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biology > 4.2.2 classification > Flashcards

4.2.2 classification Flashcards

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1
Q

what is taxonomy?

A

practise of biological classification which enables us to arrange species into groups based on their evolutionary origins and relationships
group organisms into taxa to make it easier to understand
different ranks within the classification

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2
Q

taxonomic rank in the system

A

domain
kingdom
phylum
class
order
family
genus
species

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3
Q

hierarchical classification system

A

the higher ranks contain more organisms with less similarity between them
the lower ranks contain fewer organisms with more similarity between them

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4
Q
A
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5
Q

what are the three different domains?

A

eukarya - eukaryotes
bacteria - prokaryotes
archaea - prokaryotes

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6
Q

what is eukarya?

A

the domain of all eukaryotes e.g. wolf

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7
Q

why do scientists classify organisms?

A
  • To identify species – by using a clearly defined system of classification, the species an organism belongs to can be easily identified
  • To predict characteristics – if several members in a group have a specific characteristic, it is likely that another species in the group will have the same characteristic
  • To find evolutionary links – species in the same group probably share characteristics because they have evolved from a common ancestor
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8
Q

how to classify?

A
  • Observable characteristics (gross and microscopic), biochemistry (DNA, proteins RNA)
  • Separate organisms into three domains – archaea, bacteria and eukarya
  • Move down the hierarchy there are more groups at each levels but fewer organisms in each group – these organisms become more similar and share more of the same characteristics
  • Organisms are then classified as individual species – containing only one type of organism
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9
Q

what is a species?

A

a group of organisms that are able to reproduce to produce fertile offspring

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10
Q

binomial nomenclature

A
  • Binomials are the scientific name given to individual specials. They consist of the organisms genus and species name in Latin e.g. Homo sapiens (must be italicised)
  • This is useful for scientists as they allow for species to be universally identified
  • Species are also given common names which differ between countries and translations as well as common overlaps
  • The binomial nomenclature was developed by Linnaeus
  • Scientific name consists of Genus + species e.g. Homo sapien
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11
Q

what are the 3 different domains?

A

eukarya - eukaryotes
bacteria - prokaryotes
archaea - prokaryotes

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12
Q

what is archaea?

A
  • archaeal cells have no nucleus - prokaryotes
  • unique lipids found in cell membrane
  • no peptidoglycan in their cell walls
  • ribosomal structure - similar to eukaryotes
  • 70s ribosomes - RNA polymerase of different organisms contains between 8-10 proteins and is very similar to eukaryotic ribosome
  • similar in size to bacteria
  • DNA transcription is more similar to eukaryotes
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13
Q

what is bacteria?

A
  • no nucleus - prokaryotic
  • vary in size
  • divide by binary fission
  • 70s ribosomes - RNA polymerase contains 5 proteins
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14
Q

what is eukarya?

A
  • 80s ribosomes - RNA polymerase (responsible for most mRNA transcription) contains 12 proteins
  • have nuclei and membrane-bound organelles - eukaryotic
  • vary in size
  • divide by mitosis
  • reproduce sexually or asexually
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15
Q

differences between archaea and bacteria

A

initially there was no archaea domain they were all classified as bacteria
differences include:
- membrane lipids
- ribosomal RNA
- cell wall composition

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16
Q

membrane lipids in archaea and bacteria

A

archaea - consist of branched hydrocarbon chains bonded to glycerol by ether linkages
bacteria - consist of unbranched hydrocarbon chains bonded to glycerol by ester linkages

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17
Q

ribosomal RNA in archaea and bacteria

A

both - 70S ribosomes
archaea - smaller subunit, base sequence of ribosomal RNA and primary structure of ribosome proteins are more similar to eukarya

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18
Q

composition of cell walls in archaea and bacteria

A

bacteria - cell walls with peptidoglycan
archaea - cell walls do not contain peptidoglycan

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19
Q

features of the domains: cell type

A

archaea: prokaryotic
eubacteria: prokaryotic
eukaryotes: eukaryotic

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20
Q

features of the domains: chromosomes

A

archaea: circular
eubacteria: circular
eukaryotes: linear chromosomes and circular mtDNA and cpDNA

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21
Q

features of the domains: cell membrane lipids

A

archaea: glycerol - ether lipids
eubacteria: glycerol - ester lipids
eukaryotes: glycerol - ester lipids

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22
Q

features of the domains: ribosomes

A

archaea: 70S ribosomes but small subunit
eubacteria: 70S ribosomes
eukaryotes: larger 80S in cytosol and 70S ribosomes in mitochondria and chloroplasts

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23
Q

features of the domains: cell walls

A

archaea: always present without peptidoglycan
eubacteria: always present with peptidoglycan
eukaryotes: sometimes present without peptidoglycan

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24
Q

features of the domains: histones

A

archaea: yes
eubacteria: no
eukaryotes: yes

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25
Q

features of the domains: introns

A

archaea: sometimes
eubacteria: rarely
eukaryotes: yes

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26
Q

what are the 5 kingdoms?

