Water

Question 1

Benefits of water as a liquid

Answer 1

Provide habitats for living things in rives, lakes and seas
major component of tissue in organisms
reaction medium in chemical reactions
transport medium, eg. blood and vascular tissue

Question 2

What happens to liquids as they get colder

Answer 2

Becomes more dense until 4 degrees, 4-0 (ice) is less dense as molecules align in a structure less dense than water

Question 3

Benefits of ice being less dense than water

Answer 3

aquatic organisms have a stable environment throughout winter
ponds and other bodies of water are insulated against cold- reduces rate of heat loss

Question 4

How does hydrogen bonding occur between water molecules

Answer 4

Polar structure- hydrogen bonds form between neighbouring hydrogen (+) and oxygen (-) atoms of adjacent water molecules (The attraction between individual water molecules creates a bond known as a hydrogen bond.)

Question 5

Cohesion

Answer 5

When water molecules get close together, oppositely charged parts of the atom attract, forming hydrogen bonds

Question 6

Surface tension

Answer 6

resistance of external forces, allowing the surface to contract because molecules are being applied to it.

Question 7

Benefits of water as a solvent

Answer 7

molecules can move around and react together
molecules and ions can be transported around living things whilst dissolved in water (root hairs)
polarity allows water molecules to attract/bind to solute molecules

Question 8

Benefits of high specific heat capacity

Answer 8

Living things need a stable temperature for enzyme-controlled reactions to happen properly (eg. hydrolysis and condensation)
stable environment for aquatic organisms
small variations in temperature

Question 9

Benefits of high latent heat of vaporisation

Answer 9

Molecules and held together by hydrogen bonds, so a large amount of energy is needed for water to evaporate
Water can help to cool living things and keep temp stable
eg. sweat and transpiration

Question 10

Why is water referred to as polar

Answer 10

Oxygen atom in a water molecule has a greater no. protons in nucleus, exerting a stronger attraction for shared electrons
Oxygen atom becomes slightly negative, hydrogen slightly positive

Question 11

Hydrophilic

Answer 11

substances that can become part of the hydrogen bonded structure and dissolve in water