Topic B4 Flashcards
Darwin’s theory
Theory of evolution by natural selection
Evolution
Slow and continuous change of organisms from one generation to the next
Natural selection
The process by which characteristic gradually becomes more or less in a population
What supports Darwin‘s theory?
Antibiotic resistant bacteria
Fossils that provide evidence for human evolution
Ardi
Lucy
Turkana Boy
Ardi
4.4 million years old
Feet:Ape-like big time for climbing
Limbs:Ape-like 
Brain size:chimpanzee
Lucy
3.2 million years old
Feet:Arched for walking know a ape-like big toe
Limbs:between human and ape
Brain size:bit bigger than chimpanzee
Turkana boy
1.6 million years old
Feet, limbs and brain size: human like
Ways to date tools
Structural features and rock layers
How stone tools became more complex
1.Simple pebble tools used to scrape meat from bones
2.Rock shape to make more complex tools to hunt
3.Flint tools, pointed for use
Classification
Organising living organisms into groups based on their features
Five kingdoms
-Animals
-plants
-fungi
-protists
-prokaryotes
Modern classification system
Now organism genes’ can be analysed- the more similar the base sequence of a gene the more closely related the organisms
Three domains organisms are now split into before being split into the five kingdoms
-bacteria (true bacteria)
-archaea (different type of prokaryotic cell) 
-eukarya (including protists, fungi, plants and animals)
Selective breeding
Breeding plants or animals for particular characteristics
Stages of selective breeding
1.Individuals with desired characteristics bred together
2.Repeated over generations
3.Eventually all offspring have desired characteristics
Benefits of selective breeding
Agriculture:crops and animals can be bred to produce bigger yields e.g. more meat
Medicine:can be used in medical research
Risks of selective breeding
-Less genetic variation in population means it could be wiped out by new disease
-Breeding closely related animals can cause health problems
Genetic engineering
Cutting a gene responsible for useful characteristic from one organisms genome and putting it into another
Benefits of the Genetic engineering
Agriculture:can make crops resistant to herbicides
Medicine:GM bacteria can produce human insulin which is used to treat diabetes
Risks of genetic engineering
-Some GM animals have health problems
-GM crops can negatively affect food chains
