Water

Question 1

What are the 5 functions of water?

Answer 1

> Water is a reactant
> Water is a solvent
> Water transports subtances
> Water helps with temperature control
> Water is a habitat

Question 2

Give example of water been a reactant.

Answer 2

Water is a reactant in reaction such as photosyntheses and in hydrolysis reactions such as digestion of starch, proteins and lipids.

Question 3

how the role of water been a reactant important?

Answer 3

its role as a reactant is important for digestion and synthesis of large molecules

Question 4

Describe water been a solvent.

Answer 4

water is a solvent, which means more substance dissolve in it.

Question 5

Advantages of water been a solvent

Answer 5

> Molecules and ions can move around and react together in water - many such reactions happen in the cytoplasm of cells
molecules and ions can be transported around living things whilst dissolved in water

Question 6

Describe water as transporting subtances

Answer 6

the fact its a liquid and a solvent means it can easily transport all sorts of materials, like glucose and oxygen around plants and animals

Question 7

Describe water been able to help with temperature control

Answer 7

Because it has a high specific heat capacity and a high latent heat of evaporation

Question 8

Describe water as a habitat

Answer 8

the fact that it helps with temperature control, is a solvent and become less dense when it freezes means many organism can survive and reproduce

Question 9

How is water a polar molecule?

Answer 9

because it has a partial negative charge on one side and a partial positive charge on the other

Question 10

What gives water a high specific heat capacity?

Answer 10

Hydrogen bonds as the bonds between water molecules can absorb a lot of energy

Question 11

What does water having a high specific heat capacity mean

Answer 11

it means water takes a lot of energy to heat it therefore it doesn’t experience rapid temperature change

Question 12

Definition of specific heat capacity

Answer 12

this is the temperature needed to raise the temperature of 1G of a substances by 1DC

Question 13

Advantage of liquid been at room temperature

Answer 13

> Provide habitats for living thing in rivers, lakes and seas
Form a major component of the tissues in living organism
Provide a reaction medium for chemical reactions

Question 14

Why does water have high latent heat of evaporation ?

Answer 14

because hydrogen bonds take a lot of energy to break

Question 15

Definition of high latent heat of evaporation

Answer 15

a lot of energy is used up when water evaporates ( changes from a liquid to a gas)

Question 16

Advantage of water having a high latent heat of evaporation

Answer 16

its useful for living organisms because it means water’s great for cooling things e.g. mammals are cooled when sweat evaporates

Question 17

What is cohesion?

Answer 17

its the attraction between molecules of the same type

Question 18

Describe water molecules as been cohesive

Answer 18

they are very cohesive ( they tend to stick together) because they’re polar

Question 19

Pro of water been cohesive

Answer 19

it helps water to flow making it great for transporting substances e.g. helps water to be transported up plant stems in the transpiration system

Question 20

What is surface tension?

Answer 20

all water molecules are hydrogen bonded to the one beneath them, hence more attracted to the one beneath than to the air molecules. this means the surface of the water contracts and gives the surface an ability to resist force applied to it

Question 21

pros of water having surface tension

Answer 21

Insects like pond - skaters can walk on water

Question 22

what makes ice less dense than water

Answer 22

water molecules are held further apart in ice than they are in liquid water because each water molecules forms four hydrogen bonds to other water molecules making it a lattice

Question 23

Pros of ice been less denser than water

Answer 23

> aquatic organisms have a stable environment in which to live through the winter
ice forms an insulating layer on top of water

Question 24

What is a hydrogen bond?

Answer 24

a weak bond between a slightly positively charged hydrogen atom in one molecule and a slightly negatively charged atom in another molecule