Classification and evolution

  • Created by: Emily.T
  • Created on: 20-04-17 21:27
What does the term 'monophyletic' mean?
Evolved from one common ancestor
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What is a common ancestor?
Where two or more species are descendants from the same ancestor
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Explain the differences between taxonomy and classification?
Classification is placing living things into groups whereas taxonomy is the classifying and naming of organisms in an ordered system intended to indicate natural (evolutional) relationships
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Why do we study how closely related we are to other organisms?
To find common ancestors a
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Why do we classify living things?
To identify species, predict characteristics, find evolutionary links
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What are taxa?
The name given to a classification group to which organisms are place in based on the relationships between the organisms
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What is the order for the main heirarchal taxa?
1) Domain 2) Kingdom 3) Phylum 4) Class 5) Order 6) Family 7) Genus 8) Species
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What is the mnemonic to help remember the main heriarchal taxa?
Don't Kick Phil's Cat Out For Gods Sake
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What are the 3 Domains?
Eukarya, Bacteria, Archae
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Describe the differences between plants and fungi
Plants have cellulose cell walls whereas fungi have chitin cell walls, fungi do not contain chlorophyll and do not photosynthesise like plants can
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Compare prokaryotes with protoctists
Protoctists are eukaryotic cells and prokaryotes are prokaryotic cells, prokaryotes are just unicellular when protoctists can be unicellular or simple multicellular organisms
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List three features of organisms belonging to the Kingdom Funig
1) Cell walls made out of chitin 2) Are saprotrophic 3) Are single-celled/multicellular
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What does saprotrophic mean?
Means that an organism absorbs substances from dead or decaying organsisms for food
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What does autotrophic mean?
Means that an organism is able to produce their own food
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What does photoautrophic mean?
That an organism is able to produce their own food using light (e.g. a plant)
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State two features that fungi have in common with plants
1) both eukaryotic 2) can both be multicellular
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What is phylogeny?
The study of the evolutionary history of groups of organisms that tells us who's related to whom and how closely they are
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Outline the advantages of phylogenetic classification
- Done without ref. to Linnaean C, - confirm C groups are correct or causes them to be changed, - produces a continuous tree, - not misleading (is clear)
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What does the closeness of the branches on a phylogenetic tree mean?
The closer the branches are, the close the ebolutionary relationship (so the more closely related the species are)
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What is variation defined as?
any difference between cells, individual organisms, or groups of organisms of any species caused either by genetic differences or by the effect of environmental factors
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What is genetic variation?
Variation caused by differences in genes and the combination of genes and alleles
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What is environmental variation?
Variation cause by the environment in which an organism lives in
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What is continuous variation?
Variation with a full range of intermediate phenotypes between 2 extremes
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What is discontinuous variation?
Variation with discrete groups of phenotypes with no or very few individuals in between
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What is interspecific variation?
Variation between species
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What is intraspecific variation?
Variation within a species
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Outline the main causes of genetic variation - Alleles
Genes have diff. alleles - a gene with a particular charact.- diff. alleles produce diff. effects - so individuals in a pop. may inherit diff. alleles
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Outline the main causes of genetic variation - Mutations
Changes in the DNA sequence - so genes lead to changes in the proteins coded for which effects the physical and metabolic charact. - mutation in somatic (body) cells individual - in gametes is passed onto offspring
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Outline the main causes of genetic variation - Meiosis
Gametes contain 1/2 the genetic material - in each parent - where independent assortment and crossing-over swaps and jumbles the genetic info. around
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Outline the main causes of genetic variation - Sexual Repoduction
Offsrping is produced from 2 individuals where they inherit genes (+ alleles) from each parent, so each individual differs from the parents
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Outline the main causes of genetic variation - Chance
Chance of the gametes combining - each ind. differs from their siblings as each contains a unique combo of genetic material
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List 4 characteristics that show continuous variation
1) Mass (+ Height) 2) Milk Yield 3) Surface Area 4) Mass of seeds
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List 4 characteristics that show discontinuous data
1) Blood groups 2) Eye/Skin colour 3) Seed shape 4) Colour (seed)
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Describe how continuous variation is displayed graphically
- Individuals in a pop. vary within a range, - there's no distinct categories, e.g. humans can be any height within a range
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Describe how discontinuous variation is displayed graphically
- there are two or more distinct categories, - each individual falls into only one of these categories, - there are no intermediates
