classification + evolution Flashcards
classification definition
the process by which living organisms are sorted into groups with each group containing organisms with similar features
what classification system is most widely used
the linnaean classification system - developed by 18th century scientist carl linnaeus
what are the 7 taxonomic groups in the linnaean classification system
(domain) - this was added after
kingdom
phylum
class
order
family
genus
species
species definition
a group of organisms that are able to successfully reproduce to have fertile offspring
what are the 3 domains
eukarya
bacteria
archaea
what are the differences between the 3 domains
organisms in different domains contain a unique form of rRNA and different ribosomes
what type of ribosomes and rRNA is found in eukarya
80s ribosomes
RNA polymerase has 12 protein subunits
what type of ribosomes and rRNA is found in bacteria
70s ribosomes
RNA polymerase contains 5 protein subunits
what type of ribosomes and rRNA is found in archaea
70s ribosomes
RNA polymerase of different organisms has 8-10 different protein subunits, similar to eukaryotes
what is RNA polymerase
an enzyme responsible for mRNA transcription
what are the 5 kingdoms
prokaryotae
fungi
protoctista
plantae
animalia
describe the features of organisms in the kingdom prokaryotae
- unicellular
- no nucleus or membrane bound organelles
- can contain chlorophyll
- cell wall made of peptidoglycan
- genetic material floats freely in cytoplasm, in the form of a plasmid
- small ribosomes
- no visible feeding mechanism, nutrients absorbed through cell wall or produced internally
what is the difference between archaebacteria and eubacteria
archaebacteria live in extreme environments e.g. high temps or pH, anaerobic conditions
eubacteria are found in all environments, most bacteria are eubacteria
describe the features of organisms in the kingdom fungi
- unicellular or multicellular
- contains nucleus, membrane bound organelles
- doesn’t contain chloroplasts / chlorophyll
- cell walls made of chitin
- no locomotive mechanism
- mostly made up of mycelium or hyphae
- most are saprophytic
- some are parasitic
- food stored as glycogen
describe the features of organisms in the kingdom protoctista
- mostly unicellular
- contains nucleus, membrane bound organelles
- some have chloroplasts, cilia, flagella, for food or movement
- can be autotrophic or heterotrophic or both
- some are parasitic
describe the features of organisms in the kingdom plantae
- multicellular
- contains nucleus, membrane bound organelles
- contains chloroplasts + chlorophyll
- cell walls made of cellulose
- no locomotive mechanism, although gametes can move sometimes
- autotrophic
- store food as starch
describe the features of organisms in the kingdom animalia
- multicellular
- contains nucleus, membrane bound organelles
- no cell wall
- no chloroplasts / chlorophyll
- can move with the aid of contractile proteins, sometimes in the form of muscular organs, gametes can move with cilia + flagella
- heterotrophic
- food stored as glycogen
saprophyte definition
organisms which obtain nutrients from decaying material
autotroph definition
organisms which can acquire / synthesise their own nutrients via photosynthesis
heterotroph definition
organisms which obtain nutrients by ingesting other organisms
who developed binomial nomenclature
carl linnaeus
why is binomial nomenclature so useful
- universal system so it helps scientists more than common names, which are different in different languages
- often animals have multiple common names
- they are indicative of closeness of species
- remember no 2 organisms have the same species AND genus name
phylogeny definition
the evolutionary history of organisms, explored through evolutionary relationships between different organisms - this can be shown through phylogenetic trees
give 4 reasons why classification is important
- to identify species
- to predict characteristics
- to find evolutionary links between species e.g. common ancestors
- creates a universal system for global research and collaboration
intraspecific variation definition + example
variation between individuals WITHIN a species
e.g. height, intelligence
interspecific variation definition + example
variation BETWEEN different species
e.g. number of legs
genetic variation definition
differences between the genetic material of organisms, mostly of the same species, inherited by parents, due to meiosis + fertilisation of gametes
- this cannot be changed
environmental variation definition + examples
differences between organisms, mostly of the same species, due to their environments
e.g. based on nutrition, or physical appearance, hair colour, scars
- this can be changed and is not always determined by genetics
what are 4 causes of genetic variation
- alleles + genetics inherited from parents
- mutations which cause new alleles
- meiosis which creates unidentical gametes and allows for independent assortment + crossing over
- sexual reproduction which allows for random fertilisation between 2 unique gametes, ensuring offspring differs from parents
allele definition
variations of a single gene
discontinuous variation definition + examples + how is data displayed + link to genetics
characteristics that can only appear in certain categories, no in between
e.g. eye colour, blood type
displayed on a bar chart or pie chart
often these are caused by a single gene
continuous variation definition + examples + how is data displayed + link to genetics
characteristics that can have numerical values or exist within a range
e.g. height, weight
displayed on a line graph
are not controlled by a single gene and can be affected by environment
brief history of the theory of evolution
charles darwin studied finches in the galapagos islands, and found that different islands had different finches - the beaks and claws were different shapes and sizes
this lead to the development of the theory of natural selection - different islands had different conditions + food so finches evolved differently, underwent geographical speciation
outline the process of natural selection
- new alleles and characteristics arise as a result of mutations
- due to selection pressures e.g. food availability, organisms born with traits more suited to the environment willl survive longer
- these organisms with advantageous characteristics are more likely to survive and reproduce
- as a result, advantageous alleles are passed down to offspring
- those without advantageous alleles will die out
- over many generations + mutations this results in the evolution of the species
convergent evolution definition
when 2 species evolve to become more alike
divergent evolution definition
when two species evolve to become more different
what are 4 pieces of evidence for evolution
- fossil record
- comparative anatomy between living organisms
- comparative biochemistry between living organisms
- evidence from embryology
how does the fossil record provide evidence for evolution
- it provides information about ancient species
- this allows for evolutionary relationships between extinct and modern species to be suggested, and the evolution of a single species to be tracked
what is a disadvantage of using fossils as evidence for evolution
the conditions for fossils to form are very rare - often only prints or parts are found, and soft bodied creatures aren’t able to fossilise due to quick decomposition
how does comparative anatomy between living organisms provide evidence for evolution
- homologous structure - parts of living organisms may appear superficially different or have different functions but the underlying structures are the same
- this could provide evidence for divergent evolution
what controls homologous structure + link to evolutionary relationships
homologous structure is controlled by hox genes - these are highly conserved
- could be evidence for divergent evolution
- remember as they are highly conserved they will be similar among many organisms
how does comparative biochemistry between living organisms provide evidence for evolution
- comparative biochemistry is doen through examining molecular DNA or base sequences
- this allows for estimates to be made about when organisms last had a common ancestor - the more differences, the longer ago they diverged
how does embryology provide evidence for evolution
- 2 organisms that look very similar may develop in a similar way, suggesting a degree of relation
- as new structures evolve, they often develop at the end of an organisms development
- this allows for the evolutionary history of an organism to be traced back
