Chap 10 - Classification & Evolution Flashcards
Define classification
process of sorting living organisms into groups
Define taxonomy
study of naming and classifying groups of biological organisms based on shared characteristics
Define taxonomic group
hierarchical group of classification
Define phylogeny
evolutionary relationships between organisms
List the taxonomic groups from broadest to smallest
domain
kingdom
phylum
class
order
family
genus
species
State 3 reasons why scientists classify organisms
- to identify species
- to predict characteristics - if several members have a specific characteristic, likely that another species in the group has the same one
- to find evolutionary links - same group probably share characteristics bc they share a common ancestor
Define species
group of organisms with similar features that are able to breed together to produce fertile offspring
Explain why horses and donkeys are separate species and why mules are not given a scientific name and are not a separate species.
- horses and donkeys can interbreed but the offspring (mule) is not fertile - they are separate species by definition.
- mules are not a separate species because they are infertile (odd number of chromosomes so meiosis cannot happen)
Define binomial nomenclature
system of naming species by giving each a name composed of two parts:
- first word - genus
- second word - species (specific name)
State the conventions when writing scientific names
- first word is capitalised
- if typed - italics
- if handwritten - underline
Explain the value of the binomial nomenclature system of the scientific community
- allows for identification and comparison of organisms based on characteristics
- allows all organisms to be named according to a globally recognised scheme
Name the 5 kingdoms and give examples of the organisms they contain
- prokaryotae (E. coli)
- protoctista (Plasmodium)
- fungi (Yeast)
- plantae (Wheat)
- animalia (Lion)
Describe the characteristics of prokaryotae
- unicellular
- no nucleus or any membrane-bound oragnelles
- small ribosomes
- no visible feeding mechanism - nutrients absorbed through cell wall or produced by photosynthesis
Describe the characteristics of protoctista
- mainly unicellular
- cucleus and membrane-bound organelles
- some have chloroplasts
- some sessile, some move by cillia, flagella or ameboid mechanisms
- autotrophs, heterotrophs or both, some parasitic
Describe the characteristics of fungi
- uni or multicellular
- nucleus and membrane-bound organelles
- chitin cell wall
- no chloroplasts or chlorophyll
- no mechanism for locomotion
- body or mycelium made of threads or hyphae
- saprophytic feeders (absorb externally digested nutrients), some parasitic
- food storage as glycogen
Describe the characteristics of plantae
- multicellular
- nucleus and membrane-bound oragnelles
- cellulose cell wall
- all contain chlorophyll
- generally dont move
- autotrophic (photosynthetic)
- food storage as starch
Describe the characteristics of animalia
- multicellular
- nucleus and membrane-bound organelles
- no cell wall
- no chloroplasts
- move using cillia/flagella/contractile proteins (muscle)
- nutrients ingested - heterotrophic
- food storage as glycogen
State the 3 domains of life and 6 kingdoms that this system uses.
3 domains:
- bacteria
- archaea
- eukarya
6 kingdoms:
- eubacteria
- archaebacteria
- protoctista
- fungi
- plantae
- animalia
Describe the characteristics of eukarya (domain)
- 80s ribosomes
- RNA polymerase contains 12 proteins
Describe the characteristics of archaea (domain)
- 70s ribosomes
- RNA polymerase contains 8-10 proteins
Describe the characteristics of bacteria (domain)
- 70s ribosomes
- RNA polymerase contains 5 proteins
Describe the evidence used to create the three domain system
- eubacteria are chemically different to archaebacteria (they have peptidoglycan cell wall)
- archaebacteria live in extreme conditions (hot, anaerobic, highly acidic)
Define phylogenetic tree
diagram used to represent the evolutionary links between organisms (and how closely related they are)
Define sister group
two descendents that split from the same node
Define node
point on an phylogenetic tree
Describe the advantages of using phylogenetic trees as a form of classification as opposed to just using taxonomic groupings.
- species can have similar characteristics (dolphins and fish) but phylogeny confirms they come from different ancestors
- phylogeny produces continuous tree, classification requires discrete taxonomical groups (not forced to put organisms in groups they dont quite fit)
- classification implies different groups within the same rank are equivalent (cats and orchids both families but orchids 70mil years older)
State 3 sources of evidence for evolution
- palaeontology - study of fossils
- comparative anatomy - study of similarities and differences between organisms anatomy
- comparative biochemistry - similarities and differences between the chemical makeup of organisms
Explain how the age of fossils can be determined
- over period of time, sediment deposit forms different layers (strata) of rock which correspond to different geological eras
- within different strata - fossils different so sequence from oldest to youngest can be established
Explain how the fossil record provides evidence for evolution.
