a level biology > Classification > Flashcards

Classification Flashcards

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1
Q

Classification

A
  • the name given to the process by which living organisms are sorted into groups
  • the organisms within each group share similar features
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2
Q

Taxonomic groups

A
  • the hierarchal groups of classification
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3
Q

what are the taxonomic groups

A
  • kingdom
  • phylum
  • class
  • order
  • family
  • genus
  • species
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4
Q

kingdom

A
  • biggest and broadest taxonomic group
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5
Q

species

A
  • smallest and most specific classification
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6
Q

Linnaean classification

A
  • hierarchal classification system
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7
Q

which level of classification was added

A
  • domain
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8
Q

Domain

A
  • top of the classification hierarchy
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9
Q

why do scientists need to classify organisms

A
  • to identify species
  • predict characteristics
  • find evolutionary links
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10
Q

identifying species

A
  • by using a clearly defined system of classification
  • the species an organism belongs to can be easily identified
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11
Q

predict characteristics

A
  • if several members in a group have a specific characteristic
  • it is likely another species in the group will have the same
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12
Q

finding evolutionary links

A
  • species in the same group
  • share characteristics
  • as they have evolved from a common ancestor
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13
Q

why is using a single classification important

A
  • scientists can share their research
  • links can be seen even if they live on different continents
  • universal language scientists from all over the globe can understand
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14
Q

why have classification systems been created

A
  • to order observed organisms
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15
Q

how are the organisms initially classified

A
  • by separating organisms into the 3 domains
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16
Q

3 domains

A
  • archaea
  • bacteria
  • eukarya
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17
Q

as you move down the classification system what happens

A
  • there are more groups at each level
  • fewer organisms in each group
  • organisms in each group become more similar / share more similar characteristics
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18
Q

what is the last level organisms are classified into

A
  • individual species
  • smallest units of classification
  • only contains one type of organism
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19
Q

species - definition

A
  • a group of organisms that are able to reproduce to produce fertile offspring
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20
Q

when a horse is bred with a donkey, mules or hinnys are produced - why aren’t these classed as species

A
  • infertile
  • cells contain an odd number of chromosomes
  • therefore meiosis and gamete production cannot take place correctly as all chromosomes must pair up
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21
Q

human species

A

homo sapiens

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22
Q

why is naming organisms by their physical characteristics useful

A
  • working with scientists internationally
  • organisms may have more than 1 common name
  • different names in different languages
  • common names do not provide information about the relationships between organisms
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23
Q

binomial nomenclature

A
  • to ensure scientists internationally are discussing the same organism
  • this system was developed
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24
Q

