Summary - Life Sciences (Biology)

Topic 1.1. Chemistry of life




All living organisms are made up of atoms of
different elements.
Some elements can be minerals or compounds.
 Atoms: The smallest unit of substance.
 Elements: A pure substance made up of
identical atoms.

,  Compound: A substance containing two or more
elements in a fixed ratio.
 Minerals: Simple inorganic substances required
by living organisms.
 Micro-elements: Needed in a small quantity
 Macro-elements: Needed in a large quantity

Table of minerals, the function and deficiency are
found on pages 36-38 of textbook.

Use of fertilisers in over-utilised soils
Plants need nutrients from the air and soil.
When living organisms die, they decompose.

 Farmers use fertilisers to replace the nutrients.
 If too much fertiliser is used :

,  Eutrophication occurs: The high amount of
nutrients in the water causes algae and other
aquatic plants to grow quickly and rapidly
 The overpopulating algae and plants decrease
the suns ability to reach the bottom of the water
body.
 The plants die and rot
 The number of decomposition bacteria increase
and use up large amounts of oxygen