Classification and evolution Flashcards
what is classification
placing organisms into groups according to similarities
what is the order of taxonomic hierarchy with an example of the human classification
domain=eukaryote
kingdom=animalia
phylum=chortata
class=mammalia
order=primates
family=hominidae
genus=homo
species=sapiens
what is this system
universal
what is the binomial system
all organisms are given one internationally accepted scientific name
how to write a binomial name
example
first part of the name=genus name and has a capital letter
second part of the name=species name and begins with a lower case letter
always written in italics and or underlined if they are handwritten
eg. Homo sapiens
prokaryotae features
example
-unicellular
-no membrane-bound organelles
-small ribosomes
-a ring of DNA with no associated proteins
-has no feeding system (absorbs nutrients across its system or photosynthesises)
bacteria
protoctista features
example
-unicellular or simple multicellular
-eukaryotic cells
-usually live in water
-does have a nucleus and membrane-bound organelles
-some have cillia for movement
-some have flagella for mobility
-nutrients are absorbed (either by photosynthesis, ingestion of other organisms or some are parasites).
algae, protoza
fungi
example
-unicellular or multicellular
-eukaryotic
-chitin cell wall
-have a nucleus and membrane-bound organelles
-no chloroplasts
-cannot move
-saprotrophic (nutrients/substances absorbed by dead or decaying organisms)
-food can be stored at glycogen
moulds, yeasts, mushrooms
plantae
example
-multicellular
-eukaryotic
-have a nucleus and membrane-bound organelles
have chloroplasts and don’t move
-cell walls made of cellulose
-contain chlorophyll
-nutrients absorbed by photosynthesis (autotrophic)
-food stored as starch
mosses, ferns, flowering plants
animalia
examples
-multicellular
-eukaryotic
-have a nucleus and membrane-bound organelles
-no cell walls
-no chloroplasts
-can move using cilia, flagella or muscles
-nutrients obtained by ingestion (heterotrophic) and food can be stored as glycogen
molluscs, insects, fish, reptiles, birds, mammals
EVIDENCE FOR CLASSIFICATION-
what did early classification systems use?
how was the accuracy of classification improved?
observable features, and groups based solely on physical features do not show how closely related they are.
taxonomists look at embryological evidence, fossil evidence and molecular evidence.
MOLECULAR EVIDENCE FOR CLASSIFICATION-
- the more similar the DNA base sequence, the more closely related they are
- the more similar amino acid sequence of cytochrome C in two different species, the more closely related the species are likely to be
changing the classification of species
with new technologies (eg new DNA analysis techniques and better microscopes) , new discoveries can be made and scientists can share their new discoveries in meetings and scientific journals.
who proposed a new classification system?
And in 1990 what happened?
- Carl Woese
- 3 domains were added
what were the 3 domains?
what happened to the kingdom prokaryotae?
where are the organisms with cells that contain a nucleus?
what does Eukarya include?
- Bacteria, Archaea, Eukarya
- (contains unicellular organisms without a nucleus) are separated into 2 domains = Bacteria and Archea.
- Eukarya
- 4/5 kingdoms = protoctista, fungi, plantae, animalia
what does the 3 domain system reflect?
-how different the Archea and Bacteria are and this system is an example of how scientific knowledge is always changing and improving
the lower hierarchy stays what?
why was the 3 domain system proposed?
evidence showing differences between archea and bacteria:
- the same = kingdom, phylum, class, order, family, genus, species
- because of new evidence, mainly molecular
molecular evidence:
-RNA polymerase is different in bacteria and archea
- Archea, but not Bacteria, have similar histones to Eukarya
cellular evidence:
- the bonds of the lipids in the cell membranes of Bacteria and Archea are different
- the development and composition of flagellae are also different
- most scientists agree that Archea and Bacteria evolved separately and that Archea are more closely related to Eukarya than bacteria
EVIDENCE THAT HAS LEAD TO NEW CLASSIFICATION SYSTEMS-
explain how biological molecules can provide evidence that species have evolved?
-nuclear DNA or nucleic acid or RNA
-in samples from two species, similarity in nucleic acid or nuclear DNA or RNA can imply an evolutionary relationship, difference in sequence implies evolutionary distance.
-proteins or cytochrome C or haemoglobin or polypeptides
-in the same protein from two species, amino acid sequence similarity implies evolutionary relationship, difference in sequence implies evolutionary distance
EVIDENCE THAT HAS LEAD TO NEW CLASSIFICATION SYSTEMS-
how is DNA used to provide evidence?
