Chemical elements and water

The most frequently occurring elements in all living things:• Carbon (19%) • Hydrogen (10%) • Oxygen (65%) • Nitrogen (3%)

Other elements required in small amounts:

Sulphur (0.25%) Calcium (1.5%) Phosphorus (1%) Iron (0.7%) Sodium (0.15%)

The role of certain elements(S) In certain amino acids (cysteine and methionine), proteins form disulphide bonds(Ca) Found in bones and teeth, also involved in neurotransmitter release in synapses(P) Component of nucleic acids and cell membranes.(Fe) Found in haemoglobin (animals), allowing for oxygen transport(Na)Involved in the generation of nerve impulses in neurons

Structure of water molecules

Hydrogen is slightly positive

Oxygen is slightly negative

Hydrogen bonds between water molecules

Hydrogen bonds are weak.

Give an example of where this is

significant.

Special properties of water

Write 3 or 4 sentences for each of the properties of water:Thermal PropertiesCohesive PropertiesSolvent PropertiesOther Properties

The relationship between the properties of water and its use in living organisms as a coolant, medium for

metabolic reactions and transport medium

Outline this relationship using the following headings:

Coolant

Medium for Metabolic Reactions

Transport Medium