Glucose and Test Tube Essay

Submitted By sabby1118
Words: 1576
Pages: 7
Open Document
Lab: Testing for Nutrients Purpose: To observe the indicator reaction test for specific nutrients and test for the presence of lipids, carbohydrates and proteins.

Introduction: Substances in food that can be used by an organism for energy or for growth and repair are called nutrients. Nutrients include carbohydrate, proteins, fats, minerals, and vitamins. Cells of all organisms are composed of the nutrients and water. There are several chemical tests that can be used to determine which nutrients, if any, are present in a substance. You will use some of these tests in this activity.

We will use these indicators:
1) Benedict’s Solution tests for simple sugars (monosaccharides)
2) Lugol’s Iodine Solution tests for starch ( a polysaccharide)
3) Biuret’s Solution tests for protein

Materials:
Reagent Solutions
Benedict's solution
Iodine solution
Biuret solution
HCl (hydrolysis rxn of unknown)
Sodium Bicarbonate

Organic Compounds
Glucose
Albumin
Starch
sucrose
General Supplies
Pipettes
Beaker (400 mL)
Test tube holder
Timer
Hot water Bath
Clean test tubes
Paper bag
Spatula
Balance
Test tube holder*
Goggles*

*Safety equipment must be used when handling all chemicals and/or hot tubes and solutions

Procedure and Observation:

Part I. Testing for Carbohydrates Starches and sugars belong to the group of organic compounds called carbohydrates. Starch molecules are composed of many simple sugar molecules linked together. Starch molecules and simple sugar molecules have different chemical behaviors. For this reason, different chemical reagents, or testing agents, are used to test for starch and for simple sugars.

You will use different chemical tests to determine the nature of four unknown samples (#1 - #4).

I. A solution of iodine, Lugol’s iodine solution, is the reagent used to test for the presence of starch. Lugol’s solution is yellow brown. However, it reacts chemically with starch to form a blue-black substance called iodine of starch.

1. Add two drops of the four unknowns and water to wells on a spot plate.
2. Add one drop of iodine solution to each of the four samples. 3. What are your determinations about the four unknown samples to this point in the exercise?

Light yellowbrown = Negative test for starch
Purple, violet or blueblack ± precipitate = Positive test for starch
II. Benedict’s solution, a clear blue solution of sodium and copper salts, is used to test for the presence of reducing sugars. Reducing sugars have a free ‘ COOH ‘ which can reduce other compounds. In the presence of reducing sugar, Benedict’s solution changes color to green (low), yellow (medium) and brick red (high), depending on the amount of reducing sugar present. Reducing sugars are those that have a free or potentially free aldehyde or ketone. In a solution of pH 8 or higher the sugar is capable of reducing certain weak oxidizing agents such as cupric hydroxide along with a resultant oxidation of the carbonyl group of the sugar. Both Benedicts and Barfoeds tests identify reducing sugars. The following reaction is an example:

(reducing sugar) glucose + 2Cu(OH)2 --------- > Cu2O + 2H2O + glucose
(oxidized cupric ions: blue) (reduced cuprous ions: red)

1. Label a clean test tube for each of the remaining unknown solutions and water. Using a hand pipette, add 5 mL of each solution into the test tubes. Then set it in the test tube rack/beaker.
2. To each test tube add 2 ml of Benedict solution.
3. Carefully place both test tubes in a 950 water bath for 3 minutes. During the heating, observe the contents of each tube for any color changes.
4. At the end of 3 minutes, remove your test tubes with a test tube holder and place then in the test tube/beaker rack. Caution: Avoid getting splashed with hot water. Never touch hot test tubes with bare hands.
5. What are your determinations about the unknown samples to this point in the exercise?