what are the 2 parts of a species scientific name

A
  • first word indicates organisms genus / generic name
  • second word indicates organisms species / specific name
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25
how do we write the name of an organism
- upper case letter for the first letter of the genus - otherwise all in lowercase
26
how many kingdoms
5
27
5 kingdoms
- prokaryotae (bacteria) - protoctista (unicellular eukaryotes) - fungi - plantae - animalia
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prokaryotae
- unicellular - no nucleus - no membrane bound organelles - small 70s ribosomes - a ring of 'naked' DNA - no visible feeding mechanism - nutrients absorbed by cell wall / produced by photosynthesis internally
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protoctista
- mainly unicellular - a nucleus - membrane bound organelles - some have chloroplasts - some sessile - some move by cilia, flagella - nutrients acquired by photosynthesis or - ingestion of other organisms
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example of prokaryotae
- e coli
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example of protoctista
- amoeba
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fungi
- unicellular/multicellular - nucleus - membrane bound organelles - cell wall made of chitin - no chloroplasts/chlorophyll - no mechanisms for locomotion - most have a body or mycelium made of threads/hyphae - nutrients acquired by absorption - most store their food as glycogen
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how are nutrients acquired by absorption in fungi
- decaying material - fungi are saprophytic feeders - some fungi are parasitic
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fungi examples
- yeast - mushrooms - moulds
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plantae
- multicellular - nucleus - membrane bound organelles - chloroplasts - cellulose cell wall - chlorophyll - most do not move - nutrients acquired by photosynthesis - stores food as starch
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plantae are autrophic feeders, what is this
- they make their own food
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example of plantae
- flowering plants - roses - oak trees - grasses
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how many plantae species
over 250,000
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animalia
- multicellular - nucleus - membrane bound organelles - no cell walls - no chloroplasts - move with aid of cilia, flagella or contractile proteins - nutrients acquired by ingestion = heterotrophic feeders - food stored as glycogen
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how many animalia
over 1 million
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animalia examples
- mammals, e.g cats - reptiles, e.g lizards
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why are classification systems changing
- through the study of genetics and biological molecules - evolutionary relationships between organisms can be studied
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what happens when organisms evolve to their genetics
- DNA changes - this determines the proteins which are made - determining organisms characteristics - which is why external and internal features may change
44
how can scientists discover evolutionary relationships
- by comparing the similarities in DNA - and proteins of different species
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how does haemoglobin indicate a common ancestry between different primate groups
- haemoglobin in humans differs from chimpanzees in only 1 amino acid - humans differ from gorillas in 3 amino acids - humans differ from gibbons in 8 amino acids - overall structure is the similar between organisms
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haemoglobin structure
- protein - 4 polypeptide chains - each chain is made up of a fixed number of amino acids
47
what are the 3 domains
- archaea - bacteria - eukarya
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what are the differences between the 3 domains
- unique form of rRNA - different ribosomes
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Eukarya
- 80 s ribosomes - RNA polymerase (12 proteins) -
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RNA polymerase
- responsible for most mRNA transcription
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Archaea
- 70 s ribosomes - RNA polymerase of different organisms - 8-10 proteins - similar to eukaryotic ribosome
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Bacteria
- 70 s ribosomes - RNA polymerase ( 5 proteins)
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Bacteria - kingdoms
- eubacteria
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Archaea - kingdoms
- archaebacteria
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Eukarya - kingdoms
- protoctista - plantae - animalia - fungi
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Prokaryotae kingdoms
- eubacteria - archaebacteria
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why is eubacteria and archaebacteria classified into their own kingdoms
- different chemical makeup - eubacteria contains peptidoglycan in their cell wall wheras archaebacteria do not
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Archaebacteria
- lives in extreme environments - e.g hot thermal vents - e.g anaerobic conditions
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eubacteria
- true bacteria - found in all environments - most bacteria
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phylogeny
- the name given to evolutionary relationships between organisms
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phylogenetics
- the study of evolutionary history of groups of organisms - it reveals which group an organism is related to - how closely related these organisms are
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phylogenetic trees
- diagram used to represent evolutionary relationships between organisms - branched diagrams - they show that different species have evolved from a common ancestor
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Structure pf phylogenetic trees
- earliest species at the base of the tree - most recent species are found at tips of branches
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how are phylogenetic trees produced
- looking at similarities and differences in species physical characteristics and genetic makeup
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advantages of phylogenetic classification
- confirms classification groups are correct - can be done without reference to Linnaean classification - produces a continuous tree - Linnaean classification can be misleading
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Phylogeny produces a continuous tree-
- better because classification requires discrete taxonomical groups - scientists are not forced to put organisms into a specific group that they do not fit
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linnean classification system can be misleading
- it implies different groups within the same rank are equivalent
68
Darwin - theory
- theory of evolution
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evolution
- theory that describes the way in which organisms change over many years - due to natural selection
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Theory of evolution
- organisms best suited their environment are more likely to survive and reproduce - passing on characteristics onto offspring - gradually a species changes over time - giving a more advantageous phenotype for the environment in which it lives - advantageous characteristics are passed onto 1 generation to the next - by genes in DNA molecules - slow process - small changes gradually accumulate over time
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Observations - Darwin
- HMS beagle = Galapagos islands - finches - pigeons = England
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Issues with the theories of evolution and natural selection
