A-level Biology - 3.1.10 Species and Taxonomy
A species is a group of similar organisms that can interbreed and produce fertile offspring. Members of the same species share common characteristics and genetic makeup, allowing successful reproduction. This definition helps distinguish one species from another in biological classification.
Define Species
Group of similar organisms able to reproduce to give fertile offspring
Key Terms
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 writ...
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
...
What is phylogeny?
Study of evolutionary history of groups of organisms
What is this known as?
Phylogenetic tree
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| Term | Definition |
|---|---|
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 |