Topic 1.7 - Water

Question 1

How do hydrogen bonds occur between water molecules? (2)

Answer 1

• Water is a polar molecule
• Slightly negative charged oxygen atoms attract slightly positively charged hydrogen atoms of other water molecules

Question 2

What are the 5 key properties of water?

Answer 2

1) Metabolite
2) Solvent
3) Cohesive
4) High specific heat capacity
5) High latent heat of vaporisation

Question 3

What is the importance of water being a metabolite?

Answer 3

Used in condensation / hydrolysis / photosynthesis / respiration

Question 4

What is the importance of water being a solvent? (2)

Answer 4

1) Allows metabolic reactions to occur
2) Allows transport of substances

Question 5

What is the importance of water being a cohesive? (2)

Answer 5

1) Supports columns of water (transpiration stream in the xylem)
2) Produces surface tension (supporting small organisms to walk on water)

Question 6

What is the importance of water having a high specific heat capacity? (4)

Answer 6

1) Buffers changes in temperature
2) As it can gain / lose a lot of heat / energy without changing temperature
3) Good habitat for aquatic organisms as temperature is more stable than land
4) Helps organisms maintain a constant internal body temperature

Question 7

What is the importance of water having a high latent heat of vaporisation? (2)

Answer 7

1) Allows effective cooling via evaporation of a small volume e.g. sweat
2) So helps organisms maintain a constant internal body temperature