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A Level Biology > 10.1 - Classification > Flashcards

10.1 - Classification Flashcards

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1
Q

Why do we classify ?

A
  • to help identify new species
  • to predict characteristics
  • to find evolutionary links
  • to make the study or living things more manageable
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2
Q

How do we classify ?

A

Observable characteristics ( gross and microscopic ) biochemistry ( DNA , proteins rRNA )

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3
Q

Define 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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4
Q

What are the 7 taxonomic groups ?
* remember the song*

A

Kingdom
Phylum
Class
Order
Family
Genus
Species

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5
Q

Define taxonomy

A

The focus on physical similarities

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6
Q

What is the binomial naming system ?

A

Genus species ( italics )

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7
Q

Why is the binomial naming system useful ?

A
  • analyse evolutionary relationships between organisms
  • predict characteristics
  • identify species
  • share findings internationally
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8
Q

What are the 5 kingdoms?

A
  • prokaryotae
  • protoctista
  • fungi
  • plantae
  • animalia
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9
Q

What are the 3 domains ?

A
  • Bacteria
  • archaea
  • eukarya
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10
Q

What are the general features of prokaryotae ?

A
  • unicellular
  • no nucleus or other membrane bound organelles
  • a ring of ‘naked’ DNA
  • small ribosomes
  • no visible feeding mechanism - nutrients are absorbed through the cell wall or produced internally by photosynthesis
  • eg. Escherichia coli
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11
Q

What are species ?

A

A group of organisms that can inbreed to produce fertile offspring

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12
Q

What species are humans?

A

Homo sapiens

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13
Q

What is binomial nomenclature?

A
  • developed in the 18th century by Carl Linnaeus
  • all species are given a scientific name consisting of two parts :
  • the first word indicates the organisms genus ( generic name )
  • the second word indicates the organisms species ( specific name )
  • no two species have the same generic and specific name
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14
Q

What are the general features of the protoctista?

A
  • mainly unicellular
  • a nucleus and other membrane bound organelles
  • some have chloroplasts
  • some are sessile but others move by cilia, flagella or by amoeboid mechanisms
  • nutrients are acquired by photosynthesis ( autorophic feeders ) ingestion of other organisms ( heterorophic feeders ) or both - some are parasitic
  • eg. Amoeba
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15
Q

What are the general features of fungi ?

A
  • unicellular or multicellular
  • a nucleus and other membrane bound organelles and a cell wall - mainly composed of chitin
  • no chloroplasts or chlorophyll
  • no mechanisms for locomotion
  • most have a body for mycelium made of threads or hyphae
  • nutrients are acquired by absorption - mainly from decaying material - they’re SAPROPHYTIC feeders - some are parasitic
  • most store their food as glycogen
  • eg. Mushrooms, moulds and yeast
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16
Q

What are general features of plantae ?

A
  • over 250,000 species - the plant kingdom is the second largest of the kingdoms
  • multicellular
  • a nucleus , other membrane bound organelles including chloroplasts and a cell wall —> composed of cellulose
  • all contain chlorophyll
  • most do not move - although gametes of some plants move using cilia or flagella
  • nutrients are acquired by photosynthesis - they’re autotrophic feeders ( organisms that make their own food )
  • store food as starch
  • eg. Flowering plants such as Roses , trees such as oak and grasses
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17
Q

What are some features of animal?

A
  • largest kingdom
  • multicellular
  • nucleus and other membrane bound organelles —> no cell walls
  • no chloroplasts
  • move with the aid of cilia, flagella or contractile proteins —> sometimes in the form of muscular organs
  • nutrients are acquired by ingestion - they’re heterotrophic feeders
  • food stored as glycogen
  • eg. Mammals , reptiles, birds , insects etc.
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18
Q

What is a saprotroph ?

A

An organism that feeds on or derives nourishment from decaying organic matter

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19
Q

Define heterotroph

A

An organism that feeds on other organisms

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20
Q

Define autotroph

A

An organism that makes its own food

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21
Q

What is Archaebacteria ?

A
  • ancient bacteria
  • can live in extreme environments
  • eg. Hot thermal vents , anaerobic conditions and highly acidic environments
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22
Q

What is Eubacteria ?

A
  • true bacteria
  • found in all environments
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23
Q

State two differences between fungi and plants

A
  • plants have chloroplasts where as fungi don’t
  • plants are autotrophs whilst fungi are heterotrophs
24
Q

Explain why prokaryotes are now classified as two separate domains

A
  • old classification does not show correct phylogeny
  • cell walls differ - peptidoglycan not found in archaea
25
Q

Describe how and why classification systems have changed over Time

A
  • living organisms classified into two kingdoms based on major differences in characteristics
  • for eg. Those that moved and ate animals and those that didn’t
  • there is more scientific advances and the use of microscope allowed smaller details to be observed
  • organisms divided into 5 kingdoms - plants,animals, fungi, protoctista and prokaryotes
  • advances in DNA and proteins to be studied
  • provided evidence for evolutionary relationships
  • three domain proposed
  • relevant scientists eg. Linnaeus, Whittaker or Woese
26
Q

What is phylogeny ?

A

The study of evolutionary relationships between organisms

27
Q

What is a species according to phylogeny ?

A

The smallest group that shares a common ancestor - end of the branch

28
Q

What are some advantages of phylogeny over classification ?

