Biological Molecules (WATER)

Question 1

Is water an organic or inorganic molecule

Answer 1

organic molecule

Question 2

Describe what is meant by the term diploar

Answer 2

when there is an unequal distribution of charge

Question 3

Which atom is described as slightly negative in a water molecule

Answer 3

Oxygen

Question 4

Which atom is described as slightly positive in a water molecule

Answer 4

Hydrogen

Question 5

What are hydrogen bonds and when are they formed

Answer 5

Hydrogen bonds are weak bonds formed between the slightly positive hydrogen of one water molecule with the slightly negative oxygen of another water molecule

Question 6

Give 5 important properties of water

Answer 6

Its an important metabolite (used in hydrolysis and condensation reactions)
Its a good solvent
It has a high latent heat of vaporisation
It can buffer changes in temperature
Its very cohesive

Question 7

Explain why water is a good solvent

Answer 7

Because water is polar, the slightly positive hydrogen will attract any negative ions and the slightly negative oxygen will attract any positive ions. This means the ions will get totally surrounded by water molecules and dissolve

Question 8

Why is the fact that water is a good solvent useful

Answer 8

Living organisms can take up useful substances dissolved in water and transport it around the body

Question 9

What molecules cant dissolve in water

Answer 9

Ones that are non polar eg: lipids

Question 10

How does water have good cohesion + why is it useful

Answer 10

Due to their polarity and hydrogen bonding, water molecules tend to “stick together”
Strong cohesion helps water to flow, allowing it to move up the xylem in a continuous coloumn of water

Question 11

What does strong cohesion provide

Answer 11

surface tension - organisms such as pond skaters can live on the surface off water and therefore are protected from prey above

Question 12

Why is the fact that water can buffer ( resist) changes in temperature useful

Answer 12

Due its hydrogen bonds, water has a high specific heat capacity, therefore water doesn’t experience rapid changes in temperature so aquatic organisms habitats remain fairly stable. This also means enzyme activity isn’t affected

Question 13

What is the fact that water as a high specific latent heat of vaporisation useful

Answer 13

Living organisms are provided with a cooling effect when they sweat as when water evaporates, it carries away heat energy from a surface, lowering the skins temperature without loosing too much water

Question 14

Is water more or less dense in its frozen, solid form

Answer 14

Less dense - when water freezes it can float atop of water creating an insulating layer and maintains a liquid environment for aquatic organisms