Water

Question 1

Covalent bonding in water:

Answer 1

In water molecules the 2 hydrogen atoms are slightly positively charged and the oxygen atom is slightly negatively charged.

Question 2

Water is a polar molecule…

Answer 2

This means that water molecules attract each other and form weak interactions called hydrogen bonds.

Question 3

5 properties of water:

Answer 3

• as a metabolite
• as a solvent
• high latent heat of vaporisation
• high specific heat capacity
• cohesion

Question 4

Water in metabolite reactions:

Answer 4

Water is involved in many metabolic reactions including hydrolysis, condensation, photosynthesis and respiration.

Question 5

Water is a solvent;

Answer 5

Many substances dissolve in water. Many metabolic reactions in organisms rely on dissolved substances being able you react with each other. Polar ( hydrophilic molecules ) dissolve in water.

Question 6

High latent heat of vaporisation:

Answer 6

• it takes a large amount of energy to evaporate water ( to change its state from a liquid to a gas ) due to its many hydrogen bonds
• sweating is effective cooling for the skin for this reason as it requires more energy than it would without the hydrogen bonds

Question 7

High specific heat capacity:

Answer 7

• the many hydrogen bonds in water impede water molecules from moving.
• a large amount of energy is needed to increase the temperature of water. It has a high specific heat capacity
• this means that large bodies of water such as lakes have a fairly constant temperature ( thermal buffer ) providing a stable environment for living organisms

Question 8

Cohesion:

Answer 8

• the hydrogen bonds in water stop molecules from moving. They hold the molecules of water together by cohesion.
• cohesion between water molecules allows a continuous stream of water to be drawn through the xylem of plants in a continuous colum
• cohesion at the surface of a body of water is called surface tension which some small organisms take advantage of