1 Food and 1 Food and Energy Energy

Section

1

Food and Energy

Objectives

After completing this lesson, students will be able to

15.1.1

Explain why the body needs food.

15.1.2

Describe how the six nutrients needed by the body help carry out essential processes.

15.1.3

Explain how the Food Guide Pyramid and food labels can help in planning a healthy diet.

Target Reading Skill

Outlining

Explain that using an outline format helps students organize information by main topic, subtopic, and details.

Sample Answer

Food and EnergyI. Why You Need Food

A. NutrientsB. Energy

II. CarbohydratesA. Simple CarbohydratesB. Complex Carbohydrates

III. FatsA. Kinds of FatsB. CholesterolC. Nutritionists’ Recommendations

IV. ProteinsA. Amino AcidsB. Complete and Incomplete ProteinsC. Nutritionists’ Recommendations

V. Vitamins and MineralsA. Fat-Soluble and Water-Soluble

VitaminsB. Importance of VitaminsC. Importance of Minerals

VI. Water

Teaching Resources, Unit 3

•

Transparency LS147

Preteach

Build Background Knowledge

Energy and Calories

Ask students to name foods that they think supply them with energy. Write their responses on the board. Then ask them what they think a Calorie is and write those responses on the board. Revisit the responses once students have read the section.

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Skills Focus

Posing questions

Materials

none

Time

15 minutes

Tips

Write the statements on the board or use an overhead projector to project the statements on a screen.

Expected Outcome

All the statements are false. At this stage, you may wish to

collect students’ opinions and look for misconceptions, then address specific issues later as you teach the chapter.

Think It Over

Encourage students to volunteer additional statements about nutrition and to discuss whether the statements are true.

Integrating Health

1 Food and Energy

Food Claims—Fact or Fiction?1. Examine the list of statements at the

right. Copy the list onto a separate sheet of paper.

2. Next to each statement, write agree or disagree. Give a reason for your response.

3. Discuss your responses with a small group of classmates. Compare the reasons you gave for agreeing or disagreeing with each statement.

Think It OverPosing Questions List some other statements about nutrition that you have heard. How could you find out whether the statements are true?

Reading PreviewKey Concepts• Why does your body need food?

• How do the six nutrients needed by the body help carry out essential processes?

• How can the Food Guide Pyramid and food labels help you have a healthy diet?

Key Terms• nutrient • calorie • carbohydrate • glucose • fat • protein • amino acid • vitamin • mineral• Food Guide Pyramid• Percent Daily Value• Dietary Reference Intakes (DRIs)

Target Reading SkillOutlining As you read, make an outline about the six groups of nutrients needed by the body. Use the red headings for the main ideas and the blue headings for the supporting ideas.

Imagine a Thanksgiving dinner. You see roast turkey on a plat-ter, delicious stuffing, lots of vegetables, and pumpkin pie. Thedinner includes an abundance of colors and delicious aromas.Food is a central part of many celebrations, of times sharedwith friends and family. Food is also essential. Every livingthing needs food to stay alive.

Why You Need FoodFood provides your body with materials for growing and forrepairing tissues. Food also provides energy for everythingyou do. For example, running, playing a musical instrument,reading, and even sleeping require energy. Food also helps yourbody maintain homeostasis, or a stable internal environment.By filling your energy needs, food enables your body to keepthis balance during all your activities.

Nutrients Your body breaks down the foods you eat intonutrients. Nutrients (NOO tree unts) are the substances infood that provide the raw materials and energy the body needsto carry out all its essential processes. There are six groups ofnutrients necessary for human health—carbohydrates, fats,proteins, vitamins, minerals, and water.

Food and Energy

I. Why You Need Food

A. Nutrients

B.

II. Carbohydrates

A.

Fact or Fiction?a. Athletes need more protein in their diets than other people do.b. The only salt that a food contains is the salt that you have added to it. c. As part of a healthy diet, everyone should take vitamin supplements.

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Differentiated Instruction

Instruct

Why You Need Food

Teach Key Concepts

Calories and Energy

Focus

Ask:

What are some reasons that your body needs food?

(Sample answers: To feel your best, to perform well in school and sports, to reduce your risk of illness)

Teach

Ask:

How do a slice of pizza and a slice of bread compare in Calories and the energy each provides?

(The pizza has more Calories, so it provides more energy.)

Why do you need to eat a certain number of Calories each day?

(To provide your body’s energy needs and to grow properly)

Apply

Ask students to hypothesize what might happen if a person their age does not take in enough Calories.

(The person might lose weight and would not have the energy needed to grow and to repair tissues.)

learning modality: logical/mathematical

Independent PracticeTeaching Resources, Unit 3

•

Guided Reading and Study Worksheet:

Food and Energy

Student Edition on Audio CD

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L2

Less Proficient Readers

Recording Information

Help students create a framework for a three-column table on the board. Label the columns

Nutrient, Function,

and

Source

. Then have a volunteer read aloud the boldfaced sentence under

Why You Need Food

that names the six nutrients. List them in the

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first column of the table. Review key words or phrases within the text that provide clues for understanding the functions of each nutrient, such as

perform, provide,

and

helps

. Students can copy the table and fill in the remaining columns as they read.

learning modality: verbal

Monitor Progress L2

Writing

Have students explain why they need food and list the six main types of nutrients. Students can save their responses in their portfolios.