A

prokaryota
protoctista
fungi
plantae
animalia

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27
Q

prokaryota

A
  • prokaryotic
  • includes bacteria and cyanobacteria (blue-green bacteria)
  • mostly unicellular
  • cell walls made of peptidoglycan and cytoplasm
  • no nucleus, nuclear envelopes or mitochondria
  • may have cell vacuoles
  • may have fagella
  • vary in size
  • divide by binary fission
  • some are autotrophic, others are heterotrophic
  • E.g. Staphlococcus aureus
28
Q

protoctista

A
  • eukaryotic
  • unicellular and multicellular
  • diversity in all aspects of life
  • have nuclear envelopes and organelles
  • some have cell walls, some have vacuoles:
  • protozoa - no cell walls, small temporary vacuoles
  • algae - have cellulose cell walls and chloroplasts, large permanent vacuoles
  • autotrophic and heterotrophic
  • some have flagella or cilia
  • E.g. amoeba, algae, silme moulds
29
Q

fungi

A
  • eukaryotic cells
  • have non-cellulose cell walls (often made from chitin)
  • don’t have cilia
  • have nuclear envelopes, large permanent vacuoles and organelles
  • heterotrophs - use organic compounds as their source of energy by digesting dead/decay matter extracellularly or from being parasites of living organisms
  • reproduce using spores that disperse onto the ground
  • can be unicellular
  • some consist of long threads called hyphae that grow from the main fungus body and form a network of filaments called the mycelium
  • some possess fruiting bodies that release large numbers of spores
  • E.g. Amoeba, mould fungi
30
Q

plantae

A
  • multicellular eukaryotes
  • cellulose cell walls
  • possess large permanent vacuoles that provide structural support
  • able to differentiate into specialised cells to form tissues and organs
  • possess chloroplasts that enable photosynthesis
  • gametes of some plants have flagella
  • autotrophs - can synthesise their organic compounds and molecules for energy use and building biomass from inorganic compounds
  • complex body forms - have branching systems above and below the ground
  • E.g. liverworts, mosses, ferns, conifers, flowering plants
31
Q

animalia

A
  • multicellular eukaryotic organisms
  • able to differentiate into many different specialised cell types that can form tissues and organs
  • small temporary vacuoles e.g. lysosomes
  • no cell walls
  • have cilia sometimes
  • heterotrophs and have wide range of feeding mechanisms
  • muscular tissue
  • communication within their complex body takes place through a nervous system and chemical signalling
  • E.g. jellyfish, coral worms, insects, vertebrates
32
Q

changes to the classification system

A
  • Originally classification systems were based on observable features then through the study of genetics and biological molecules scientists can study the evolutionary relationships between organisms
  • During evolution, DNA, internal and external features change – DNA determines the proteins that are made, which determines the characteristics
  • For characteristics to change the DNA must too
  • Scientists compare similarities in DNA and proteins of different species to discover evolutionary relationships between them
33
Q

how has haemoglobin changed structure?

A
  • 4 polypeptide chains made up of a fixed number of amino acids
  • Haemoglobin differs in different animals – number of amino acids
34
Q

current classification system

A

Three Domain System by Carol Woese
- domains are a further level of classification at the top of the hierarchy
- groups organisms using differences in the sequences of nucleotides in the cells’ ribosomal RNA as well as the cells’ membrane lipid structure and their sensitivity to antibiotics
- observation of these differences made possible through advances in scientific techniques
- classified into 3 domains and 6 kingdoms
- different domains contain a unique form of rRNA and different ribosomes

35
Q

eukarya ribosomal structure

A

80s ribosomes
RNA polymerase (responsible for most mRNA transcription) contains 12 proteins

36
Q

archaea ribosomal structure

A

70s ribosomes
RNA polymerase of different organisms contains between 8-10 proteins and is similar to eukaryotic ribosome

37
Q

bacteria ribosomal structure

A

70s ribosomes
RNA polymerase contains 5 proteins

38
Q

Woese’s system

A
  • prokaryotae kingdom divides into archaebacteria and eubacteria
  • 6 kingdoms: archaebacteria, eubacteria, protoctista, fungi, plantae and animalia
39
Q

difference between archaebacteria and eubacteria

A

both: single celled organisms
eubacteria: different chemical makeup e.g. contains peptidoglycan in cell wall
archaebacteria: does not

40
Q

archaebacteria

A
  • ancient bacteria
  • can live in extreme environments including hot thermal vents, anaerobic conditions and highly acidic environments
  • e.g. methanogens live in anaerobic environments like sewage treatment plants and make methane
41
Q

eubacteria

A
  • true bacteria
  • found in all environments
  • where most bacteria is found
42
Q

homology definition

A

grouping organisms based on the features they shared
evolved from a common ancestor

43
Q

disadvantages of using homology

A

traditional biological classification systems used homology
hard to determine evolutionary relationships of species using physical features
often leads to wrong classification of species

44
Q

phylogeny definition

A

the evolutionary history of organisms
uses phylogenetic trees

45
Q

how has advances in research allowed scientists to investigate the evolutionary relationships between species

A
  • advances in DNA, RNA, protein sequencing and immunology led to research into the evolutionary relationships between species
  • allowed us to understand the true phylogeny of taxa to correctly group them together
46
Q

what three types of sequence data are used to investigate evolutionary relationships

A

DNA
mRNA
amino acids

47
Q

how can sequencing technology determine the order of DNA bases?

