Enzymes | OCR A-Level Biology A (H420)
Enzymes
- 43 questions
- 3 subtopics
- Module 2: Foundations in biology
- Component 01, Component 02 and Component 03
Enzymes is the fourth section of Module 2.
It covers what an enzyme does to the activation energy of a reaction, the lock and key and induced fit models of the active site, the conditions that raise and lower activity, and the cofactors, coenzymes and inhibitors that change how an enzyme works.
Sample questions from Enzymes
Answer each one closed book first, then open the answer.
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Enzyme action: lock and key and induced fit
Name an enzyme that catalyses intracellular reactions.
Show the answer
Catalase. -
Enzyme action: lock and key and induced fit
How does the induced-fit hypothesis differ from the lock and key model?
Show the answer
The induced-fit hypothesis proposes that the active site changes shape slightly as the substrate binds, forming a more precise fit. -
Factors affecting enzyme activity
In the Q₁₀ formula, what do R₁ and R₂ represent?
Show the answer
R₁ is the rate of reaction at the lower temperature; R₂ is the rate of reaction at a temperature 10°C higher. -
Factors affecting enzyme activity
How is temperature kept constant in an enzyme investigation?
Show the answer
The tubes are placed in a thermostatically controlled water bath, and the enzyme and substrate are left to reach that temperature separately before they are mixed. -
Cofactors, coenzymes and enzyme inhibition
How do competitive inhibitors reduce enzyme activity?
Show the answer
Competitive inhibitors bind to the active site of an enzyme, preventing substrate binding. -
Cofactors, coenzymes and enzyme inhibition
What is a non-reversible inhibitor?
Show the answer
A non-reversible inhibitor binds permanently to an enzyme, permanently preventing enzyme activity.
The 3 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Enzyme action: lock and key and induced fit | Intracellular and extracellular enzymes, what determines specificity, the active site and the two models of how a substrate binds, and the lowering of activation energy. | 13 |
| Factors affecting enzyme activity | How temperature, pH, enzyme concentration and substrate concentration change the rate, the temperature coefficient Q10, and why serial dilutions are used. | 18 |
| Cofactors, coenzymes and enzyme inhibition | Cofactors and coenzymes and where they come from, competitive and non-competitive inhibitors, reversible and non-reversible inhibition, and end-product inhibition. | 12 |
How the guide is worked
Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.
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Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
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Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
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Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.
Read the full method, the return schedule and the research behind it.
Nearby sections
OCR A-Level Biology A Active Recall Guide
Every section, not just this one. 1,833 questions with their answers.