Answers

Figure 1

Playing basketball

In Calories; 1 Calorie is the same as 1 kilocalorie, or

1,000 calories

Energy When nutrients are used by the body for energy, theamount of energy they release can be measured in units calledcalories. One calorie is the amount of energy needed to raisethe temperature of one gram of water by one degree Celsius.Most foods contain many thousands of calories of energy. Biolo-gists use the term Calorie, with a capital C, to measure theenergy in foods. One Calorie is the same as 1 kilocalorie (kcal)or 1,000 calories. For example, one serving of popcorn maycontain 60 Calories (60 kcal), or 60,000 calories, of energy. Themore Calories a food has, the more energy it contains.

You need to eat a certain number of Calories each day tomeet your body’s energy needs. Your daily energy requirementdepends on your level of physical activity. Your needs alsochange as you grow and age. As an infant and child, you grewvery rapidly, so you likely had very high energy needs. Yourcurrent growth and level of physical activity affect the numberof Calories you need now. The more active you are, the greateryour energy needs are.

How is energy in foods measured?

FIGURE 1Burning Calories The number of Calories you burn depends on your weight as well as your level of activity. The more active you are, the more Calories you burn.Applying Concepts Which activity do you think burns the most Calories per hour—playing basketball, walking, or reading?

Playing basketball Walking Reading


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Carbohydrates

Teach Key Concepts

The Two Groups of Carbohydrates

Focus

Ask:

What are some examples of carbohydrates?

(Sample answers: Bread, potatoes, corn)

Teach

Explain that carbohydrates are categorized into two groups. Ask:

How are the two groups alike?

(Both are made of sugar molecules.)

Ask:

How are they different?

(Simple carbohydrates are known as sugars and provide quick energy for the body. Complex carbohydrates are made of many sugar molecules that must be broken down by the body before they can be used.)

Ask:

Why do you need a large proportion of Calories to come from carbohydrates?

(The glucose in carbohydrates is the major source of energy for your body’s cells.)

Apply

Ask:

Why are foods that are made with a lot of sugar not a good source of fiber?

(Fiber is a complex carbohydrate; foods with a lot of sugar are generally simple carbohydrates.)


Integrating Chemistry

Write the chemical formula for glucose on the board: C

6

H

12

O

6

. Explain that fructose has the same formula, but its atoms are arranged differently than those of glucose. Sucrose, or “table sugar,” is a simple carbohydrate made up of two molecules, glucose and fructose, that are combined chemically. A carbohydrate that is made up of only one or two sugar molecules is considered a simple carbohydrate. Tell students the sugar found in milk, lactose, is a compound made of two single sugars, glucose and galactose, that are combined chemically. Although its molecules each consists of two sugar subunits, lactose is still considered a simple carbohydrate.

To illustrate the chemical difference between the simple and complex carbohydrates, show students a chain of beads and tell them it represents a carbohydrate. Ask:

What does each bead represent?

(One sugar molecule)

What does the chain represent?

(A complex carbohydrate)

learning modality: visual

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Watermelon (1 slice)Total Carbohydrates 22 g

Sugars 18 gStarches 3 gFiber 1 g

Brownie (1 square)Total Carbohydrates 18 g


Simple Carbohydrates

Milk (1 cup)Total Carbohydrates 12 g


FIGURE 2

CarbohydratesSimple carbohydrates, or sugars, are found in fruits, milk, and some vegetables. Sugars are also added to cookies, candies, and soft drinks. Complex carbohydrates are found in rice, corn, pasta, and bread. Fruits, vegetables, nuts, and whole-grain foods also contain fiber.Applying Concepts Why is fiber important in the diet?

CarbohydratesThe nutrients called carbohydrates (kahr boh HY drayts),which are composed of carbon, oxygen, and hydrogen, are amajor source of energy. One gram of carbohydrate provides yourbody with four Calories of energy. In addition to providingenergy, carbohydrates provide the raw materials to make cellparts. Based on their chemical structure, carbohydrates aredivided into simple carbohydrates and complex carbohydrates.

Simple Carbohydrates Simple carbohydrates are alsoknown as sugars. One sugar, glucose (GLOO kohs), is the majorsource of energy for your body’s cells. However, most foods donot contain large amounts of glucose. The body converts othertypes of sugars, such as the sugar found in fruits, into glucose.Glucose is the form of sugar the body can most easily use.

Complex Carbohydrates Complex carbohydrates are madeup of many sugar molecules linked together in a chain. Starch is acomplex carbohydrate found in foods from plants, such as pota-toes, rice, wheat, and corn. To use starch as an energy source, yourbody first breaks it down into smaller, individual sugar molecules.Only then can your body release the molecules’ energy.

Like starch, fiber is a complex carbohydrate found inplants. But unlike starch, fiber cannot be broken down intosugar molecules by your body. Instead, fiber passes through thebody and is eliminated.


Calculating Calorie Content

Materials

Calorie requirement charts for different age groups, references providing the nutrient content and calories of foods

Time

20 minutes

Focus

Ask students to list foods that they commonly eat.

Teach

Have students work in groups to determine their recommended daily Calorie intake. Then have them use nutrition textbooks or calorie-counting references to find and list the nutrient content and Calories of the foods they commonly eat.

Apply

Have students use the information on their lists to calculate the nutrient and Calorie content of one day’s meals and snacks. Ask them to calculate the proportion of Calories that came from carbohydrates. If the proportion is above or below the recommended percentage, have them describe how they can modify their intake to meet recommended percentages.


Skills Focus

Predicting

Materials

fruits and vegetables (potatoes, rice, bread, and breakfast cereals), soft drinks (diet and regular), iodine solution, plastic dropper, test tubes, notebook

Time

20 minutes

Tips

Place each food sample in a labeled test tube. Set up stations and have students

rotate in groups of three or four from station to station.

Expected Outcome

Foods such as potatoes, pasta, rice, and cereal contain starch. Other fruits and vegetables also may contain small amounts of starch.