Light blue =
Show More

Related Documents: Glucose and Test Tube Essay

Enzyme Lab Report

sugars) into simple sugar’s (glucose and galactose). There is a medical conditions known as being lactose and tolerant. That means that your stomach doesn’t break down the lactose. The withdrawals of being lactose and tolerant are cramps, production…

Words 1567 - Pages 7

Test to Determine the Presence of Glucose Essay

Experiment 2. The test for glucose (a) Half fill a beaker with tap water and place it on a tripod and gauze. Heat the water with a Bunsen burner. While waiting for the water to boil, carry on with instructions (b) to (d). (b) Label four test-tubes 1-4. 1% starch solution into tube 1 10% glucose solution into tube 2 (c) Put 20 mm (depth) of…

Words 681 - Pages 3

Trader Joe's Milk

digestive enzyme that serves as a catalyst for the purposes of breaking down Lactose, with the addition of Water, at lower activation energy. Consequently, this hydrolysis reaction and absorption of Lactose results in the production of Galactose and Glucose. It is important to indicate that the enzyme Lactase is located in the small intestine of mammals, specifically in the brush border (microvilli) (Swagerty et al., 2002). With this in mind, the specific enzyme Lactase can only bind with a specific…

Words 1310 - Pages 6

Building Blocks Essay

Carbohydrates Introduction The purposes for the experiments were to detect if the substances would test positive for the following: Protein, Starch and Sugar. Proteins are made up of amino acids and have various functions such as transportation, regulation and chemical breakdown. Starch is a polysaccharide made of many glucose units. Plants store glucose as starch for energy storage. Glucose is used as ready energy and made of one sugar molecule which is a major source of cellular fuel for all…

Words 987 - Pages 4

Tests To Detect The Presence Of Carbohydrates, Proteins And Lipids

and lipids we have to do experiments. The Iodine test is used to detect the presence of carbohydrates. This test is used to distinguish starch (polysaccharide) from carbohydrates. Reaction between starch and Iodine produce a dark grey, black color and it means that the test is positive. A yellow color means that test is negative. But other polysaccharides may give other colors including blue or red. In order to detect the presence of glucose (monosaccharide) we have to use a Clinitest tablet…

Words 891 - Pages 4

Essay about Diffusion : Science

through a membrane State Lab . Question : How does starch and glucose move through a membrane ? Hypothesis : Starch and glucose can move out of the cell Materials : Dialysis Tubing Dental Floss (Benedict's) Glucose Indicator Solution (Lugol's) Starch Indicator Solution (containing Iodine) Test Tube Rack 7 Test Tubes Tap Water Concentrated Glucose Solution Starch Solution DroppersIPipettes Beaker Test Tube Holder Hot Water Bath Paper Towel Introduction :…

Words 2462 - Pages 10

Fermintation Lab Essay examples

fermentation when different sugars are added. The reason for this lab is to better understand why and how this bacteria can use this form of cellular respiration. To test the different conditions that yeast might be in, and to see there effects, multiple test tubes with yeast in them will be exposed to different carbohydrates like Glucose, Maltose, and Starch. There also will be a control which will just have water added. Also tested will be temperature. one of each of the yeast mixtures will be put…

Words 639 - Pages 3

Helper: Cellular Respiration and Glucose Essay

oxygen concentration), many organism, including yeast obtain the energy from the process of fermentation. In alcoholic fermentation, characteristic of many yeast species, the fermentation process starts with one molecule of the six carbons sugar- glucose, and terminates with two molecules of the two carbons alcoholic- ethanol, two molecules of CO2: Fermentation is an anaerobic process in which fuel molecules are broken down to create pyruvate and ATP molecules. Both pyruvate and ATP are major energy…

Words 873 - Pages 4

Macromolecules Lab Report

different food samples, specifically samples from McDonald’s. The hypothesis was that the chicken nuggets and cheeseburger would contain proteins, the french fries would contain starch, the apples would contain carbohydrates, and the sprite would contain glucose. There are four organic molecules that are present in every living organism: Carbohydrates, lipids, proteins, and nucleic acids. These are known as macromolecules, and are large, carbon-based structures. These molecules are created when several monomers…

Words 989 - Pages 4

Amylase And Starch Lab Report

this experiment, 4 test tubes were tested with benedict’s solution. This solution will turn the substance orange if sugars are present. One tube was filled with starch, another filled with glucose, one containing starch and the enzyme, amylase, and finally a tube filled with distilled water to be used as a control because water would not change color. An additional 3 tubes…

Words 826 - Pages 4