Lesson 3.3.3.1

3.3.3.1 Digestion and absorption of food Quiz: AQA Biology, Unit 3

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.3.3.1, Digestion and absorption of food: 20 multiple choice questions for the AQA Biology (7402), Unit 3: Organisms exchange substances with their environment, written with Revision Ninja.

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The 20 questions

  1. Which enzyme hydrolyses starch into maltose in the mammalian digestive system?

    • Endopeptidase, secreted by the stomach wall and active only at low pH values.
    • Maltase, bound to the membrane of epithelial cells in the stomach lining.
    • Lipase, secreted by the liver and stored in the gall bladder until a meal is eaten.
    • Amylase, secreted by the salivary glands and the pancreas.

  2. Which enzymes hydrolyse disaccharides such as maltose and sucrose to monosaccharides in the ileum?

    • Pancreatic lipases secreted into the lumen of the ileum from the pancreatic duct.
    • Endopeptidases secreted by the stomach wall and carried into the small intestine.
    • Membrane-bound disaccharidases on the epithelium of the ileum.
    • Salivary amylases that continue to digest starch throughout the whole of the small intestine.

  3. What is the role of bile salts in the digestion of lipids?

    • They emulsify lipid droplets, increasing their surface area for the action of lipase.
    • They bind to glucose molecules and transport them across the epithelium by facilitated diffusion.
    • They neutralise the acid from the stomach so that proteins can be digested in the ileum.
    • They hydrolyse lipids directly into fatty acids and glycerol, without the help of any enzyme.

  4. Which enzymes are involved in the digestion of proteins in the mammalian gut?

    • Lipases and bile salts that act on triglycerides in the small intestine.
    • Amylases, maltases and sucrases that act on starch and disaccharides.
    • Pepsinogens and lactase that act on milk proteins and sugars only.
    • Endopeptidases, exopeptidases and membrane-bound dipeptidases.

  5. Which substances are absorbed into the epithelial cells of the ileum by co-transport?

    • Bile salts and cholesterol, which are transported by carrier proteins against the gradient with ATP.
    • Fatty acids and glycerol, which pass through the phospholipid bilayer by simple diffusion.
    • Maltose and sucrose, which pass into the cells directly by osmosis of water.
    • Amino acids and monosaccharides such as glucose, using the sodium ion gradient.

  6. What is the role of micelles in the absorption of lipids?

    • They digest triglycerides into glucose so that the cells can absorb it by co-transport.
    • They carry amino acids across the epithelium by facilitated diffusion through channels.
    • They carry fatty acids and monoglycerides to the epithelium, where they are absorbed.
    • They are attached to the cell walls of the ileum and digest maltose into glucose.

  7. Which statement describes the digestion of starch in a mammal?

    • Starch is converted to amino acids by endopeptidases before it reaches the ileum.
    • Starch is hydrolysed directly to glucose by a single enzyme with no intermediate products.
    • Starch is hydrolysed to maltose by amylase, and maltose is then hydrolysed to glucose by maltase.
    • Starch is converted to fatty acids by lipase, which is then absorbed by co-transport.

  8. A researcher uses Visking tubing containing starch and amylase in water. After 30 minutes the water is tested. Which result would show absorption of the products of digestion?

    • The water contains maltose or glucose that passed through the tubing wall.
    • The water contains no sugars because the tubing is impermeable to all small molecules.
    • The water contains starch because amylase has not yet started to digest it.
    • The water contains proteins because the tubing allows amylase to pass out of the tube.

  9. A pH or bile salt investigation measures the rate of digestion by a digestive enzyme. Which result would be expected if bile salts are added to a lipase reaction?

    • The rate of lipid digestion increases, because bile salts emulsify the lipid droplets.
    • The rate of lipid digestion is unchanged, because bile salts have no effect on lipid droplets.
    • The rate of lipid digestion decreases, because bile salts denature lipase immediately.
    • The rate of lipid digestion increases, because bile salts convert lipase into amylase.

