. Which ofthese protein-rich foods do youthink a vegetarian would choose?

Caption AnswerFigure 17-3 peas, beans, nuts

DiscussionInterpersonal Have stu-dents discuss whether

milk is the perfect food. Milkdoes supply many of the nutri-ents, but it is not a perfect foodand does lack certain essentialvitamins and minerals. L2

Carbohydrates are the mainsource of energy for the body.Meals consumed before anyactivity such as running, shouldhave less fats and proteins.

Think Critically 1. potato skins, sizzling rice

soup, vegetable salad,mashed potatoes, bakedpotato, boiled rice, greenbeans, fresh fruit, orangejuice

2. Blanca wants to load herliver and muscles withglycogen to use as energyduring the race. Even withcarbohydrate loading, shewill probably deplete hercarbohydrate supply afterrunning about 30 to 33km, at which time herbody will begin to usestored fat.

3. potato skins, sizzling ricesoup, vegetable salad,mashed potatoes, bakedpotato, boiled rice, greenbeans, fresh fruit P

Mathematics Calculate the percentageof fat in foods by noting the grams of fat,then multiply this number by 9, the number ofCalories used when 1 g of fat is oxidized. Di-vide this number by the total number of Calo-ries in the food item. The calculation will givethe percent of Calories from fat. Recommen-dations are that no more than 30 percent ofyour Calorie intake come from fat. L2


17-1 NUTRITION 467


ProteinsYour body uses proteins for growth. As enzymes, they affect

the rate of chemical reactions in your body. They also areinvolved in the replacement and repair of body cells. Proteinsare large molecules that contain carbon, hydrogen, oxygen,and nitrogen. A molecule of protein is made up of a large num-ber of subunits, or building blocks, called amino acids. Somesources of proteins are shown in Figure 17-3.

Essential Amino AcidsProteins are made according to directions supplied by

genes that you inherit. Your body needs 20 different aminoacids to be able to construct the proteins needed in your cells.

Figure 17-2 Carbohydrates arefound in three forms: sugar, starch, andcellulose. While all three are made of car-bon, hydrogen, and oxygen, their mol-ecules have different kinds of chemicalbonds and structures.

Glucose Molecule

CarbonOxygen

Hydrogen

CH2OH

HH H

OHHO

H OH

OH H

OC

C C

CH2OH

HH H

H OH

OOH

CH2OH

HH H

H OH

OH HO

CH2OH

HH H

H OH

OHO

CH2OH

HH H

H OH

OH

Starch Molecule

O OOO

CH2OH

OH

H H H

H

H OH

OH

CH2OH

HH

H OH

OH HO

CH2OH

OH H

H OH

HO

CH2OH

HH

HH OH

OH

Cellulose Molecule

O O O O

B Starch is stored in plant cells. During thedigestive process, your body breaks downthe complex starch molecules into the sim-ple sugar glucose.

C Cellulose is a complex carbo-hydrate that is a major part ofthe strong cell walls in aplant. While your body can-not break down cellulose, itsfiber is important in maintain-ing a smooth-running diges-tive system. Sources ofcellulose include fresh fruits,vegetables, and grains.

Carbohydrates

ISUALIZINGV

ISUALIZING

G

V ISUALIZINGV

A A simple sugar called glucose is thebasic fuel that provides the energy tocarry out life’s processes.


Teacher FYIApproximately 100 g of

body proteins are brokendown into amino acids eachday and resynthesized intonew protein molecules.

ActivityLinguistic Have stu-dents read the labels of

canned and packaged foods.Discuss the major sources ofvarious nutrients in the foodsthey eat each day. L2

Figure 17-2 Samples ofthe three types of carbohy-drates—simple sugars,starch, and cellulose—aregiven along with their basicmolecular structures. Havestudents note the ratio oftwo hydrogen atoms andone oxygen atom for everycarbon atom. L2

LearningVISUAL

Health Have the school lunchroom man-ager or a hospital dietitian discuss with stu-dents how a balanced diet can be achievedwith a variety of foods. L2


VideodiscGlencoe Science VoyagesInteractive Videodisc—PhysicalSide 2, Lesson 5 Carbohydratesand Hydrocarbons

!7/>$KT~"1227Refer to Videodisc TeacherGuide for additional bar codes.

17-1 NUTRITION 469

VitaminsThose essential, organic nutrients needed in small quanti-

ties to help your body use other nutrients are called vitamins.For instance, bone cells need vitamin D to use calcium. In gen-eral, vitamins promote growth and regulate body functions.

Most foods, like those in Figure 17-5, supply some vita-mins, but no one food has them all. Although some people feelthat taking extra vitamins is helpful, eating a well-balanceddiet is usually good enough to give your body all the vitaminsit needs.

Vitamins are placed into the two groups. Somevitamins dissolve easily in water and arecalled water-soluble vitamins. Others dissolve only in fat and are called fat-soluble vitamins. While you get mostvitamins from outside sources, yourbody makes vitamin D when yourskin is exposed to sunlight. Somevitamin K is made with the help ofbacteria that live in your large intes-tine. Table 17-1 lists some major vita-mins, their effects on your health, andsome of the foods that provide them.

Vitamin Body Function Food Sources

Water Soluble

B growth, healthy nervous meat, eggs, milk, (thiamine, riboflavin, system, use of carbohydrates, cereal grains, niacin, B6, B12) red blood cell production green vegetables

C growth, healthy bones citrus fruits, and teeth, wound recovery tomatoes, green

leafy vegetables

Fat Soluble

A growth, good eyesight, green/yellow vege-healthy skin tables, liver and fish,

liver oils, milk, yellow fruit

D absorption of calcium and milk, eggs, fishphosphorus by bones and teeth

E formation of cell vegetable oils, membranes eggs, grains

K blood clotting, green leafy vegetables, wound recovery egg yolks, tomatoes

Vitamins

Table 17-1

Figure 17-5 Fruits and vegeta-bles are especially good sources ofvitamins. However, to get all of thevitamins that your body needs, youmust eat a balanced diet thatincludes a variety of foods.

17-1 NUTRITION 469

Using Science WordsLinguistic The Latinword for life is vita.

Have students relate themeaning of this word to thedefinition and the function ofvitamins.

DiscussionLinguistic Explain whysalt is iodized. Have stu-

dents read a salt label to findout how the iodine is sup-plied. L2

L2

Vitamins and Health Have students writea paragraph about why it might be a dis-advantage to substitute vitamin pills for aproper diet. Their entries should indicate

an understanding that other nutrients be-side vitamins are needed for maintaininghealth. A well-balanced diet supplies therange of needed vitamins. PL2

CD-ROMGlencoe Science VoyagesInteractive CD-ROMExplorationsHave students do the interactiveexploration How can a healthfuldiet be designed?

Megadoses offat-soluble vitamins over aprolonged period of timemay be toxic to your body.Even water-soluble vita-mins may be toxic in verylarge doses. Excessive in-take of vitamin K cancause anemia, jaundice,and gastrointestinal prob-lems while megadoses ofvitamin D can result inweight loss, calcification ofsoft tissues, and kidneyfailure.

ontent Background

ontent Background

CC

FatsYou may not think of fat as being a necessary part of your

diet. In today’s health-conscious society, the term fat has anegative meaning. However, fats are necessary because theyprovide energy and help your body absorb some vitamins.Fats are stored in your body in the form of fat tissue asshown in Figure 17-4. This tissue cushions your internalorgans. You learned that carbohydrates are the main sourceof energy for your body. This is because people eat a largeamount of carbohydrates. However, a gram of fat can releasetwice as much energy as a gram of carbohydrate. During thisprocess, fat breaks down into smaller molecules called fattyacids and glycerol. Because fat is such a good storage unitfor energy, any excess energy we eat is converted to fat untilthe body needs it.

Types of FatFats are classified as unsaturated and saturated. Un-

saturated fats, which come from plants, are usually liquid atroom temperature. Corn, sunflower, and soybeanoils are all unsaturated fats. Some unsaturatedfats also are found in poultry, fish, and nuts. Sat-urated fats are found in red meats and are usu-

ally solid at room temperature. Saturated fatshave been associated with high

levels of blood cholesterol. Cho-lesterol occurs normally in all yourcell membranes. However, too muchof it in your diet causes excess fatdeposits to form on the inside wallsof blood vessels. The deposits cut offthe blood supply to organs andincrease blood pressure. Heart dis-ease and strokes may result if bloodis cut off to the heart and brain.

