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 ma
...
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, protein, fat,
vitamins, minerals and water
2. How are these nutrients used by your body? They are used to keep your body healthy and
working properly.
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?
You add the food sample then added a drop of
benedict and heated for 5 min.
2. The Benedict test is a test for monosaccharides; simple sugars like glucose or fructose
(fruit sugar). In contact with monosaccharides, the Benedict solution turns from blue to pink.
Does Sample A contain monosaccharides? ___yes______
Note: Disaccharides such as sucrose (table sugar) and lactose (milk sugar) are more
complex than monosaccharides. The Benedict test does not detect disaccharides directly.
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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. Does sample A contain monosaccharides?
_yes____
(Recall that a pink color is a positive test for monosaccharides.)
2. Test: The Lugol test uses iodine to test for starch, a polysaccharide (complex sugar). 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
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