A
  • using mRNA bases and amino acids within an organism’s genome
  • useful for comparison with extinct species
  • useful when distinguishing between species that are physically similar
  • scientists choose specific proteins or sections of the genome for comparison between organisms
48
Q

classification and phylogeny

A

can occur without phylogeny
objective of many scientists to develop a classification system that takes into account phylogeny

49
Q

phylogenetic trees

A

diagram used to represent the evolutionary relationships between different taxa
branched to show species evolved from a common ancestor
earliest species is found at the base of the tree
most recent found at tips of branches

50
Q

how do phylogenetic trees work?

A

produced by looking at similarities and differences in species’ physical characteristics and genetic makeup

51
Q

differences between phylogenetic classification and the Linnaean classification

A
  • done without Linnaean classification
  • classification uses knowledge of phylogeny in order to confirm the classification groups are correct or causes them to be changed
  • produces a continuous tree whereas classification requires discrete taxonomical groups - forcing scientists to put organisms into specific groups they don’t fit into
  • hierarchal nature of linnaean classification can be misleading as it implies different groups within the same rank are equal
  • groups organisms that are not comparable
52
Q

what is evolution?

A

theory that describes the way in which organisms change over many years as a result of natural selection

53
Q

Darwin’s theory of evolution

A

Darwin realised that organisms best suited to their environment are more likely to survive and reproduce, passing on their characteristics to their offspring
A species changes over time to have a more advantageous phenotype for its environment - this is passed on from one generation to the next by genes in DNA molecules

54
Q

Darwin’s research in the Galapagos

A
  • Darwin challenged geologists’ claims that geological formations were as a result of biblical events such as floods - led him to believe that evolution was a slow process
  • Darwin carried out observations in the Galapagos Islands - noticed that different islands had different finches - similar but different beaks and claws
  • Darwin realised that their shapes in the design of the finches’ beaks was due to the food on each island
  • birds with a beak more suited to its food would survive longer and have more offspring - passing on its advantageous characteristic
  • Darwin sent specimens back to the UK for other scientists to preserve and classify - allowing them to spot characteristics and links between organisms
  • he spent years developing his ideas and carrying out experimental breeding of pigeons to gain direct evidence of his ideas
55
Q

Wallace’s research

A
  • Wallace was working on his own theory of evolution in Borneo at the same time
  • he sent his ideas to Darwin for peer review
  • ideas were so similar that they proposed the theory of evolution through a joining presentation of two scientific papers
  • Darwin later published ‘On the Origin of Species’ - named the theory they had presented as the theory of evolution by natural selection
  • book was controversial as it conflicted religious views and implied that humans evolved from apes
56
Q

evidence of evolution

A

palaeontology
comparative anatomy
comparative biochemistry

57
Q

what is palaeontology?

A

the study of fossils and the fossil record

58
Q

what is comparative anatomy?

A

the study of similarities and differences between organisms’ anatomy

59
Q

what is comparative biochemistry?

A

similarities and differences between the chemical makeup of organisms

60
Q

how do fossils provide evidence for evolution?

A
  • fossils of simple organisms are found in the oldest rocks whereas fossils of more complex organisms are found in recent rocks - supports the evolutionary theory that simple life forms gradually evolved over a long period of time into more complex ones
  • sequence in which the organisms are found matches their ecological links to each other
  • by studying similarities in the anatomy of fossil organisms scientists can show how closely related organisms have evolved from the same ancestor
  • fossils allow relationships between extinct and living organisms to be investigated
61
Q

disadvantages of using fossils to explain evolution

A

the fossil record is not complete
many organisms decompose before they can be fossilised
many fossils have been destroyed by environmental factors like volcanoes
some fossils are undiscovered

62
Q

what is a homologous structure?

A

a structure that appear superficially different in different organisms but has the same underlying structure e.g. pentadactyl limb of vertebrates

63
Q

evidence of divergent evolution

A

presence of homologous structures provide evidence for divergent evolution
this describes how, from a common ancestor, different species have evolved, each with a different set of adaptive features
this type of evolution will occur when closely related species diversify to adapt to new habitats as a result of migration or loss of habitat

64
Q

how does comparative biochemistry provide evidence for evolution

A

slight changes that occur can help identify evolutionary links
to discover how closely related species are, the molecular sequence of a particular molecule is compared
the number of differences are plotted against the rate the molecule undergoes neutral base pair substitutions
scientists can estimate the point at which the two species last shared a common ancestor
closely related species have similar DNA and proteins
ribosomal RNA has a slow rate of substitution so is used with fossil information to determine relationships between ancient species

65
Q

the hypothesis of neutral evolution

A

states that most of the variability in the structure of a molecule does not affect its function because most of the variability occurs outside of the molecule’s functional regions
changes that do not affect a molecule’s function is called neutral since they have no effect on function, their accumulation is not affected by natural selection
as a result, neutral substitutions occur at a fairly regular rate, although that rate is different for different molecules

biology (10 decks)

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