Genetics and Evolution Flashcards
Mendel’s discovery
Looked at breeding different kinds of peas
Some characteristics were dominant
Accepted theory in 19th century
Lamarck’s theory
All organisms linked by “fountain of life”
Animals are all adapted and evolved to suit environment
Way organisms behaved affected features of body
Theory influenced Darwin
Darwin’s main ideas of evolution
Individual organisms in a particular species show wide range of variation for each characteristics
Reproduction gives more offspring than environment can support = inherited characteristics best suited to environment makes them more likely to survive
Breed, pass characteristics enabled them to revive next generation
What experiments did Darwin do?
Breeding experiments with pigeons
Wanted to show how featured could be artificially selected
What reasons was Darwin’s theory of evolution by natural selective selected by
Conflict with religion and God, all animals and plants made on Earth
Insufficient evidence
No mechanism for explaining variation and inheritance
Russel Wallace theory
If a species existed in various forms, those which were poorly adapted to the change were likely to die out, leaving only the better form to survive and breed
Isolation
Where 2 populations of a species become separated
Genetic variation
Genetic variation is the difference in DNA among individuals or the differences between populations
E.g. mutation and genetic combination
Natural selection
Alleles selected to control characteristics = helping organism survive and breed successfully
Why might a part of a population become isolted
Because of new environmental changes
Speciation
Populations become so different that successful interbreeding is no longer possible
Geographical isolation
Leads to speciation
Species evolved to survive with in isolated environments are vulnerable to climate change or habitat loss
Environmental isolated
When climate changes in 1 area
Eventually new species emerge
How can fossils be formed?
Animals and plants don’t decay e.g. - no oxygen, poisonous gas kills bacteria needed for decay, temperatures too low
Harder parts of animal or plants replaced by minerals as they decay and become part of the rock
Mould fossils formed when organism is made of mud and becomes fossilised
Preserved traces left behind = footprints, burrows, droppings
Why are fossil records incomplete
Earliest forms of life were soft-bodies organisms = little fossil trace, destroyed by geological activity (volcanoes, earthquakes)
Most organisms did not fossilise = right conditions for fossil formation were rare
Many fossils that are still to be found
Using fossil records
Helps scientists understand how much organisms have changed since life developed on Earth
Extinction
Permanent loss of all members of a species
New species evolve better suited to environment, old species die out = natural selection
Change in temperature, catastrophic events
Organisms that cause extinction
New predators = wipe out prey with no adaptations to avoid predators, predators may evolve, existing species might move into new territory, human intervention
New diseases
New mutations = give one organism an advantage
Environmental changes
Temperatures fallen = ice age
Lack of food or being too cold to breed
Extinction on a large scale
Single catastrophic event = volcanic eruption, giant asteroids
What destroyed the dinosaurs?
Asteroid had huge impact = fires, earthquakes, landslides, tsunamis, big amounts of material blasted into atmosphere, dust made it dark
Melting of ice triggered mass extinction, drop in sea level flooded seas with very cold water
Layer of rock formed from crater debris in countries. = iridium found which is only formed when rock hits with force such as an asteroid hit
Antibiotic resistant bacteria
Resistant bacteria can survive and reproduce increasing population of resistant bacteria
Spreads rapidly = no one is immune
Prevent resistant strains or bacteria appearing
Important not to overuse antibiotics
Important to finish course of medicine every time so all bacteria are killed = none survive to mutate and form resistant strains
Important to restrict agricultural use of antibiotics to prevent spread of antibiotic resistance form animal to humans
Measures to stop the spread
Antibiotics only used when needed
Specific bacteria treated with specific antibiotics
Medical staff wash hands with soap and water
Medical staff wear disposable clothing or regularly sterilised
Hospitals have high standards of hygiene
Patients infected with antibiotic resistant bacteria isolated
Visitors wash hands before and after entering