✔

✔Reading Check

Why are fats a neces-

sary part of your diet?

Figure 17-4 Fat isstored in certain cells inyour body.

B The first source of energy for yourbody comes from the sugars in carbo-hydrates. When the supply of sugarsruns low, your body begins to use thereservoir of energy stored in body fat.


A The cytoplasm andnucleus are pushed tothe edge of the cell bythe fat deposits.

Nucleus

Magnification: 400�

Cytoplasm


Correcting Misconceptions

Students may have the mis-taken notion that if vitaminsare good for you, more is bet-ter. Some vitamins should notbe taken in high doses. An ex-cess of vitamin A can causeliver, skin, and muscle prob-lems. Too much vitamin Dcan cause an imbalance ofblood calcium, resulting in digestive and nervous systemdisorders.

Answer to

Reading Check ✔

Fats are necessary because

they provide energy and help

absorb some vitamins.

Gifted Have students research a particularvitamin deficiency. They should include infor-mation about how the vitamin was discovered.L3

Inclusion StrategiesInclusion Strategies

VideodiscThe Infinite Voyage: ATaste of HealthChapter 2 Pima Indians: Copingwith Disease 7:00Refer to the Teacher Guide forbar codes and teaching strategies.

EnrichmentKinesthetic Have stu-dents test for fats in

foods by rubbing variousfoods on a piece of brownkraft paper (grocery bags). Atranslucent spot on the paperindicates the presence of a fator oil. Moist foods produceonly a wet spot that disap-pears after evaporation. L1

a variety of body functions. One of these functions is the for-mation and maintenance of bone, as shown in Figure 17-6.Some minerals, called trace minerals, are required in onlysmall amounts. Copper and iodine are usually listed as traceminerals.

WaterYou don’t have to be lost in a desert to know how impor-

tant water is for your body. Next to oxygen, water is the mostvital factor for survival. You could live a few weeks withoutfood, but only a few days without water. Most of the nutri-ents you have studied in this chapter can’t be used by yourbody unless they are carried in a solution. This means thatthey have to be dissolved in water. Water enables chemicalreactions to take place in cells.

Water in Your BodyAs shown in Figure 17-7, different organisms require

different amounts of water to survive. The human body is about 60 percent water by weight. This water is foundin and around cells and in plasma and lymph. Waterremoves waste products from cells. Wastes dissolved inwater leave your body as urine or perspiration. To balancewater lost each day, you need to drink about 2 L of liq-uids. But, don’t think that you have to drink just water to

Figure 17-7 Humans have to consume waterevery couple of days, while animals like the camelhave adaptations that allow them to conserve theirwater intake for weeks.

Visit the Glencoe ScienceWeb Site at www.glencoe.com/sec/science/ca formore information aboutwater in the human body.

17-1 NUTRITION 471

17-1 NUTRITION 471

DiscussionDiscuss water in vegetables

such as turnips and squashes.Many students have the im-pression that drinking wateris the only source of water.Point out that water is neces-sary for chemical reactions inthe body and that water is aby-product of the breakdownof molecules in the process ofrespiration. Have studentscomment on the statementthat where there is water,there is life.

3 AssessCheck for UnderstandingActivity

Have students review thevitamins Table 17-1 to obtaina general concept of sourcesof each type of vitamin. Thenhave students infer the vita-mins contained in some simi-lar but unlisted fruits andvegetables.

ReteachVisual-Spatial Havestudents make flash

cards with names of fruits orvegetables. On the reverseside, identify the major vita-min content of each food. Stu-dents can test each otherusing the flash cards.

ExtensionFor students who have

mastered this section, use theReinforcement and Enrich-ment masters. L1

L1

L2

For Internet tips, see Glencoe’s Using the Internet in the Science Classroom.

Internet Addresses

Page 471: 7b

CA Science ContentStandards


MineralsInorganic nutrients that regulate many chemical reactions

in your body are minerals. They are chemical elements suchas phosphorus. About 14 minerals are used by your body to build cells, take part in chemical reactions in cells, sendnerve impulses throughout your body, and carry oxygen to body cells. Minerals used in the largest amounts in your body are presented in Table 17-2. Of the 14 minerals,calcium and phosphorus are used in the largest amounts for

Mineral Health Effect Food Sources

Calcium strong bones and teeth, milk, eggs, green blood clotting, muscle and leafy vegetablesnerve activity

Phosphorus strong bones and teeth, cheese, meat, cerealmuscle contraction, stores energy

Potassium balance of water in cells, bananas, potatoes, nerve impulse conduction nuts, meat

Sodium fluid balance in tissues, meat, milk, cheese,nerve impulse conduction salt, beets, carrots

Iron oxygen is transported in raisins, beans, spinach, hemoglobin by red blood eggscells

Iodine (trace) thyroid activity, seafood, iodized saltmetabolic stimulation

Minerals

Table 17-2

Figure 17-6 Calcium andphosphorus are used in the forma-tion and maintenance of yourbones. In this x-ray, you can seethat the lack of these minerals hascaused the bones in this woman’sspine to become less dense and,as a result, to bend.


History Have students do research onhow the need for certain minerals in the dietwas recognized after the causes of deficiencydiseases in livestock were discovered. L2


EnrichmentHave students keep track of

all the foods and liquids theyconsume in one day. Estimatehow much water was taken inand compare with the 2 L orso of water lost daily. ELLL2

In addition tothe minerals listed in Table17-2, other minerals foundin significant amounts inthe body tissue(macrominerals) includechloride, magnesium, andsulfur. Chloride is found inall foods and table salt;magnesium is found ingreen vegetables, milk,meats and nuts; and sulfuris found in all protein-con-taining foods.

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Using an AnalogyPerspiration of water from

the body is like the transpira-tion of water from plants. Inanimals and plants, excessiveloss of water can have pro-found effects on the health ofthe organism.

Mineral Intake Have students keeptrack of everything they eat for one day.Have students use the data to analyzetheir mineral intake.


Food GroupsBecause no one food has every nutrient, you need to eat a

variety of foods. Nutritionists have developed a simple sys-tem to help people plan meals that include all the nutrientsrequired for good health.

Foods that contain the same nutrients belong to a foodgroup. The food pyramid in Figure 17-9 pre-sents the basic food groups and serving sug-gestions. Eating a certain amount fromeach food group each day will supplyyour body with the nutrients it needsfor energy and growth. Of course,most people eat foods in com-bined forms. Combinations offood contain ingredients frommore than one food groupand supply the samenutrients as the foodsthey contain. Chiliand macaroni andcheese are bothfood groupc o m b i n a -tions.

Fats, Oils, &Sweets, Use sparingly

Milk, Yogurt, &Cheese Group,2-3 servings

Vegetable Group, 3-5 servings

Meat, Poultry,Fish, DryBeans, Eggs, & Nuts Group,2-3 servings

Fruit Group,2-4 servings

Bread, Cereal,Rice, & PastaGroup, 6-11servings

1. List six classes of nutrients and give one example of a food source for each.

2. Describe a major function of each class of nutrient.

3. Discuss the relationship between your diet andyour health.

4. Explain the importance of water in the body.5. Think Critically: What foods from each food

group would provide a balanced breakfast?Explain why.

6. Skill BuilderInterpreting Data Nutritional infor-

mation can be found on the labels of most foods.Do the Chapter 17 Skill Activity on page 722 tointerpret the information found on different food-product labels.

Section AssessmentSection Assessment

Spreadsheet Use the format of Table 17-2 andprepare a spreadsheet for a data table of the miner-als. Use reference books to gather informationabout the following miner-als and add them to thetable: sulfur, magnesium,copper, manganese, cobalt,and zinc. If you need help,refer to page 702.

Figure 17-9 The pyramidshape reminds you that you shouldconsume more servings from thebread and cereal group than fromthe meat and milk group. Whereshould the least number of serv-ings come from?

