topic 10 classification and evolution Flashcards
species
a group of organisms that can reproduce to produce live, fertile offspring
what does classification allow scientists to do
-identify new species
-study evolutionary relationships
-understand shared traits and adaptations
-share research globally to identify links with organisms on other continents
problems with common names
- species can have a different common name in different places
-different species can have the same common name
when was the linnaean classification system discovered
1700s
lots of taxon are called
taxa
is the taxonomic group hierarchical
yes
broadest groups containing the most species at top and most specific groups at bottom
the 8 major taxonomic groups
domain
kingdom
phylum
class
order
family
genus
species
three domains orgnisms can be classified into
bacteria
archaea
eukarya
which domain includes all eukaryotes
eukarya
4 kingdoms in eukarya
plantae (plants)
animalia (animals)
protoctista (unicellular eukaryotes)
fungi (eg yeasts)
he binomial name consists
-the genus- has uppercase first letter
-the species - all lowercase
underlined or italicised when written down
the five kingdom system was developed as more organisms were discovered. what are they
prokaryotae
animalia
plantae
fungi
protoctista
which of the five kingdoms are eukaryotic
animalia
plantae
fungi
protoctista
prokaryotae features
-all unicellular
-no nucelus or membrane bound organelles
-dna forms circular loop and not bound to histone proteins
-small 70S proteins
-nutrients by absorbtion from the environment through the cell wall or by photosynthesis
-autotrophic, heterotrophic or parasitic
-contain cell wall often made of peptidoglycan
-stores sugar in glycogen
-reproduces through binary fission
animalia features
-all multicellular organisms
-heterotrophic
-glucose is stored as polysaccharide glycogen
-cells of animalia have a nucleus and membrane bound organelles but never chloroplasts or a cell wall
-movement often occurs by protein contraction (Eg muscles)
-reproduction can vary
plantae features
-multicellular
-cellulose cell wall as well as chlorophyll in chloroplasts
-autotrophic and use photosynthesis
-glucose stored as starch
-most dont move but have exceptions like the venus fly trap and in some the male gametes use flagella t o move
-contain nucleus and membrane bound organelles
-use seeds or spores to reproduce
fungi features
-unicellular or multiccellular w a body made of hyphae
-cell wall made of chitin
-consist of fine threads called hyphae forming a larger mass called mycelium
-cannot move and cannot photosynthesise and never contain chlorophyll
-fungi are saprophytes meaning they absorb nutrients from around them often from decaying matter
-use glycogen as a storage form of glucose
-some fungi are parasites
-reproduce through spores
protocista features
-most are unicellular but some are multicellular
-can be heterotrophic such as amoeba or autotrophic like euglena. some are parasites like giardia
-some move using flagella or cillia while amoeba move by spreading which is called amoeboid movement. some have no active mechanism of moving at all
-nucleus and other membrane bound organelles are present sometimes including chloroplasts
why did Carl Woese propose a new taxonomic group
he analysed ribosomal RNA from a range of prokaryotes including Ecoli and found archeabacteria are very different to bacteria such as Ecoli such as the cell wall does not contain peptidoglycan and
different protein synthesis
what was the new taxonomic group carl woese proposed
domain
what did the three domain system propose and why
six kingdoms instead of five because there is evidence for splitting the kingdom prokayote into two seperate kingdoms, eubacteria and archeabacteria
domain bacteria features
-contains the kingdom eubacteria only, found in all environments
-prokaryotic unicellular organisms
-distinct cell membrane lipids
-have peptidoglycan in their cell walls
-unique RNA polymerase enzyme
domain archae features
-contains the kingdom archeabacteria only, typivally found in extreme environments
-prokaryotic unicellular organisms
-have histones so genes and protein synthesis is more similar to eukarya than bacteria
-no peptidoglycan in their cell walls
-different cell membranes that contain fatty acids bound to glycerol by either linkages
-have more complex form of RNA polymerase than bacteria
domain eukarya
-contains four kingdoms from the five kingdom system, animalia, plantae, fungi, protoctista
-all have nucli and membrane bound organelles
phylogeny
the evolutionary relationships between organisms
what does the phylogenetic classification reveal about organisms
how closely related they are
adavantages of phylogenetic classification
-it produces a continuous tree that doesnt force organisms into specific taxonomic groups they dont quite fit
-there is no overlap between the groups produced
what do phylogenetic trees show
how different species can evolve from an common ancestor
features of phylogenetic trees
-time flows from the bottom to the top. species further in the past are shown at the bottom and more recent at the top
-the branch points are called nodes and they show a common ancestor of the descendants from that node
-two descendants from the same node are called sister groups
-at the base of the tree is the common ancestor of all the species shown on the tree
