3.1.10 Species and Taxonomy Flashcards Preview

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Flashcards in 3.1.10 Species and Taxonomy Deck (36)
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Define Species

Group of similar organisms able to reproduce to give fertile offspring


Describe how the binomial naming system work

Each species is given a Latin name that has 2 parts

  1. Genus 
    • Has capital letter 
  2. Species
    • Lower case letter 
  • Names are written in italics or they're underlined if handwritten e.g. Homo sapiens


Why is the binomial naming system used?

Avoids confusion of using common names


Name 3 difficulties of defining species

  • Species are not fixed forever
  • Can change and evolve over time into new species
  • Many species are extinct and most left no fossils
  • Some species are sterile  


What is phylogeny?

Study of evolutionary history of groups of organisms


What is this known as?

Phylogenetic tree


What does the 1st branch point represent? 

Common ancestor of all family members   


Orangoutangs was the 1st group to _____ (evolve to become different species) from this common ancestor?



What does each following branch points represent?

Another common ancestor from which a different group diverged


Closely related species...

diverged away from each other most recently


What is taxonomy?

Science of classification


Why is taxonomy used?

Makes it easier to identify and study organisms


How many taxa are there?

8 taxas


How are the taxa arranged?

In a hierarchy: largest groups at top & smallest at bottom


Organisms only belong to __ group at each level in hierarchy - no overlap



Name all the taxa (from largest to smallest)

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

(Taxa Mnemonic: Dear King Philip Came Over For Good Soup)


As you move down hierarchy... 

there are more groups but fewer organism in each group & organisms in each group become more closely related


What can be used to help classify species?

Courtship Behaviour


 Courtship behaviour is carried out by organism to...

attract a mate of the right species


Describe how courtship behaviour can be used to help classify species

  1. Courtship behaviour = species specific
  2. Only members of same species will do/respond to it
  3. ∵ of this specificity - courtship behaviours can be used to classify organisms


Why do organisms carry out courtship behaviour? Name 2 reasons

  • Allows same species to recognise each other
  • Prevents interbreeding and making reproduction more successful


More closely related species are = the more _____ their courtship behaviour is



Name 3 advances in techniques that can help clarify evolutionary relationships

  1. Genome Sequencing 
  2. Comparing Amino Acid Sequence
  3. Immunological Comparisons


Describe how genome sequencing can help clarify evolutionary relationships

  1. Advances in genome sequencing = entire base sequence of organism's DNA can be determined
  2. DNA base sequence can be compared to DNA base sequence of other organisms = to see how closely related they are
  3. Closely related species = higher percentage of similarity in their DNA base order


Describe how comparing amino acid sequence can help clarify evolutionary relationships

  1. Sequence of amino acids in protein is coded by base sequence in DNA
  2. Related organisms have similar DNA sequences and so similar amino acid sequences in their proteins

(e.g. Cytochrome C = protein found in many species → more similar amino acid sequence of cytochrome C in 2 different species = mores closely related spices are likely to be)


Describe how immunological comparisons can help clarify evolutionary relationships

  1. Mix together antibody and proteins
  2. Similar proteins will also bind to same antibodies & form precipitate
  3. More precipitate = more similarities in protein/DNA between the species (more evolutionarily close)
    • Similar species have a similar immune response to a protein

e.g. If antibodies to a human version of a protein are added to isolated samples from other species, any protein that's like human version will be recognised by that antibody


Explain how courtship behaviour increases the probability of successful mating (4)

  • Indication of fertility 
  • Recognises same species
  • Attracts mate
  • Stimulates release of gametes


Explain how a phylogenetic system differs from a simple hierarchy (3)

  • Phylogenetic system is based on evolutionary history
    • Shows ancestry of groups/points of divergence
  • Hierarchical system is based on shared characteristics (seen today)


What is meant by a hierarchy?

  • Groups within groups
  • No overlap between groups


What is meant by a phylogenetic group?

(grouped according to) common ancestry

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