Explain what happens to glucose and amino acids after they have been absorbed into the blood from the small intestine.

Eduqas GCSE Biology — 1.3.2 Digestion and absorption · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Glucose and amino acids are absorbed into the blood through the villi of the small intestine.
They are carried by the hepatic portal vein directly to the liver.
In the liver, glucose is released into the bloodstream for use in cellular respiration, providing energy for cells.
Amino acids are taken up by the liver and other tissues to synthesise new proteins needed for growth and repair.

Examiner tips

  • Use the exact sequence: absorption → portal vein → liver → utilisation. Mention ‘cellular respiration’ for glucose and ‘protein synthesis’ for amino acids. Keep answer concise and use UK spelling.
  • common_mistakes
  • :
  • Confusing the portal vein with the systemic circulation. Failing to specify that glucose is used for energy via respiration. Lumping all amino acids into a single function without noting protein synthesis.

Mark scheme (4 marks)

  1. Glucose and amino acids are absorbed into the blood / bloodstream via the villi
  2. They are transported to the liver via the hepatic portal vein
  3. Glucose is used in respiration (by cells / for energy)
  4. Amino acids are used to build / synthesise new proteins (for growth and repair)

Key terms in this question

glucose · amino acids

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