3.1.10 Species and Taxonomy Flashcards
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
- Genus
- Has capital letter
- 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?
diverge
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
1
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
- Courtship behaviour = species specific
- Only members of same species will do/respond to it
- ∵ 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
similar
Name 3 advances in techniques that can help clarify evolutionary relationships
- Genome Sequencing
- Comparing Amino Acid Sequence
- Immunological Comparisons
Describe how genome sequencing can help clarify evolutionary relationships
- Advances in genome sequencing = entire base sequence of organism’s DNA can be determined
- DNA base sequence can be compared to DNA base sequence of other organisms = to see how closely related they are
- Closely related species = higher percentage of similarity in their DNA base order
Describe how comparing amino acid sequence can help clarify evolutionary relationships
- Sequence of amino acids in protein is coded by base sequence in DNA
- 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
- Mix together antibody and proteins
- Similar proteins will also bind to same antibodies & form precipitate
- 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
Describe the process of DNA hybridisation
- Heat DNA from 2 different species
- To break hydrogen bonds and separate strands
- Mix and cool strands to allow h-bonds to reform
- Complementary bases joined together by h-bonding
- Non-complementary bases that cannot pair join together
DNA hybridisation
When two species share a recent common ancestor/are closely related, what are results like (i.e. the hybrid DNA strands)?
- More complementary base pairing
- More hydrogen bonds forming
- More heat/energy needed to break (the hybridised) strands apart
DNA hybridisation
What are hybrid strands where two species are distantly related like & what is needed to separate the two strands?
Few bases are paired up
Lower temperature is sufficient to separate the two strands
Name the 3 domains
Eukarya, Bacteria & Archaea
Name the 5 kingdoms
- Prokaryotae
- Protoctista
- Fungi
- Plantae
- Animalia
What is meant by species diversity?
Number of species in a community
