Lesson 4.2.2.1

4.2.2.1 The human digestive system Quiz: AQA Combined Science, Unit 2

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 4.2.2.1, The human digestive system: 20 multiple choice questions for the AQA GCSE Combined Science (8464), Unit 2: Organisation, written with Revision Ninja.

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The 20 questions

  1. Which enzyme breaks down starch?

    • Protease
    • Bile
    • Amylase
    • Lipase

  2. What are proteins broken down into by proteases?

    • Glucose
    • Glycerol
    • Amino acids
    • Fatty acids

  3. What are lipids broken down into by lipases?

    • Glucose and amino acids
    • Amino acids only
    • Glycerol and fatty acids
    • Nucleotides and sugars

  4. What do carbohydrases break carbohydrates down into?

    • Simple sugars
    • Fatty acids
    • Glycerol ions
    • Amino acids

  5. Where in the body is bile stored?

    • Gall bladder
    • Stomach
    • Liver
    • Pancreas

  6. How does bile assist in lipid digestion?

    • Absorbs glucose
    • Emulsifies fats
    • Digests proteins
    • Acidifies stomach

  7. What substance does alkaline bile neutralise in the gut?

    • Amylase
    • Hydrochloric acid
    • Bile salts
    • Amino acids

  8. What feature of an enzyme determines its specificity?

    • Tail length
    • Active site shape
    • Mass
    • Colour

  9. Which model explains how a substrate fits an enzyme?

    • Bohr model
    • Plum pudding model
    • Lock and key model
    • Fluid mosaic model

  10. What does the loss of blue-black iodine colour indicate in an amylase test?

    • Acid is neutralised
    • Lipids are formed
    • Protein is present
    • Starch is gone

  11. Why does an enzyme reaction rate increase as temperature rises towards its optimum?

    • More frequent collisions
    • Enzymes become larger
    • Active sites multiply
    • Substrates are destroyed

  12. What happens to an enzyme when exposed to a pH far from its optimum?

    • Molecules stop moving completely
    • Temperature decreases rapidly
    • Active site changes shape
    • Substrate becomes an enzyme

  13. A reaction produces 60 cm³ of gas in 30 seconds. What is the rate?

    • 2 cm³ per second
    • 1800 cm³ per second
    • 30 cm³ per second
    • 0.5 cm³ per second

  14. Which process increases the rate of fat digestion by lipase?

    • Emulsification
    • Oxidation
    • Neutralisation
    • Denaturation

  15. Why is a water bath used during enzyme practical investigations?

    • Control temperature
    • Increase pH level
    • Stop substrate decay
    • Speed up reactions

  16. What is the role of bile in the small intestine?

    • Digest proteins directly
    • Neutralise stomach acid
    • Absorb fatty acids
    • Produce amino acids

  17. Which food type is detected by a positive Benedict's test?

    • Lipids
    • Proteins
    • Starch
    • Reducing sugars

  18. Biuret reagent turns purple in a food sample. What is present?

    • Protein
    • Lipid
    • Glucose
    • Starch

  19. What are the products of digestion used to build in the body?

    • Inorganic mineral ions
    • Digestive enzymes only
    • New cell components
    • Waste excretions

  20. What are proteins broken down into during digestion?

    • Amino acids
    • Glycerol
    • Fatty acids
    • Simple sugars

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