Water

Question 1

Cohesion

Answer 1

Water molecule ‘sticking together’ due to hydrogen bonds

Question 2

Adhesion

Answer 2

Water molecules ‘sticking to other molecules on surfaceses’ due to hydrogen bonds

Question 3

Capillary action

Answer 3

Adhesion of water molecules to the inner surface of tube pulls water upwards across the surface

Question 4

Important features

Answer 4

Cannot be compressed- provides support eg hydrostatic skeletons and turgor pressure in plants
Transparent light can pass through to reach plants and animals in aquatic environments

Question 5

Application of water

Answer 5

• can be transported as a continuous column in xylem vessels as they can form hydrogen bonds with other molecules and the surface
• can be used as a medium for transport and enable chemical reactions
• readily dissolves gasses ( co2, o2), inorganic ions + small hydrophilic molecules ( amino acids and atp), waste (ammonia and urea) and enzymes

Question 6

Describe a water molecule

Answer 6

The two hydrogens are slightly positive and the oxygen has two lone pairs so is slightly negative

Question 7

Water as a habitat

Answer 7

Cohesion causes surface tension- pondskaters use as a habitat
Liquid water has a higher density then ice - ice floats on surface insulating from cold air so the lake or ocean never completely freezes
Ice is used as a habitat
Has a high specific heat capacity = aquatic environment maintains a relatively stable temperature regardless of weather conditions

Question 8

Water in thermoregulation

Answer 8

Has a high latent heat of vaporisation = plants and animals can lose excess heat energy by evaporation of water from their surface= maintains stable body temp

Question 9

Water in living organisms

Answer 9

Mammals 65% water
Used in metabolism
- hydrolysis
- condensation reaction
- raw material in photosynthesis