Extend

Have students group the foods tested into simple and complex carbohydrates.


Monitor Progress L2

Skills Check

Have students make compare/contrast tables for simple and complex carbohydrates and saturated and unsaturated fats, giving an example of each. Students can place their tables in their portfolios.

Answers

Figure 2

It helps keep the digestive system functioning properly.

Simple and complex; an example of a simple

carbohydrate is glucose. An example of a complex carbohydrate is starch.

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Yellow Corn (1 ear)Total Carbohydrates 19 g


Wheat Bread (1 slice)Total Carbohydrates 17 g

Sugars Starches Fiber

Pasta (1 cup)Total Carbohydrates 40 g


Complex Carbohydrates

3.5 g12.0 g

1.5 g

Because your body cannot digest it, fiber is not considered anutrient. Fiber is an important part of the diet, however, becauseit helps keep the digestive system functioning properly.

Nutritionists’ Recommendations Nutritionists recom-mend that 45 to 65 percent of the Calories in a diet come fromcarbohydrates. It is better to eat more complex carbohydrates,such as whole grains, than simple carbohydrates. Foods madewith whole grains usually contain a variety of other nutrients.Foods made with a lot of sugar, such as candy and soft drinks,have few valuable nutrients. Also, while sugars can give you aquick burst of energy, starches provide a more even, long-termenergy source.

What are two types of carbohydrates? Give an example of each.

FatsLike carbohydrates, fats are energy-containing nutrients thatare composed of carbon, oxygen, and hydrogen. However, fatscontain more than twice the energy of an equal amount ofcarbohydrates. One gram of fat provides your body with nineCalories of energy. In addition to providing energy, fats haveother important functions. Fats form part of the cellmembrane, the structure that forms the boundary of a cell.Fatty tissue protects and supports your internal organs andinsulates your body.

PredictingYou can do a test to see which foods contain starch.

1. Put on your apron.2. Obtain food samples from

your teacher. Predict which ones contain starch. Write down your predictions.

3. Use a plastic dropper to add three drops of iodine to each food sample. CAUTION: Iodine can stain skin and clothing. Handle it carefully. If the iodine turns blue-black, starch is present.

Which foods contain starch? Were your predictions correct?

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Fats

Teach Key Concepts

Types of Fats

Focus

Refer students to Figure 3.

Teach

Ask students to identify the main type of fat in the foods shown. Point out that foods can contain different types of fats. Ask:

What is the basis for classifying fats?

(Chemical structure)

How are fats beneficial?

(They provide energy, form part of cell membranes, protect and support internal organs, and insulate your body.)

Apply

Ask:

Which food item shown has the healthiest type of fat?

(Olive oil)


Identifying Fats in Foods

Materials

foods or pictures of foods that are mostly fats or contain fats, such as a can of vegetable shortening, a bottle of olive oil, a bag of chips, and a box of cereal or crackers

Time

5 minutes

Focus

Ask students to recall the three types of fats.

Teach

Show each food item and have students classify it by the main type of fat it contains. Students may have difficulty with the food items in boxes. Explain that reading food labels can help determine the presence of saturated fats and trans fats. The words “hydrogenated” or “partially hydrogenated” on the ingredient list indicate trans fats. Pass around a container on which this information appears for students to examine.

Apply

Ask:

How can you reduce the amount of saturated fats and trans fats in your diet?

(Possible answers: Eat low-fat dairy products, read food labels to try to limit the amount of foods you eat that have trans fat, and cook with unsaturated rather than saturated fats.)


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Saturated, Unsaturated, and Trans Fats

Fat

(gra

ms)

12

11

10

9

8

7

6

5

4

3

2

1

0Butter Margarine Olive Oil

Saturated fatUnsaturated fatTrans fat

Key

Kinds of Fats Fats may be classified as unsaturated or satu-rated based on their chemical structure. Unsaturated fats areusually liquid at room temperature. Most cooking oils areunsaturated fats. Saturated fats are usually solid at roomtemperature. Meat and dairy products contain relatively largeamounts of saturated fat.

You may have heard about trans fat. Trans fats are madewhen manufacturers add hydrogen to vegetable oils. Foodscontaining trans fats stay fresh longer than foods containingunsaturated fats. Trans fats are found in margarine, chips, andcommercially baked goods. Both trans fats and saturated fatsare considered to be less healthful than unsaturated fats.

Cholesterol Cholesterol (kuh LES tur awl) is a waxy, fatlikesubstance found only in animal products. Like fats, cholesterolis an important part of your body’s cells. Your liver can makeall of the cholesterol your body needs. Therefore, cholesterol isnot a necessary part of the diet.

Nutritionists’ Recommendations Nutritionists recom-mend that no more than 30 percent of the Calories eaten eachday come from fats. Extra fats and cholesterol in the diet canlead to a buildup of fatty material in the blood vessels. Thisfatty buildup can cause heart disease.

FIGURE 3Many foods contain saturated, unsaturated, and trans fats. Unsaturated fats are considered to be more healthful than saturated fats and trans fats.Interpreting Graphs Which item has the most unsaturated fat—butter, tub margarine, or olive oil?

What is cholesterol?

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Address Misconceptions

The Role of Fat in a Healthful Diet

Focus

Students may think that if low fat is good for you, then no fat is better.

Teach

Tell students that some fats contain essential fatty acids, which help regulate blood pressure, blood clotting, and the immune response. Healthy skin and hair also are maintained by fat.

Apply

Ask: How might a person’s health be affected by eating too little fat? (The person might develop irritated skin and infections.) learning modality: logical/mathematical

Proteins

Teach Key ConceptsFocus Refer students to Figure 4.