17-1 NUTRITION 473

17-1 NUTRITION 473

Caption AnswerFigure 17-9 fats, oils, andsweets

4 CloseProficiency PrepUse this quiz to check stu-dents’ recall of section content.

1. What provides energyand materials for devel-opment, growth, and re-pair? nutrients

2. What are three types ofcarbohydrates? starch,sugar, cellulose

AssessmentPerformance Assess students’ abilities tomake and use tables by having them useTable 17-3 to find out how much water ( inliters) is lost through skin. Use PerformanceAssessment in the Science Classroom,p. 37. Page 472: 7a, 7c, 7e

Page 473: 7b


1. carbohydrates: bread;proteins: fish; fats: butter;vitamins: fruit; minerals:vegetables; water: juice

2. carbohydrates: source ofenergy; proteins: growthof cells; fats: source of en-ergy; vitamins: growth;minerals: nerve activity;water: enables chemicalreactions to occur

3. A nutritionally balanceddiet provides the sub-stances needed forgrowth and good health.

4. dissolves and carries nutri-ents in the body, removeswastes, enables chemicalreactions to occur

5. Think Critically Studentsshould be able to supporttheir answers with infor-mation in Figure 17-9.


Have students compare their spreadsheets.


keep your cells supplied. Most foods havemore water in them than you realize. Anapple is about 80 percent water, and manymeats are as much as 90 percent water.

Your body also loses about 2 L of waterevery day through excretion, perspiration,and respiration. Table 17-3 shows howwater is lost from the body. The body is equipped to maintain its fluid content,however. When your body needs water, itsends messages to your brain, and you feelthirsty. Drinking a glass of water usuallyrestores the body’s homeostasis (hoh meeoh STAY sus). Homeostasis is the regula-tion and maintenance of an organism’sinternal environment. Once homeostasis isrestored, the signal to the brain stops.

Through Amount (mL/day)

Exhaled air 350

Feces 150

Skin (mostly as sweat) 500

Urine 1800

Water Loss

Table 17-3

Measuring the Water Content of Food

Procedure

1. Use a pan balance to find the mass of an empty250-mL beaker.

2. Fill the beaker with sliced celery and find themass of the filled beaker.

3. Estimate the amount of water you think is in the celery.

4. Put the celery on a flat tray. Leave the celery outto dry for one to two days.

5. Determine the mass of the celery.

Analysis

1. How much water was in the fresh celery?2. Infer how much water might be in other fresh

fruits and vegetables.

Figure 17-8 About two-thirdsof your body water is locatedwithin your body cells. Water helpsmaintain the cells’ shapes andsizes. During exercise, the waterthat is lost through perspiration andrespiration must be replaced.

Waterinside of

body cells

Water outside ofbody cells

Purpose

Logical-MathematicalStudents will calculate the

water content of fresh celery.

Materialspan balance, cut-up celery, 250-mL beaker

Teaching StrategiesTroubleshooting Dry thefresh celery with a paper towelbefore determining the mass.

Analysis1. The water content will vary

with the freshness of the cel-ery used, but students shouldfind that vegetables aremostly water. Celery may beabout 90 percent water.

2. Students’ answers will vary,but most will predict that leafyvegetables have more waterthan hard vegetables such ascauliflower or broccoli.

Performance Have studentsuse their lab skills to determine thewater content of fruits. Use Per-formance Assessment in theScience Classroom, p. 25.

Assessment


Display a 2-L soda bottle full of waterto emphasize the amount of water aperson needs to drink each day.

Multiple Learning StylesMath Students may use either a circle orbar graph to show the percent of water lostby various means, as shown in Table 17-3.L2


Making a ModelMake a three-dimensional

display of the food pyramidusing models and packagesof representative food items.

COOP LEARNELLL2

Science Society&

AntioxidantsIn the 1990s, food scientists learned that certain nutrients helplower the risk of getting various diseases. Animal studiesshow that some cancers may be prevented—possibly cured—by chemicals in certain nutrients. Many of these cancer-combating chemicals are being tested to find out how theyenhance cellular defenses against disease.

Fighting Cancer Scientists are closely studying onegroup of chemicals called anti-oxidants. Antioxidants are subatancesthat prevent other chemicals fromreacting with oxygen. Chemicals thatenter the body from smoking or frompollutants in the air may cause can-cer when combined with oxygen. By preventing this reaction, antioxidantshelp fight cancer. Antioxidants also can prevent cancer cells fromrepairing their damaged DNA.Carotenoids—the yellow-orange pig-ments in carrots (far left), squashes,

and other produce—are antioxidants. Vitamin C (seecrystals in inset) is also an antioxidant, as is vitamin D.Two unusually good sources of antioxidants are tomatosauce and green tea.

Taking antioxidants along with anticancer drugs usedto fight cancer seems to make these drugs more effective.Some doctors are prescribing antioxidants for theirpatients, either to try to prevent cancer or to help fight anexisting cancer condition. However, researchers have cau-tioned that the use of antioxidants may not successfullyeliminate all the cancer cells in a person’s body. Further-more, some antioxidants can have harmful side effects, maydisrupt certain bodily functions, and may interfere with theeffectiveness of radiation treatments. But, if laboratory testsshow conclusively that antioxidants are successful fighters ofsome diseases, you may one day hear, “Eat your antioxidants.

They’re good for you!”

Science Society&

CONNECTION

NETinter

17-1 NUTRITION 475

Visit the Glencoe Science WebSite at www.glencoe.com/sec/science/ca for more infor-mation about antioxidants.Look for the most recentinformation on how antioxi-dants are used to preventdisease.

17-1 NUTRITION 475

For More Information:Cancer Information ClearinghouseNational Cancer Institute9000 Rockville PikeBuilding 31, Room 10A18Bethesda, MD 20205

Oxidation is the reaction of asubstance with oxygen. Some-times this takes place rapidly,and heat and light are pro-duced. An example is theburning of a fuel. In othercases, the process is slow andthe heat is not noticeable. Ex-amples are the rusting of ironand the oxidation of food dur-ing the metabolic processes.

Teaching Strategies• Place an equal number of

apple slices into each of twobowls. Rinse the apples inone bowl with lemon juiceand the apples in the otherbowl with water. After 30minutes, note that theascorbic acid in the lemonjuice is an antioxidant. Itprevents oxygen from re-acting with the apple slicesand keeps them from turn-ing brown.

• Point out that painting ironprevents it from reactingwith oxygen (rusting). Thisis analogous to antioxi-dants’ preventing chemi-cals in the body from react-ing with oxygen.

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Internet Addresses

Page 474: 7a, 7c, 7ePage 475: 5b


Activity

17•1


Procedure 1. Make a data table like the example shown to

record your observations.2. Label the test tubes 1 through 10.3. Predict which juices contain vitamin C.

Record your predictions in your table.4. Measure 5 mL of indophenol into each of the

ten test tubes. CAUTION: Wear your gogglesand apron. Do not taste any of the juices.Indophenol is a blue liquid that turns colorlesswhen vitamin C is present. The more vitamin Cin a juice, the less juice it takes to turn indo-phenol colorless.

5. Add 20 drops of water to test tube 1. Recordyour observations.

6. Begin adding orange juice, one drop at a time,to test tube 2.

7. Record the number of drops needed to turnindophenol colorless.

8. Repeat steps 6 and 7 to test the other juices.

Conclude and Apply1. What is the purpose of testing water for the

presence of vitamin C?2. Does the amount of vitamin C vary in fruit

juices?3. Which juice did not contain vitamin C?

Identifying Vitamin C ContentVitamin C is found in a variety of fruits and vegetables. In

some plants, the concentration is high; in others, it is low.Try this activity to test various juices and find out which containsthe most vitamin C.

What You’ll InvestigateWhich juices contain vitamin C?

Goals• Observe differences in the vitamin C content of juices.

Test Prediction NumberTube Juice (yes or no) of drops

1 water no 52 orange yes 33 pineapple no 44 apple no 45 lemon yes 36 tomato yes 47 cranberry no 58 carrot no 59 lime yes 3

10 vegetable yes 4

Test Results for Vitamin C

Activity 17 1

Materials• Indophenol solution• Graduated cylinder

(10 mL)

*graduated container• Glass-marking pencil

*tape• Test tubes (10)

*paper cups• Test-tube rack• Dropper• Dropping bottles (10)• Test substances: water,

orange juice, pineapplejuice, apple juice, lemonjuice, tomato juice, cranberry juice, carrotjuice, lime juice, mixedvegetable juice

*Alternate Materials

Using Scientific MethodsUsing Scientific Methods


Purpose

Visual-Spatial Studentswill identify and compare

juices that contain vitamin C.