- fossils of simplest organisms in oldest rocks, complex organisms in more recent rocks - supports theory that simple organisms gradually evolved into complex ones
- sequence in which organisms found matches their evolutionary links to each other (plants appear before animals - animals require plants to survive)
- analysis of anatomy of fossils studied to show how closely related organisms have evolved from same ancestor
- allows relationships between extinct and living organisms to be investigated
Explain how comparative anatomy provides evidence for evolution
- study of similarities and differences in anatomy of different living species
- example: vertebrate limbs structures very similar - same bones adapted to carry out range of different functions
- led to theory that all vertebrates evolved from common ancestor
Define homologous structures
structure that appears superficially different but has same underlying structure
Define divergent evoluton
process where groups from same common ancestor evolve and accumulate differences - forms new species
Define comparative biochemistry
study of similarities and differences in the proteins and other molecules that control life processes
Explain how comparative biochemistry provides evidence for evolution
- cytochrome c and rRNA studied
- they remain almost unchanged amont species throughout time
- slight changes that occur can help identify evolutionary links
- species with most similar structures - more closely related than those w different structures
- to check how closely related - compare molecular sequences of a particular molecule (order of DNA bases or amino acid sequence) - can estimate the point at which the species last shared common ancestor
Summarise how Darwin and Wallace formulated the theory of evolution by natural selection.
- darwin carried out observations on finches in Galapagos islands - different islands had different finches which were similar, tf closely related but beaks and claws different
- darwin realised that beak structure was linked to food available on island
- conclusion - bird born with more suitable beak will survive longer, have more offspring and pass on the characteristic until all have it
- wallace independently worked on his theory of evolution, ideas so similar they did joint presentation
- darwin published On the Origin of Species, detailing the theory of evolution by natural selection - very controversial and influential
Define variation
differences in characteristics between organisms
Define interspecific variation
variation between members of different species
Define intraspecific variation
differences between organisms within a species
Name and describe two causes of variation
- an organism’s genetic material - differences in genetic material an organism inherits form parents - genetic variation
- environment - causes environmental variation
Describe 5 causes of genetic variation between individuals within a population.
- alleles - genes have different alleles, individuals may inherit different alleles
- mutations - changes to DNA sequence can lead to change in proteins coded, if occurred in gamete it can be passed on
- meiosis - indepednent assortment and crossing over leads to gametes showing variation
- sexual reproduction - offspring inherits alleles from each parent - each individual is different to parent
- chance - many different gametes produced from parental genome, result of chance which two combine so offpsring differ from their siblings
State 3 characteristics that are solely genetically-determined
blood group, hair color, eye color
State 3 characteristics that are solely environmentally-determined
scars, hair length, muscle strength
State 3 characteristics that are a combination of genetics and the environment.
height, skin color, intelligence
Explain what continuous variation is
characteristics that can take any value within range
- eg. mass, intelligence, height, weight
Explain what discontinuous variation is
characteristics that can only result in certain values
- eg. distinct features, blood group
Describe the causes of variation that result in discontinuous variation.
purely genetic
Define polygenic
characteristics that are controlled by number of genes
- usually show continuous variation
Define multifactorial
characteristic caused by many factors, can be both genetic and environmental
Describe the causes of variation that result in continuous variation
multiple genes (polygenic) & influenced by environmental factors
State the types of graph used to represent continuous and discontinuous variation within population.
continuous: line graph
discontinuous: bar chart
Define mean
average value in a data set
Define mode
most common number in data set
Define median
middle value in data set
Give the 4 characteristics of a normal distribution
- mean, mode median are the same
- bell shape distribution, symmetrical about mean
- 50% of values are less than mean, 50% greater than mean
- most values lie close to mean value, number of individuals at extremes is low
Define range
difference between largest value and smallest value
Define standard deviation
the measure of how spread out the data is
Describe the usefulness of standard deviation over range
range uses only the extreme values whereas SD uses all the values in the set
What is the formula for standard deviation
State the type of graph used to show whether there is a correlation between two variables.
scatter graph
Define correlation
the statistical relationship between two variables
Explain why there can be correlation between two variables without there being a direct causal link.
there could be a missing third variable that links the two
Explain why statistical tests are important and what they are used for.
statistical tests used to determine significance of data collected
Define null hypothesis
prediction that there is no significant difference between specified populations
- represents “status quo belief”, such as absence of a characteristic or lack of an effect
- eg: there will be no difference in the length of leaves growing in light vs in the shade
Explain what a test statistic is
random sample from population
- used to decide whether or not to reject the null hypothesis
Explain what a p-value is
probability of obtaining test results at least as extreme as the test statistic, under the assumption that the null hypothesis is correct
Explain what interpretation can be drawn from the p-value
- if less than significance level, reject null hypothesis
- if greater than significance level, do not reject null hypothesis
Describe when a Student’s t-test would be used.
used to compare the means of data values of two populations
- eg - determining whether there is statistical significance between length of ivy grown in light vs in shade
Describe when a Spearman’s rank correlation test would be used.