  10. A student claims that co-transport requires energy from ATP at every step. Which evaluation is most accurate?

    • The claim is partly wrong, because the sodium gradient is set up by active transport, and co-transport then uses it.
    • The claim is correct, because co-transport moves substances down a gradient using ATP directly.
    • The claim is wrong, because co-transport uses sodium to move substances only by simple diffusion.
    • The claim is correct, because co-transport always requires ATP hydrolysis at the carrier protein.

  11. Which enzyme is responsible for hydrolysing peptide bonds within a polypeptide chain in the stomach or small intestine?

    • Endopeptidase
    • Exopeptidase
    • Lipase
    • Dipeptidase

  12. A person lacks membrane-bound disaccharidases in the ileum. What is the most likely effect on digestion?

    • Amino acids are absorbed faster, because the epithelium has no enzymes to compete with.
    • Fatty acids cannot be absorbed, because bile salts are not able to emulsify them at all.
    • Starch cannot be digested in the mouth, so glucose is not released into the blood at all.
    • Disaccharides such as maltose and sucrose cannot be fully hydrolysed to monosaccharides for absorption.

  13. Which of these events is an example of hydrolysis during digestion?

    • A peptide bond is broken by water to release two smaller polypeptides or amino acids.
    • Two amino acids are linked by a peptide bond to form a dipeptide with water released.
    • Fatty acids are joined to glycerol to form a triglyceride with water as a product.
    • Two glucose molecules are joined by a glycosidic bond to release a water molecule.

  14. Which property of amino acid co-transport explains its dependence on the sodium gradient?

    • The amino acid is converted into sodium ions inside the cell before absorption occurs.
    • The carrier protein binds sodium and amino acid together and moves both across the membrane.
    • The amino acid diffuses through the bilayer, and sodium is then pumped out with ATP.
    • The amino acid binds to a channel that opens only when sodium is absent from the cell.

  15. A diet high in fat is eaten. Which process is most reliant on micelles?

    • Absorption of maltose through membrane-bound disaccharidases in the epithelium.
    • Absorption of fatty acids and monoglycerides by the epithelial cells of the ileum.
    • Absorption of amino acids by co-transport with sodium ions in the ileum.
    • Absorption of glucose by co-transport with sodium ions from the lumen.

  16. Why is digestion of large molecules to smaller ones necessary before absorption across the ileum?

    • Large molecules are always absorbed by osmosis, so digestion is not needed for them at all.
    • Large molecules are already in solution, so digestion is needed only to remove them from the blood.
    • Large molecules are absorbed more quickly than small ones, so digestion is needed only for glucose.
    • Large molecules cannot cross the membranes of epithelial cells, but smaller products can be absorbed.

  17. Which statement about enzymes in the small intestine is correct?

    • Digestive enzymes are only found in the stomach and do not act in the small intestine.
    • Digestive enzymes are unaffected by pH and act at the same rate in all parts of the gut.
    • Some digestive enzymes are attached to the epithelium, so the final hydrolysis takes place at the cell surface.
    • All digestive enzymes are secreted into the lumen and none remain attached to the epithelium.

  18. Which sugar is absorbed by the ileum after maltose has been hydrolysed by maltase?

    • Glucose, absorbed by co-transport with sodium ions into the epithelial cells.
    • Starch, which is absorbed intact into the epithelial cells by osmosis of water.
    • Sucrose, which is absorbed intact through aquaporin channels in the membrane.
    • Maltose, which is absorbed intact into the epithelial cells by simple diffusion.

  19. What is the function of lipase in the small intestine?

    • It hydrolyses starch into maltose in the lumen of the ileum by breaking glycosidic bonds.
    • It hydrolyses triglycerides into fatty acids and monoglycerides.
    • It emulsifies fat droplets into smaller droplets by lowering the surface tension of the fat.
    • It transports fatty acids across the epithelium by facilitated diffusion through channels.

  20. A dipeptide is hydrolysed by a membrane-bound dipeptidase. What are the products?

    • One maltose molecule and one amino acid.
    • One amino acid and one glucose molecule.
    • Two fatty acids and one glycerol molecule.
    • Two amino acids.

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