Teach Ask: What kinds of foods have complete proteins, and what kinds have incomplete proteins? (Meats contain all the essential amino acids. Plant foods lack one or more essential amino acids.)

Apply Ask: Why is it important for teens to get enough protein? Proteins are needed for tissue growth, and teens are growing rapidly. learning modality: logical/mathematical

Math Skill Calculating percent

Focus Tell students that calculating the percent of Calories from different nutrients helps them to get the recommended amounts.

Teach Remind students which numbers to use in the fraction.

Answer27%

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Gifted and TalentedPreparing a Display Have students use reliable sources, such as the American Dietetic Association or the American Heart Association, to prepare a display with information on healthful vegetarian diets. Some of the information they may wish to present includes the following

L3 recommendation: Foods with incomplete proteins do not have to be combined to provide complete proteins within a given meal, but should be eaten over the course of a day to provide essential amino acids. learning modality: logical/mathematical

Monitor Progress L2

Writing Have students explain why protein is important to health.

AnswersFigure 3 Olive oil has the most unsaturated fat.

Cholesterol is a waxy, fatlikesubstance found only in

animal products.

Amino acids make up proteins.

ProteinsProteins are nutrients that contain nitrogen as well as carbon,hydrogen, and oxygen. Proteins are needed for tissue growthand repair. They also play an important part in chemicalreactions within cells. Proteins can serve as a source of energy,but they are a less important source of energy than carbohy-drates or fats. About 10 to 35 percent of your daily Calorieintake should come from proteins.

Amino Acids Proteins are made up of small units calledamino acids (uh MEE noh), which are linked together chemi-cally to form large protein molecules. Thousands of differentproteins are built from only about 20 different amino acids.Your body can make about half of the amino acids it needs.The others, called essential amino acids, must come from thefoods you eat.

Complete and Incomplete Proteins Foods from animalsources, such as meat and eggs, are sources of complete pro-teins because these foods contain all the essential amino acids.Proteins from plant sources, such as beans, grains, and nuts,are called incomplete proteins because they are missing one ormore essential amino acid. Different plant sources lack differ-ent amino acids. Therefore, to obtain all the essential aminoacids from plant sources alone, people need to eat a wide vari-ety of plant foods.

What are the units that make up proteins?

FIGURE 4Complete and Incomplete Proteins Animal products such as meats and eggs contain complete proteins. Incomplete proteins are found in beans, nuts, and grains.

Percentage A percentage (%) is a ratio that compares a number to 100. For example, 30% means 30 out of 100.

Suppose that a person eats a total of 2,000 Calories in one day. Of those Calories, 300 come from protein. Follow these steps to calculate the percentage of Calories that come from protein.

1. Write the comparison as a fraction:

2. Multiply the fraction by 100% to express it as a percentage:

Practice Problem Suppose that 540 Calories of the person’s 2,000 Calorie total come from fats. What percentage of the Calories comes from fats?

3002,000---------------

3002,000--------------- 100%� 15%�


Vitamins and Minerals

Teach Key ConceptsThe Role of VitaminsFocus Students may think that all nutrients provide energy. Remind them that a nutrient is a substance in food that provides the raw materials and energy the body needs to carry out all its essential processes.

Teach Ask: Are vitamins and minerals sources of energy? (No) Why are vitamins and minerals nutrients? (They help to carry out chemical processes.) Explain that chemical reactions must take place for processes to occur in the body, such as blood clotting, helping the body get energy from foods, and sending messages through the nervous system. Ask: Why is it important to get vitamins and minerals from food? (The body cannot make minerals and some vitamins.) Which group of vitamins are important to include every day in the diet and why? (Water-soluble vitamins because they cannot be stored in the body)

Apply Tell students that a nutrient-dense food provides many nutrients relative to the number of Calories. Many nutrient-dense foods contain important vitamins and minerals. Refer students to Figure 6. Ask them to use the information in the chart with what they have learned in this section to give some examples of nutrient-dense foods. (Sample answers: Dairy products have protein, some carbohydrates, calcium, and some B vitamins. Fruits have carbohydrates, vitamins, and minerals.) learning modality: logical/mathematical

For: Links on foods and energyVisit: www.SciLinks.org Web Code: scn-0421

Download a worksheet that will guide students’ review of Internet resources on essential nutrients.

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Vitamins and MineralsTwo kinds of nutrients—vitamins and minerals—are neededby the body in very small amounts. Unlike the other nutrients,vitamins and minerals do not provide the body with energy orraw materials. Instead, they help the body carry out variousprocesses.

Vitamins act as helper molecules in a variety of chemicalreactions in the body. Vitamin K, for example, helps yourblood to clot when you get a cut or a scrape. Figure 6 lists thevitamins necessary for health. The body can make a few ofthese vitamins. For example, your skin can make vitamin Dwhen exposed to sunlight. Most vitamins, however, must beobtained from foods.

Fat-Soluble and Water-Soluble Vitamins Vitamins areclassified as either fat-soluble or water-soluble. Fat-solublevitamins dissolve in fat, and they are stored in fatty tissues inthe body. Vitamins A, D, E, and K are all fat-soluble vitamins.Water-soluble vitamins dissolve in water and are not storedin the body. This fact makes it especially important to includesources of water-soluble vitamins—vitamin C and all of theB vitamins—in your diet every day.

Importance of Vitamins Although vitamins areonly needed in small amounts, a lack of certain vita-mins in the diet can lead to health problems. In the1700s, sailors on long voyages survived on hard, drybiscuits, salted meat, and not much else. Because ofthis limited diet, many sailors developed a seriousdisease called scurvy. People with scurvy suffer frombleeding gums, stiff joints, and sores that do not heal.Some may even die.

