Victory for the ACT Student Text 15e

S CIENCE R EVIEW • 347

Passage IV Graph I shows the relationship between the relative rates of activity of enzymes A and B and temperature, with pH held constant. Graph II shows the relationship between the relative rates of activity of enzymes A and B and pH, with temperature held constant.

Passage Perfect Quickly comparing the similarities and differences of these two graphs can give you an edge when answering accompanying questions. You’ll understand the experiment more, and it’s likely the relationship between the graphs will be questioned.

Under which conditions is enzyme A most active? F. 40°C and a pH of 5 G. 45°C and a pH of 5 H. 45°C and a pH of 9 J. 50°C and a pH of 9 The optimum environment for enzyme B is: A. acidic. B. basic. C. either acidic or basic. D. neutral. At which of the following temperatures do enzymes A and B exhibit approximately the same relative rate of activity? F. 6.9°C G. 10°C H. 37°C J. 47°C At which pH do both enzymes A and B exhibit approximately the same relative rate of activity? A. 6.7 B. 10 C. 37 D. 60

24. At what temperature does enzyme A have about half the activity of enzyme B? F. 20°C G. 30°C H. 42°C J. 53°C At what temperature does enzyme B have about half the activity of enzyme A? A. 20°C B. 30°C C. 42°C D. 53°C 26. Over which of the following pH ranges will both enzymes A and B be active? F. 1 to 3 G. 3 to 6 H. 6 to 7.5 J. 7.5 to 10 27. At what pH will both enzymes A and B be at their maximum activity? A. 2 B. 5 C. 8.5 D. No such pH exists. 25.

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