classification and evolution Flashcards
what is the definition of taxonomy?
study of principles behind classification by naming organisms and organising them into groups based on their characteristics and differences
give an example of a phylum trait
possession of backbone (organisms with the same body plan)
why is the binomial naming system effective?
language is universal so everyone can understand it
name the 5 kingdoms
protoctist, plantae, prokaryotae, fungi, animalia
features of prokaryotae
-unicellular
- no nucleus in membrane
-no membrane bound organelles
what is phylogeny?
the study of how closely related different species are and their evolutionary relationships e.g. humans and chimps
what does phylogeny take into account in closely related species?
appearance
anatomy
physiology
what is cladistics
method of hypothesising relationships among organisms
selection pressure?
an evolutionary force that may cause a particular phenotype to be better suited to a certain environment
what do fossils show in regards to evidence for natural selection?
they show anatomical features that help us understand relationships and age of species
what are the issues with fossils?
- not a complete record
- conditions needed for fossilisation not always present
- soft body organisms decompose quickly
what is meant by continuous variation? and give an example
two extremes and a full range of intermediate values e.g. height
what is meant by discontinuous variation? and give an examples
regulated by one gene and not influences by environment e.g. eye colour, sex
what is Cytochrome.C?
mutations in DNA sequence that all organisms have which comes from a common ancestor
what is meant by adaptation?
a characteristic that enhances survival in a habitat
give examples of adaptation applicable to an environment (practical)
- reproducing
- finding water/food
- defence against predators
state the 3 components of adaptation
- behavioural
-anatomical
-physiological
what is convergent evolution
when two organisms have very similar adaptations but are classified in different taxonomic groups which can happen when they evolve in similar environments e.g. spiders and insects
give examples of how the two different species of mole (marsupial and placental) have evolved to have similar adaptations
- short tail
- tough nose (protection)
- large claws
- small blind eyes
what is speciation
formation of a new species from a pre existing species - they can no longer interbreed
how has pesticide resistance increased?
strong selection pressure occurs and those with mutations for resistance multiply
why is pesticide resistance a problem?
becomes more difficult to kill pests on crops decreasing yield, so more pesticide has to be used cause bioaccumulation
- pest is a disease, vector = mosquitos can transfer
- making a new pesticide can be costly
why do we classify?
-for convenience
-easier to identify organisms
-see relationships between species
at which taxon level do we need to greatest amount of information to classify?
species
what is the pneumonic to remember the 8 taxonomic groups
delicious king prawn curry or fat greasy sausages
what are the rules associated with the binomial naming system?
- genus first, then species
- must be written in italics
- genus must start with capital letter
- species must always be lowercase
unicellular
no nucleus
no membrane bound organelles
prokaryote
eukaryotic
photosynthetic
cellulose cell wall
plantea
eukaryotic
non photosynthetic
no cellulose cell wall
fungi
definition of species
a group of organisms that can freely interbreed to produce fertile offspring
what is the phylogenetic explanation of a species
set of individuals which have the same evolutionary lineage - similarities in anatomy, physiology, genetics etc.
why aren’t viruses in a kingdom?
viruses are non-living nor dead so they form their own group.
if sequences of cytochrome C are the same, the two species must be…
closely related
if sequences of cytochrome C are different, the two species must be…
not closely related
the more differences found between the sequences…
the common ancestor is further back in time
how can we use DNA to classify?
use PCR and electrophoresis to separate DNA based on size (synoptic link to module 6 manipulating genomes)
what are the key differences between archaea and bacteria that suggest they should be classified as two different domains?
- different enzymes
- different mechanisms for DNA replication
- differing cell membrane
describe 3 differences between domain and kingdom
- domain is one of the three taxonomic categories of living organisms, whereas kingdom is one of the 5 major groups of living organisms.
