Biological Molecles - Water

Question 1

How are hydrogen bonds formed in water

Answer 1

An attraction forms between the delta positive part of the hydrogen and delta negative part of the oxygen

Question 2

What type of molecule is water

Answer 2

Water is a dipolar molecule

Question 3

Define specific heat capacity

Answer 3

Specific heat capacity is the energy required to raise the temperature of 1kg of water by 1’c

Question 4

Why does water have a high specific heat capacity

Answer 4

Because it takes a lot of energy to break the hydrogen bonds between the H2O molecules

Question 5

How does water having a high specific heat capacity benefit humans

Answer 5

It acts as a buffer to body cells as it’ s temperature doesn’t change too much

Question 6

How does water having a high specific heat capacity benefit aquatic animals

Answer 6

Seas and lakes don’t change temperature too much so animals are protected

Question 7

Define latent heat of vaporisation

Answer 7

Latent heat of vaporisation is the amount of energy required to change 1kg water to a gas

Question 8

How is water cooled by having a large latent heat of vaporisation
(2 things)

Answer 8

1. When heated some of the H2O molecules gain enough KE to escape into the atmosphere
2. When true molecules evaporate they take the KE with them and so cool the water down

Question 9

What is the KE lost from evaporation

Answer 9

The KE lost is the latent heat of vaporisation

Question 10

Hope does having a large latent heat of vaporisation benefit humans

Answer 10

When humans sweat is removes KE and so cools the body down

Question 11

Define what cohesion is

Answer 11

Due to the polarity of water, H2O molecules become attracted to each other and form hydrogen bonds

Question 12

Why does strong cohesion help water

Answer 12

It’s allows H2O molecules to stick together and flow as a continuous steam (mass flow)

Question 13

How is strong cohesion of water beneficial to plants

Answer 13

Water moves from the roots to the leaves of a plant up the xylem in a continuous stream

Question 14

How is strong cohesion of water beneficial to small insects

Answer 14

Forms surface tension on lakes where water meets air and so small animals can live on the top of the water as it acts as a surface skin

Question 15

Define what a solvent is

Answer 15

A solvent is a liquid that dissolves solutes

Question 16

How do molecules dissolve in water

Answer 16

The delta charges in water pull polar molecules apart causing them to separate and dissolve

Question 17

What types of molecules can water dissolve

Answer 17

Water can dissolve polar molecules

Question 18

Name two ways in which water being a good solvent benefits humans

Answer 18

1. All metabolic reactions happen when dissolved in water

2. When dissolved, molecules can be transported around the human body

Question 19

Define what a metabolite is

Answer 19

A metabolite is a substance that is formed or is needed for metabolic reactions to take place

Question 20

Why is water a good metabolite for humans (2 things)

Answer 20

1. Hydrolyses large molecules in digestion

2. Condensation reactions when synthesising important molecules

Question 21

How ins ice useful

Answer 21

As ice is less dense than water it floats on the surface of water and and traps infrared radiation in the water to keep it insulated