AQA A Level Biology

Revision Notes

1.1.3 Monosaccharides

Test Yourself

Monosaccharides: Common Examples

  • 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 Benedict’s test as they reduce the soluble copper sulphate to insoluble brick-red copper oxide

  •  Examples of reducing sugars include: glucose, fructose and galactose
    • Fructose and galactose have the same molecular formula as glucose however they have a different structural formula
    • The different arrangement of atoms in these monosaccharides gives them slightly different properties

  • 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

OILRIG, downloadable IGCSE & GCSE Biology revision notes

The is a helpful mnemonic to remember the definitions of oxidation and reduction.

Exam Tip

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).

You've read 0 of your 0 free revision notes

Get unlimited access

to absolutely everything:

  • Downloadable PDFs
  • Unlimited Revision Notes
  • Topic Questions
  • Past Papers
  • Model Answers
  • Videos (Maths and Science)

Join the 80,663 Students that ❤️ Save My Exams

the (exam) results speak for themselves:

Did this page help you?

Lára

Author: Lára

Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.