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Define adaptation
The adjustment or changes in behavior, physiology, and structure of an organism to become more suited to an environment that enhances survival and long-term reproductive success
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Outline behavioural adaptations
They are ways an organism ACTS that increases their chance of survial - e.g. 'play dead'
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Outline physiological/hiochemical adaptation
Processes inside an organisms body that increases its chance of survival, e.g. hibernation and homeostasis
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Outline anomatical (structural) adaptation
Structural features of an organisms body that increases its chance of survival, e.g. a streamlined body (dolphin)
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Describe how anatomical adaptations provide evidence for convergent evolution
Convergent evolution occurs when unrelated species begin to share simialr traits. Similarities evolve as organisms adapt to simialr environ's./other selection pressures - live in a similar way
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Define Natural Selection
The process in nature by which, according to Darwin's theory of evolution, only the organisms best adapted to their environment tend to survive and transmit their genetic characters in increasing numbers to succeeding generations while those less ada
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Define Evolution
The gradual development of organisms over time
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The Theory of Natural Seclection
Varation (mutation), Overproduction, Struggle for existence due to selection pressures, Survival of the fittest, Advanatageous features inherited, Gradual change in the pop.
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What are selection pressures?
They are environmental factors that determines a species survival, e.g. a predator, a disease, a natural hazard
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Define speciation
The formation of a new species from a pre-existing one
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How does speciation occur?
2 pop's. of same species become isolated, both experience diff. selection pressures so pop's. develop diff. adaptations, speciation has occure when 2 pop.'s can no longer interbreed & prodcue fertile offsrping
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What is allopatric isolation?
It's geographical isolation where the 2 populations are isolated from one another by geographical barries, i.e. mountainds, oceans (islands)
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What is sympatric isolation?
Isolation between 2 populations occurs becuase of reproductive barriers arise which prevents one member breeding with another (from the other species/population)
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Outline the steps by which resistance to an insecticide may arise and spread in an insect popualtion
Mutation = minority has insecticide resistant alleles, Insecticide = selection pressure (wipes out majority - don't have advantageous adapt'n), Insecticide resistant alleles passed onto offsrping from the minority who survided the insecticide
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Outline the possible consequences of a separation on the populations of musk deer (for example)
The two populations being isolated from each other could result in genetic drift as the founder effect occurs, reducing the genetic diversity and the gene pool
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Evidence for evolution:
- Fossil Evidence, - Comparative Anatomy, - DNA, - Molecular
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How does fossil evidence support Darwin's theory of evolution?
Remains of organisms that lived millions of years ago are preserved in sedimentary rock, past species are very diff. to current ones, old species died out, new species arisen, new species often simialr to old species - but are gaps in fossil record
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Outline the steps by which resistance to antibiotics may arise and spread in a bacteria popluation
Mutation = minority has antibiotics resist. alleles, Antibtiotics = selection pressure (wipes out maj. - don't have advantageous adapt'n), Adaptive alleles passed on from surving bacteria to offspring = anitbiotic-resistant
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How does a high proportion of a population posses the advantageous characterisitcs?
By the minority of that population surviving the seleciton pressure(s) and successfully reproducing and passing those advantageous alleles onto their offspring and so forth
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Example for different taxonomic groups showing similar anatomical features - Marsupial and Placental mammals
Marsupial = Australian, Placental = American - e.g. of convergent evolution where the species in each continent resemble each other as they've adapted to fill simialr niches
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Characteristics of Marsupial mammals (e.g. Kangaroos)
- Have shorter gestation (pregnancy) period, - Don't develop full placenta, Born early in their development and climb into mother's pouch - become attached to a teat & recieve milk while continue to develop
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Characteristics of Placental mammals (e.g. Humans)
- Have a longer gestation (pregnancy) period, - Develop a placenta during pregnancy - allows exchange of nutrients & waste products between fetus & mother, - born more fully developed
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Marsupial moles and Placental moles
Are not closely related - evolved independently on diff. countries, share similar anatomical features as they've evolved in similar conditions, i.e. live in tunnels in ground, burrow for food supply
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Adaptations of Marsupial and Placental moles to their lifestyle:
Small/nonexistent eyes (don't need to see underground), no external ears (streamlined head for burrowing), scoop shaped&powerful front paws &claws (digging), tube-shaped body & cone-shaped head (push through soil/sand)
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What is a common ancestor?


Where two or more species are descendants from the same ancestor

Card 3


Explain the differences between taxonomy and classification?


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Card 4


Why do we study how closely related we are to other organisms?


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Card 5


Why do we classify living things?


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