Identifying Nutrients SE done PDF

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Date: ________________________

Student Exploration: Identifying Nutrients Vocabulary: carbohydrate, disaccharide, lipid, monosaccharide, polysaccharide, protein, starch

Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 1. What are the major types of nutrients you can get from food? Carbohydrates (CHO), Lipids (fats), Proteins, Vitamins, Minerals, Water 2. How are these nutrients used by your body The body uses three main nutrients to function— carbohydrate, protein, and fat. These nutrients are digested into simpler compounds. Carbohydrates are used for energy (glucose). Fats are used for energy after they are broken into fatty acids. Gizmo Warm-up Have you ever wondered what is in your food? Scientists use a variety of tests to determine the nutritional content of food. You will learn four of those tests with the Identifying Nutrients Gizmo. 1. Below the Food samples label, drag tube A into the Food sample holder. Below the Benedict test, click the Test button. What is done in the Benedict test? The food sample and Benedict solution are added to a test tube. The tube is heated in a water bath for five minutes. 2. The Benedict solution is a test for monosaccharides; simple sugars like glucose or fructose (fruit sugar); and some disaccharides such as lactose and maltose. In contact with these sugars, the Benedict solution turns from blue to green to orange. For simplicity, we will consider the Benedict test a test for monosaccharides only. Does Sample A contain these sugars? yes_ Note: Sucrose (table sugar) is a disaccharide that is not detected by the Benedict test. Foods sweetened only with table sugar will show a negative Benedict test.

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Activity A: Identifying nutrients

Get the Gizmo ready:  Click Reset.  Drag Sample A into the Food sample holder.

Introduction: Most food is composed of three types of molecules: carbohydrates, proteins, and lipids. 

Carbohydrates such as starches and sugars are major source of energy. Simple sugars are found in sweets and fruits. Starches are found in potatoes, cereal, pasta, flour, and other plant products.



Proteins are used in body structures such as muscles, skin, and hair. Rich sources of proteins include meats, dairy products, and beans.



Lipids (fats and oils) are used for energy, insulation, and as an essential building block of cells. Meats, dairy products, and oily plants such as olives are rich in lipids.

Question: How do you test for carbohydrates, proteins, and lipids? 1. Test: Under the Benedict test, click Test. Is the Benedict test positive for sample A? yes_ Recall that orange is a positive test for monosaccharides (and some disaccharides).

2. Test: The Lugol test uses iodine to test for starch, a polysaccharide (complex carbohydrate). Iodine turns dark purple in the presence of starch. Under Lugol test, click Test. Does sample A contain starch? no

3. Test: The Biuret test uses a solution of potassium hydroxide (KOH) and copper sulfate (CuSO4) to test for protein. The Biuret solution turns purple when proteins are present. Under Biuret test, click Test. Does sample A contain proteins? no

4. Test: The Sudan Red test uses a fat-soluble dye, Sudan Red, to indicate the presence of lipids. When lipids are present, the dye will be absorbed into the lipids, and will appear as concentrated spots of color in the test tube. (No spots indicates that lipids are not present.) Under Sudan Red test, click Test. Does sample A contain lipids? no_

5. Summarize: What nutrients does sample A contain? __ A contains monosaccharides 6. Analyze: What kind of food is sample A most likely to be? (Circle your choice) A. Apple juice

B. Baked beans

C. Oatmeal

D. Scrambled eggs

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Activity B:

Get the Gizmo ready:

Nutrients and food types

 Click Reset.

Question: What nutrients does each food sample contain? 1. Collect data: Use the four available tests to find the nutritional content of samples E, G, and M. (Sample A has been done for you as an example.) Record results on the table below.

Biuret test

Sudan Red test

Monosaccharides

Starches

Proteins

Lipids

Test results – are these nutrients present?

Lugol test

Lipids Test

Benedict test

Protein Test

Food sample

Carbohydrate Tests

A

+

–

–

–

Yes

No

No

No

E

-

-

+

+

no

no

yes

yes

G

-

-

-

-

no

no

no

no

M

-

+

-

-

no

yes

no

no

2. Analyze: Look at the results for samples A, E, G, and M. A. Is sample E most likely to be steak, bread, or butter? Justify your answer. __ Steak. Sample E has protein and fat. Of the choices, only steak has protein and fat_________________________________________________________________ B. Is sample G most likely to be table sugar, pasta, or olive oil? Justify your answer. _ Table sugar. Sample G has no monosaccharides, but it may have disaccharides like sucrose. Pasta would be positive for starch, and olive oil contains lipids.__________________________________________________________________ C. Is sample M most likely to be chicken, rice, a mango, or butter? Justify your answer.

Rice. Sample M has starch, which is found in rice. Chicken is rich in protein, mangoes in monosaccharides, and butter in lipids. 3. Draw conclusions: Why is it important to understand the nutritional content of food? What we eat is important to our health. A healthy diet is low in sugar and contains a balance of carbohydrates, proteins, and fat. To have a healthy diet, it is important to learn about the nutritional contents of different types of food.

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Activity B (continued from previous page) 4. Practice: Determine the nutritional content of the remaining food samples.

Biuret test

Sudan Red test

Monosaccharides

Starches

Proteins

Lipids

Test results – are these nutrients present?

Lugol test

Lipids Test

Benedict test

Protein Test

Food sample

Carbohydrate Tests

B

-

-

+

+

no

No

yes

yes

C

-

+

-

-

no

yes

no

No

D

-

-

+

-

no

no

yes

no

F

-

-

-

-

no

no

no

no

H

-

-

+

+

no

no

yes

yes

I

+

-

-

-

yes

no

no

no

J

-

-

+

+

no

no

yes

yes

K

+

-

-

-

Yes

no

No

no

L

-

-

-

-

No

No

No

No

N

-

+

-

-

No

Yes

No

No

O

-

-

-

-

No

No

No

No

P

+

-

-

-

Yes

No

No

No

Q

-

-

+

+

No

No

Yes

Yes

R

-

+

-

-

No

Yes

No

No

S

-

-

+

+

no

No

yes

Yes

5. Think and discuss: If possible, discuss these food samples with your classmates and teacher. Try to come up with a type of food that corresponds to each sample. In general, meats are rich in proteins and lipids. Fruits and products flavored with corn syrup contain monosaccharides. Grain and potato products contain starch. Samples that are negative for every test are likely to contain disaccharides such as table sugar. 6. Extend your thinking: In general, a balanced diet contains relatively even amounts of carbohydrates, proteins, and lipids. Too much sugar is unhealthy. Fruits and vegetables are important sources of vitamins and minerals.Do you consider your diet balanced and healthy? Why or why not? My diet is healthy because it contains a balance of starch,

proteins, and lipids. I also eat a lot of fruits and vegetables. [Unhealthy diets may be high in sugar, fats, carbohydrates, and processed foods.

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