O LevelBiologyCambridgeTopic Questions5. Enzymes5.1 Enzyme Action

Enzyme Action (Cambridge O Level Biology)

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1
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Which of the following best describes what an enzyme is?

  • A catalyst that speeds up reactions in cells, being used up in the process

  • A protein that speeds up reactions in cells, being used up in the process

  • A carbohydrate that functions as a biological catalyst

  • A protein that functions as a biological catalyst

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2
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What is a feature of all catalysts?

  • They are made from protein

  • They are not changed by the reaction

  • They are broken down in the reaction

  • They are altered by the rate of the reaction

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3
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What can be said to be true of all enzymes?

  their optimum pH is 7 they are made from amino acids they move about randomly in a fluid
A X X X
B X ✓ ✓
C ✓ X ✓
D ✓ ✓ X

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4
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What is the name for the group of compounds that ensures metabolic reactions take place in living organisms at a speed necessary to sustain life?

  • Proteins

  • Enzymes

  • Catalysts

  • Hormones

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51 mark

What is the correct description of enzymes?

  • biological catalysts made of lipids

  • biological catalysts made of proteins

  • catalysts that slow down chemical reactions and are changed by the reaction

  • catalysts that speed up chemical reactions and are changed by the reaction

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1
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The image below represents a chemical reaction.

5-q4-specificity-1

Which of the following best represents the enzyme responsible for catalysing this reaction?

5-q4-specificity-2

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2
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The action of an enzyme in a chemical reaction is outlined in the diagram below.

5-q6-enzyme-substrate

Which row of the table below is correct?

  product enzyme enzyme-substrate complex
A E H G
B E G F
C H G F
D H F G

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3
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The diagrams below show an amylase enzyme catalysing the breakdown of part of a starch molecule into smaller molecules of maltose.

Which diagram has three correct labels?

5-q13-starch-digestion

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11 mark

Enzyme action can be explained by the lock and key hypothesis. 

Which row is correct for the active site and the substrate?

  active site is on
the enzyme		 active site is on
the substrate		 substrate is the
lock		 substrate is the
key
A ✓ x ✓ x
B ✓ x x ✓
C x ✓ ✓ x
D x ✓ x ✓

Key:

✓ = Yes

x = no

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