- used to consider the relationship between two sets of data
- possible outcomes are: no correlation, +ve correlation and -ve correlation
Describe when to use paired or unpaired t-test when analysing data
- paired - determine if significant difference between means of two codependent samples
- unpaired - determine if significant difference between means of two independent samples
Describe when to use paired or unpaired t-test when analysing data
- paired - determine if significant difference between means of two codependent samples
- unpaired - determine if significant difference between means of two independent samples
Define adaptations
characteristics that increase an organism’s chance of survival and reproduction in its environment
State the 3 types of adaptations
- anatomical
- behavioral
- physiological
Define anatomical adaptation
physical features (internal/external)
Define behavioural adaptation
the way an organism acts
- can be inherited or learned
Define physiological adaptation
processes that take place inside an organism
Give 4 examples of anatomical adaptations.
- body covering - hair/scales/feathers/shells, can help fly/stay warm/provide protection
- camouflage - harder for predators to spot
- teeth - shape and type related to diet
- mimicry - allows harmless organisms to scare predators away by appeearing poisonous/dangerous
Give 4 examples of behavioural adaptations
- survival behaviors - opossum plays dead/rabit freezes
- courtship - scorpions “dance” to attract partner, increasing chance of reproducing
- migration - moving from one region to another when environmental conditions are more favorable
- hibernation - inactivity to reduce requirement for food during winter
Give 3 examples of physiological adaptations
- poison production - to kill prey or protect themselves
- antibiotic production - some bacteria use antibodies to kill other species and outcompete them
- water holding - species of frog can store water in its body, allowing for longterm survival without access tow ater
Define analogous structures
adapted to perform the same function but have different genetic origin
Define convergent evolution
unrelated species begin to share similar traits
- due to organisms adapting to similar environments
Compare the features of the marsupial mole and the placental mole
- resemble each other bc adapted to fill similar niches
- both embryos start life in uterus
- in placental - placenta connects embryo to mother’s circulatory system in uterus, nourishing embryo and reaching high maturity before birth
- in marsupial - embryo leaves and enters marsupium where they complete development with milk
Define evolution
gradual change that takes place over many generations where organisms slowly change their physical characteristics as a result of natural selection
Define natural selection
process by which organisms best suited to their environemnt survive and reproduce, passing on their characteristics to their offpsring through their genes
Define gene pool
sum of all the genes in a population at a given time
Define allele frequency
relative frequency of a particular allele in a population at a given time
Define selection pressure
factors that affect an organism’s chance of survival or reproductive success
Define selectively neutral allele
does not alter fitness of individual to survive and reproduce
Describe the steps in the process of adaptations evolving by natural selection
- organisms within species show variation in their characteristics caused by differences in their genes. New alleles can arise by mutation
- those with characteristics that are best adapted to a selection pressure have increased chance of survival and successfully reproducing - ‘survival of the fittest’
- successful organisms pass on the allele encoding the advantageous characteristic into offspring.
- process repeated for many generations, over time proportion of individuals with adv. adaptation increases -> frequency of adv. allele increases in gene pool
- over very long period of time, can lead to evolution of a new species
Explain how natural selection has resulted in the change in frequency of dark and pale moths in populations of the peppered moth near industrial towns and cities over time.
- before industrial revolution, most were pale - camo against tree bark, dark ones were easily spotted and eaten
- during industrial revolution, trees became darker bc covered in soot and loss of lichen cover - dark moths were better adapted bc more highly camouflaged
- more and more of them survived and reproduced, increasing frequency of ‘dark’ allele
- over time their number became much higher than pale due to natural selection where dark color was the advantageous characteristic
- after clean air act, trees became paler and number of pale moths increased again
Describe how human activity has resulted in evolution in populations of Staphylococcus aureus.
- bacteria reproduce rapidly and evolve in short time
- a mutation arose in S. aureus that allowed resistance to methicillin
- when bacteria exposed to antibiotic, resistant individuals survived and reproduced, passing the allele for resistance onto offspring
- non-resistant individuals died
- over time number of resistant individuals increased - establishing MRSA as species
Describe how human activity has resulted in evolution in populations of Flavobacterium.
- live in waste water of factories that produce nylon 6
- they have evolved to digest nylon - beneficial for cleaning up factory waste
- no other strain of Flavobacterium has nylonases
- it is thought that gene duplication + frameshift mutation led to tis adaptation, it was advantageous and therefore naturally selected bc it provides them with another source of nutrients
Define how human activity has resulted in evolution in populations of the Sheep blowfly
- they cause fatal condition for sheep - flystrike
- in 1950s, used diazinon pesticide to kill them and prevent the condition
- within 6 years, they developed resistance to diazinon - individual insects with resistance survived and passed on their advantageous characteristics through their alleles, allowing resistant population to evolve