A Scottish doctor, James Lind, hypothesized thatscurvy was the result of the sailors’ poor diet. Linddivided sailors with scurvy into groups and fed dif-ferent foods to each group. The sailors who were fedcitrus fruits—oranges and lemons—recovered fromthe disease. Lind recommended that all sailors eatcitrus fruits. When Lind’s recommendations werecarried out, scurvy disappeared. Today scientistsknow that scurvy is caused by the lack of vitamin C,which is found in citrus fruits.

List the fat-soluble vitamins.

FIGURE 5Eat Your Vegetables! Fresh vegetables are full of vitamins and are fun to pick as well.

For: Links on foods and energyVisit: www.SciLinks.orgWeb code: scn-0421


http://www.scilinks.org/fromoutside.asp?sciLINKSNumber=scn-0421


Use Visuals: Figure 6Essential VitaminsFocus Refer students to Figure 6.

Teach Have students identify the water-soluble vitamins. (B vitamins, biotin, folic acid, pantothenic acid, vitamin C) Ask: What is a primary function of these vitamins? (Most are involved in breaking down other nutrients and releasing energy.) Which foods are good sources of this type of vitamin? (Whole-grain foods and green vegetables)

Apply Ask: What might be some effects of a deficiency of water-soluble vitamins? (Not growing properly, tiredness, anemia, infections) learning modality: visual

Interpreting Data About Vitamins

Materials printouts of information from reliable Internet sources, reference books on nutrition

Time 20 minutes

Focus Remind students that they need to eat a variety of foods to get the kinds and amounts of vitamins they need.

Teach Divide the class into small groups, and assign each group three or four of the vitamins listed in Figure 6. Have students use the reference materials to find the daily amount of each vitamin recommended for people their age, additional foods that provide each vitamin, and additional functions of each vitamin. Have the groups present their findings to the class.

Apply Ask students to prepare a sample menu for one day of three meals and two snacks that includes all of the vitamins they should take in during a day. learning modality: logical/mathematical

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English Learners/IntermediateVocabulary: Link to Visual Pair students with native English speakers. Have them create a vitamin chart similar to the one in Figure 6, listing food sources for each of the vitamins in both English and their native languages. Provide nutrition books and cookbooks to help English learners connect the words to the visuals. learning modality: visual

L2 English Learners/AdvancedComprehension: Key Concepts Have students look in magazines for foods in Figure 6, for example, dark green vegetables and broccoli. Then have them list the foods in English along with the nutrients each food contains. Example: broccoli—carbohydrates and vitamins. learning modality: verbal

L3

Monitor Progress L2

Skills Check Have students list their favorite foods and then classify them according to the vitamins the foods provide.

AnswersFigure 6 Green, leafy vegetables

A, D, E, K

FunctionSourcesVitamin

FunctionSourcesVitamin

Fat-Soluble Vitamins

Water-Soluble Vitamins

Maintains healthy skin, bones, teeth,and hair; aids vision in dim light

Maintains bones and teeth; helps in the use of calcium and phosphorus

Aids in maintenance of red blood cells

Aids in blood clotting

Needed for breakdown of carbohydrates

Needed for normal growth

Needed for release of energy

Helps in the breakdown ofproteins, fats, and carbohydrates

Maintains healthy nervous system;needed for red blood cell formation

Aids in the release of energy

Needed for red blood cell formation

Needed for the release of energy

Needed to form connective tissue andfight infection

Dairy products; eggs; liver; yellow, orange,and dark green vegetables; fruits

Fortified dairy products; fish; eggs; liver;made by skin cells in presence of sunlight

Vegetable oils; margarine; green, leafyvegetables; whole-grain foods; seeds; nuts

Green, leafy vegetables; milk; liver; made by bacteria in the intestines

Pork; liver; whole-grain foods; legumes; nuts

Dairy products; eggs; whole-grain breads and cereals; green, leafy vegetables

Many protein-rich foods; milk; eggs; meat;fish; whole-grain foods; nuts; peanut butter

Green, leafy vegetables; meats; fish;legumes; fruits; whole-grain foods

Meats; fish; poultry; dairy products; eggs

Liver; meat; fish; eggs; legumes; bananas;melons

Green, leafy vegetables; legumes; seeds; liver

Liver; meats; fish; eggs; whole-grain foods

Citrus fruits; tomatoes; potatoes; dark greenvegetables; mangoes

A

D

E

K

B1 (thiamin)

B2 (riboflavin)

B3 (niacin)

B6 (pyridoxine)

B12

Biotin

Folic acid

Pantothenic acid

C

FIGURE 6

Essential VitaminsBoth fat-soluble vitamins and water-soluble vitamins are necessary to maintain health. Interpreting Tables What foods provide a supply of both vitamins E and K?


Use Visuals: Figure 7Essential MineralsFocus Have students review the minerals in the chart.

