Water

Question 1

Water is a covalent compound made up of ……….

Answer 1

2 hydrogen atoms and 1 oxygen . Oxygen has a slight negative charge and hydrogen atoms have a slight positive charge = polar molecule.

Hydrogen bond form between water molecules causing them to stick together.

Question 2

High specific heat capacity

Answer 2

Water absorbs relatively large amounts of heat before its temperature changes so it acts as a buffer to temperature fluctuations.

This helps maintain body temp of body and the bodies of water e.g. lakes.

Question 3

Large latent heat of vaporisation

Answer 3

Water absorbs large amount of heat before it evaporates so its effective in cooling.
It helps organisms to maintain a constant body temperature

Question 4

Cohesion between water molecules

Answer 4

Water molecules tend to stick together so column of water doesn’t break when pulled up a narrow tube e.g. xylem during transpiration. Also produce surface tension at an air water surface e.g. pond skater can walk on water.

Question 5

Metabolite in many metabolic reactions

Answer 5

Water is reactive. Condensation reactions release H2O and forms a chemical bond and hydrolysis requires H2O to break bond

Question 6

Universal solvent

Answer 6

Ions and polar molecules can be dissolved so water can dissolve other substances e.g. oxygen, urea. So most metabolic reactions take place in solutions. The advantage of metabolic reactions taking place in solution is that random movement if molecules increases so the rate of successful collisions increases.