- conflicted with religious view that God had created all of the animals and plants on Earth - suggests humans are evolved from apes - conflicted with belief that God created man in his own image
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Evidence for evolution
- palaontology - comparative anatomy - comparative biochemistry
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palaeontology
- study of fossils - and the fossil record
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comparative anatomy
- study of similarities and differences - between organisms anatomy
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comparative biochemistry
- similarities and differences - between chemical makeup of organisms
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how are fossils formed
- when plant and animal remains are preserved in rocks - sediment is deposited on the Earth to form layers of rock
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what do the different layers of rock formed from fossils correspond to
- different geological eras - most recent layer found on the top
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fossil record
- within the rock strata different fossils are found - a sequence from oldest to youngest is found in rock strata - showing how organisms gradually change over time
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evidence for fossil record
- fossils of simplest organisms like bacteria are found in the oldest rocks - sequence in which organisms are found matches their ecological links to each other - by studying similarities in anatomy of fossil organisms scientists can show how closely related organisms have evolved from the same ancestor - allow relationships between extinct and living organisms to be investigated
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why isn't the fossil record complete
- many organisms are soft bodied and decompose quickly - before they have a chance to fossilise - conditions needed for fossils to form are not often present - other fossils may have been destroyed by Earths movements / could be undiscovered
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comparative anatomy - homologous structure
- structure that appears superficially different in different organisms - but has the same underlying structure
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example of a homologous structure
- pentadactyl limb of vertebrates
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vertebrate limbs
- wide variety of functions - running, jumping, flying - basic bone structures of all vertebrate limbs are all similar - bones are just adapted to suit different functions - showing all vertebrates have evolved from a common ancestor
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what does the presence of homologous structures provide evidence for
- divergent evolution
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divergent evolution
- how species have evolved from a common ancestor - each with a set of adaptive features
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when does divergent evolution occur
- when closely related species diversity will adapt to new habitats - as a result of migration or loss of habitat
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comparative biochemistry - most common molecules studied
- cytochrome
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cytochrome
- a protein - involved in respiration - involved in ribosomal RNA
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how can comparative biochemistry be used to discover how closely species are related
- molecular sequence of a particular molecule is compared
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in comparative biochemistry what information can scientists gather
- the point at which the 2 species last shared a common ancestor - species that are closely related have more similar DNA and proteins - those distantly related have fewer similarities - rRNA is commonly used with fossil information to determine relationship between ancient species
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variations
- differences in characteristics between organisms
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interspecific variation
- widest type of variation is between members of different species
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intraspecific variation
- differences between organisms within a species
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2 causes of variation
- an organisms genetic material = differences in the genetic material an organism inherits from its parents - the environment in which the organism lives
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2 types of variation
- genetic - environmental
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genetic variation causes
- due to genes (alleles) an individual possesses
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genetic causes of variation
- alleles - mutations - meiosis - sexual reproduction - chance
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allelles - causing genetic variation
- genes have different alleles - different alleles produce different effects - individuals in a species population may inherit different alleles of a gene
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alleles
- alternative forms of genes
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mutations - causing genetic variation
- causes changes to DNA sequence - leading to changes in the proteins - can affect physical and metabolic characteristics
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what happens if a mutation occurs in somatic (body cells)
- only the individual is affected
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what happens if a mutation occurs in the gametes
- it can be passed onto the organisms offspring
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Meiosis - causing genetic variation
- during meiosis the nucleus divides - chromatids of a chromosome separate - genetic material inherited by 2 parents is mixed up - due to independent assortment and crossing over - gametes of an individual show variation
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what happens during meiosis
- gametes are produced - organisms reproduce sexually - each gamete receives half the genetic content of a parent cell
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sexual reproduction - genetic variation
- offspring produced from 2 individuals inherits genes from each parent - so each individual differs from parents
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chance - genetic variation
- many different gametes are produced from parental genome - during sexual reproduction it is down to chance as to which 2 gametes combine - individuals produced differ from siblings - as each contains a unique combination of genetic material
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in which type of reproduction is variation more likely
- sexual reproduction - as asexual reproduction produces clones
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how do organisms which reproduce asexually have variation
- mutations
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example of genetic variation
- blood group
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which organism is more affected by environmental variation
- plants - as plants have lack of mobility
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example of a characteristic that is due to environmental variation
- scars
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example of variation due to environmental and genetic factors
- height - skin colour
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height
- tall parents = inherit genes to allow you to grow a tall height - if you eat a poor diet/suffer from disease = you may only grow to a below average height
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skin colour
- determined by pigment of melanin - more melanin = darker skin - amount of melanin determined by genetics - if you expose your skin to sunlight more melanin is produced - due to UV rays
