Variation & Evolution (chpt. 17) Flashcards
Classification
Placing organisms into groups based on similar characteristics
Taxonomy
The study of classification
Species
A group of organisms capable of interbreeding naturally to produce fertile offspring
Variation
The difference in characteristics between members of the same species
Can be acquired or inherited
What causes inherited variation
- Independent assortment of chromosomes during meiosis
- Crossing over of linked genes during meiosis
- Range of variation is possible when the egg and sperm join
Mutation
A sudden change in the amount or structure of DNA
E.g. of a gene mutation
Sickle cell anaemia
Cystic fibrosis
E.g. of a chromosome mutation
Down Syndrome
What is a gene mutation
A change in bases in the gene
E.g. cystic fibrosis
What is a chromosome mutation
A change in chromosome number or alteration of genes within a chromosome
Causes of mutations
- Spontaneous mutations
- Ionising radiation (UV rays, X-rays)
- Chemicals
- Viruses
Mutagens
Agents that cause mutations
Evolution
The way living things change genetically to produce new forms of life over long periods of time
Charles Darwin & Alfred Wallace
Natural selection
The process by which individuals with favourable variations are better adapted to the environment and will survive long enough to reproduce and pass on their genes to new generations
The theory of natural selection
1. More offspring produced than can be supported, causing competition to survive
2. Survival of the fittest
3. Accumulation of advantageous variations will result in variation
