water

Question 1

Explain how water is involved in the transport of molecules in living organisms.

Answer 1

1. water is a solvent ;
2. water is {slightly charged / dipole / polar / eq}
3. idea that {polar molecules / charged molecules / ions}
   dissolve/eq in water ;
4. correctly named example of a solute transported ;

Question 2

Vitamin C is soluble in water.
(a) The diagram below shows the structure of vitamin C. Using the information in the diagram, suggest why vitamin C is soluble in water.
page 28 classified

Answer 2

1. presence of -OH/hydroxyl groups ;
2. these are polar groups ;
3. form hydrogen bonds with water (molecules) ;

Question 3

what type of molecule is water?

Answer 3

Its polar (dipolar) due to oxygen is slightly negatively charged and hydrogen is slightly positively charged causing it to be a polar molecule (uneven distribution of charge)

Question 4

What type of bonds does each water molecule contain?

Answer 4

2 covalent bonds
4 hydrogen bonds

Question 5

define hydrogen bond

Answer 5

a bond formed between a slightly positive hydrogen and non-metal that slightly negative it’s an attraction force (they are weak but numerous in water)

Question 6

What are some key properties of water

Answer 6

it’s an excellent solvent
it’s dipolar
high melting and boiling points
high surface tension
High specific heat capacity
high latent heat of vaporisation
its density and freezing point
high cohesion force
low viscosity

Question 7

What is the importance of water being an excellent solvent

Answer 7

• It’s an excellent solvent for ions and polar molecules as it’s dipolar.

-many ionic substances will dissolve in it and allow them to move freely and transport from one place to another

-enzymes and hormones are dissolved in water and are easily transported

-minerals can be absorbed by plants except when it’s dissolved in water

-transports and dissolves oxygen carbon dioxide hormones nutrients antibodies wastes digested food all around the body

Question 8

what is the importance of water having high specific heat capacity

Answer 8

-forms a stable internal environment (blood, cytoplasm) as it minimises fluctuations in temperatures inside cells (avoid rising up temperature of living organisms)

-suitable environments (seas, oceans) for organisms as the sea temperature is constant

-needed to prevent denaturing of enzymes

Question 9

what is the importance of water having a high latency to vaporisation

Answer 9

-has a cooling effect when it’s evaporated in sweating and transpiration

-dehydration is prevented and living organisms are protected

Question 10

what is the importance of water having high surface tension

Answer 10

-many aquatic organisms spent it from this property (example water striders), insects that live on the surface of the water

-sticking of water molecules together (they pull each other up) allows water to rise up in the Xylem without falling down

Question 10

what is the importance of water having high cohesion force

Answer 10

-due to numerous hydrogen bonds water molecules stick together following as one unbroken column (mass flow), example: blood vessels and Xylem

-water molecules pull other water molecules along due to cohesion force making it great for transport

Question 11

What is the importance of water having low viscosity

Answer 11

-it’s easy and fast to flow in vessels without friction and can pass through Xylem without resistance

Question 12

What is the importance of water having density that decreases when the temperature falls below 4°C

Answer 12

ice therefore floats on liquid water and insulates the water under it, thus reducing the tendency of aquatic living organisms to freeze and completely so increasing their chance of survival in cold conditions