Lab Quiz

Chemical and Physical Processes of Digestion Lab Quiz

This activity contains 20 questions.

	Refer to Activity 1: Assessing Starch Digestion by Salivary Amylase. What do tubes 2, 6 and 7 reveal about pH and amylase activity?   pH does not affect amylase activity. Amylase has no affect on starch. Amylase needs to be at body temperature to work. pH has a strong affect on amylase activity.

	Which pH buffer allowed the highest amylase activity?   9.0 7.0 5.0 2.0

	Which tube indicates that the amylase did not contain maltose?   1 3 5 7

	If control tubes were left out, what objections could be raised against the statement "Amylase digests maltose to starch"?   Starch has to be mixed with water to be broken down. Starch needs to be present to initiate maltose breakdown. Contamination of maltose or starch would yield a false positive result. Amylase has to be in the presence of water to function.

	Why would the amylase present in the saliva not be active in the stomach?   The pH in the stomach is constantly changing. The pH in the stomach is too high. The temperature in the stomach is too low. The pH in the stomach is too low.

	What effect does boiling have on enzyme activity?   Boiling inactivates enzymes. Boiling lowers the activation energy of enzymes. Boiling renatures enzymes. Boiling enhances enzyme activity.

	Refer to the data you collected for Activity 2: Assessing Cellulose Digestion. Which tubes showed a positive test for the IKI reagent?   Tubes 6 and 7 Tubes 1 and 2 Tubes 4, 5, and 6 Tubes 1, 2, and 3

	Which tubes showed a positive test for the Benedict's reagent?   Tubes 1, 2, 3, and 7 Tubes 4, 5 and 6 Tubes 6 and 7 Tubes 4 and 5

	What was the effect of freezing tube 1?   Freezing enhanced the enzyme activity. Freezing inactivated the enzyme. Freezing had no effect. Freezing denatures the enzyme.

	How does the effect of freezing differ from the effect of boiling?   Freezing enhances enzyme activity. Freezing denatures enzymes. Freezing causes enzymes to be more sensitive to pH. Freezing has no effect on enzyme activity.

	Which of the following explanations best describes the effect of amylase on glucose in tube 3?   Amylase had no effect on the glucose. Amylase caused the glucose to bind together and form glycogen. Amylase was inactivated by the glucose. Amylase enhanced glucose breakdown.

	What was the effect of amylase on cellulose in tube 4?   Amylase denatured the cellulose. Amylase caused the cellulose to bind together to form lecithin. Amylase had no effect on cellulose. Amylase enhanced cellulose breakdown.

	Judging from the results of tubes 4, 5, and 7, what can be concluded about the digestion of cellulose?   Whether or not cellulose is digested is dependent on the pH level. Cellulose is not digestible by bacteria. Salivary amylase does not digest cellulose. Salivary amylase digests cellulose.

	What was the effect of peptidase in tube 6?   Peptidase initiated starch breakdown. Peptidase had no effect because it doesn't work on carbohydrate substrates. Peptidase digested the starch. Peptidase denatured the starch.

	Refer to Activity 3: Assessing Protein Digestion by Pepsin. Which pH provided the highest pepsin activity?   7.0 2.0 5.0 9.0

	Tubes 1 and 2 contained the same substances. Why were their optical density measurements different?   The spectrophotometer was not working. The contents of tube 1 were boiled, which inactivated the pepsin; therefore there was no activity in tube 1. The contents of tube 2 were incubated for a longer period of time than the contents of tube 1. The contents of tube 2 were not boiled; therefore there was no activity in tube 2.

	What would happen if the temperature were decreased to 10°C?   The amount of BAPNA digested would be greater. The amount of BAPNA digested would be the same. BAPNA would not be digested because the temperature would be too low. The amount of BAPNA digested would be less.

	Refer to Activity 4: Assessing Fat Digestion by Pancreatic Lipase and the Action of Bile. What was the difference in activity between test tubes 1 and 2?   Tube 2 had greater activity because there was no bile to inhibit the enzyme function. Tube 2 had less activity because water and oil do not mix. Tube 1 had greater activity because of the presence of bile. Tube 1 had limited activity due to the presence of bile.

	Which pH resulted in maximum lipase activity?   2.0 5.0 7.0 9.0

	In theory, would lipase be active in the mouth?   No, lipase would not be active in the mouth because the pH conditions in the mouth are too low. Yes, in theory lipase would be active in the mouth because the pH optimum is relatively neutral.

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