Topic 1: Water

Question 1

Describe how hydrogen bonds form between water molecules.

Answer 1

-Water is a polar molecule.
-Hydrogen bond forms between the slightly negative oxygen atom of one water molecule and the slightly positive hydrogen atom on another water molecule.

Question 2

State the 5 properties of water.

Answer 2

-Metabolite
-Solvent
-High specific heat capacity
-High latent heat of vaporisation
-Strong cohesion between water molecules.

Question 3

Explain the importance of water being a metabolite.

Answer 3

Used in metabolic reactions

Question 4

Explain the importance of water being a good solvent.

Answer 4

-Allows metabolic reactions to occur (faster in solution)
-Allows transport of substances

Question 5

Explain the importance of water having a high specific heat capacity.
(Animals + Aquatic organisms)

Answer 5

-Helps organisms maintain a constant internal body temperature as water buffers changes in temperature, due to the hydrogen bonds absorbing fair amounts of energy, so a lot of heat is needed to change the temperature.
-Good habitat for aquatic organisms as temperature more stable than land

Question 6

Explain the importance of water having a high latent heat of vaporisation.

Answer 6

Allows effective cooling via evaporation, as a lot of energy is used to convert water from a liquid to a gas.
Evaporation of water from skin’s surface takes a lot of heat energy with it.
Helps organisms maintain internal body temperature

Question 7

Explain the importance of water being cohesive.

Answer 7

-Able to support columns of water - useful in the transpiration stream
-Water molecules stick together when in contact with air, which creates surface tension, allowing small organisms to walk on water.

Question 8

Define high specific heat capacity.

Answer 8

The amount of energy required to raise the temperature of 1Kg of that substance by 1*C