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Secondary Biology: Enzymes and Metabolic Reactions (Paper 1)
Secondary Biology: Enzymes and Metabolic Reactions (Paper 1)
Ten original questions cover enzymes as protein catalysts, optimum temperature and pH, the active site and rate calculations from two experiments.
Direct answer Rate is product divided by time, so convert units before comparing. Too much heat denatures the enzyme and the change is not reversed on cooling.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 |
| Suggested time | 25 |
| Difficulty mix | Foundation 4 · Intermediate 3 · Challenge 2 · Error redo 1 |
| Chapter | Chapter: Secondary Biology: Enzymes and Metabolic Reactions |
| Level | 4 basic, 3 advanced, 2 challenge and 1 redo question |
02 Questions (10 items)
- FoundationWhat kind of chemical is an enzyme?
- FoundationWhat is the optimum temperature for most human enzymes?
- FoundationWhat is the region where an enzyme binds its substrate called?
- Foundation24 cm³ of gas is produced in 8 minutes. What is the mean rate?
- IntermediateTube A gives 12 cm³ in 4 minutes and tube B gives 18 cm³ in 6 minutes. Which is faster?
- IntermediateRaising the temperature from 20 to 30 degrees takes the rate from 2 to 4 cm³ per minute. By what factor does it rise?
- IntermediateWhy does enzyme activity fall almost to zero above 70 degrees Celsius?
- ChallengeAn enzyme works best at pH 2. What happens to its rate at pH 7?
- ChallengeEnzyme is added to 15 cm³ of solution and the reaction finishes in 5 minutes. What happens if the amount of enzyme doubles?
- Error redoA pupil writes that a hot enzyme is broken down into amino acids. What is the error?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | A protein, acting as a biological catalyst. | Enzymes are proteins and are reused rather than used up. |
| 2 | About 37 degrees Celsius. | The rate peaks near body temperature and falls when it is too hot. |
| 3 | The active site. | The active site is complementary in shape to the substrate, like a lock and key. |
| 4 | 3.0 cm³ per minute (24 divided by 8). | Rate equals product formed divided by time, and the unit must be given. |
| 5 | Neither: both give 3.0 cm³ per minute (12 divided by 4 equals 18 divided by 6). | Convert both results to the same time unit before comparing; do not compare raw volumes. |
| 6 | It rises 2 times (4 divided by 2). | Warmer molecules move faster and collide with the active site more often. |
| 7 | The enzyme denatures, so the active site changes shape and the substrate no longer fits. | Denaturation is irreversible; cooling back does not fully restore activity. |
| 8 | It falls sharply because the change moves the enzyme away from its optimum pH. | Optimum pH differs between enzymes: pepsin is acidic while trypsin is alkaline. |
| 9 | The rate roughly doubles to about 6.0 cm³ per minute, but it levels off when substrate becomes limiting. | Doubling helps only while enzyme is limiting; extra enzyme does nothing when substrate runs short. |
| 10 | Heat changes the shape of the enzyme (denaturation); it is not broken into amino acids. | Denaturation disrupts the three-dimensional shape while the peptide bonds remain. |
04 What to do after marking
- After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
- Repeat the same item two days later; move to the next paper only when both attempts are correct.
- Parents only need the answer and note columns; there is no need to explain every item.
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Questions and answers are written originally by the TutorZone team and are not taken from any school, publisher or examination authority paper. Every value is checked by computer.
