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Biology AS CIE

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  1. 1-cell-structure
    10 主题
  2. 2-biological-molecules
    19 主题
  3. 3-enzymes
    13 主题
  4. 4-cell-membranes-and-transport
    16 主题
  5. 5-the-mitotic-cell-cycle
    8 主题
  6. 6-nucleic-acids-and-protein-synthesis
    9 主题
  7. 7-transport-in-plants
    11 主题
  8. 8-transport-in-mammals
    16 主题
  9. 9-gas-exchange
    6 主题
  10. 10-infectious-diseases
    6 主题
  11. 11-immunity
    10 主题
课 2, 主题 14
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2-2-carbohydrates-and-lipids AS reducing-and-non-reducing-sugars

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Exam code:9700

Reducing & non-reducing sugars

  • Sugars can be classified as reducing or non-reducing; this classification is dependent on their ability to donate electrons

  • Reducing sugars can donate electrons (the carbonyl group becomes oxidised), the sugars become the reducing agent

    • Thus reducing sugars can be detected using the Benedict’s test as they reduce the soluble copper sulphate to insoluble brick-red copper oxide

    • Examples: glucose, fructose, maltose

  • Non-reducing sugars cannot donate electrons, therefore they cannot be oxidised

    • To be detected non-reducing sugars must first be hydrolysed to break the disaccharide into its two monosaccharides before a Benedict’s test can be carried out

    • Example: sucrose

Diagram explaining OIL RIG; oxidation is the loss of electrons, reduction is the gain of electrons, with highlighted words for clarity.
The mnemonic to remember the definitions for oxidation and reduction

Examiner Tips and Tricks

Become familiar with the OILRIG mnemonic to remember what happens to a molecule when electrons are lost from it (oxidation) or gained by it (reduction). 

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