2 - Foundations

Question 1

2.1.2

Why is water a polar molecule?

Answer 1

• Water forms covalent bonds between atoms
• In covalent bonds the electrons often spend more time closer to one atom than the other
• The atom with the greater share of negative electrons will be slightly negative
• Therefore the other atom will be slightly positive

Question 2

2.1.2

What is polarity?

Answer 2

When a molecule has regions of negativity and regions of positivity

Question 3

2.1.2

How do water molecules interact with eachother?

Answer 3

• Because they are polar they form hydrogen bonds due to the different positive and negative regions of the molecule interacting with the positive and negative regions of another water molecule
• Hydrogen bonds are weak interactions so they break and reform between the constantly moving water molecules

Question 4

2.1.2

Why does water have such unique characteristics?

Answer 4

The hydrogen bonds in water that occur in high numbers allow it to have unique characteristics that are essential to life

Question 5

2.1.2

What is good about water being a universal solvent?

Answer 5

It can dissolve many substances so chemical reactions can occur in the cytoplasm and can be used in transport in the blood

Question 6

2.1.2

What is good about water being a liquid at room temperature?

Answer 6

It can provide a liquid environment within cells and provides a habitat for aquatic organisms

Question 7

2.1.2

What is good about water specific heat capacity?

Answer 7

• Water has a high specific heat capacity due to large amounts of energy needed to break its bonds
• This allows water to resist temperature changes, creating a stable environment within cells and for aquatic organisms

Question 8

2.1.2

What is good about waters latent heat of fusion?

Answer 8

Water is slow to freeze and so can provide a stable environment for cells and aquatic organisms

Question 9

2.1.2

What is good about waters latent heat of vaporization?

Answer 9

The evaporation of water from an organisms surface provides a cooling effect e.g. sweat and transpiration

Question 10

2.1.2

What is good about the density of water?

Answer 10

• When water is a solid it is less dense so can float
• When bodies of water freeze over this stops them from becoming completely solid so the aquatic organisms can survive under the ice

Question 11

2.1.2

What is good about the capillarity of water?

Answer 11

• Water can go against gravity in narrow tubes, which is good for transpiration and the movement of water around roots and shoots

Question 12

2.1.2

what is good about surface tension in water?

Answer 12

The bonds in water give it surface tensions, which allows it to support aquatic animals, plants and insects on

Question 13

2.1.2

Why does water have so many properties?

Answer 13

Because it is polar

Question 14

2.1.2

What elements do carbohydrates contain?

Answer 14

only:
Carbon
Oxygen
Hydrogen

Question 15

2.1.2

What is the general formula for a carbohydrate?

Answer 15

Cx(H20)y

Question 16

2.1.2