- domain consists of archae, bacteria, and eukarya but kingdom consists of animalia, plantea, protoctista, and prokaryotae
- prokaryotes are split into different domains whereas in kingdoms prokaryotes are classified under the same kingdom.
monophyletic
group of organisms descended from a common ancestor not shared with any other group.
evolutionary distance
number of nucleotide substitutions per site between two DNA sequences
what is meant by variation?
the presence of differences between individuals
interspecific variation
variation between species
what is discontinuous variation
regulated by one gene and not influenced by the environment
explain why it’s harder to identify interspecific variation between closely related species?
- fewer mutations means more similarities
- less time has past
explain why skin is a continuously variable feature
- depends on temperature which can vary depending on what country you live in.
- exposure/lack of exposure to sun
- hotter countries have tanner skin
how to work out frequency density
frequency/class width
in a graph, the longer the error bar…
the higher the standard deviation and the more spread out the results were from the mean.
what is adaptation
characteristic that enhances survival in a habitat
give examples of adaptation
reproducing, finding water, defence against predators and disease
behavioural adaptations of marram grass
- rolls leaves tightly
- closes its stomata
in hot temps, the hinge cells loose water - this loss of water causes the leaf…
to curl more tightly
+ stomata lose water so become flaccid and close
marram grass cells maintain a low…
water potential than other plants so increases their tolerance to water
what is convergent evolution
when two organisms show very similar adaptations but are classified in different taxonomic groups.
explain why placental and marsupial moles are examples of convergent evolution?
marsupial moles and placental moles are different species and occupy different areas - however they have evolved similar adaptations:
- short fur
- large claws
- small blind eyes
- tough nose (protection)j
selection pressure
an evolutionary force that may cause a particular phenotype to be more translated in a certain environmental condition.
explain the steps of natural selection (write 7 steps on whiteboard)
- genetic variation within a species caused by mutation.
- individuals of a species show variation in their phenotypes (infraspecific variation).
- selection pressure creates struggle for survival.
- those better adapted survive (state how) and have a selective advantage.
- more likely to survive and reproduce.
- pass on advantageous gene to offspring.
- passed down multiple generations till feature is common in a population.
predation is a biotic adaptation, give 2 examples of this
- camouflage
- thorns
how has pesticide resistance become a problem for the human population?
- becomes difficult to kill pests on crops = lowering yield.
- need to add more pesticides = bioaccumulation.
- disease transmission if pest is a disease, vector => mosquitos
- new pesticide needs to be generated = costly
how does antibiotic resistance arise?
random mutation causes bacteria to become resistant to certain antibiotics which creates selection pressures - allowing bacteria to survive + reproduce causing further infection.
what are the issues with using fossils?
- not complete record
- conditions needed for fossilisations are not always present
- organisms soft bodied decompose quickly
- many fossils destroyed or lie undiscovered.
why are domains better than kingdoms?
- fits better with phylogeny
- differences between prokaryote and eukaryotes
what is the difference between eukaryae, bacteria and archaea in terms of ribosomes
eukaryae = 80s
prokaryotae = 70s
archae = 70s
what is the difference between eukaryae, bacteria and archaea in terms of RNA polymerase
eukaryae = 12 proteins
prokaryotae = 8-10 proteins
archae = 5 proteins
in the new classification system, what are the 6 new kingdoms?
eubacteria, archaebacteria, protoctista, fungi, plantae, animalia
what is the difference between the habitats of archaebacteria and eubacteria?
archabacteria (ancient bacteria) live in extreme conditions e.g. anaerobic
eubacteria are found in all environments
what are the 3 main sources of evidence for evolution
biochemistry, anatomy, palaeontology
what is palaeontology?
study of fossils - tellings us of the earths past.
what are homologous structures
differences in different organisms, but same underlying structures
what do homologous structures provide evidence for?
divergent evolution
what is divergent evolution
two species which have diverged but share the same common ancestor
what are causes of genetic variation? x5
- alleles
- mutations
- meiosis
- sexual reproduction
- chance
