1.7 Water

Question 1

Is water polar

Answer 1

Yes

Question 2

Which part of a water molecule has a higher affinity for electrons

Answer 2

the oxygen

Question 3

Which atom in a water molecule is delta plus

Answer 3

the hydrogen

Question 4

Which atom in a water molecule is delta negative

Answer 4

oxygen

Question 5

What type of bond bonds the hydrogen to oxygen in a water molecule

Answer 5

a covalent bond

Question 6

Is water a dipolar molecule

Answer 6

yes

Question 7

What creates the cohesion in a water

Answer 7

the hydrogen bonds between the water molecules (NOT THE ATOMS)

Question 8

Are hydrogen bonds weak or strong

Answer 8

Individually weak but together they are considerably strong

Question 9

What is a hydrogen bond

Answer 9

An attraction between the slightly negative oxygen and slightly positive hydrogen

Question 10

why is there surface tension in water

Answer 10

because the hydrogen bonds face down because hydrogen bonds can’t bond water with air.

Question 11

What are the 8 properties of water

Answer 11

• Universal solvent
• High latent heat of evaporation
• High specific heat capacity
• Metabollite
• Ice less dense than water
• Cohesion
• Low viscosity
• Transparent

Question 12

What property of water is creates this biological importance: Chemical reactions inside cells happen in aqueous solutions; water is also the main transport medium in organisms

Answer 12

Universal solvent

Question 13

What property of water creates this biological importance: COOLANT: heat is lost from a surface when water evaporates from it, which acts as a cooling mechanism e.g. sweating

Answer 13

High latent heat of evaporation

Question 14

What property of water creates this biological importance: TEMP STABILISER: cells can absorb/ lose a lot of heat energy, but only show a small temperature changes, organisms can live in extreme climates

Answer 14

High specific heat capacity

Question 15

What property of water creates this biological importance: Water required in photosynthesis, in condensation reactions to synthesise biological polymers, and in digestion of polymers via hydrolysis

Answer 15

Metabollite

Question 16

What property of water creates this biological importance: THERMAL INSULATION : Ice floats on water insulating organisms to live below it

Answer 16

Ice less dense than water

Question 17

What property of water creates this biological importance: TRANSPORT MEDIUM: This means that long chains of water molecules don’t break

Answer 17

Cohesion

Question 18

What property of water creates this biological importance: Water can flow easily therefore act as a lubricant

Answer 18

Low viscosity

Question 19

What property of water creates this biological importance: Light can pass through it so underwater plants can photosynthesise

Answer 19

Transparent

Question 20

Explain how the polarity of the water molecule is created

Answer 20

When the atoms covalent bind the oxygen becomes slightly negative due to it have a higher affinity for the electrons, leaving the hydrogen slightly positive- meaning the water molecule is slightly charged , therefore polar

Question 21

What are the names of the bonds that attract water molecules together

Answer 21

Hydrogen bonds

Question 22

Define the term solvent

Answer 22

A liquid that substances can be dissolved in

Question 23

Give two properties of water that are important in the cytoplasm of cells.
For each property of water, explain its importance in the cytoplasm. ( 4 marks )

Answer 23

• Polar molecule
• Acts as a universal solvent
• Universal solvent
• Metabolic reactions occurs faster in solutions
• Reactive
• Takes place in hydrolysis/ condensation