Process SkillsObserving, classifying, measuring,predicting, interpreting data, ex-perimenting, communicating,comparing and contrasting

Time50 minutes

Teaching StrategiesThis test for vitamin C requires

students to titrate by carefullyadding a reactant to the orangejuice. The indophenol solution maybe purchased from chemical sup-ply houses. To make a dilute solution of hydrochloric acid, add10 mL of HCl to 990 mL of water.Troubleshooting CAUTION:Students are not to mix up thedroppers from the test-solution bottles. Use caution when workingwith acid. Always add the acid tothe water. Use care when handlingsharp objects.

Answers to Questions1. It was the control.2. Yes, the amount of vitamin C is

influenced by whether vitaminC has been added; whetherwater has been added; orwhether the juice is fresh,frozen, or canned.

3. Apple, cranberry, carrot, andvegetable; answers may vary ifjuices fortified with vitamins areused.

COOP LEARNELL

L2

Performance To further assess students’abilities to identify vitamin C content, have themtest for vitamin C in water that stood overnightwith either shredded lettuce or shredded cab-bage cores. Use Performance Assessmentin the Science Classroom, p. 25.

Assessment


blood, food molecules are transported across the cell mem-brane to be used by the cell. Molecules that aren’t absorbedare eliminated and pass out of your body as wastes.

The major organs of your digestive tract—mouth, esoph-agus (ih SAH fuh guhs), stomach, small intestine, large intes-tine, rectum, and anus—are shown in Figure 17-10. Foodpasses through all of these organs. However, food doesn’tpass through your liver, pancreas, or gallbladder. These threeorgans produce or store enzymes and chemicals that helpbreak down food as it passes through the digestive tract.

EnzymesChemical digestion is possible only because of the actions

of certain kinds of proteins. These proteins are calledenzymes. Enzymes (EN zimez) are molecules that speed upthe rate of chemical reactions in all living organisms. You cansee in Figure 17-11 that they speed up reactions withoutthemselves being changed or used up. One way enzymesspeed up reactions is by reducing the amount of energy nec-essary for a chemical reaction to begin.

Enzymes in DigestionA variety of enzymes are involved with the digestion of

carbohydrates, proteins, and fats. Amylase (AM uh lays) is anenzyme produced by the salivary glands in the mouth. Thisenzyme begins the process of breaking down the complexcarbohydrate into simpler sugars. In the stomach, the enzymepepsin causes complex proteins to break down into less com-plex proteins. In the small intestine, a number of otherenzymes continue the process by breaking down the proteinsinto amino acids. The pancreas, an organ on the back side of

✔

Enzyme

Molecule

Molecule

A

B

Temporarycomplex forms

MoleculeC

Enzyme isunchanged

CHEMISTRY INTEGRATION

✔Reading Check

Explain the role of

enzymes in chemical

digestion.

Figure 17-11 Enzymes speedup the rate of certain body re-actions. During these reactions, the enzymes are not used up orchanged in any way. What happensto the enzyme after it is released?

A The surface shape of anenzyme fits the shape ofspecific molecules that needto be broken down.

B The enzyme and the mol-ecules join and the reactionoccurs.

C Following the reaction,the enzyme and the moleculeseparate. The enzyme is notchanged by the reaction. Theresulting new molecule has anew chemical structure.

17-2 YOUR DIGESTIVE SYSTEM 477


2 Teach

Tying to PreviousKnowledge

Recall that one feature ofliving things is that they useenergy. Discuss with stu-dents that food is the sourceof energy for cell activities,but that it must be processedinto usable molecules. This isthe function of the digestivesystem.

Proteins in the cell membranetransport nutrients. Other proteinscarry sodium ions out of cellsand potassium ions into cells.

Use the Flex Your Brain activity to have students explore DIGESTION.

Flex Your BrainFlex Your Brain

Quick DemoSubstances called meat ten-

derizers contain enzymes.Often used is papain, an en-zyme from papaya juice.Sprinkle some meat tender-izer on a small cube of beef.On another cube of beef,sprinkle some sugar. Heatboth pieces in an oven at250°F until brown. Whencooled, examine both piecesand compare for tenderness.

Caption AnswerFigure 17-11 It is free to joinwith another molecule in anotherreaction.

Nearly every chemical reactionwithin the body involves organic catalysts—enzymes. There is an intricate relationship among enzymes, vitamins andminerals. In many cases, enzymes cannotfunction without another substance.

Certain energy-releasing reactions can only occur when the appropiate enzyme has the vitamin thiamin present. Rennin cannot react with milk protein unless calcium is present.

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Your Digestive System

Processing FoodLike other animals, you are a consumer. The energy you

need for life comes from food sources outside yourself. Tokeep the cells in your body alive, you take in food every day.Food is processed in your body in four phases: ingestion,digestion, absorption, and elimination. Whether it is a fast-food burger or a home-cooked meal, all the food you eat istreated to the same processes in your body. As soon as itenters your mouth, or is ingested, food begins to be brokendown. Digestion is the process that breaks down food intosmall molecules so they can move into the blood. From the

How to distinguish betweenmechanical and chemicaldigestionThe organs of the digestivesystem and what takes placein eachHow homeostasis is main-tained in digestion

Vocabularydigestionenzymemechanical digestionchemical digestionsalivaperistalsischymevilli

Through the processes of thedigestive system, the food youeat is made available to yourcells.


It's Important

You'll Learn

It's Important It's Important


It's Important

You'll Learn

It's Important

You'll Learn

Salivaryglands

Mouth

Tongue

Epiglottis

Esophagus

Liver

Stomach

Ileum

Colon

Gallbladder

Pancreas

Large intestine

Smallintestine

Rectum

Duodenum

Appendix

Anus


Figure 17-10 The humandigestive system can be describedas a tube divided into severalspecialized sections. If stretchedout, an adult’s digestive system is 6 m to 9 m long. Where in thedigestive tract does digestionbegin?

17 2


Prepare

PreplanningRefer to the Chapter Orga-nizer on pp. 462A–B.

1 Motivate

Caption AnswerFigure 17-10 mouth

SECTION 17•2

Bellringer

Before presenting the lesson,display Section Focus Transparency 49 on the

overhead projector. Use the accompanying Focus Activityworksheet. ELLL2

Copyright©Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

49

49

MEETING YOUR ENERGY NEEDS

Think of all the ways you use energy each day. You use the energy provid-

ed by your body to think, walk, play sports, and even to sleep. You also use

energy generated from Earth’s energy resources when you ride a bus, play a

radio, watch television, or cook your dinner.

1. What are some of the ways you use energy (electricity) in your everyday

life? Where does this energy come from?

2. Why does your body need energy? Where does it get the energy it needs?

3. How is the way in which your body gets energy similar to the way in

which energy is provided to a community by a power plant?

SECTION FOCUS TRANSPARENCY

Section 17-2

Refer to Diges-tion, Absorption, andOther Organs on p. 462F.

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The following Teacher Classroom Resources can be used with Section 17-2:

Reproducible MastersActivity Worksheets, pp. 93–94, 96 Enrichment, p. 49 Laboratory Manual, pp. 99–102 Reinforcement, p. 49

Study Guide, pp. 67–68

TransparenciesTeaching Transparency 33 Teaching Transparency 34 Science Integration Transparency 17 L2

L2

L2

ELLL1

L2

L2

L3

L2

Resource Manager


In Your MouthMechanical digestion be-

gins in your mouth. There,your tongue and teeth breakfood up into small pieces.Humans are adapted withseveral kinds of teeth for cut-ting, grinding, tearing, andcrushing.

Some chemical digestionalso starts in your mouth. As you chew, your tonguemoves food around and mixesit with a watery substancecalled saliva. Saliva is pro-duced by three sets of glandsnear your mouth that areshown in Figure 17-12. Saliva(suh LI vuh) is made upmostly of water, but it alsocontains mucus and theenzyme salivary amylase. Youlearned that salivary amylasestarts the breakdown of starch to sugar. Food that is mixedwith saliva becomes a soft mass. The food mass is moved tothe back of your tongue where it is swallowed and passesinto your esophagus. Now the process of ingestion is com-plete, and the process of digestion has begun.

Passing Through the EsophagusYour esophagus is a muscular tube about 25 cm long.

Through it, food passes to your stomach in about 4 s to 10 s.No digestion takes place in the esophagus. Smooth musclesin the walls of the esophagus move food downward by asqueezing action. These waves, or contractions, called peristalsis (per uh STAHL sus), move food along throughoutthe digestive system. Figure 17-13 shows how peristalsisworks.

