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TO THE STUDENTWelcome to this experimental science test. We hope that you will find it interesting and worthwhile. Carefully read through these directions and the directions on the next page before you begin to work.You may be part of a group for the first part of this exercise. Each group should carry out the experiment and collect the data together, but each student must record the data in his or her own booklet. Be sure to record the data exactly as you observe them. After the data has been collected, each student should answer the questions independently. After you have finished your experiment and have recorded all of the data, you will be asked to answer some questions about the experiment and the data you recorded. Your answers must be written in this test booklet in the space provided. Make sure that you understand each question before you begin to write. At any time while you are writing your answers, you may look back to the directions for the experiment and the data you collected. Be sure that your answers are written as clearly and neatly as possible. Before you turn the page, read the list of materials given below and check to make sure that your group has everything listed.
AFTER YOU HAVE READ THE DIRECTIONS, TURN TO THE NEXT PAGE AND BEGIN.
THE NUTRITIONAL CONTENT OF FOOD Humans, like all animals, obtain the energy and nutrients we need to survive from the foods that we eat. Different types of food contain different types and different amounts of the various nutrients. Typically, this Information is provided in some fashion on the labels of food products. Many consumers use this information when choosing foods to buy. You have been given three unknown samples (A, B and C). You will perform two chemical tests to determine whether these unknowns contain protein and/or starch. The reagents you will be using will cause discoloration and are
corrosive or toxic. Tap water will serve as your control for the experiment. Assume that the tap water does not contain either protein or starch. Be sure to clean the stirring rod before placing it in the different samples. Divide the 8 cups you have been given into 2 sets of 4 cups each. In each set, label 1 cup as (A), 1 cup as (B), 1 cup as (C) and 1 cup as (W). Perform the experiments one at a time. This will help you keep track of what you are doing. Work slowly and carefully. Add 10 mL of each unknown to the appropriately labeled cup. Add 10 mL of tap water to the cup labeled (W). To each cup add five drops of LugolÍs solution. This solution will indicate the presence of starch. Stir the solutions. Record your results in the data table provided. Add 10 mL of each unknown to a new cup. Also set up your control. Now add 10 drops of copper sulfate and 10 drops of sodium hydroxide to each cup. Stir the contents of the cups. This test will indicate the presence of proteins. Record your observations in the data table below. Dispose of your gloves and samples as directed by your teacher. Clean up your work area and thoroughly wash your hands.
Questions Please answer the following questions by yourself.
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