Teach Ask: To obtain enough calcium, what foods should people eat if they do not drink milk? (Cheese, dark green, leafy vegetables, tofu, legumes) What does the body use calcium for? (Building bones and teeth, clotting blood, and nerve and muscle function)

Apply Tell students that most teens do not get the recommended amount of calcium, which is 1,300 mg per day. Ask them to use the chart to name specific foods people could eat if they do not like milk or cannot drink milk. (Spinach, broccoli, peas, beans, tofu, cheese) learning modality: visual

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Mineral Sources Function

Essential Minerals

Calcium Milk; cheese; dark green, leafy vegetables; tofu; legumes

Helps build bones and teeth; aids in blood clotting; muscle and nerve function

Chlorine Table salt; soy sauce Helps maintain water balance

Fluorine Fluoridated drinking water; fish

Helps form bones and teeth

Iodine Seafood, iodized salt Helps in the release of energy

Iron Red meats; seafood; green, leafy vegetables; legumes; dried fruits

Needed for red blood cell function

Magnesium Green, leafy vegetables; legumes; nuts; whole-grain foods

Aids in muscle and nerve function; helps in the release of energy

Phosphorus Meat; poultry; eggs; fish; dairy products

Helps produce healthy bones and teeth; helps in the release of energy

Potassium Grains; fruits; vegetables; meat; fish

Helps maintain water balance; muscle and nerve function

Sodium Table salt; soy sauce Helps maintain water balance; nerve function

Source of sodium

Source of calcium

▼

▼

Source of potassium

▼

FIGURE 7Eating a variety of foods each day provides your body with the minerals it needs.Interpreting Tables Which minerals play a role in regulating water levels in the body?

Importance of Minerals Nutrients that are not made byliving things are called minerals. Minerals are present in soiland are absorbed by plants through their roots. You obtainminerals by eating plant foods or animals that have eatenplants. Figure 7 lists some minerals you need. You probablyknow that calcium is needed for strong bones and teeth. Iron isneeded for the proper functioning of red blood cells.

Both vitamins and minerals are needed by your body insmall amounts to carry out chemical processes. If you eat awide variety of foods, you probably will get enough vitaminsand minerals. Most people who eat a balanced diet do not needto take vitamin or mineral supplements.

What are minerals?


Water

Teach Key Concepts

Getting Enough Water

Focus

Ask:

How much water do you think you take in every day?

(Encourage students to include beverages other than water, such as fruit juices, and fruits and vegetables.)

Teach

Ask:

How does water work with vitamins and minerals to carry out body processes?

(Vitamins and minerals help carry out chemical reactions, which take place in water.)

Tell students that water contains substances called electrolytes that regulate many processes in cells. Heavy perspiring can result in a reduction in the body’s water content and electrolytes. Signs of losing too much water include weakness, rapid breathing, and weak heartbeat.

Apply

Ask:

How can you help prevent dehydration when you are very physically active?

(Drink water before, during, and after participating in physical activities; be alert to signs of dehydration)


Food and Digestion

Show students the Video Field Trip to help them understand the importance of the digestive system. Discussion Question:

According to the Food Guide Pyramid, what category of food should we consume the most servings of?

(Foods rich in complex carbohydrates)

L2

Monitor Progress L2

Answers

Figure 7

Chlorine, potassium, and sodium

Nutrients that are not made by living things

Water

FIGURE 8Water—An Essential Nutrient All living things need water. Without regular water intake, an organism would not be able to carry out the processes that keep it alive.

WaterImagine that a boat is sinking. The people onboard are getting into a lifeboat. They have roomfor only one of these items: a bag of fruit, a can ofmeat, a loaf of bread, or a jug of water. Whichitem should they choose?

You might be surprised to learn that the lifeboat passengersshould choose the water. Although people can probably survivefor weeks without food, they will die within days without freshwater. Water is the most abundant substance in the body. Itaccounts for about 65 percent of the average person’s body weight.

Water is the most important nutrient because the body’s vitalprocesses—including chemical reactions such as the breakdownof nutrients—take place in water. All the cells in your body arecomposed mostly of water. Water makes up most of the body’s flu-ids, including blood. Nutrients and other important substances arecarried throughout the body dissolved in the watery part of theblood. The water in blood also carries waste materials that must beremoved from your body.

On a hot day or after exercising, your body produces perspira-tion, or sweat. Perspiration consists of chemicals dissolved in water.The water in perspiration comes from body tissues. Sweat glands inyour skin release the water on the surface of your body. Perspirationhelps regulate body temperature by cooling the body. Some wastechemicals are dissolved in perspiration. Therefore, when you per-spire, you are also removing wastes.

Under normal conditions, you need to take in about 2 litersof water every day. When you perspire a lot, you need morewater. You can obtain water by drinking water and other bever-ages. In addition, you take in water when you eat foods thatcontain a lot of water. Fruits and vegetables such as melons andtomatoes have a large amount of water.

What is the most abundant substance in the body?

Video PreviewVideo Field TripVideo Assessment

Food and Digestion

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The Food Guide Pyramid

Teach Key ConceptsShape of the Food Guide PyramidFocus Refer students to Figure 9.

Teach Ask: Why are the food groups shaped like a pyramid? (The wider base indicates that the greatest portion of a person’s diet should be from this group; the servings decrease as the levels get smaller.)

Apply Ask: How do the types and amounts of food in each group reflect the recommendations for the percentage of Calories that should come from the different nutrients? (The highest percentage of Calories should come from carbohydrates, which make up the two bottom levels. As shown in the Pyramid, protein should make up the next highest percentage, then fats.) learning modality: visual


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For: The Food Guide Pyramid activityVisit: PHSchool.comWeb Code: cep-4022

Students learn about the food groups and how they can be combined to form a healthy diet.

Classifying Foods

Materials note cards

Time 15 minutes

Focus Ask each student to list a favorite food on each of ten note cards.

Teach Have students work in small groups to classify the foods, using the Food Guide Pyramid. Explain that some foods, such as pizza, fall into more than one category. Then have students use their cards to plan nutritious meals.