In Your StomachThe stomach, shown in Figure 17-13, is a muscular bag.

When empty, it is somewhat sausage shaped, with folds onthe inside. As food enters from the esophagus, the stomachexpands, and the folds smooth out. Both mechanical andchemical digestion take place in the stomach. Mechanically,food is mixed by the muscular walls of the stomach and byperistalsis. Food also is mixed with strong digestive juices,

Esophagus

Esophagus

Musclescontract

Musclesrelax

Loweresophagus

Food movesdown

Foodmass

Stomach

Figure 17-13 During peristal-sis, muscles behind the food con-tract and push the food forward.Muscles in front of the food relax.

INTEGRATIONPHYSICS

Surface AreaBesides mixing food andsaliva, chewing food breaks itup into smaller pieces. Thisgives the food a larger sur-face area, exposing it to moredigestive enzymes. Comparethe surface area of two toyblocks when they are sepa-rate and when they are puttogether.


Correcting Misconceptions

Logical-MathematicalHave students make in-

ferences about peristalsis ac-tion aboard a spacecraft. Be-cause peristalsis is an actioncontrolled by muscles, thezero gravity of space does notaffect the swallowing andmovement of food to thestomach. L2

VideodiscThe Infinite Voyage: ATaste of HealthChapter 4 Consequences of aFatty Diet 3:00Refer to the Teacher Guide forbar codes and teaching strategies.

Students should conclude fromtheir observations that two toyblocks will have a greater surfacearea when they are separatedthan when they are put together.

The digestive systems of variousanimals are reflective of their life styles anddiets. Grain-feeding birds have a specializedstomach chamber, the gizzard, that containssmall stones. These stones aid in grinding

the food—a process that is needed in the ab-sence of teeth. Mammals that subsist ongrasses have stomach storage pouches inwhich their food is ground more thoroughlyfor subsequent bacterial action.

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the stomach, secretes several enzymes through a tube into thesmall intestine. Some continue the process of starch break-down that started in the mouth. The resulting sugars areturned into glucose and used by the body’s cells. Otherenzymes are involved in the breakdown of fats.

Other Enzyme ActionsEnzyme reactions are not only involved in the digestive

process. Enzymes also are responsible for building yourbody. They are involved in the energy production activities ofmuscle and nerve cells. They also are involved in the blood-clotting process. Without enzymes, the chemical reactions ofyour body would not happen. You would not exist.

Where and How Digestion OccursDigestion is both mechanical and chemical. Mechanical

digestion takes place when food is chewed and mixed in themouth and churned in your stomach. Chemical digestionbreaks down large molecules of food into different, smallermolecules that can be absorbed by cells. Chemical digestiontakes place in your mouth, stomach, and small intestine.Some digestive processes are both physical and chemicalsuch as when bile acts on food.

Figure 17-12 About 1.5 Lof saliva are produced each dayby salivary glands in your mouth.What happens in your mouthwhen you think about a foodyou like?

Salivary gland

Salivary duct

Tongue

Salivary glands

Salivary duct


Quick DemoTo illustrate the need for me-

chanically breaking downfood, do this demonstration.Into one container with waterat room temperature, drop apiece of hard candy. Into asimilar container with waterat room temperature, drop apiece of hard candy that hasbeen crushed into smallpieces. Record the time it takeseach piece of candy to dissolvecompletely. Discuss the rela-tionship between particle sizeand rate of dissolution.

Caption AnswerFigure 17-12 You begin tosalivate.

ELL

VideodiscThe Infinite Voyage: ATaste of HealthChapter 3 Developing Taste7:30Refer to the Teacher Guide forbar codes and teaching strategies.

Teacher FYIThe names of many en-

zymes are designated with thesuffix -ase. For example, theenzyme that is responsible forthe conversion of sucrose iscalled sucrase. Other examplesare lactose � lactase, lipids �lipase, and amylose � amylase.

DiscussionLinguistic What are thecharacteristics of the or-

ganic catalysts, called en-zymes, that affect chemicalreactions within the body?The enzymes remain unchangedby their activity; they are effec-tive in small amounts; theyspeed up chemical change; andthey are specific in their actions.

Chemistry Certain bacteria in the mouthutilize sugars to help them adhere to the sur-face of teeth. The network structure of theglue they produce allows other bacteria tofind shelter. This community of bacteriaspecies forms tooth plaque. As the bacteriadigest sugars in the mouth, acid wastes areproduced that can cause cavities on theteeth.

Integrating the SciencesIntegrating the Sciences

Language Arts In one of Robert Frost’spoems he describes a rotting woodpile as the“slow smokeless burning of decay.” Havestudents compare this to the oxidation offoods that is part of the digestive process. L2



makes large fat particles float to the top ofthe liquid. Bile physically breaks up theseparticles into smaller pieces, the way deter-gent acts on grease on dishes. This processis called emulsification (ih mul suh fuhKAY shun). Although the bile physicallybreaks apart the fat into smaller droplets,the fat molecules are not changed chemi-cally. Chemical digestion of carbohydrates,proteins, and fats occurs when the diges-tive juices from the pancreas are added.

You learned that the pancreas producesenzymes that help break down carbo-hydrates, fats, and proteins. Your pancreasalso makes insulin. Insulin is a hormonethat allows glucose to pass from the blood-stream into your body’s cells. Without asupply of glucose, your body’s cells mustuse proteins and fats for energy.

In addition to insulin, the pancreas produces another solution. This solutioncontains bicarbonate. Bicarbonate helpsneutralize the stomach acid that is mixedwith chyme.

Gallbladder

Pancreaticduct

Pancreas

Stomach

Bile duct

Liver

Opening for bile andpancreatic ducts

Duodenum,part of smallintestine

Determining How Fats Are Emulsified

Procedure

1. Fill two glasses with warm water. Add a largespoonful of cooking oil to each glass.

2. Add a small spoonful of liquid dish-washingdetergent to one glass. Stir both glasses.

Analysis

1. Compare what happens to the oil in each glass.2. How does emulsification change the surface

area of the oil drops?3. How does emulsification speed up digestion?4. Where in the digestive system does emulsifica-

tion take place?5. What is the emulsifier in the digestive system?

✔Reading Check

What digestive

process occurs in

the duodenum?

Figure 17-15 The liver,gallbladder, and pancreas are atthe beginning of the small intes-tine. If your gallbladder had tobe removed, what nutrientwould your doctor advise youto eat less of?


Purpose

Visual-Spatial Studentswill observe how fats are

emulsified and compare the sur-face area involved.

Materialstwo glasses warm water, largespoon, small spoon, cooking oil,liquid detergent

Teaching StrategiesStudents should carefully ob-

serve how the large ring of oil isbroken down into smaller glob-ules. Repeat this activity using aliquid hand soap and motor oil tosee the emulsifying action. Relatethis to washing hands.

Analysis1. In the glass with the detergent,

the large ring of oil is brokendown into smaller globules.

2. The surface area is greatlyincreased.

3. More surface area is availablefor the chemical action ofdigestion.

4. in the small intestine5. Bile is the emulsifier in the

digestive system.

Oral Have students use theirMiniLab results to explain how thesurface area is increased whenthe large ring is broken down intonumerous small globules. Com-pare this to a sugar cube beingbroken down into the individualcrystals of sugar. Use Perfor-mance Assessment in theScience Classroom, p. 71.

COOP LEARN

ELLL2

Assessment

Gifted Have students research the chemicalprocess involved in neutralizing an acid. Theycan demonstrate the process to the class bymixing a solution of vinegar (5 mL in 100 mLwater) with a solution of baking soda(5 mL in 100 mL water). Test with blue litmuspaper to show that the combined solution isno longer acidic. Note the reaction will pro-duce some bubbles of carbon dioxide gas. L3


Page 480: 5a, 5b, 7bPage 481: 5a, 5b, 7c, 7d,7e



Caption AnswerFigure 17-14 By the action ofthe stomach muscles.Figure 17-15 fats

VideodiscSTV: Human Body, Vol. 1Unit 2 Digestive System, Stom-ach 2:10

!8Há4kVH"13799-17725Unit 2: Digestive System, Mouth2:30

!7\z-?tC"5787-10288Refer to the Teacher Guide foradditional bar codes and teach-ing strategies.


