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CIE AS Biology (9700) 2019-2021 Revision Notes

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2. Biological Molecules

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Exam Tip

It is important to know where the hydrogen bonds form between water molecules (oxygen of

one water molecule to the hydrogen atom of another).

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CIE AS Biology (9700) 2019-2021 Revision Notes

savemyexams.co.uk

2. Biological Molecules

YOUR NOTES

⬇

© 2015-2021 Save My Exams Ltd

CIE AS Biology (9700) 2019-2021 Resources

REVISION NOTES 

 

  TOPIC QUESTIONS 

 

  PAST PAPERS

Page 70

2.3.8 THE ROLE OF WATER IN LIVING ORGANISMS

Water Molecules: In Living Organisms

Water has many essential roles in living organisms due to its properties:

The polarity of water molecules

The presence and number of hydrogen bonds between water molecules

Solvent

As water is a polar molecule many ions (e.g. sodium chloride) and covalently bonded polar

substances (e.g. glucose) will dissolve in it

This allows chemical reactions to occur within cells (as the dissolved solutes are more

chemically reactive when they are free to move about)

Metabolites can be transported efficiently (except non-polar molecules which are

hydrophobic)