Water

Question 1

What makes a water molecule polar? Which atoms make this happen and how?

Answer 1

Uneven distribution of charge within the molecule
Oxygen attracts electrons more strongly than hydrogen atoms

Question 2

Is water negatively or positively charged near its oxygen atom

Answer 2

Slightly negative

Question 3

Is water negatively or positively charged near its hydrogen atom

Answer 3

Slightly positive

Question 4

Examples of metabolic reactions where water is the metabolite

Answer 4

Condensation and hydrolysis

Question 5

What does water being a solvent do?

Answer 5

It allows gases to readily diffuse as well as enzymes and waste products such as ammonia and urea
It allows metabolic reactions to occur (faster in solution)

Question 6

Does water have a high or low specific heat capacity

Answer 6

High

Question 7

Why does water have a high specific heat capacity

Answer 7

Because water molecules stick together with LOTS of hydrogen bonds meaning lots of energy is required to break them

Question 8

What does water having a high specific heat capacity help with

Answer 8

It helps to minimise temperature fluctuations in living things, acting as a buffer

Question 9

Are hydrogen bonds weak or strong? Why does this differ for water molecules?

Answer 9

Individual hydrogen bonds are weak and easily broken
However, they occur in very large numbers in water and in organic polymers, creating a major force in combination

Question 10

What type of bonds are present in water

Answer 10

Hydrogen bonds

Question 11

What do the hydrogen bonds in water require to evaporate? What does this mean?

Answer 11

A lot of energy to evaporate 1 gram of water
This means water has a relatively large latent heat of vaporisation

Question 12

What does the large latent heat of vaporisation of water mean for evaporation? What does this help with? Give an example

Answer 12

Evaporation of water provides a cooling effect with little water loss
This helps organisms maintain a constant internal body temperature
Eg sweating

Question 13

What does strong cohesion between molecules in water enable? How?

Answer 13

Effective transport of water in a tube (like the xylem)
The strong cohesion supports columns of water because the surface tension at the water air boundary is high

Question 14

What are the 5 properties of water

Answer 14

Metabolite
Solvent
Has a relatively high specific heat capacity
Relatively large latent heat of vaporisation
Has strong cohesion between water molecules

Question 15

Why is water being a metabolite important

Answer 15

It can be used in metabolic reactions such as condensation/hydrolysis/photosynthesis/respiration

Question 16

Why does water having a high SHC mean it can act as a buffer? Why is this helpful for aquatic animals?

Answer 16

Because it can gain or lose lots of energy without changing temperature
It makes a good habitat for aquatic organisms as the temperature is more stable than land and helps them to maintain a constant internal body temperature

Question 17

What does a solvent do

Answer 17

Dissolves solutes (other substances)