Apply Ask students to write a paragraph describing whether they need to include more or less of any food groups in their daily diets. learning modality: logical/mathematical

L2

L2

Fats, Oils, and Sweets (Use sparingly)

Meat, Poultry, Fish, Dry Beans, Eggs, and Nuts Group (2–3 servings)

Fruit Group(2–4 servings)

Bread, Cereal, Rice, and Pasta Group (6–11 servings)

Milk, Yogurt, and Cheese Group (2–3 servings)

Vegetable Group(3–5 servings)

The Food Guide PyramidThe Food Guide Pyramid, shown in Figure 9, is a diagram thathelps people plan a healthy diet. The Food Guide Pyramidclassifies foods into six groups. It also indicates how manyservings from each group should be eaten every day tomaintain a healthy diet. You can use the pyramid’s guidelinesand your own food preferences to have a healthy diet contain-ing foods you like.

How many groups are in the Food Guide Pyramid?

FIGURE 9

The Food Guide PyramidThe Food Guide Pyramid recommends the number of servings that a person should eat each day from six food groups.

For: The Food Guide Pyramid activityVisit: PHSchool.comWeb code: cep-4022


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Food Labels

Teach Key Concepts

Interpreting Food Labels

Focus

Tell students that the Food Guide Pyramid helps you plan your food choices, but it does not tell you the amounts of specific nutrients you need.

Teach

Refer students to Figure 10. Ask students to locate the different types of information on the food label as a student volunteer reads aloud the explanation for each item. Reinforce that food labels are only a guide; teens may need more nutrients than the Percent Daily Values indicate.

Apply

Have students bring in food labels from their favorite snacks, work in small groups to read and interpret the labels, and then prepare a chart comparing the nutritional value of two or more snacks.



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Calculating Percent of Calories From Fat

Focus

Explain that the Calories from fat in every single food you eat do not have to be less than 35%. Some foods can be higher in fat as long as others are lower.

Teach

Model how to use labels from snacks to find the percent of Calories that come from fat.

Apply

Have students use food labels from their favorite snack foods to calculate the percentage of fat in each serving.


Example: 30 potato chipsCalories 340Calories from Fat 200200

÷

340

×

100 = 58.8%

L2

L2

Monitor Progress L2

Answers

Figure 10

Two; one serving provides 45%.

Six

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Food LabelsAfter a long day, you and your friends stop into a storeon your way home from school. What snack should youbuy? How can you make a wise choice? One thing youcan do is to read the information provided on foodlabels. Food labels allow you to evaluate a single foodas well as to compare the nutritional value of twodifferent foods.

How to Read a Food Label Figure 10 shows a foodlabel that might appear on a box of cereal. Refer to thatlabel as you read about some of the important nutritionalinformation it contains.

Serving Size This information tells you the size of asingle serving and the number of servings in the con-tainer. The information on the rest of the label is based onserving size. If you eat twice the serving size, then you’llconsume twice the number of Calories.

Calories This information tells you how muchenergy you get from one serving of this food, includinghow many Calories come from fat.

Percent Daily Value The Percent Daily Value showsyou how the nutritional content of one serving fits intothe recommended diet for a person who consumes2,000 Calories per day. For example, one serving of thiscereal contains 12% of the total amount of sodium a personshould consume in one day. You might eat more or less than2,000 Calories per day. But, you can still use this percentageas a general guide.

Ingredients The ingredients are listed in order byweight, starting with the main ingredient. The list canalert you to substances that have been added to a food toimprove its flavor or color, or to keep it from spoiling. Inaddition, reading ingredients lists can help you avoid sub-stances that make you ill.

Using Food Labels Food labels can help you makehealthful food choices. Suppose you are shopping forbreakfast cereals. By reading the labels, you might findthat one cereal contains little fat and a high percentage ofthe Daily Values for complex carbohydrates and severalvitamins. Another cereal might have fewer complex car-bohydrates and vitamins, and contain significant amountsof fat. You can see that the first cereal would be a betterchoice as a regular breakfast food.

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FIGURE 10Food Label By law, specific nutritional information must be listed on food labels. Calculating How many servings of this product would you have to eat to get 90% of the Daily Value for iron?


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Answer

Guidelines for the amounts of nutrients needed daily

Assess

Reviewing Key Concepts

1.

a.

Any two: growing, repairing tissues, providing energy, maintaining homeostasis

b.

The amount of energy needed to raise the temperature of one gram of water by one degree Celsius; the more Calories a food has, the more energy it contains.

c.

Individuals who are growing and who are very active have high energy needs.

2.

a.

Carbohydrates, fats, proteins, vitamins, minerals, and water

b.

Carbohydrates and fats provide energy and raw materials the body needs; and fatty tissue supports, protects, and insulates the body. Proteins are needed for growth and repair, and for chemical reactions. Vitamins and minerals act as helper molecules in chemical reactions. Water is needed because all the body’s chemical reactions take place in water.

c.

Proteins in plant foods are incomplete proteins. However, if vegetarians eat different plant foods in combination, they will get all the essential amino acids.

3.

a.

The Food Guide Pyramid classifies food into six groups, and a food label contains nutritional information about the food.

b.

The Food Guide Pyramid indicates how many servings from each food group you should eat every day to maintain a healthy diet. You can use food labels to evaluate a single food and to compare the nutritional value of different foods in planning a healthy meal.

Reteach

Help students compare subcategories of carbohydrates, fats, and proteins—for example, simple and complex carbohydrates.

Performance Assessment

Drawing

Have small groups of students prepare posters showing one nutrient, its functions, and sources of the nutrient.


•

Section Summary:

Food and Energy

•

Review and Reinforce:

Food and Energy

•

Enrich:

Food and Energy

L1

L2

Keep Students on Track

Remind students to record foods soon after they eat, as remembering later can be difficult. Encourage students not to modify their diets during the project. Recording what they eat will help them better understand how their habits affect their health.

Math Skill

Calculating percent

Answers

4.