- DNA is found in all organisms
-some sequences are highly conserved
-can make a comparison of DNA between species
-similar base sequence indicates recent common ancestor
individuals can also be classified using
the phylogenetic system, this is when species are grouped according to their evolutionary relationships and origins
what is phylogeny
-evolutionary relationships between organisms
- the study of closeness of evolutionary relationships
-phylogeny is used in modern classification
-the closer the evolutionary relationship, the closer the taxonomic grouping
- eg. gorillas and chimpanzees are closely grouped
all organisms have evolved from what?
and what is this shown on?
shared common ancestors
a phylogenetic tree
what is the smallest group that shares a common ancestor?
a species
what does each branchpoint in the phylogenetic tree indicate?
the common ancestor a species evolved from
how are phylogenetic trees created?
picture of a phylogenetic tree
by examining the physical characteristics and genetic makeup of organisms, fossils are also used.
what were Darwin’s observations?
-organisms produce more offspring than survive
- there’s variation in the charecteristics of members of the same species
-some of these charecteristics can be passed on from one generation to the next
-individuals that are best adapted to their environment are more likely to survive
state the name given to the evolution of a new species
speciation
Darwins theory of evolution by natural selection to explain his observations: (list)
example
-individuals within a population show variation in their phenotypes (characteristics)
-selection pressures create a struggle for survival (predation, disease, competition)
-individuals with better adaptations are more likely to survive and have reproductive success= pass on advantageous adaptations onto offspring
-over time, the proportion of the population possessing the advantageous adaptations increases
-over generations this leads to evolution as the favourable adaptations become more common in the population
eg. alleles that determine advantageous characteristics may be passes on = more dark peppered moth now because of their camouflage
how did Wallace contribute?
- similar ideas to Darwin
-arrived at independently
-published paper together
-he increased the weight of evidence to support the theory of evolution by natural selection
EVIDENCE TO SUPPORT EVOLUTION-
how do fossils show evidence?
-fossils show that organisms have changed over time
-fossils and rocks can be dated OR arranged in chronological order
-fossils showing intermediate sequences = fossil records of horses shows a gradual change in characteristics including increasing size, lengthening of limbs and hoof development
-compare DNA extracted from fossils
EVIDENCE TO SUPPORT EVOLUTION-
how can DNA be used to provide evidence to support the theory of evolution by natural selection?
-DNA is found in all organisms
-some sequences are highly conserved
-comparison of DNA between species also looking at differences in mitochondrial DNA in eukaryotic cells
-similar base sequence indicates common ancestor
EVIDENCE TO SUPPORT EVOLUTION-
how are proteins and other molecules used to provide evidence? (molecular evidence)
-comparing the sequence of amino acids in proteins
-compare antibodies
-organisms that diverged away from each other more recently have more similar molecules as less time has passed for changes in proteins and other molecules to occur
define variation
differences within or between species
what is intraspecific variation?
variation within a species
what is interspecific variation
variation between different species
what is continuous variation? (list)
-no defined categories (no gaps between bars on bar chart) = REF to bell shaped curve/binomial distribution
-range of values
-influenced by many genes and the environment
-quantitative/has to be measured
continuous variation- example characteristics-
animals?
-height = humans can be any height within a range, not just tall or short
-mass = human can be any mass within a range
-milk yield = cows can produce any volume of milk within a range
continuous variation- example characteristics-
plants?
-surface area of leaves = the surface area of each of a trees leaves can be any value within a range
-mass = the mass of the seeds from a flower head varies within a range
continuous variation- example characteristics-
microorganisms?
-width = the width of E.coli bacteria varies within a range
-length = the length of the flagellum can vary within a range
what is discontinuous variation? (list)
-few genes
-qualitative
-discrete categories/ no intermediates
-little/no environmental effects
-large genetic effect/ only genetic effect
discontinuous variation- example characteristics-
animals?
-blood group = humans can only be group A, B, AB or O
discontinuous variation- example characteristics-
plants?
-colour = courgettes are either yellow, dark green or light green
-seed shape = some pea plants have smooth seeds and some have wrinkled seeds
discontinuous variation- example characteristics-
microorganisms?
-antibiotic resistance = bacteria are either resistant or not
-pigment production = some types of bacteria produce a coloured pigment, some cant
causes of variation-
genetic factors?
examples of variation caused by genetic factors?
-alleles an organism has make up its genotype, the difference in genotype result in variation in phenotype (characteristics) = variation caused by genetic factors is inherited
-eye colour in humans
-blood type in humans
-antibiotic resistance in bacteria
causes of variation-
environmental factors?
examples?
-caused by differences in environment = climate, food, lifestyle. characteristics controlled by environmental factors can change over an organisms life
-accents
-piercings
causes of variation-
both genetic and environmental factors?
examples?
-genetic factors determine the characteristics an organisms born with, but environmental factors can influence how some characteristics develop
-height = genes determine how tall an organism can grow, but diet or nutrition availability affect how tall an organism actually grows
-flagellum = genes determine how tall an organism can grow a flagellum, but some will only start to grow a flagellum in certain environments eg. if metal ions are present
what is being adapted to an environment?
means an organism has features that increase its chances of survival and reproduction and also the chances of its offspring reproducing successfully
what are the 3 types of adaptations?
behavioural
physiological
anatomical (structural)
what are behavioural adaptations?
example?