Internet Addresses

Answer to

Reading Check ✔

Digestion of proteins, fats, and

carbohydrates is completed in

the duodenum.


which include hydrochloric acid and enzymes. The acid ismade by cells in the walls of the stomach. The stomach,shown in Figure 17-14, also produces a mucus that lubricatesthe food, making it more slick. The mucus protects the stom-ach from the strong digestive juices. Food moves throughyour stomach in about four hours. At the end of this time,the food has been changed to a thin, watery liquid calledchyme (KIME). Little by little, chyme moves out of yourstomach and into your small intestine.

In Your Small IntestineYour small intestine may be small in diameter, but it is 4 m

to 7 m in length. As chyme leaves your stomach, it enters thefirst part of your small intestine, called the duodenum (dooAUD un um). The major portion of all digestion takes placein your duodenum. Digestive juices from the liver and pan-creas are added to the mixture. Your liver, shown in Figure17-15, produces a greenish fluid called bile. Bile is stored in asmall sac called the gallbladder. The acid from the stomach

Stomachentrance

Stomachexit

Stomachlining (wall)

Small intestine

Esophagus

Figure 17-14 The stomach is amuscular, baglike organ with a bandof muscle at each end. How is food mechanically digested in thestomach?

Visit the Glencoe ScienceWeb Site at www.glen-coe.com/sec/science/ca for more information aboutthe stomach’s role indigestion.

It takes betweenone and six hours for thefood undergoing digestionto move through the smallintestine. The small intes-tine is subdivided intothree parts: the duode-num, jejunum, and ilium.Most of the digestiveprocesses occur in theduodenum and most ofthe absorption of nutrientstakes place in the duode-num and the jejunum.

ontent Background

ontent Background

CC



Caption AnswerFigure 17-17 the appendix

1. Mechanical digestion in-volves cutting, grinding,tearing, and crushing byteeth and tongue in themouth and peristalsis bythe walls of the stomach.Chemical digestion in-volves the actual chemi-cal breakdown of foodinto usable materials.

2. mouth, esophagus, stom-ach, small intestine, largeintestine, rectum, anus

3. Water is removed and re-turned to the body.

4. Think Critically Com-plex carbohydrates in thecracker are broken downinto simple sugars.


AssessmentOral Assess students’ abilities to infer byhaving them suggest what happens to di-gestion and nutrition in people who havelost their teeth. Use Performance Assess-ment in the Science Classroom, p. 17.

5. Skill BuilderThe food would be undi-gested and continue to be

acidic from the stomach, possibly caus-ing ulcers.


Surface Area of the Small IntestineLook at the wall of the small intestine in Figure 17-16. The

walls of your small intestine are not smooth like the inside ofa garden hose. Rather, they have many ridges and folds.These folds are covered with tiny, fingerlike projectionscalled villi. Villi make the surface of the small intestinegreater so that food has more places to be absorbed.

Food AbsorptionAfter the chyme leaves the duodenum, it has become a

soup of molecules that is ready to be absorbed through thecells on the surface of the villi. Peristalsis continues to moveand mix the chyme. In addition, the villi themselves moveand are bathed in the soupy liquid. Molecules of nutrientspass by diffusion, osmosis, or active transport into bloodvessels in each villus. From there, blood transports the nutri-ents to all the cells of the body. Peristalsis continues to forcethe remaining materials that have not been digested orabsorbed slowly into the large intestine.

Figure 17-16 Hundreds ofthousands of densely packed villigive the impression of a velvet clothsurface. If the surface area of your villi could be stretched out,it would cover an area the size of a baseball diamond. What wouldhappen to a person’s weight if thenumber of villi were drasticallyreduced? Why?

Small intestine

Capillary(bloodstream)

Lymph vessel(collects excessfluid from tissues)

Villus

Microvilli

Villi


Caption AnswerFigure 17-16 The personwould lose weight because not asmany nutrients could be ab-sorbed by the body; the surfacearea involved in the process wasreduced.

Journal entries should re-flect that churning actionand the digestive processare probably slowed be-cause the stomach is not aslarge as it was. Also, pa-tients are advised to eatsmall portions of foods andto eat frequently. This putsless stress on the stomach’sdigestive activities.

3 AssessCheck for UnderstandingMaking a Model

Kinesthetic Have stu-dents contruct a three-

dimensional model of an en-zyme molecule system. Onesuch model may be similar toa lock-and-key system.

ReteachVisual-Spatial Havestudents prepare a chart

with these parts of the digestivesystem listed in the first col-umn: mouth, stomach, smallintestine, and large intestine. Inthe second column, across fromthe body part, give a brief de-scription of the digestiveprocess associated with it.

ExtensionFor students who have

mastered this section, use theReinforcement and Enrich-ment masters.

4 CloseProficiency Prep Use this quiz to check stu-dents’ recall of section content.

1. What are proteins thatspeed up digestive reac-tions? enzymes

2. What causes the mechan-ical mixing of food in thestomach? peristalsis

3. What structures increasethe surface area of thesmall intestine? villi

L1

COOP LEARNELL

L2

Guided Reading Strategy

Pair of Pairs This strategy encourages stu-dents as partners to respond to a question.They brainstorm together, recording on onepaper their ideas. After a few minutes, theycombine with another pair and share re-sponses. Finally, the teacher asks the groupsof four to share any responses. Have studentsuse the Pair of Pairs strategy on a Think Criti-cally question in a Section Assessment in thischapter.


In Your Large IntestineAs chyme enters the large intestine, it is

still a thin, watery mixture. The main job ofthe large intestine, shown in Figure 17-17, isto absorb this water from the undigestedmass. In doing so, large amounts of waterare returned to the body, and homeostasis ismaintained. Peristalsis slows down some-what in the large intestine. As a result, chymemay stay in the large intestine for as long asthree days. After the excess water is absorbed,the remaining undigested materials becomemore solid.

The Role of BacteriaBacteria that live in your large intestine feed

on undigested materials like cellulose. This is asymbiotic relationship. The bacteria feed on cel-lulose, and in return they produce several vita-mins that you need. Muscles in the rectum andanus control the release of solidified wastes from the body inthe form of feces.

Food is processed in your digestive system for the pur-pose of supplying your body with raw materials for metabo-lism. These raw materials are in the form of nutrients. Whatis not digested is eliminated.

1. Compare mechanical and chemical digestion.2. Name, in order, the organs through which food passes as

it moves through the digestive system.3. How do activities in the large intestine help maintain home-

ostasis?4. Think Critically: Crackers contain starch. Explain why

a cracker held in your mouth for five minutes begins totaste sweet.

5. Skill BuilderObserving and Inferring What would hap-

pen to food if the pancreas did not secrete its juices into thesmall intestine? If you need help, refer to Observing andInferring in the Skill Handbook on page 684.


Write a para-graph in your Science

Journal explaining whatwould happen to themechanical and chemi-cal digestion process offoods if a person had amajor portion of thestomach removed dueto a disease.

Figure 17-17 The large,twisting tube in this X ray is thelarge intestine. What do youthink the thinner tube con-nected to the left end of theintestine is?

Page 482: 5a, 5bPage 483: 5a, 5b


Using Scientific MethodsUsing Scientific Methods

Test Your Hypothesis

Analyze Your Data

Draw Conclusions


Plan1. Decide how your group will test

your hypothesis.2. Your teacher will supply you with

three test tubes containing gelled,unflavored gelatin. Pepsin pow-der will liquefy the gelatin if theenzyme is active.

3. As a group, list the steps you willneed to take to test your hypothe-sis. Consider the following factorsas you plan your experiment.Based on information provided byyour teacher, how will you use thepepsin and the acid? How oftenwill you make observations?

Be specific, describing exactlywhat you will do at each step.

4. List your materials.5. Prepare a data table and

record it in your Science Jour-nal so that it is ready to use asyour group collects data.

6. Read over your entire experi-ment to make sure that all stepsare in logical order.

7. Identify any constants, variables,and controls of the experiment.

Do1. Make sure your teacher approves

your plan before you proceed.2. Carry out the experiment

as planned.

3. While the experiment is going on,write down any observations thatyou make and complete the datatable in your Science Journal.

1. Compare your results withthose of other groups.

2. Did you observe a difference in the test tubes?

3. Identify the constants in thisexperiment.

1. Did the acid have any effect onthe activity of the pepsin? Howdoes this relate to the activity ofthis enzyme in the stomach?

