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24 Cards in this Set
- Front
- Back
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What is the definition of species? |
a group of similar organisms able to reproduce and produce fertile offspring |
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What system is used to name species? |
binomial system which means each species has a two word scientific name |
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When naming a species, the first word is the... |
genus name |
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When naming a species the second word is the... |
species name |
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When classifying organisms they are placed into... |
taxa (groups) |
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How are species put into groups? |
It is based on their characteristics |
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How many levels of taxa are there? |
8 |
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What is the definition of a hierarchical system? |
smaller groups are contained within larger groups. There is no overlap. |
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List the groups of a hierarchical system. |
1) Domain 2) Kingdom 3) Phylum 4) Class 5) Order 6) Family 7) Genus 8) Species |
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What is phylogenetics? |
The study of patterns of evolutionary history |
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How can you tell if a species is more closely related? |
Organisms that share the same common ancestor more recently are said to be more closely related |
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How is an evolutionary relationship displayed? |
A phylogenetic tree |
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Why is it difficult to decide which species an organism belongs to? |
1) They are extinct 2) They reproduce asexually 3) Practical or ethical issues |
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What were classification systems originally based on? |
observable features |
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What do we use to classify organisms? |
genetic and molecular evidence |
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How can genetic comparisons be made? |
Direct examination of DNA or of the proteins coded for. Species can then be classified into different groups based on similarities in their genes. |
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How is DNA used to classify species? |
The more closely related the species the more similar their DNA base sequence |
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What could affect results when classifying organisms based on DNA? |
Mutations that could change the DNA sequence |
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Describe how you would compare DNA. |
DNA hybridisation 1) Take DNA from 2 species 2) Heat to separate strands 3) Add radioactive label to DNA strand from one species 4) Mix DNA and cool- producing DNA hybrids 5) Increase temperature 6) Measure the amount of hybrid DNA with double strands at each temp. |
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How do the results of DNA hybridisation indicate whether two species are related or not? |
The more similar the species the greater the number of hydrogen bonds between complementary bases |
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Why do you increase the temperature during DNA hybridisation? |
The more hydrogen bonds present the higher the temperature required to completely separate the two strands. |
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What can the data produced in DNA hybridisation be used for? |
To ploy a phylogenetic tree |
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How can proteins be used to classify organisms? |
Related organisms have similar DNA base sequences and so have similar amino acid sequences within their proteins |
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Describe how immunological comparisons can be used to classify organisms. |
1) Specific antibodies to the protein taken from species A are produced by injecting them into a rabbit 2) Antibodies are then purified and mixed with the same protein type from a different species 3) If species B has similar proteins then the antibodies will bind to the protein and produce a white precipitate |
