CAIE A Level Biology 9700 · Biological molecules

Biological molecules: explain question

Explain6 marksChallenge

Water has several properties that are important for life. The table below lists three biological roles of water.

Biological roleProperty of water
Sweating cools the body
Many metabolic reactions occur in aqueous solution
Water acts as a temperature buffer in aquatic habitats

(a) Complete the table by writing the correct property from the list below next to each role.

Properties: solvent action, high specific heat capacity, high latent heat of vaporisation

(b) Explain how hydrogen bonding between water molecules gives rise to the property that enables sweating to cool the body.

0 words · 6 marks

No account needed for your first marks. Your answer is used only to mark it.

How this question is marked

6 marks, so the mark scheme is looking for about 6 separate creditworthy points. Making the same point twice in different words earns it once.

Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.

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