Lesson 2.1.4a
2.1.4a Enzyme action and factors affecting rate Quiz: OCR Biology, Unit 1
20 questions
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Lesson 2.1.4a, Enzyme action and factors affecting rate: 20 multiple choice questions for the OCR Biology (H020), Unit 1: Foundations in biology, written with Revision Ninja.
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The 20 questions
-
How do enzymes increase metabolic reaction rates?
- Increase kinetic energy
- Alter reaction equilibrium
- Consume substrate molecules
- Lower activation energy
-
Where does the enzyme catalase carry out its function?
- Inside cells
- Synaptic cleft
- Gut lumen
- Blood plasma
-
Where does the enzyme amylase act during digestion?
- Inside ribosomes
- Extracellularly
- Intracellularly
- Within lysosomes
-
Which region of an enzyme binds to the substrate?
- Promoter region
- Active site
- Allosteric site
- Polar head
-
Which model proposes that enzyme active sites change shape upon substrate binding?
- Sliding-filament model
- Induced-fit model
- Fluid-mosaic model
- Lock-and-key model
-
What is the direct effect of lowering a reaction's activation energy?
- Increased reaction rate
- Increased activation time
- Decreased temperature
- Decreased substrate mass
-
What primarily determines an enzyme's high substrate specificity?
- Tertiary structure
- Primary sequence
- Quaternary assembly
- Fibrous nature
-
Why does enzyme reaction rate plateau at very high substrate concentrations?
- Product accumulation
- Substrate inhibition
- Enzyme denaturation
- Active site saturation
-
A reaction has rate 5 units/s at 20 degrees C, and its Q10 is 2. What is the rate at 30 degrees C?
- 7.5 units/s
- 20 units/s
- 10 units/s
- 5 units/s
-
What is the main cause of enzyme denaturation at high temperatures?
- Increased collisions
- Enzyme synthesis
- Bonds breaking
- Substrate depletion
-
How do extreme pH levels cause enzyme denaturation?
- Shortening polypeptides
- Removing coenzymes
- Adding kinetic energy
- Disrupting ionic bonds
-
When substrate is in excess, what is rate proportional to?
- Product volume
- Activation energy
- Enzyme concentration
- Inhibitor presence
-
Product forms at 12 cm3 in 60 s in an enzyme investigation. What is the mean rate?
- 720 cm3 per second
- 5 cm3 per second
- 0.05 cm3 per second
- 0.2 cm3 per second
-
What fraction of original concentration remains after a serial dilution halves enzyme concentration three times?
- One eighth
- One sixteenth
- One quarter
- One sixth
-
What causes the sharp fall in the rate of an enzyme-catalysed reaction above the optimum temperature?
- Inhibition
- Depletion
- Saturation
- Denaturation
-
What factor primarily causes the rate of an enzyme reaction to roughly double for each 10 degree rise?
- Substrate depletion
- Activation loss
- Enzyme synthesis
- Kinetic energy
-
What factor limits the rate when reaction speed remains constant despite adding more enzyme?
- Inhibitor presence
- Substrate concentration
- Enzyme concentration
- Optimum temperature
-
Where does the optimum pH typically lie if rates are 40 at pH 5, 80 at pH 7, and 20 at pH 9?
- Below pH 5
- Above pH 9
- Near pH 7
- At pH 6
-
A reaction runs at rate 4 units at 25 degrees C with Q10 = 2. What is the rate at 45 degrees C?
- 16 units
- 8 units
- 32 units
- 12 units
-
What structural feature is directly destroyed when heat causes an enzyme to denature?
- Peptide bonds
- Substrate molecule
- Primary structure
- Active site
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