T6 genetics and evolution Flashcards
outline the theory of evolution by natural selection
individuals of a species show a wide range of variation for a characteristic
those with the characteristic most suited to the environment will survive, breed most successfully
the desirable characteristic that has enabled the individuals to survive are passed onto their offspring
why was Darwin’s theory of evolution not accepted initially
most people believed in creationism
insufficient evidence to prove the theory
mechanism of variation and inheritance was not known at the time
Jean-Baptiste Lamarck’s theory of inheritance
that changes during the lifetime of an organism can be inherited
what is speciation
formation of a new species, when 2 populations become so varied that they cannot interbreed to produce fertile offspring
definition of a species
groups of organisms with similar characteristics which are able to interbreed to produce fertile offspring
outline the process of speciation through geographic isolation
2 populations of the same species are separated geographically
geographic isolation prevents interbreeding and mixing of genes between the populations
due to different selection pressures, different mutations occur producing different phenotypes in each population
over time, the 2 populations may evolve so that they can’t interbreed
why is genetic variation important in speciation
produces phenotypic variation, some of which are better suited to the environment and are selected for
how did Mendel study inheritance
through carry breeding experiments on plants and analysing the ratio of characteristics in offspring
why was Mendel’s work not recognised until after his death
couldn’t explain mechanism of inheritance as chromosomes were discovered after
not communicated well to other scientists and not published in a reputable scientific journal
2 kinds of evidence used to show evolution
fossils
antibiotic resistance in bacteria
how are fossils formed
parts of organisms that haven’t decayed due to conditions needed for decay being absent
parts of organisms that have been replaced by minerals as they decayed
traces of organisms are preserved, covered in sediment and becoming rock
why are there few traces of early life-forms left behind
mostly soft-bodied
how do fossils act as evidence for evolution
scientists can identify the ages of the fossils and use them to show how organisms change over time
what do branches in evolutionary trees indicate
where speciation has occurred
factors that may lead to extinctions
new disease predation competition changes to the environment catastrophic events
