Physioex Exercise 8
CHEMICAL AND PHYSICAL PROCESSES OF DIGESTION - ANSWERS
Please note: I do not include the charts as you still have to do the experiments and print the data and graphs.
What do tubes 2, 6, and 7 reveal about pH and amylase activity? Hint: What variable was changed in the procedure?
a. maximum of amylase is at pH 7.0 (tubes 2 & 5, brownish red) and pH 9.0 showed little activity (tubes 6 & 7, green)
Which pH buffer allowed the highest amylase activity?
Which tube indicates that amylase was not contaminated with maltose?
a. 3 - showed water
Which tubes indicate that the deionized water did not contain contaminating starch or maltose?
a. 3, 4 and 5 - all showed water
If we left out control tubes, 3, 4 and 5, what objections could be raised to the statement: "Amylase digests starch to maltose"? (Hint: Think about the purity of the chemical solutions.)
a. if control tubes 3, 4, and 5 were not done, then what is perceived as digestion might really be starch or maltose contamination.
Would the amylase present in saliva be active in the stomach? Explain your answer.
a. Saliva would not be active in the stomach because the stomach pH is too low.
What affect does boiling have on enzyme activity?
a. Boiling inactivates, or denatures, enzymes.
Which tubes showed that starch or cellulose was present?
a. 4, 5 and 6
Which tubes tested positive for the presence of reducing sugars?
a. 1, 2,3 and 7
What was the affect of freezing tube 1?
a. Freezing had no affect
How does the effect of freezing differ from the affect of boiling?
a. Freezing does not restrict enzyme activity
Does amylase use cellulose as a substrate? Hint: Look at the results for tube 4.
a. Amylase had no affect on the cellulose in tube #4
What effect did the addition of bacteria have on the digestion of