the proximity of species to each other on the phylogenetic trees indicates
the closeness of the evolutionary relationship
artifical classification groups organims based on
differences that are useful at the time such as colour and size
modern taxonomy uses this evidence to determine phylogeny
-molecular comparisons
-development studies
-anatomical examinations
-behavioural analyses
what is the theory of evolution by natural selection
that organisms best suited to their environment are likely to survive, reproduce and pass on their advantagous characteristsics to their offspring
what are fossils
the remains of organisms preserved in rocks
key evidence from fossil records supporting evolution
-simple bacteria and algae fossils are found in the oldest rocks progressing to more complex vertebrates in newer rocks
-plant fossils appear before those of animals that feed on these plants indictaing a natural order of evolution
why the fossil record is incomplete
-many organisms decompose before they can fossilise
-fossilisation is uncommon and requires very specific conditions for an organisms to be preserved
-some organisms fossilise very rarely eg animals without a skeleton
-fossils can be lost due to erosion or geological processes
-many organisms have not yet been discovered
how comparative anatomy provides evidence for evolution
-organisms who share homologous structures likely evolved from a common ancestor and adapted these structures for different functions
-homologous structures are evidence for divergent evolution where organisms evolve different adaptive traits as they occupy new ecological niches
what are homologous structures
-homologous structures are physical features in different species but have the same internal structure but may serve different functions
what does comparative biochemistry involve studying
the molecular aspects of organisms to uncover evolutionary relationships
useful molecules to study evolutionary links
-cytochrome c- protein involved in aerobic respiration found inmost eukaryotic organisms
-ribosomal RNA- integral to protein synthesis so changes slowly
-nuclear, mitochondrial or chloroplast DNA
-messenger RNA
-amino acids
why are noncritical amino acids useful to identify evolutionary links
amino acids essential for a proteins function are highly conserved but non critical amino acids chnage overtime as species evolve and by conparing these amino acid sequences can show hoe closely related species are
(cytochrome c’s amino acids are usually used to make these comparisons)
hypothesis of neutral evolution states that
most variability in a molecules structure does not affect its function
why the hypothesis of neutral evolution is useful in the study of evolution
-‘neutral ‘ changes that dont affect the function accumulate at a fairly regular rate as they are not affected by natural selection. comparing the rates of neutral substitutions in the molecular sequences of species lets scientists estimate the time since two species diverged from a common ancestor. (more differences , more ancient divergence)
variation
differences observed among individuals within any given population
genetic variation is caused by
the genetic material that an organism inherits
sources of genetic variation
-mutations
-meiosis
-random fertilisation
-random mating
in organisms that carry out asexual reproduction what causes genetic variation
mutations
environmental factors that cause variation
-light
-nutrient and food availability
-tempreture
-rainfall
-soil conditions
-ph
polygenes
genes that work together to influence a single phenotypic trait
what type of variation are polygenes usually and why
continuous variation because they exhibit a range of phenotypes forming a continuum
intraspecific variation
variation between members of the same species
variation between members of the same species is less pronounced
interspecific variation
variation that occur between different species
variation is often very significant
continuous variation
when there is a range of values between two extremes without distinct categories which produce a spectrum of phenotypes
-typically affected by genes, polygenes and environment
continuous variation can have any value within a range what is this called
continuum of values
how is continuous variation usually represented
histogram overlaid with a curve / normal distribution curve
discontinuous variation (discrete)
features that can only have specific values
-often controlled by a single gene
how is discontinuous variation usually represented
bar chart
what does standard deviation measure
how spread out the values are from the mean
what is a students t test
a statistical test used to determine if there is a significant difference between the mean values of a particular variable across two populations
conditions for using a unpaired t test
-in two categorical groups
-from two different individuals
-interval data (same scale)
when do you reject the null hypothesis
if the value of t is greater or equal to the critical value
conditions of using paired t test
-two categorical groups that include the same individuals
-each measurement in one group is paired with a measurement in the other group
-both groups are the same size
2 types of t test
-unpaired t test- used when comparing means of two groups of different individuals
-paired t test- used when comparing the means of two sets of data that have come from the same individuals
