Enzymes (OCR A Level Biology)

Exam Questions

3 hours33 questions
1
Sme Calculator
1 mark

Most human biological reactions require a catalyst.

Which of the following are functions of enzymes?

  • Enzymes cannot act on more than one substrate

  • Enzymes can catalyse chemical reactions

  • Enzymes can increase the activation energy

  • Enzymes can only catalyse one chemical reaction

Did this page help you?

2
Sme Calculator
1 mark

Which of the following factors can denature an enzyme?

  • Enzyme concentration

  • Inhibitors

  • Substrate concentration

  • Temperature and pH

Did this page help you?

3
Sme Calculator
1 mark

Which of the following statements is true regarding enzyme specificity?

  • Enzymes are not affected by the shape of the substrate

  • Enzymes can bind to any molecule they encounter

  • Enzymes can catalyse a wide range of different reactions

  • Enzymes can only bind to one specific substrate

Did this page help you?

4
Sme Calculator
1 mark

What is the role of coenzymes in enzyme-catalysed reactions?

  • Act as substrates for the enzyme

  • Carry electrons or chemical groups between enzymes

  • Facilitate the binding of the enzyme to another enzyme

  • Inhibit enzyme activity

Did this page help you?

5
Sme Calculator
1 mark

Which of the following statements is true regarding competitive inhibition?

1 It cannot be reversed
2 Inhibitor does not need to resemble substrate
3 The rate of the reaction is slowed down
  • 1, 2 and 3

  • Only 1 and 2

  • Only 2 and 3

  • Only 3

Did this page help you?

1
Sme Calculator
1 mark

Which of the following, A to D, is true of a competitive enzyme inhibitor?

  • binds to a site other than the active site

  • can bind irreversibly to the active site

  • changes the shape of the active site

  • effects can be overcome by adding more substrate

Did this page help you?

2
Sme Calculator
1 mark

The image below shows a diagram of an enzyme.

q15-1-paper-2-june-2019-ocr-a-level-biology

Which of the following could be a competitive inhibitor of this enzyme?

q15-2-paper-2-june-2019-ocr-a-level-biology

    Did this page help you?

    3
    Sme Calculator
    1 mark

    The following graph shows the rate of reaction of an enzyme in different substrate concentrations.

    q5-paper-1-june-2018-ocr-a-level-biology

    Which letter, A to D, shows the rate of reaction with a fixed quantity of competitive inhibitor?

      Did this page help you?

      4
      Sme Calculator
      1 mark

      The graph below shows how the rate of reaction of the enzyme trypsin changes with temperature. 

      xlh3y1-t-enzyme-rate-of-reaction-temp-mcq

      What is the temperature coefficient, Q10, of this reaction before the enzyme denatures? 

      • 0.05

      • 0.39

      • 1.19

      • 1.76

      Did this page help you?

      5
      Sme Calculator
      1 mark

      What is the correct definition of the term coenzyme?

      • A non-protein organic molecule, not permanently attached to an enzyme, but needed to allow the enzyme to function.

      • A molecule that binds to the enzyme, changing the shape of the active site, preventing an enzyme-substrate complex from forming.

      • An inorganic ion that forms the centre of a globular protein.

      • A metal ion that attaches to the enzyme, changing the shape of the active site, increasing the likelihood of a reaction.

      Did this page help you?

      6
      Sme Calculator
      1 mark

      Which of the graphs, A to D, represents the energy changes involved during an enzyme-controlled catabolic reaction?

      energy-changes-in-enzyme-catalysed-reactions-mcq

        Did this page help you?

        7
        Sme Calculator
        1 mark

        Which of the following, A to D, is an incorrect statement about enzymes?

        • Catalase catalyses extracellular reactions

        • Catalase catalyses intracellular reactions

        • Extracellular enzymes are produced inside the cell

        • Extracellular enzymes work outside the cell

        Did this page help you?

        8
        Sme Calculator
        1 mark

        A student investigated the effect of pH on the rate of an enzyme controlled reaction. The student measured the rate of product formation from the reaction. 

        What would be a suitable control for this investigation?

        An identical tube set up with:

        • No buffer

        • No buffer and no enzyme

        • No enzyme

        • No substrate

        Did this page help you?

        9
        Sme Calculator
        1 mark

        A student wished to use a starch solution of 0.01% for an enzyme experiment. A stock solution of 1.0% starch solution was provided. 

        Which of the following dilutions would be the best method to achieve the desired concentration with greatest precision, using standard laboratory equipment? 

        serial-dilution-method-mcq

          Did this page help you?

          1
          Sme Calculator
          1 mark

          Which of the following options is an intracellular process controlled by enzymes?

          • Digestion of a pathogen inside a phagolysosome

          • Hydrolysis of starch into simple sugars

          • Digestion of wood by hyphae of fungi

          • Conversion of fibrinogen to fibrin during blood clotting.

          Did this page help you?

          2
          Sme Calculator
          1 mark

          An investigation into the activity of catalase on liver tissue at different temperatures was completed with the volume of oxygen collected measured at different time intervals as an indication of catalase activity.

          The table below shows the results with the mean rate of reaction at each temperature calculated:

          Temperature (oC) Mean rate of reaction (cm3s-1)
          0 0
          10 0.21
          20 0.44
          30 0.86
          40 1.69
          50 1.32

          What is the correct calculated temperature coefficient (Q10) for the reaction between 20 oC and 30 oC.

          • 0.38

          • 0.51

          • 1.95

          • 2.02

          Did this page help you?

          3
          Sme Calculator
          1 mark

          Vitamins B2 and B3 are fundamental in the production of NAD and FAD which have an important role in some of the stages of respiration.

          Which of the following statements explain why it is recommended that patients suffering from fatigue take these vitamins as supplements?

          • NAD and FAD are coenzymes that carry electrons to the electron transport chain.

          • NAD and FAD are cofactors that stabilise the structure of ATP synthase.

          • NAD and FAD are inhibitors that reduce the activity of the Kreb’s cycle.

          • NAD and FAD are prosthetic groups that help to form the structure of ATP synthase.

          Did this page help you?

          4
          Sme Calculator
          1 mark

          The following graph shows a mammalian enzyme reaction taking place at different temperatures.ocr-a-1-4h-mcq-enzymes-graph

          Which of the following statements does not explain the differences in the shapes of the curves at different temperatures?

          • At 65oC there were more successful collisions.

          • The curve at 37oC levels off as the enzyme denatures.

          • At 20oC the reaction was not completed in 60 minutes.

          • The initial rate of reaction at 37oC was slower to begin with than at 65oC.

          Did this page help you?