General Biology

Name: Hannah Cuthbert Biol 1009 Lab Exercise 2: Enzyme Activity and Digestion of Carbohydrates and Proteins Instructions: Respond to the following questions from lab exercise 2 using complete sentences (where appropriate). For more information about each question, see the lab manual. Part A. Carbohydrate Digestion Macerated coleoples, water, and Benedict’s soluon 1. Is there a color change in the soluon? Is this a posive or negave Benedict’s test? Yes, there was a color change in the soluon. It turned reddish brown. This means it was a posive Benedict’s test. 2. Which substance was oxidized? Glucose was oxidized 3. Which substance was reduced? The cupric ion was reduced. Dry, ungerminated corn seeds Benedict’s soluon 4. Do ungerminated corn seeds store sugar or starch? Ungerminated corn seeds store starch. When I tested them with the Benedict soluon it turned a greenish color. 5. What is responsible for the conversion of starch to sugar in a seedling? The cotyledon secretes gibberellic acid into the outer layer of the endosperm, called the Aleurone layer. Then, the aleurone layer secretes enzymes into the center of the seed breaking down the starch into sugar. 6. Of what advantage to the plant is the presence of two forms of carbohydrates? The two advantages of the presence of these two forms of carbohydrates:  Starch stores the sugar unl it is ready to be used  Sugar is used for plant growth Part B: Protein Digestion Pineapple and hard-boiled egg white 7. What happens to the egg white in the two tubes? Hint: you must carefully look at the edges of the cooked egg white. Tube A (unboiled): the eggs have broken down a lile bit and created a cloudy soluon Tube B (boiled): the eggs looked the same and did not break down at all. 8. What eﬀect does boiling have on the enzyme bromelin? Boiling the pineapple juice destroys the enzyme bromelin . 9. Would you expect all enzymes to act similarly if they were boiled? Why? Yes, I would expect all enzymes to act similarly if they were boiled because all enzymes have a certain range of tolerance to pH and temperature to survive. Part C: Starch Digestion in Animals Soda cracker and Benedict’s soluon 10. Does a color change occur? Yes – turned a reddish brown 11. Is this a posive or negave test for a reducing sugar? This is a posive test for a reducing sugar Saliva and Benedict’s soluon 12 Does your saliva contain reducing sugar? No, my saliva does not contain a reducing sugar. The test remained a blue color. 12. Does it contain starch? No, it does not contain starch.

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