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why is it difficult to investigate causes of variation
- many characteristics is due to a combination of both genetic and environmental causes - nature vs nurture
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how do we study variation
- Identical twin studies - determines how much of a characteristic is a result of genetic variation - how much is down to environment
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how are identical twins produced
- when an egg splits after fertilisation - each twin contains 100% same genetic material - no genetic variation
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how do twin studies work
- if brought up in different environments - result of environmental variation can be seen easily - twins will grow, showing variation - the characteristics which show most variation between twins is something more influenced by environment than genes - those where twins show less variation = more genetic
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discontinuous variation
- a characteristic that can only result in certain values - no inbetween values
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example of discontinuous variation
- genetic factors - e.g animals sex
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how is discontinuous variation normally represented
- using a bar chart - sometimes a pie chart
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continuous variation
- characteristic that can take any value within a range - there is a graduation in values - from 1 extreme to another - continuum
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example of continuous variation
- environmental factors
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how is continuous variation usually presented
- frequency table - data then plotted on a histogram
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normal distribution curve
- when continuous variation data are plotted onto a graph - a bell shaped curve is produced - data is normally distributed
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characteristics of a normal distribution
- mean, mode, median is the same - distribution has a bell shape which is symmetrical about the man - 50% values less than mean, 50% are greater than the mean - most values lie close to the mean - number of extreme values are lpw
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standard deviation
- measure of how spread out the data is
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greater the standard deviation ...
- greater the spread of the data - large amount of variation
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what other statistical tests can be used to determine the significance of data collected
- t test - correlation coefficient
131
t test
- used to compare means of data values of 2 populations
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correlation coefficient
- used to consider the relationship of between 2 sets of data
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what does T test measure
- mean values of 2 sets of data
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what correlations can 2 sets of data show
- no correlation - positive correlation - negative correlation
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no correlation
- no relationship between the data
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positive correlation
- as one set of data increases in value - other set of data also increases in value
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negative correlation
- as one set of data increases in value - other set of data increases in value
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adaptations
- characteristics that increases an organisms chance of survival and reproduction in its environment
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types of adaptations
- anatomical adaptations - behavioural adaptations - physiological adaptations
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anatomical adaptations
- physical features - (internal and external)
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behavioural adaptations
- the way an organism acts - inherited or learnt from parents
142
physiological adaptations
- processes that take place inside an organism
143
examples of anatomical adaptations
- body covering - camoflauge - teeth - mimicry
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body covering
- hair - scales - spines - feathers - shells - these can help the organism to fly - help organisms stay warm - provide protection
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body covering - helping organisms fly
- feathers on birds
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body covering - helping organisms stay warm
- thick hair on polar bears
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body covering - protection
- snail shell - thick waxy layers prevent water loss on plants
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camoflage
- outer colour of an animal - allows it to blend into its environment - making it harder for predators to spot it
149
example - camoflage
- snowshoe hare - white in winter - matching snow - turns brown in summer - blends with soil
150
teeth
- shape and type - related to diet - herbivores = sheep have molars - carnivores = tigers have sharp canines
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mimicry
- copying another animals appearance or sounds - allow a harmless organism to fool predators into thinking it is poisonous
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example of mimicry
- hoverfly mimics markings of a wasp - detering predators
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behavioural adaptations
- survival behaviours - courtship - seasonal behaviours
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survival behaviours
- an opossum plays dead - rabbit freezes when they think they have been seen
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courtship
- many animals exhibit elaborate courtship behaviours - to attract a mate - to increase chances of reproducing
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example = courtship
- scorpions perform a dance - to attract a partner
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seasonal behaviours
- adaptations enable organisms to cope with changes in the environment
158
types of seasonal behaviours
- migration - hibernation
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migration
- animals move from 1 region to another - then back again when environmental conditions are more favourable
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why may migration occur
- better climate - food source
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hibernation
- period of inactivity - an animals body temperature, HR, breathing rate slow down - to conserve animals - reducing animals requirement for food
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example of hibernation
- brown bears hibernate during winter
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2 categories of behavioural adaptations
- innate behaviour - learned behaviour
164
innate behaviour
- ability to do this is inherited through genes
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example of innate behaviour
- behaviour of spiders to build webs
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learned behaviour
- adaptations learned from experience - from observing other animals
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example of learned behaviour
- use of tools
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physiological adaptations
- poison production - antibiotic production - water holding
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poison production
- many reptiles produce venom - to kill their prey - many plants produce poisons in leaves - protect themselves being eaten
170
antibiotic production