Carbohydrates: 1200

÷

2500 = 0.48; 0.48

×

100 = 48% Fats: 875

÷

2500 = 0.35; 0.35

×

100 = 35%Proteins: 48% + 35% = 83%; 100%

−

83% = 17%

Section 1 Assessment

Target Reading Skill Outlining Use the information in your outline about nutrients to help you answer the questions below.

Reviewing Key Concepts1. a. Identifying Name two ways in which foods

are used by the body.b. Defining What is a calorie? How does it

relate to the amount of energy in foods?c. Inferring Why do young children and

active teenagers have high energy needs?2. a. Listing List the six nutrients that are

needed by the body.b. Summarizing For each nutrient you listed,

briefly describe the role it plays in the body.c. Applying Concepts Why is it especially

important that vegetarians eat a varied diet?

3. a. Reviewing What kinds of information are found in the Food Guide Pyramid and on food labels?

b. Applying Concepts How can you use this information to plan a healthy meal?

1

Dietary Reference Intakes Food labelscan also help you monitor the nutrients inyour diet. Guidelines that show the amountsof nutrients that are needed every day areknown as Dietary Reference Intakes (DRIs).For example, the DRIs for vitamins recom-mend that people your age get 45 milligramsof vitamin C every day.

DRIs also show how the Calories thatpeople eat each day should be split amongcarbohydrates, fats, and proteins. The PercentDaily Values listed on food labels can helpyou make sure that you are meeting the DRIsfor different nutrients.

What are Dietary Reference Intakes?

4. Percentage Suppose that a person eats 2,500 Calories in one day. Of those Calories, 1,200 are from carbohydrates, 875 are from fat, and the rest are from protein. What percentages of the person’s Calories are from carbohydrates, from fats, and from proteins?

FIGURE 11Reading Food Labels Food labels allow you to compare the nutritional content of similar kinds of foods.


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Raisin’ the Raisin Question

Preparing for Inquiry

Skills Objectives

Students will be able to:

•

measure the masses of the components of a consumer product

•

calculate the percentage by mass of the components of a consumer product

•

understand why a variable in an experiment was controlled

Prep Time

20 minutes

Class Time

40 minutes

Safety

Warn students not to eat the cereal or raisins.

Guide Inquiry

Introducing the Procedure

Ask:

How do you calculate the percentage of part of a mixture if you know the amount of the mixture and the amount of the part?

(Divide the amount of the part by the amount of the mixture, and multiply by 100.)

Troubleshooting the Experiment•

Students should place raisins back into the empty beaker as they find them. After students separate all the raisins from the flakes, they should go through the flakes one more time to make sure no raisins are left behind.

•

Students should re-zero the balance between cereals, and remeasure the mass of the empty beaker as well.

•

No form of packing should be done, including banging the container on the tabletop.

•

Depending on the level of the student, you may wish to introduce the concept of significant figures. For lower level students, suggest that they round off calculations to 1 or 2 decimal places.

Expected Outcome

Commercial raisin brans are about 30 to 35 percent raisins by mass.

L2

Analyze and Conclude

1.

So that the mass of the beaker is not included in the calculations.

2.

Answers will depend on brands used.

3.

Answers will depend on brands used.

4.

The way the flakes fit into different sized containers may influence the packing, and the size of the sample influences the per-centage error, so the containers should be the same for each sample.

5.

Accept answers that correctly identify the raisin bran with most raisins based on the

data table, that explain how sampling was done, and how the data were analyzed.

Extend Inquiry

Design an Experiment

Samples contain random errors. The best way to reduce error is to measure several samples and average the results.

Raisin’ the Raisin Question

ProblemRaisins are a good source of the mineral iron. Which raisin bran cereal contains the most raisins?

Skills Focusmeasuring, calculating, controlling variables

Materials• balance• beaker (250 mL)• raisin bran cereals (several brands)

Procedure1. Use a balance to find the mass of a clean

250-mL beaker. Record the mass in a data table like the one below.

2. Fill the beaker to the top with one of the brands of raisin bran cereal, but do not pack down the cereal. CAUTION: Do not put any cereal in your mouth. Write the brand name in the data table. Measure and record the mass of the beaker plus cereal. Subtract the mass of the empty beaker to get the mass of the cereal alone. Record the result.

3. Pour the cereal onto a paper towel. Separate the raisins from the bran and place the rai-sins back in the beaker. Measure and record the mass of the beaker plus raisins. Subtract the mass of the empty beaker to get the mass of the raisins alone. Record the result.

4. Repeat Steps 1–3 with each of the other brands of cereal.

Analyze and Conclude1. Measuring Why did you first measure the

mass of an empty beaker and then the mass of the beaker plus cereal?

2. Calculating Calculate the percentage mass of raisins in each cereal as follows:

Record the results in your data table.

3. Interpreting Data Based on your observa-tions, which brand of cereal had the greatest percentage of raisins by mass?

4. Controlling Variables Was it important that all of the cereal samples were collected in the same-size beaker? Why or why not?

5. Communicating Based on your results, write a paragraph that could be printed on a box of raisin bran cereal that would help con-sumers understand that this brand is the best source of iron.

Design an ExperimentIn this investigation, you examined a sample of cereal rather than the contents of the entire box. Scientists often use samples because it is a more practical way to make observations. Redesign this experiment to improve upon the sampling technique and increase the accuracy of your results. Obtain your teacher’s permission before carrying out your investigation.

% Mass of raisinsMass of raisinsMass of cereal---------------------------------------- 100%��

Data Table

Cereal BrandMass (g)

EmptyBeaker

Beakerplus Cereal Cereal Beaker plus

Raisins Raisins

PercentageMass of Raisins (%)

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