-ways an organism changes the ways it acts that increase chance of survival, genetic or learnt from parents
-hedgehogs curl up when in being threatened to escape attack = increases chance of survival
what are physiological adaptations?
example?
-processes inside an organisms body that increase its chance of survival
-hedgehogs hibernating in the winter and slowing their metabolic rate = conserves energy so dont have to look for food in the months when its scarce
what are anatomical (structural) adaptations?
example?
-structural internal or external physical features that increases an organisms change of survival
-spikes on a hedgehog, or streamline shape on otters making it easier to glide through the water = easily catch prey and escape predators = increasing their chance of survival
why organisms from different taxonomic groups may show similar anatomical features?
why does this happen?
-due to convergent evolution
-when different species are exposed to similar selection pressures (eg environmental conditions), they will undergo natural selection for similar alleles and become more genetically similar = evolving similar characteristics independently of one another
why organisms from different taxonomic groups may show similar anatomical features?
why does this happen?
-due to convergent evolution
-when different species are exposed to similar selection pressures (eg environmental conditions), they will undergo natural selection for similar alleles and become more genetically similar = evolving similar characteristics independently of one another
example of convergent evolution?
explanation?
-marsupial and placental mammals
-marsupials are found mainly in australia and america and diverged from placental mammals millions of years ago and have been evolving separately ever since
marsupial mammals (kangaroos) and placental mammals (humans) differences?
Marsupial:
-have a short gestation period (pregnancy)
-don’t develop a full placenta
-are born early in their development and climb into their mothers pouch, they become attached to a teat and receive milk while they continue to develop
placental:
-have a longer gestation period
-develop a placenta during pregnancy, which allows the exchange of nutrients and waste products between the fetid and the mother
-are born fully developed
the mechanism by which natural selection can affect the characteristics of a population over time?
- Random mutations occur within the population
- This introduces genetic variation to the population
- Whilst some mutations are harmful, sometimes new alleles
created by mutations provide an organisms with an advantage to
survive in their environment. Conditions within the environment
which drive natural selection are called selection pressures (e.g.
competition for resources, new diseases, new predators, changes to the climate) - The new allele provides a reproductive selective advantage. Therefore, the individuals with the allele are more likely to reproduce and pass the allele onto their offspring. These individuals have reproductive success
- Over many generations, there will be an increase in the frequency of this allele within the population
- Evolution is a change in the allele frequency of a population
the evolution of pesticide resistance can be explained by natural selection:
example?
-there is variation in a population of insects, genetic mutations make some insects naturally resistant to a pesticide
-if the population of insects is exposed to that pesticide, only the individuals with resistance will survive to reproduce
-the alleles which cause the pesticide resistance will be passed on to the next generation. over many generations, the population will evolve to become more resistant to the chemical
-DDT resistance in mosquitoes
what are the implications of pesticide resistance for humans?
if the insects are resistant to specific pesticides, what might farmers have to do?
a population of insects could also evolve resistance to all pesticides in use, to prevent this?
crop infestations with pesticide-resistant insects are harder to control ( some insects are resistant to lots of different pesticides) = it takes farmers a while to figure out which way pesticide will kill the insect and in that time all the crop could be destroyed.
-use broader pesticides, which could kill beneficial insects. And if disease-carrying insects (eg mosquitoes) become pesticide resistant, the spread of disease could increase
-new pesticides need to be produced which takes time and costs money
evolution of drug resistance example?
some of the protoctists that cause malaria are resistant to several drugs used to treat malaria
what are the implications of drug resistance for humans?
there could come a point where a pathogen has become resistant to all the drugs we currently use against it, to prevent this?
-infections caused by drug-resistant microorganisms are harder to treat = it can take doctors a while to figure out which drugs will get rid of the infection and in that time the patient could become very ill or die
-new drugs need to be developed= takes time and costs money
INVESTIGATING VARIATION-
how do we measure how much variation there is in a sample?
using the mean and standard deviation
what is the mean?
how do you calculate the mean?
how can it be used to tell if there is variation between samples?
-an average of values collected in a sample
- mean= total of all the values in the data / the number of values in the data
-a bell-shaped graph (symmetrical), called a normal distribution.
what is standard deviation?
how to calculate standard deviation?
standard deviation is a method of calculating the dispersion of data, what is another?
why is standard deviation better than the range?
-tells you how much the values in a single sample vary from the mean
-look at maths sheet in folder
-calculating the range
-because it takes into account all the data in the data set, whereas, the range only uses two.
CORRELATIONS IN VARIATION-
what is spearman’s rank correlation coefficient (rs)?
how to calculate?
-tells you whether or not the two variables are related (eg. if there is a correlation between a genetic or environmental factor) and will also tell you how strongly related.
-look at maths sheet in folder
