The enzyme _______ has a pH optimum most similar to peak A in the above graph.

Question

A.  lipase
B.  pepsin
C.  pancreatic amylase
D.  trypsin
E.  salivary amylase
F.  chymotrypsin

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?

Gather Content
· What do you know about optimal pH for an enzyme? What other information is related to the question?

Choose Answer
· Given what you now know, what information is most likely to produce the correct answer?

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

B.  pepsin

Clarify Question
· What is the key concept addressed by the question?
        o The question asks about enzymes that work at pH 2.
· What type of thinking is required?
        o You are being asked to analyze the optimal pH for an enzyme.

Gather Content
· What do you know about optimal pH for an enzyme? What other information is related to the question?
        o Enzymes have an optimal pH that is typically matched to the environment in which they are active. Saliva has a pH of 7.4 and salivary amylase would have an optimal pH in this range, as seen in curve B. The pancreas secretes many digestive enzymes including trypsin and chymotrypsin, which digest proteins; pancreatic amylase, which digests starch; and lipase, which digests fat. Pancreatic fluid also contains bicarbonate, which neutralizes the HCl from the stomach and gives the chyme in the duodenum a slightly alkaline pH as seen in curve C. The stomach has a pH of 2 and the enzyme pepsin will have an optimal pH as seen in curve A.

Choose Answer
· Given what you now know, what information is most likely to produce the correct answer?
        o Pepsin is active in the acidic environment of the pH with an optimal pH of 2.

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o This question asked you to analyze the optimal pH for an enzyme. If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you think that the lower pH was an alkaline environment? Did you think that pancreatic enzymes were more active at an acidic than an alkaline environment?