2. Predict the effects of the pepsinon the gelatin if you increased or

decreased the concentration ofthe acid.

3. Is time a factor in the effective-ness of the pepsin on the gelatin?Explain.

17-2 FUNCTIONS OF NUTRIENTS 485

Teaching StrategiesTroubleshooting Prepare thegelatin for this activity following thedirections on the packet. To pre-vent the gelatin from melting, placethe test tubes in a glass of coldwater. Students will need to notethe amount of liquid after the acid isadded in order to compare with theamount when the gelatin liquefies.

Expected OutcomeMost results will reflect an in-

crease in the amount of liquid inthe test tube with acid.

Error AnalysisHave students compare results

and hypotheses and explain anydifferences that occurred.

1. Student results should be consistent with those of othergroups.

2. Yes, the test tube with acid had more liquid than the onewithout acid.

3. gelatin and pepsin

1. Pepsin is active only in an acidmedium. Acid is added to thefood material from the walls ofthe stomach. This allows di-gestion to occur.

2. Students might predict that thepepsin is active only in a nar-row range of acidity.

3. Yes, as more liquid is formed,the acid is diluted and thepepsin will be less effective.

Analyze Your Data

Draw Conclusions

Process Have students predict what wouldhappen to the digestive process if a person tookmedicine that stopped the production of stomachacid because he or she had indigestion. UsePerformance Assessment in the ScienceClassroom, p. 17.

Assessment

Activity

17•2Design Your OwnExperiment

Possible Materials• Test tubes with gelled,

unflavored gelatin (3)• Dropper• Test-tube rack• Pepsin powder • Glass-marking pen• Cold water• Dilute hydrochloric

acid• Beaker• Watch or clock

Protein DigestionYou learned that proteins are large, complex, organic compounds

necessary for living things to carry out their life processes. To beuseful for cell functions, proteins must be broken down into their indi-vidual amino acids. The process of chemically breaking apart proteinmolecules involves several different factors, one of which is the pres-ence of the enzyme pepsin in your stomach.

Under what conditions will the enzyme pepsin begin the digestionof protein?

Formulate a hypothesis about what conditions are necessary for pro-tein digestion to occur. When making your hypothesis, consider thevarious contents of the digestive juices that are found in your stomach.

Activity 17 2Activity 17 2

Recognize the Problem

Form a Hypothesis


Goals• Design an experiment that

tests the effect of a variable,such as the presence orabsence of acid, on the activityof the enzyme pepsin.

• Observe the effects of pepsinon gelatin.

Safety PrecautionsAlways use

care when working with acid andwear goggles and an apron.Avoid contact with skin and eyes.Wash your hands thoroughlyafter pouring the acid.


Purpose

Logical-MathematicalStudents will design and

carry out an experiment to deter-mine what happens to proteins inthe digestive system.

Process Skillsobserving, measuring in SI, inter-preting data, experimenting, infer-ring, communicating, recognizingcause and effect, forming hypothe-sis, separating and controlling variables

Time50 to 60 minutes

MaterialsThe hydrochloric acid should beprepared by adding acid to thewater.

Safety PrecautionsHydrochloric acid (HCl) is an

irritant and is corrosive. Vaporsare harmful. Any spillage or con-tact with skin should be flushedwith water.

Possible HypothesesMost student hypotheses will re-

flect that an acidic environment isnecessary for protein digestion bythe enzyme pepsin.

Possible ProceduresOne possible procedure is to

prepare the gelatin and pour anequal amount into each of threetest tubes. The third tube shouldcontain gelatin, acid, and nopepsin. When the gelatin sets, add10 drops of acid to one of the testtubes. Sprinkle enough pepsinpowder to cover the surface of thegelatin in both test tubes. Observethe gelatin every 10 minutes.

P

Recognize the Problem

Form a Hypothesis

Test Your Hypothesis

Physically Challenged Place studentswho have difficulty manipulating glasswareand acids in charge of formulating the hy-pothesis, observing, and recording the obser-vations of the reaction.


Infer why the activity of pepsin stops in the small intestine. Test your inference and seewhether the enzyme activity stops. Pepsin action stops because an alkaline substancestops the action of the acid. If a baking soda so-lution is used to neutralize the hydrochloric acid(HCl), foaming will take place. Do not let thefoam spill over the top of the test tube becausethis will obscure the results.

Protein Digestion by Pepsin

Time Pepsin Pepsin(minutes) (with acid) (without acid)

10 little liquid no liquid

20 increase in liquid no liquid

30 lots of liquid little liquidPage 484: 7a, 7c, 7d, 7ePage 485: 7a, 7c, 7d, 7e


CHAPTER 17 REVIEWING MAIN IDEAS 487

✔Reading Check

Choose a section of this

chapter and summarize

its main idea in one sen-

tence. Then, list five to

seven important details

from that section that

support this main idea.

Section

17-2 THE DIGESTIVE SYSTEM

The digestive system breaks down food mechan-ically by chewing and churning, and chemically with thehelp of enzymes. Food passes into the mouth and thenthrough the esophagus. A wavelike motion called peri-stalsis pushes the food downward toward thestomach. In the stomach, gastric juicesand enzymes break down some ofthe food. As food enters the smallintestine, the digestive process con-tinues. Bile produced by the liverhelps emulsify fat. The pancreasalso produces enzymes that helpdigest the food in the small intes-tine. The large intestine absorbswater, and waste is eliminatedthrough the anus. Where doesmechanical digestion occur?

ABSORPTION OF FOOD

Nutrients are absorbed through the villi into thebloodstream in the small intestine. Water isabsorbed in the large intestine. Bacteria that live inyour large intestine produce several vitamins thatare absorbed into the bloodstream at this stage.Undigested food or feces is eliminated from thebody through the anus.How do the useful sub-stances from the nutri-ents reach the cells?

CHAPTER 17 REVIEWING MAIN IDEAS 487

Answers to Questions

Section 17-1Nutrients A poor diet willnot provide the necessary nu-trients for cell activities,which can result in ill health.Functions of Nutrients Anapple supplies the body withcarbohydrates, a nutrient thatcan easily be converted to thesugars the body uses for en-ergy.

Section 17-2The Digestive System Me-chanical digestion occurs inthe mouth and in the stom-ach.Absorption of Food Usefulsubstances from nutrients areabsorbed from the small in-testine into blood vessels thatcarry the substances to cells.

Portfolio Encourage students to place intheir portfolios one or two items of whatthey consider to be their best work. Exam-ples include:• Problem Solving, p. 467• Science Journal, p. 469• Activity 17-2, pp. 484–485

Performance Additional performance as-sessments may be found in PerformanceAssessment and Science Integration Ac-tivites. Performance Task Assessment Listsand rubrics for evaluating these activitiescan be found in Glencoe’s PerformanceAssessment in the Science Classroom.

P

Assessment

CD-ROMGlencoe Science VoyagesInteractive CD-ROMChapter Summaries and QuizzesHave students read theChapter Summary then take theChapter Quiz to determinewhether they have masteredchapter content.

Chapter

17ReviewingMain Ideas

For a preview of thischapter, study this

Reviewing Main Ideasbefore you read the chapter.After you have studied thischapter, you can use theReviewing Main Ideas toreview the chapter.

The GlencoeMindJogger,Audiocassettes,and CD-ROM

provide additionalopportunities for review.

Chapter Reviewing Main IdeasChapter Reviewing Main Ideas17

FUNCTIONS OF NUTRIENTS

Carbohydrates provide energy. Proteins areneeded for growth and repair. Fats store

energy and cushion organs. Vitaminsand minerals regulate body functions.

Water is used for a variety of homeo-static functions. To keep your body

strong and healthy, you must eat abalanced diet. A balanced diet

contains food from the fivefood groups. How can anapple provide energy?

Section

17-1 NUTRIENTS

All foods can be grouped into six kinds of nutrients:carbohydrates, fats, proteins, minerals, vitamins, andwater. Nutrients are the parts of food your body can use.Each kind of nutrient has a function in maintaining thehealth of the body. How can your diet affect yourhealth?



Reviewing Main Ideas canbe used to preview, review,reteach, and condense chap-ter content.

Preview

Linguistic Have stu-dents try to answer the

questions in their ScienceJournal. Use student answersas a source for discussionthroughout the chapter.

Review

Interpersonal Havestudents answer the

questions on separate piecesof paper and compare theiranswers with those of otherstudents in the class.