A
  • produces a continuous tree whereas classification uses discrete taxonomic groups
  • shows the history of different species far more accurately
  • hierarchal nature of Linnaean classification can be misleading as it implies different groups within the same rank are equivalent
29
Q

What are phylogenetic trees ?

A
  • A diagram used to represent the evolutionary relationships between organisms
  • they’re branches diagrams - show that different species have evolved from a common ancestor
  • the earliest species is found at the base of the tree and the most recent species are found at the tips of the branches
30
Q

How are phylogenetic trees produced ?

A

By looking at similarities and differences in species physical characteristics and genetic makeup

Much of the evidence has been gained from fossils

31
Q

State the main difference between early classification systems and systems based on phylogeny

A

Historical classification systems are based ok physical characteristics where as phylogeny is based on evolutionary relationships

32
Q

What is a homologous structure ?

A
  • structure that appears superficially different and may perform different different functions in different organisms but has the same underlying structure
33
Q

What is evolution ?

A

The way in which organisms change as a result of natural selection over many generations

34
Q

What is molecules evidence ?

A

Gathering molecular evidence and analysing the similarities in proteins and DNA

35
Q

What is phylogeny evidence ?

A

Comparing the fossil record

36
Q

What is embryological evidence ?

A

Comparing the development of organisms from an embryo

37
Q

What are 3 points of evidence for evolution ?

A
  1. Palaeontology - the study of fossils and the fossil record
  2. Comparative anatomy - the study of similarities and differences between organism’s anatomy
  3. Comparative biochemistry - similarities and differences between the chemical makeup of organisms
38
Q

How are fossils formed ?

A
  • when animal and plant remains are preserved in rocks
  • over long periods of time - sediment is deposited on the earth to form layers of rock
  • different layers corresponded to different geological eras
  • within the different rock strata the fossils found are quite different - forming a sequence from oldest to youngest which shows that organisms have gradually changed over time = fossil record
39
Q

What are some evidence provided by fossil records ?

A
  • fossils of the simplest organisms such as bacteria and simple algae are found in the oldest rocks - more recent rocks have more complex organisms such as vertebrates
  • this supports the evolutionary theory that simple life forms gradually evolved over an extremely long time period into more complex ones
  • the sequence in which the organisms are found matched their ecological links to each other for eg. Plant fossils appear before animal fossils —> this is consistent with the fact that animals require plants to survive
  • 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 t
40
Q

Why is sometimes the fossil records not complete ?

A
  • many organisms are soft bodied and decompose quickly before they have a chance to fossilise
  • the conditions needed for fossils to from are not often present
  • many other fossils have been destroyed by the earths movement such as volcanoes or still lie undiscovered
41
Q

What is comparative anatomy ?

A

Comparative anatomy is the study of similarities and differences in the anatomy of different living species

42
Q

What does the presence of homologous structures provide evidence for ?

A

Divergent evolution

43
Q

What does divergent evolution explain ?

A
  • 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
44
Q

What is comparative biochemistry ?

A

The study of similarities and differences in the proteins and other molecules that control life processes

45
Q

Explain evolutionary embryology

A
  • study of the embryos
  • an embryo is an unborn animal in its earliest phases of development
  • embryos or many different animals look very similar and it is often difficult to tell the, apart
  • this shows that the animals develop in a similar way —> implying that the processes of embryonic Development gave a common origin and the animals share common ancestry but have gradually evolved different traits
46
Q

What are the two common molecules studied ?

A
  • cytochrome C ( a protein involved in respiration )
  • ribosomal RNA
47
Q

What is the hypothesis of neural evolution ?

A
  • states that most of the variability In the structure of a molecule does not affect its function
  • due to the fact that most of the variability occurs outside of the molecule’s functional regions
  • changes that do not affect a molecules function are 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
48
Q

What do you compare to discover how close two species are together ?

A

The molecular sequence of a particular molecule

49
Q

How can scientists estimate the point at which the two species last shared a common ancestor ?

A
  • the number of differences that exist are plotted against the rate the molecule undergoes neutral base pair substitutions
50
Q

What is the molecular evidence to back up the difference between Archaea and bacteria ?

A

RNA polymerase is different and only Archaea have similar histories to Eukarya

51
Q

What is the cellular evidence to back up the difference between Archaea and Bacteria ?

A

Different bonding of lipids and different development and composition of flagellae

52
Q

Describe what is shown on a phylogenetic tree

A
  • a diagram is used to show evolutionary relationships between organisms
  • the closer the branches of the tree the closer the evolutionary relationships
53
Q

Describe two advantages and disadvantages or using the fossil record as a source of evidence for evolution

A

Advantages :
- radioisotopes can be used to date fossils
- changes can be tracked over time
- chronological order apparent in rock strata

Disadvantages :
- many organisms decompose quickly before they have a chance to fossilise / destroyed by volcanoes or destroyed by earthquakes

54
Q

Describe how the work of three scientists was used in the development of the theory of evolution

A

LYELL - suggested that fossils were actually evidence of animals that have lived millions of years ago

HUTTON - proposed theory of uniformitarianism

DARWIN - came up with the theory of evolution by natural selection through observations in the Galápagos Islands

WALLACE - came up with the theory of evolution by natural selection in Borneo

55
Q

Explain how comparative biochemistry provides evidence of evolution

A
  • study of similarities and differences in proteins and nucleic acid / DNA of an organism
  • changes in highly conserved molecules can help identify evolutionary links
  • such as cytochrome C / ribosome RNA
  • species that have the most similar DNA and proteins

A Level Biology (54 decks)

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