P2.2.1.FoodTestingF



Name: _________________________Date: ______________Ms. Kim PBS LabProject 2.2.1: Food Testing IntroductionToxicology reports ordered during Anna’s autopsy reveal that Anna had high amounts of glucose in her blood at the time of her death. This finding suggests that Anna most likely ate a large meal near the time of her death. In the first lesson of this unit, you explored the relationship between blood glucose and diabetes. Glucose levels are related to the food we consume. Given that Anna was a diabetic, she had to think carefully about her diet and choose her foods wisely. Analysis of her stomach contents at the time of her death may reveal information about Anna’s last meal and provide additional evidence regarding the conditions surrounding her mysterious death. Eating a balanced diet is necessary for good health. The main nutrients in our food are classified as carbohydrates (sugars and starches), lipids (fats and oils), and proteins. Carbohydrates, including simple sugars such as glucose, are a great source of energy. Proteins are crucial in our diet as they help build tissue, fight disease, and facilitate chemical reactions. Lipids, commonly called fats, have equally important functions, including cell membrane and hormone production. An adequate amount of each of these nutrients is needed to keep the body in balance. In this project you will perform chemical tests to determine what foods contain carbohydrates, lipids, and proteins. Checkpoint: (5 points)Nutrient CategoryFunctionThe purpose of this lab is: Scientists analyze the chemical components of a substance in a variety of ways; one of the simplest methods is to use chemical indicators. An indicator is a substance that changes to indicate the presence of a particular compound or type of compound. The indicator may change color or temperature or may produce some other substance, such as bubbles or a distinctive odor. The change in the indicator is due to a chemical reaction between the indicator and the tested substance. Indicators are very specific and function based on the chemical compositions of the indicator and the substance being detected. Some indicators are sensitive to temperature, pH, and other environmental conditions. Generally, the easiest indicators to use are ones that change color to indicate the presence of a substance.In Project 2.2.1 you will use chemical indicators to tests for the presence of sugar, starch, protein, and lipids in three common food items as well as in the stomach contents of the ill-fated Anna Garcia. Equipment Positive controls for each test:Starch solution, 5% corn starch or other starch soluble in waterProtein solution, 5% albumin in waterSugar solution, 5% glucose in waterLipid solution, cooking oilAnna Garcia simulated stomach contentsProject 2.2.1 Autopsy Report resource sheetProject 2.2.1 Anna Garcia Food Diary resource sheet3 small samples of food200 mL of distilled water in a beaker8 transfer pipettesHot plate with beaker containing distilled water (to make a hot water bath)12 test tubesTest tube rackTest tube holderTest tube brush1 beaker, 250 mL1 beaker, 500mL1 graduated cylinder, 10mLMortar and pestle (optional)Oven mittBenedict’s solutionLugol’s Iodine stainBiuret stainBrown paper, multiple pieces, approximately 2 to 3 cm square2 stirring rodsSafety gogglesGlovesRead Project 2.2.1 Autopsy Report resource sheet on the next page. Read updated information from Anna’s autopsy. Highlight any information you feel requires further investigation. Read Project 2.2.1 Anna Garcia Food Diary resource sheet. Note that because Anna was a diabetic, she kept a detailed record of her food intake. Scan the document that covers the two days before she died and the morning of her death. Note any obvious differences between the first and second day. Also note that the final entry is incomplete. Food items in italics will be tested in this activity. Project 2.2.1: Autopsy Report NOTE: This is only a partial autopsy report. You will be receiving the remainder of the autopsy report in pieces throughout the course.Office of the Medical ExaminerMetropolitan Government of AnytownCase # 77Decedent:? Anna GarciaAge: 38Weight: 165Height: 64 InchesRace: HispanicSex: Female Date and Time of Autopsy: August 15, 2012 11:00 amPerformed By: Dr. KingLaboratory Results:Toxicology:??? Blood:No evidence of alcohol.No evidence of non-prescription drugs or overdose of prescription drugs.Blood glucose level 280 mg/dL (normal range 70-125 mg/dL)Stomach Contents:No evidence of toxins or poisons125 mL of partially digested food presentInternal ExaminationGastrointestinal System: The mucosa and wall of the esophagus are intact and gray-pink, without lesions or injuries. The gastric (stomach) mucosa is intact and pink without injury. The mucosa of the three parts of the small intestine, the duodenum, the jejunum, and the ileum, and the mucosa of the large