Topic 4 - Natural Selection And Genetic Modification Flashcards
What is evolution?
Gradual change in inherited traits within population over time
How does evolution occur?
Natural selection
Outline the theory of natural selection
Genetic variation exists due to mutations
Selection pressures exist
Random mutation gives selective advantage
Organism better adapted and survives
Organism reproduces passing on alleles
Frequency of advantageous alleles increases.
Why does competition between organisms in a habitat exist?
Resources within a habitat required for survival are limited
Give some examples of competition between organisms within a habitat
Animals - food, shelter, mates…
Plants - lights, water, minerals…
Describe how antibiotic resistance in bacteria can be used as an example to illustrate the process of evolution
Genetic variation exists due to spontaneous mutations.
Antibiotics act as selection pressure.
Mutations give bacterium antibiotic resistance.
Bacterium better adapted survive.
Reproduces passing on resistant gene.
Why is development of antibiotic resistance in bacteria a good study for evolution?
Bacteria reproduce rapidly, allowing fist hand observation of evolution
How can the observation of fossils provide evidence for evolution?
Older fossils contain simpler organisms.
Newer fossils contain more complex organisms.
Can be organised in chronological order, observe changes in time.
Describe role of Darwin in development of theory of evolution by natural selection
Studied variety of organisms whilst travelling around world on HMS beagle.
Noted that traits can be passed from parents to offspring.
Proposed idea of ‘survival of fittest’
Describe role of Wallace in development of theory of evolution by natural selection
Similar to Darwin’s.
Gathered more evidence.
How has the theory of evolution by natural selection impacted modern biology and society?
Enables classification of organisms
Influences modern medicine - importance of finishing antibiotic treatments
What fossils have provided evidence for human evolution?
Ardi - 4.4 million years old
Lucy - 3.2 million years old
Leakey discovered 1.6 million year old fossils
What clues does Ardi give scientists about human evolution?
Female hominid fossil shows phenotypic traits which encompass characteristics of humans and apes.
Ape: long arms, large toes
Human: bone structure suggests upright walking
What clues does Lucy give scientists about human evolution?
Female hominid fossil shows phenotypic traits more human like than Ardi
Structure of bones and feet more adapted to walking
Brain size close to ape
How did Leakeys findings provide evidence for human evolution?
Discovered many hominid fossils.
1.6 million year old fossil Turkana Boy showed traits comparable to that of modern day humans
How has the development of stone tools provided evidence for evolution?
Correlation between development of complex tools and increased brain size.
Older tools = more basic
Describe methods used by scientists to date tools
Carbon 14 dating - estimating age of carbon containing material found in tools/alongside tools.
Stratigraphy - using age of layers of sediment around tool as indictor
What’s a pentadactyl limb?
Limb with 5 digits present in animals, birds, reptiles and amphibians
How does the pentadactyl limb provide evidence for evolution?
Presence of pentadactyl limb suggests all species which posses it have descended from common ancestor.
What is classification?
Organisation of organisms into groups
What is taxonomy?
Classification of organisms into taxa
What are the taxas ?
Kingdom, phylum, class, order, family, genus, species.
Name the 5 kingdoms.
Animals Protists Plants Fungi Prokaryotes
What happens to the numbers of organisms in each taxon as you move down the hierarchy?
Decreases
