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IGCSEBiology: Co-ordinated Sciences (Double Award)CIERevision Notes7. Human NutritionHuman Diet & DigestionHydrochloric Acid: Extended

Hydrochloric Acid: Extended (CIE IGCSE Biology: Co-ordinated Sciences (Double Award))

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Emma

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Hydrochloric Acid: Extended

Extended Tier Only

  • The stomach produces several fluids which together are known as gastric juice
  • One of the fluids produced is hydrochloric acid
  • This kills bacteria in food and gives an acid pH for enzymes to work in the stomach

How is a low pH helpful in the stomach?

  • The low pH kills bacteria in food that we have ingested as it denatures the enzymes in their cells, meaning they cannot carry out any cell reactions to maintain life
  • Pepsin, produced in the stomach, is an example of an enzyme which has a very low optimum pH - around pH 2
  • The hydrochloric acid produced in the stomach ensures that conditions in the stomach remain within the optimum range for pepsin to work at its fastest rate

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    Emma

    Author: Emma

    Expertise: Biology

    Prior to working at SME, Emma was a Biology teacher for 5 years. During those years she taught three different GCSE exam boards and two A-Level exam boards, gaining a wide range of teaching expertise in the subject. Emma particularly enjoys learning about ecology and conservation. Emma is passionate about making her students achieve the highest possible grades in their exams by creating amazing revision resources!