Biology - Variation and Evolution

Classification

placing objects into groups based on similar characteristics

Taxonomy

the science of classifying organisms

Species

a group of similar organisms that are capable of naturally interbreeding with each other to produce fertile offspring

Variation

individual members of a species show different characteristics

Acquired Variations

are not inherited but are learned or developed during life

Inherited Variations

controlled by genes

Mutation

a spontaneous change in the amount or structure of DNA

Mutagens

agents that cause mutations

Gene Mutation

aka point mutation

a change in a single gene

Sickle Cell Anaemia

an example of a gene mutation

Chromosome Mutation

a large change in the structure or number of one or more chromosomes

Down Syndrome

an example of a chromosome mutation

→ extra chromosome

Evolution

the way in which living things change genetically to produce new forms of life over long periods of time

Darwin and Wallace

the two scientists responsible for the theory of natural selection

Theory of Natural Selection

• overbreeding

• population numbers remain constant

  → there is a struggle for existence

• inherited variations occur in populations

  → natural selection

Natural Selection

the process by which organisms with genetically controlled characteristics that allow them to be well adapted to their environments will survive and reproduce to pass on their genes to following generations

Speciation

the production of new species as a result of evolution

Fossil

remains of something that lived a long time ago

→ evidence for evolution