Exercise 8: Chemical and Physical Processes of Digestion: Activity 4: Assessing Lipase Digestion of Fat Lab Report Pre-lab Quiz Results You scored 75% by answering 3 out of 4 questions correctly. 1. Which of the following is/are true true of bile? Your answer : d. It works by a chemical and physical process. Correct answer: b. It works by a physical process. 2. The substrate substrate used in this simulation simulation is You correctly answered: c. vegetable oil. 3. When fatty acids are liberated by lipase, the pH You correctly answered: b. decreases. 4. One of the the products of the chemical digestion of lipids is You correctly answered: d. fatty acids.
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Experiment Results Predict Question: Predict Question: Which tube do you think will have the the highest lipase activity? Your answer : d. tube 5 Stop & Think Questions: What does the pH measure? You correctly answered: d. both lipase activity and fatty acid release Why is it difficult to detect whether lipase is active in tube 5? You correctly answered: d. The pH is already very low, so a decrease in pH might be difficult to detect. Experiment Data: Tube No. 1 2 3 4 5 6
Reagent 1 Lipase Lipase Lipase Water Lipase Lipase
Reagent 3 Bile salts Water Bile salts Bile salts Bile salts Bile salts
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Reagent 4 p H 7 .0 p H 7 .0 p H 9 .0 p H 7 .0 p H 2 .0 p H 9 .0
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Time 60 60 60 60 60 60
Temp. 37 37 37 37 37 37
pH 6.21 6.72 9.00 7.00 2.00 8.97
Post-lab Quiz Results You have not completed the Post-lab Quiz.
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Review Sheet Results 1. Explain why you can't fully test test the lipase activity in tube 5. Your answer: Lipase activity in tube 5 is difficult to test because the reagent put into the tube is already very acidic (pH 2.0). That is why after treatment and incubation, the resulting pH is still very acidic. It is difficult to determine if this is due to lipase activity or if it is simply because of the acidic reagent. 2. Which tube had the the highest lipase activity? How well did the results compare with your prediction? Discuss possible reasons why it may or may not have matched. Your answer: My prediction and the results did not match. Highest lipase activity actually occured in the first tube wherein pH lowered the most. 3. Explain why pancreatic lipase would be active in both both the mouth and the pancreas. Your answer: Digestion is already happening in the mouth, which explains why lipase is active in the mouth. The same is true for the pancreas. 4. Describe the process of bile emulsification of lipids and how it improves lipase activity. Your answer: Emulsification separates clumps of bile. This aids lipase activity.