- some bacteria produce antibiotics - to kill other species of bacteria in the surrounding area
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water holding - example
- water holding frog - stores water in its body - can survive in the desert for more than a year without access to water
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anatomical adaptations to provide evidence for convergent evolution
- analogous structures -
173
analogous structures
- where structures perform the same function - but have a different genetic origin
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convergent evolution
- takes place when unrelated species begin to share similar traits
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why do unrelated species begin to share similar traits in convergent evolution
- different organisms adapt to similar environments / other selection pressures - organisms live in a similar way to each other
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give an example of organisms who are unrelated but share similar characteristics due to convergent evolution
- whales and fish - tail fins are similar - helping them both move efficiently through water
177
using ideas of convergent evolution, why do species of the same continent resemble each other
- they have adapted to fill similar niches
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placental mammals
- placenta connects embryo - to mothers circulatory system om uterus - nourishing the embryo - so it reaches higher maturity before birth
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marsupials
- start life in the uterus - then leave and enter marsupium (pouch) - whilst still embryos - where they complete development here - by suckling milk
180
marsupials and placental mammals separated from a common ancestor over 100 million years ago, despite this temporal and geographical separation why do marsupials in Australia and placental mammals in America produce species which are similar -
- they have adapted to similar climates - similar food supplies
181
what do marsupials and placental mammals have in common -
- overall shape is similar - type of locomotion - feeding techniques
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differences in marsupials and placental mammals -
- methods of reproduction - this feature represents their distinct evolutionary relationships
183
examples of marsupials and placental mammals which share similar characteristics due to convergent evolution -
- marsupial and placental mice - flying phalangers and flying squirrels - marsupial and placental moles
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marsupial and placental mice -
- both small - agile climbers - live in dense ground cover - forage at night for small food items - similar in size and body shape
185
flying phalangers and flying squirrels -
- both gliders - eat insects and plants - skin is stretched between forelimbs and hindlimbs (providing large SA for gliding)
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marsupial and placental moles -
- both burrow through soft soil to find worms and grubs - streamlined body shape and modified forelimbs for digging - velevety fur (smooth movement in soil) - however differ in fur colour
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example of convergent evolution in plants -
- aloe and agave - both adapted to survive in the desert - however developed entirely separately from each other
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selection pressures
- factors that affect the organisms chances of survival - or reproductive success
189
organisms that are best adapted to their environment :
- more likely to survive and reproduce - due to natural selection - these adaptations become more common in the population
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organisms that are poorly adapted to the environment
- less likely to survive and reproduce - characteristics are not passed onto the next generation - less of the population will display these characteristics
191
steps of natural selection
1- organisms within a species show variation in their characteristics that are caused by different genes 2- organisms whose characteristics are best adapted to a selection pressure have increased survival chances 3- successful organisms pass the allele encoding the advantageous characteristic onto offspring 4- process repeated for every generation 5- over a period of time, a new species can evolve
192
natural selection step 1 - expand
- organisms within a species show variation in their characteristics - that are caused by differences in their genes (genetic variation) - e.g they may have different alleles of a gene for a particular characteristic
193
how can new alleles arise
mutation
194
natural selection - stage 2 - expand
- organisms whose characteristics are best adapted to a selection pressure - have an increased chance of surviving and reproducing successfully - less well adapted organisms die/fail to reproduce - survival of the fittest
195
example of selection pressures
- predation - competition - disease
196
natural selection - step 4 - expand
- process repeated for every generation - over time proportion of individuals with advantageous adaptation increases - therefore frequency of the allele that codes for this particular characteristic - increases populations gene pool
197
natural selection step 5 - expand
- over long periods of time, many generations, and often involving multiple genes - process leads to evolution of a new species
198
modern examples of evolution
- antibiotic resistant bacteria - peppered moths - sheep blowflies - flavobacterium
199
antibiotic resistant bacteria
- MRSA developed resistance to many antibiotics
200
how does antibiotics treat bacteria
- bacteria reproduces very rapidly and evolve in a very short time - when bacteria replicate, DNA can be altered - this usually results in bacteria dying
201
how can bacteria become resistant
- a mutation in bacteria can provide resistance - when bacteria exposed to this antibiotic - resistant individuals survived and reproduced - passing allele for resistance onto their offspring - non resistant individuals die - over time number of resistant individuals in population increased
202
peppered moths
- changes in a moths environment caused changes in allele frequency of peppered moths - changed colour of moths - some were pale coloured, some darker - darker moths were easier spotted by birds and eaten - in industrial rev trees became darker - dark moths now better adapted - increased frequency of dark moths
203
sheep blowflies -
- lay their eggs in faecal matter around a sheeps tail - larvae then hatch and cause sores - leaving condition 'flystrike' - if left untreated = fatal
204
sheep blowflies - natural selection
- Australia - pesticide used to kill blowflies and prevent flystrike - blowflies became resistant to this - resistant insects passed on allele allowing resistant population to evolve - after investigating why this happened scientists discovered blowflies had a pre-existing resistance to this chemical - pre-adaptation allowed resistance
205
pre-adaptation
- when an organisms existing trait is advantageous for a new situation - can help scientists predict if resistance could occur
206
flavobacterium
- living in waste water from factories which produce nylon 6 - evolved to digest nylon - beneficial = help to clear up factory waste
207
how does flavobacterium digest nylon
- enzymes 'nylonases' to digest nylon - do not help bacteria to digest any other known material - benefits bacteria as it provides them with another source of nutrients
208
why do scientists think flavobacterium are able to digest nylon
- gene mutation - occurred to produce these enzymes - result of gene duplication - combined with a frameshift mutation
209
founder effect
- when a few individuals of a species colonise a new area - offspring initially experience a loss in genetic variation - resulting in individuals that are physically and genetically different from their source population
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