Evolution, Fossils, Speciation + Classification (paper 2) Flashcards
Evolution definition
gradual change in the
inherited characteristics of a population over a long period of time through a process of natural selection which may result in the formation of a new species
what does the theory of evolution by natural selection state
that all species of
living things have evolved from simple life forms that first developed more than three billion years ago
how does evolution arise
through natural
selection of variants that give rise to phenotypes best suited to their environment
how do you know when 2 populations of 1 species has formed into 2 new species
so different in phenotype that they can no longer interbreed to produce fertile offspring
what are the key ideas for the theory of evolution by natural selection
- individual organisms within a particular species who a wide range of variations for a characteristics –> mutations can also give rise to new variants
- individuals with characterics most suited to the environment are more likely to survive to breed successfully**
- that characteristics that have enable these individuals to survive are them passed onto the next generation –> advantageous alleles passes into offspring during reproduction
describe the process of evolution by natural selection
- genetic variation caused by mutations in the species
- those with the desirable characteristics survive + reproduce = survival of the fittest
- the allele that codes for tha characteristics gets passed down to offspring
over many generations, those with the desirable alleles increase and outcompete those without
the theory of evolution by natural selection was only gradually accepted because:
- the theory challenged the idea the God make all animals and plant that live on Earth
- Insufficient evidence at the time the theory was published to convince many scientists
- the mechanism of inheritance / genetics and variation was not know until 50 years after the theory was published
who else had a theory
Jean-Baptiste Lamarck
what was Lamarck’s theory
theory that changes that occur in a organism *during its lifetime** can be inherited
speciation =
when 2 new species form from an ancestral species
Wallace independently proposed which theory
the theory of evolution by natural selection
what is Wallace best know for
- work in warning colouration
- theory of speciation
describe the stages which give rise to new species
- genetic variation exists within a species / or random mutations leads to new variants
- population of a species become geographically isolated from each other (geographical barrier)
- the separate population are exposed to different environmental conditions
- natural selection occurs differently in both populations
- this occurs over many generations
- if two population reunite, no longer able to interbreed to produce fertile offspring - have become different species
bacteria can ………… …………… because they ………….. at a ……… ……….
evolve rapidly
reproduce
fast rate
how does antibiotics bacteria occue
- in all population there is variation
- mutations also occur naturally + spontaneously
- mutations occur in pathogenic bacteria
- this produces new strains of bacteria
- some strains might be resistant to antibiotics
how do antibiotic resistance bacteria survive and spread
- when a person takes a *specific antibiotic** it will kill specific bacteria
- however some bacteria develop random mutations in their DNA –> occasionally they become anti-biotic resistant and are not killed
- anti-biotic resistant bacteria 8*survive + rapidly reproduce**
- these is less competition for nutrients and resources since antibiotic have killed non-resistant bacteria
- anti-biotic resistant bacteria population rises = anti-biotic resistant strain
- anti-biotic resistant bacteria can then be spread to uninfected people - a communicable pathogen
- will spread further as there is no effetive treatment
what is the name of a common strain of anti-biotic resistant bacteria
MRSA - Methicillin - Resistant Staphylococcus Aureus
to reduce the rate of development of antibiotic resistant strains: (3 ways):
- doctors should not prescribe antibiotics inappropriately -
treating non-serious or viral infections - patients should complete(( their full course of antibiotics so all bacteria are killed and ((none survive to mutate and form resistant strains
- the agricultural use of antibiotics should be restricted
why is the development of new antibiotics hard
- costly
- slow
- unlikely to keep up with the emergence of new resistant strains
Fossils are …
are the ‘remains’ of organisms from millions of years ago, which are found in rocks
what are the 3 ways in which a fossils can be formed:
- from parts of organims that have not decayed because one or more of the condition needed for decay are absent:
- warmth moisture, oxygen, missing
- ice, amber
- bacteria unable to decompose
- when parts are replaced by minerals as they decay
- as preserved traces of organisms - footprints, burrows, rootlet traces
why are fossil records incomplete
- many early life forms were soft-bodied - only left a few traces behind
- most traces would have been destroyed by geological activity
- most organisms just fully decay - no not fossilise
extinction =
when no remaining individuals of a species is still alive
extinction may be caused by : (6 reasons)
- changes to the environment over geological time
- new predators
- new diseases
- increased competition - new competitors
- a single catastrophic even
how are living things traditionally classified
into groups depending on structure ad characteristics
what are tte 2 types of classification
- Linnaean system
- three domain system
who invented the Linnaean system
Carl Linnaeus
Linnaeus classified living things into:
kingdom, phylum, class, order, family, genus, species
how are organisms named
by the binomial system of genus and species
due to what where new models of classification propsed
- evidence of internal structures became more developed due to improvement in microscopes
- understanding of biochemical processes progressed
who invented the 3 domain system and how
Carl Woese - due to evidence available from chemical analysis
what is the 3 domain system divided into
Archaea - primitive bacteria usually living in extreme environments
- Bacteria - true bacteria
- Eukaryotes - protists, fungi, plants, animals
what is the anacronym for the Linnaeus system
Dear Katie Please Come Over For Great Snacks
how must the species name be written if hand written
- capital letter for Genus
- lower case for species
- both underlined
what doe evolutionary trees show
- common ancestors
- relationships between species
