Water

Question 1

Structure of water

Answer 1

The sharing of the electrons is uneven between the oxygen and hydrogen atoms → forms a dipole or polar molecule

This is what allows hydrogen bonds to form between water molecules

Question 2

Hydrogen bonding

Answer 2

Water’s polarity and its ability to form hydrogen bonds contribute to many properties:

Question 3

Properties of water: Solvent

Answer 3

Many ions (e.g., sodium chloride / NaCl) and covalently bonded polar substances (e.g., glucose) will dissolve in water

Allows chemical reactions to occur (as molecules become more reactive)

Allows efficient transport of metabolites

Question 4

Properties of water: High specific heat capacity

Answer 4

Why? Hydrogen bonds! - a lot of energy is required to break these bonds → temperature of water doesn’t change greatly

Advantage?
Provides a suitable habitat for organisms
Maintains optimal temperatures for enzyme activity and heat transfer in the blood plasma

Question 5

Properties of water: High latent heat of vaporisation

Answer 5

Large amounts of energy is required to break the many hydrogen bonds in water & change its state

Advantage?
Cooling effect - Organisms can lose a great amount of heat, without loosing too much water
E.g., transpiration from leaves, evaporation of water in sweat on the kin

Question 6

Properties of water: Cohesion & Adhesion

Answer 6

Hydrogen bonds between water molecules allows for strong cohesion between water molecules
Advantage? - Allows column of water to move through the xylem of plants & through blood vessels in animals

Water is also able to hydrogen bond to other molecules, such as cellulose, which is known as adhesion
Advantage? - This also enables water to move up the xylem due to transpiration