intestine, the colon and rectum, appears normal. Approximately 125 ml of partially digested semisolid food is found in the stomach.?Jane King_____________________Jane King, MDCounty Medical ExaminerProject 2.2.1: Anna Garcia Food Diary Saturday – August 11, 2012Breakfast2 egg whites, scrambled, no butter2 slices thick turkey bacon1 slice whole wheat toast with 1 pat butter1 cup coffee with artificial sweetener and 1 tbsp. light coffee creamerLunch1 12oz can Sprite1 turkey sandwich (2 slices whole wheat bread, 3 slices turkey lunch meat, 1 slice cheddar cheese, ? tbsp. mayonnaise)16 fat-free tortilla chips with salsaSnack1/4 cup dry roasted peanuts1 small appleDinner? cup apple juice6 ounces salmon filet1 cup brown rice cooked with salt and butter1 cup steamed broccoliDessert? cup sugar free lemon gelatinSunday – August 12, 2012Breakfast1 cup Cheerios? cup skim milk ? cup blueberriesLunch1 cup low-fat strawberry yogurt6 Ritz crackers1 cup canned, low-sodium vegetable soup1 12oz can colaSnack1 single serving bag potato chipsDinner2 slices thick crust pepperoni pizza (14” pizza)2 cups tossed salad4 tbsp. Caesar dressingDessert1 cup vanilla ice cream with ? cup mini marshmallows5 Oreo cookiesMonday – August 13, 2012 Breakfast1 cup whole milk1 biscui*Note that Anna’s entries stopped on the morning of August 13th. The entry for breakfast appears to be incomplete. ProcedurePart I. Positive Controls—Standard Positive TestsTo begin, you will need to check positive controls for each of the tests. A positive control is a sample test using a substance known to produce a positive result. Testing the positive control allows you to see how to visualize a positive result and ensures that the reagents and protocols are working properly. Put on the proper personal protective equipment. You should wear eye protection at all times throughout the activity. The indicators are chemicals that can damage your eyes, so be careful and work safely.Read each step below carefully and follow the safety precautions highlighted by your teacher.Clean the stirring rod and test tubes carefully between each test.Check point: (5 points)In your own words, what is a positive control and why do we do them?Are you allowed to take off your goggles at any point of the lab? Table 2.2.1 Food Testing (10 points)Control ResultsNegative Control Sample (water)Positive Control Sample (test material)Standard Test #1: GlucoseStandard Test #2: StarchStandard Test #3: ProteinStandard Test #4: LipidsPart II. Testing Food Samples (20 points)You are tasked to test Anna’s stomach contents to determine the makeup of her last meal. You will perform an experiment for testing this mixture as well as determining the chemical makeup of three standard food items. Obtain three food samples as well as a sample of Anna’s stomach contents (simulated). FoodGlucoseStarchProteinLipidAnna’s StomachTest three food samples as well as the simulated stomach contents using your teacher-approved procedure and record your results in the data table. Note that these three food items were items listed by Anna in her food diary. Summarize your findings below your data table by listing which food samples tested positive for each of the four molecules. The summary should follow the pattern shown below.Glucose is found in:Starch is found in:Protein is found in:Lipid is found in:Share information about the foods you tested. Add information from other groups to your summary lists in Step 6. See what you can learn about the content of all of the italicized food items on Anna’s food diary. Add information about Anna’s last meal to the Project 2.2.1 Autopsy Report – under the heading Gastrointestinal System. Include a summary of how this finding could link to her diabetes and her death. Conclusion (10 points)What was the purpose of testing distilled water with each indicator?Given what you know about diabetes, explain why diabetics have to pay attention to the types of foods they ingest?List any of the food samples that tested positive for more than one type of molecule. Explain why it is an advantage for us to eat foods that contain more than one type of molecule.5290457124770In the United States, processed food must be labeled showing information about the nutrient content. It has been argued that requiring nutritional information on these foods is too costly for consumers, because the cost to test the foods is added to the price of the food item. What is your position on this issue? In the space below, write a five to eight sentence paragraph giving at least three reasons in support of your position. Write a paragraph either in support of the current laws that require nutritional labeling, or in favor of making nutrient content labels optional. Support your position with logical, well thought out arguments.48035696576258Total Score ______/5000Total Score ______/50 ................
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