Natural Selection and Evolution Flashcards
start of life on earth
hydrogen formed and heavier elements formed in stars and early chemical reactions took place
eukaryotic cells
cells that contain a membrane bound nucleus, appeared in the proterozoic aeon
fossil record
- cast
- impression fossils
- petrification
conditions for fossilisation
- quick burial of organism
- layers of sediments build up
- left for a long period of time
- erosion and uplifting exposes fossils to the earth’s surface
relative dating
- Law of Superposition - old deep sedimentary young shallow
- measures the layers of rock (strata)
- use index fossils that have been absolute dated
absolute dating
radiometric dating
carbon dating
radiometric dating
how long it takes half of the atoms in a sample to decay into another element
carbon dating
can’t be used for fossils over 50 000 years. when an organism dies carbon 14 begins to decay at a constant rate
evidence for evolution from fossils
- presence of simpler life forms to more complex life forms in the fossil record
- presence of transitional forms of organisms that have features of old organisms with new
statements of natural selection
- there is variation within a population of a species
- if a factor in the environment changes, so may what is favourable for survival
- Those with traits most suited to the new environment are most likely to survive
- The trait becomes more prevalent in the population
evolution
the gradual development of new species from a common ancestor
what drives evolution
- there is a struggle for existence, must compete for food, mates and habitats
evidence for evolution
- biochemical evidence of cytochrome c (protein that undergoes very little mutations)
- comparative anatomy (similar structures present) (homologous structures)
- comparative embryology comparing development in the womb)
- biogeography
analogous structures
evolved independently to serve the same purpose
vestigial structures
served an important function in an ancestor but not in the modern organism
atavism
the reappearance of an ancestral form (evidences for previous evolution)
2 forms of biogeography
- isolation (when a species are separated)
- migration (where members of a species move)
antibiotic resistance
bacteria develop resistance to antibiotics rapidly
- vertically (new generations inherit gene from parent cell obtained from mutation)
- horizontally (resistance genes are transferred directly through transposons)
