Biological Molecules (WATER) Flashcards
water
Is water an organic or inorganic molecule
organic molecule
Describe what is meant by the term diploar
when there is an unequal distribution of charge
Which atom is described as slightly negative in a water molecule
Oxygen
Which atom is described as slightly positive in a water molecule
Hydrogen
What are hydrogen bonds and when are they formed
Hydrogen bonds are weak bonds formed between the slightly positive hydrogen of one water molecule with the slightly negative oxygen of another water molecule
Give 5 important properties of water
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
Explain why water is a good solvent
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
Why is the fact that water is a good solvent useful
Living organisms can take up useful substances dissolved in water and transport it around the body
eg: mineral ions
What molecules cant dissolve in water
Ones that are non polar eg: lipids
How does water have good cohesion + why is it useful
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
What does strong cohesion provide
surface tension - organisms such as pond skaters can live on the surface off water and therefore are protected from prey above
Why is the fact that water can buffer ( resist) changes in temperature useful
Lots of energy is needed to break hydrogen bonding between water molecules due to its 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
What is the fact that water as a high specific latent heat of vaporisation useful
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
Is water more or less dense in its frozen, solid form
Less dense - when water freezes it can float atop of water creating an insulating layer and maintains a liquid environment for aquatic organisms