Reteach

Visual-Spatial Havestudents look at the il-

lustrations on these pages.Ask them to describe detailsthat support the main ideas ofthe chapter found in the state-ment for each illustration.

Auditory-Musical If

time does not permit

teaching the entire chap-

ter, use the information on

these pages along with the

chapter Audiocassettes to

present the material in a

condensed format.

OUT OF

TIME?

Diet and Disease Certain cultures havediets that contain little animal fat. Such dietstypically result in low intake of fats and cho-lesterol. These diets may include largeamounts of vegetables, fruits, and grains.People in Asia have a lower incidence of heartdisease than people in the United States, pos-sibly due to having a diet that is lower in fat.

Cultural DiversityCultural Diversity

TEST-TAKING

CHAPTER 17 ASSESSMENT 489

Test-Taking Tip

Don’t Use Outside Knowledge Whenanswering questions for a reading passage,do not use anything you already knowabout the subject of the passage, or anyopinions you have about it. Always returnto the passage to reread and get the detailsfrom there.

Test Practice

Use these questions to test your ScienceProficiency.

1. The villi are tiny, fingerlike projections thatcover the wall of the small intestine. Whichstatement BEST relates their structure withtheir function?A) They are able to contract and expand

more rapidly.B) They offer the best protection against

stomach acid.C) They greatly increase the surface area

for digestion.D) They strain food passing through the

intestine.

2. Certain nutrients are needed for growthand repair. Which menu is the BEST source of foods for this function?A) milk, ham, eggs, whole wheat breadB) cereal, milk, orange juice, donutC) waffles, honey, margarine, milkD) toast, jelly, butter, apple juice

3. Everyone depends on water to survive.Which statement BEST emphasizes thatneed?A) We wash our bodies with water.B) Many foods contain lots of water.C) We add water to many foods that we eat.D) Body nutrients are in solution.

Developing Skills

If you need help, refer to the Skill Handbook.

22. Making and Using Graphs:Recommended Dietary Allowances(RDA) are made for the amounts ofnutrients people should take in to main-tain health. Prepare a bar graph of thepercent of RDA of each nutrient from theproduct information listed below.

Which nutrients are given the greatestpercent of the Recommended DietaryAllowance? Could a person on a fat-restricted diet eat this product? Explain.

23. Sequencing: In a table, sequence theorder of organs through which foodpasses in the digestive system. Indicatewhether ingestion, digestion, absorp-tion, or elimination takes place in theindividual organs.

24. Comparing and Contrasting: Compareand contrast the location, size, and func-tions of the esophagus, stomach, smallintestine, and large intestine.

25. Concept Mapping: Make a concept mapshowing the process of fat digestion.

Nutrient Percent U.S. RDA

Protein 2Vitamin A 20Vitamin C 25Vitamin D 15Calcium (Ca) less than 2Iron (Fe) 25Zinc (Zn) 15Total Fat 3.0 g 5Saturated Fat 0.5 g 3Cholesterol 0 mg 0Sodium 60 mg 3

Recommended Dietary Allowances

AssessmentAssessment

CHAPTER 17 ASSESSMENT 489

The Test-Taking Tip waswritten by The Princeton Re-view, the nation’s leader intest preparation.

1. C2. A3. D

23. mouth: ingestion, me-chanical and chemical di-gestion; esophagus: inges-tion; stomach: mechanicaland chemical digestion;small intestine: chemicaldigestion and absorption;large intestine: absorptionand elimination

24. See question 23 for func-tions. The esophagus is atube between the mouthand stomach (26 cm). Thestomach, (16 cm), is a sac located between theesophagus and small intestine. The small intes-tine is located between thestomach and large intes-tine (4.75 m). The large intestine (1.25 m), is lo-cated between the smallintestine and rectum.

25. In the mouth, fat is physi-cally broken down; itpasses through theesophogus; in the stom-ach, it mixes with diges-tive juices; in the duode-num, bile breaks fat intodroplets. Digestive juicesfrom the pancreas beginchemical digestion.

Bonus Question

What do chewing and theaction of bile have in com-mon in the digestive system?Surface area is increased, mak-ing it easier for the enzymes tocontact the substances.

Test Practice

The Test Practice Workbook provides studentswith practice in the format, concepts, and criti-cal-thinking skills tested in standardized exams.

Reproducible MastersChapter Review, pp. 33–34 Performance Assessment, p. 17 Assessment, pp. 65–68

Glencoe Technology

Chapter Review Software

Computer Test Bank

MindJogger Videoquiz

L2

L2

L2

Assessment Resources

Chapter

17Assessment Chapter AssessmentChapter Assessment17


11. Which vitamin is not used for growth?A) A C) CB) B D) K

12. Where is hydrochloric acid added to thefood mass?A) mouth C) small intestineB) stomach D) large intestine

13. Which organ produces enzymes thatdigest proteins, fats, and carbohydrates?A) mouth C) large intestineB) pancreas D) gallbladder

14. Which food group contains yogurt andcheese?A) dairy C) meatB) grain D) fruit

15. From which food group are carbohy-drates BEST obtained?A) milk C) meatB) grains D) eggs

16. From which food group should thelargest number of servings in your dietcome?A) fruit C) vegetableB) milk, yogurt, D) bread, cereal,

and cheese rice, and pasta

Thinking Critically

17. Food does not really enter your bodyuntil it is absorbed into the blood.Explain why.

18. In what part of the digestive system doantacids work? Explain your choice.

19. Bile’s action is similar to soap. Use thisinformation to explain bile working onfats.

20. Vitamins are in two groups: water solu-ble and fat soluble. Which of these mightyour body retain? Explain your answer.

21. Based on your knowledge of food groupsand nutrients, discuss the meaning of the familiar statement: “You are what you eat.”

a. amino acidb. carbohydratec. chemical

digestiond. chymee. digestionf. enzymeg. fath. food group

i. mechanical digestion

j. mineralk. nutrientl. peristalsis

m. proteinn. salivao. villip. vitamin

Each phrase below describes a science termfrom the list. Write the term that matches thephrase describing it.

1. muscular contractions that move food2. enzyme-containing fluid in the mouth3. fingerlike projections in small intestine4. subunit of protein5. liquid product that is the result of digestion

Checking Concepts

Choose the word or phrase that best answersthe question.

6. Where does most digestion occur?A) duodenum C) liverB) stomach D) large intestine

7. Which organ makes bile?A) gallbladder C) stomachB) liver D) small intestine

8. In which organ is water absorbed?A) liver C) esophagusB) small intestine D) large intestine

9. Which organ does food NOT passthrough?A) mouth C) small intestineB) stomach D) liver

10. What is produced by bacteria in the largeintestine?A) fats C) vitaminsB) minerals D) proteins

Using Vocabulary


Using Vocabulary

1. l2. n3. o4. a5. d

To reinforcechapter vo-

cabulary, use the Study Guidefor Content Mastery booklet.Also available are activities forGlencoe Science Voyages onthe Glencoe Science Web Site.www.glencoe.com/sec/science/ca

Checking Concepts

6. A 12. B7. B 13. B8. D 14. A9. D 15. B

10. C 16. D11. D

Thinking Critically

17. As food passes throughthe digestive tract it isbeing broken down intosmaller pieces and even-tually it is at the molecu-lar level. After it is ab-sorbed into the blood, it istransported to the bodycells and can be used as asource of energy.

18. The stomach, becauseacids are produced there.Antacids are used tocounteract an excess ofacid.

19. Bile breaks down fats intosmaller droplets, whichhave an increased surfacearea, so digestion occursmore quickly and easily.

20. The body would retain those vitaminsthat are fat-soluble. They are stored infat deposits. The water-soluble vitaminscannot be stored in fat deposits.

21. If we eat nutritious food, the body willhave good building blocks to use. If weeat a poor diet, the body will not havegood building blocks to use.

Developing Skills

22. Vitamin C and iron are given the greatestpercent of RDA. A person on a fat-restricted diet could eat the product be-cause the total fat is five percent of theRDA. Student graphs should have nutri-ents on the horizontal axis and percent-ages on the vertical axis.


Documents

Chapter 17: Nutrients and Digestion - mrwrightsclass.netmrwrightsclass.net/resources/old-7th-grade-text/chap17.pdf · Performance Assessment,p. 17 Chapter Review Software Computer