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Chapter 3 Practice Paper: Enzymes and the digestive system — question paper

QuizQuipPractice Series
QQ/GCSE-BIO/CH3

GCSE (9–1) · GCSE Biology (Foundation and Higher)

Chapter 3 Practice Paper

Enzymes and the digestive system

Duration: 40 minutes
Total: 30 marks
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READ THESE INSTRUCTIONS FIRST

  • Answer all questions.
  • Section A contains ten multiple-choice questions. Choose one answer, A, B, C or D, for each.
  • Section B contains structured questions. Write your answers in the spaces provided.
  • You may use a calculator.
  • The number of marks is given in brackets [ ] at the end of each question or part question.
  • The total mark for this paper is 30.

Original practice material written for the MOE GCSE Biology syllabus. It is not an official MOE or school examination paper. Chapter 3: levels of organisation, enzyme action and denaturation, the digestive enzymes and their products, bile, the food-tests and amylase-pH required practicals, and rate calculations.

For Examiner’s Use
Section A/ 10
Section B/ 20
Total/ 30

Section A: Multiple-choice questions[10 marks]

Choose one answer for each question. Each question is worth 1 mark.

  1. 1

    The active site of an enzyme is

    1. Aanywhere on the cell membrane
    2. Bthe substrate itself
    3. Cthe region where the substrate binds
    4. Dthe product of the reaction
    ( )
  2. 2

    Which sentence about denaturation is correct?

    1. Athe active site changes shape so the substrate no longer fits
    2. Bthe enzyme dies like a cell
    3. Cthe enzyme digests itself
    4. Dthe substrate changes shape
    ( )
  3. 3

    Bile is stored in the

    1. Aliver
    2. Bpancreas
    3. Csmall intestine
    4. Dgall bladder
    ( )
  4. 4

    Starch is digested into

    1. Aamino acids
    2. Bsimple sugars
    3. Cfatty acids
    4. Dglycerol
    ( )
  5. 5

    A food sample turns Biuret reagent purple. The sample contains

    1. Astarch
    2. Bsugar
    3. Cprotein
    4. Dfat
    ( )
  6. 6

    Far from its optimum pH, an enzyme reaction slows to almost nothing because

    1. Athe enzyme is denatured
    2. Bthe substrate is used up
    3. Cthe products build up
    4. Dthe enzyme leaves the body
    ( )
  7. 7

    A reaction finishes in 25 seconds. Its rate is

    1. A0.4 per second
    2. B25 per second
    3. C2.5 per second
    4. D0.04 per second
    ( )
  8. 8

    Which food test must be heated to show a positive result?

    1. Aiodine test
    2. BBenedict’s test
    3. CBiuret test
    4. Dethanol emulsion test
    ( )
  9. 9

    The products of fat digestion are absorbed mainly through

    1. Athe stomach wall
    2. Bthe liver
    3. Cthe villi of the small intestine
    4. Dthe large intestine
    ( )
  10. 10

    An organ system is

    1. Aa group of organs working together on one function
    2. Ba group of identical cells
    3. Ca single specialised cell
    4. Dany tissue inside an organ
    ( )

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided.

  1. 11

    An enzyme’s reaction rate was measured at four temperatures.

    Rate data

    Temperature (°C)Rate (arbitrary units)
    152
    254
    358
    453
    1. (a)

      Identify the temperature that gave the highest rate in this experiment.

      [1]
    2. (b)

      Explain why the rate rose between 15 °C and 35 °C.

      [2]
    3. (c)

      Explain why the rate fell at 45 °C.

      [2]
    4. (d)

      State why the true optimum may lie between 35 °C and 45 °C.

      [1]
  2. 12

    Solution X was tested with three food reagents: iodine stayed orange-brown, Benedict’s gave orange after heating, and Biuret stayed blue.

    1. (a)

      State which food X contains.

      [1]
    2. (b)

      State what the iodine result shows.

      [1]
    3. (c)

      State what the Biuret result shows.

      [1]
    4. (d)

      Explain why the Benedict’s tube was heated.

      [2]
  3. 13

    This question is about bile and fat digestion.

    1. (a)

      Name the two organs bile passes through between being made and being released into the small intestine.

      [2]
    2. (b)

      Describe what happens to fat droplets during emulsification and explain the effect on lipase.

      [2]
    3. (c)

      State one further way bile helps digestion in the small intestine.

      [1]
  4. 14

    Two enzyme reactions were timed: reaction P finished in 100 s; reaction Q finished in 50 s.

    1. (a)

      Calculate the rate of each reaction, in per second.

      [2]
    2. (b)

      State how many times faster reaction Q was.

      [1]
    3. (c)

      State one change that would halve reaction P’s time.

      [1]

— End of paper —