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About This Drill
AP Biology — Unit 3 — Environmental Impacts on Enzymes — Drill 10 is a practice drill. It contains 5 original questions created by Brian Stewart, a Barron's test prep author with over 20 years of tutoring experience.
Compare enzyme and inorganic catalyst performance across a temperature range to understand how environmental conditions affect biological catalysis. Evaluate experimental claims about enzyme denaturation and the limits of biological systems.
Passage
Researchers studied the effect of temperature on the activity of catalase, an enzyme that breaks down hydrogen peroxide (H2O2) into water and oxygen. Catalase was isolated from potato tissue and added to equal volumes of H2O2 at five temperatures. Enzyme activity was measured as the volume of O2 gas (mL) produced in 60 seconds.
Table 1. O2 production (mL) by catalase at varying temperatures.
| Temperature (C) | Trial 1 | Trial 2 | Trial 3 | Mean |
|---|
| 10 | 1.4 | 1.2 | 1.5 | 1.37 |
| 20 | 2.9 | 3.1 | 2.8 | 2.93 |
| 37 | 5.8 | 6.0 | 5.7 | 5.83 |
| 50 | 2.1 | 1.9 | 2.3 | 2.10 |
| 70 | 0.1 | 0.0 | 0.2 | 0.10 |
The same experiment was run using manganese dioxide (MnO2), an inorganic catalyst, which also decomposes H2O2. The MnO2 results showed O2 production increasing steadily with temperature across all five temperatures, including at 50C and 70C.
Questions in This Drill
- Based on the data in Table 1, which temperature represents the approximate optimum for catalase activity, and what feature of the data supports this conclusion?
- A researcher claims that the sharp decline in catalase activity between 37C and 70C is due to denaturation of the enzyme's protein structure. Which comparison from the experiment most directly supports this claim?
- If a small amount of the catalase solution that had been heated to 70C were cooled back to 37C and tested again, which result would be most consistent with irreversible denaturation having occurred?
- The enzyme catalase is found in almost all organisms that live in oxygen-containing environments. Which of the following best explains why catalase activity is critical for cell survival?
- A student argues: "Because MnO2 is a more effective catalyst than catalase at 70C, cells should use MnO2 instead of catalase to decompose H2O2." Evaluate this claim.