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40 Cards in this Set
- Front
- Back
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What is taxonomy ?
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-this makes it easier for scientists to identify and study them |
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How many different levels of groups are they and how are they arranged?
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-organisms can only belong to one group at each level in the taxonomic hierarchy-there's no overlap -similar organisms are first sorted into large groups called kingdoms -similar organisms from that kingdom are then grouped into a phylum, similar organisms from each phylum are then grouped into a class, and so on |
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Therefore, what is a hierarchy?
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Hierarchichal means they are similar groups within larger ones and there is no overlap between groups |
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What happens as you move down the hierarchy?
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-there are more groups at each level but fewer organisms in each group -the hierarchy ends with species |
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What is a species? |
-a group of similar organisms able to reproduce to give fertile offspring |
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How does the two name work? |
-the first word is the genus and the second is the species |
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Why do scientists have to update classification systems?
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-because of discoveries about new species and new evidence about known organisms |
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What is/are phylogenics? |
-phylogenics is the study of the evolutionary history of groups of organisms -all organisms have evolved from shared common ancestors -pylogenics tells us whos related to whom and how closely related they are |
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How do we identify closely related species?
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-closely related species diverged away from each other most recently |
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What is the problem with the definition of a species?
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-this is bc you can't always see their reproductive behaviour |
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What are some reasons why can't you see their reproductive behaviour?
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-they reproduce asexually-they never reproduce together even if they belong to the same species -there are practical and ethical issues involved-you can't see if some organisms reproduce successfully in the wild and you can't study them in the lab |
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Therefore, what is done to correct these problems?
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-scientists now compare DNA of organisms to see how related they are-the more DNA they have in common or the more similar their proteins the more closely related they are |
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Give another way that species can be classified? |
-by hydridisation |
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Using DNA sequencing, how can DNA be compared directly?
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-closely related species will have a higher percentage of similarity in their DNA base order -DNA sequence comparison has led to new classification systems for plants |
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What is DNA hybridisation used for?
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-to see how similar DNA is without sequencing it |
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How does it work/is it done?
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-where the base sequences of the DNA are the same on both strands, hydrogen bonds form between pairs by specific base pairing-the more DNA bases that hybridise together, the more alike the DNA is |
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What then happens to the DNA
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How can proteins be compared? |
Similar organisms will have similar proteins in their cells. Proteins can be compared in 2 ways: -directly -using immunology |
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How can the proteins be compared directly?
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-proteins are made of amino acids. The sequence of amino acids in a protein is coded for by the base sequence in DNA -related organisms have similar DNA sequences and so similar amino acid sequences in their proteins |
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How can proteins be compared by immunological comparisons?
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-similar proteins will have the same antibodies eg. if antibodies to a human version of a protein are added to isolated samples from some other species, any protein that's like the human version will also be recognised (bound) by that antibody |
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Look at data for protein similarities: |
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What is courtship behaviour used for?
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-to classify species |
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What is it?
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-courtship behaviour is carried out by organisms to attract a mate of the RIGHT species -it is species specific-only members of the same species will do and respond to that courtship behaviour. This prevents interbreeding and so make reproduction more successful |
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Therefore, how is it used?
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-the more closely related species are, the more similar their courtship behaviour |
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Give some examples of courtship behaviour:
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-crickets make sounds similar to morse code, the code being different for different species -male peacocks show off their colourful tails. This tail pattern is only found in peacocks -male butterflies use chemicals to attract females. Only those of the correct species respond |
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What is an ecosystem? |
it consists of all of the living and non living things that can be found in a certain area. The living things within an ecosystem form a community |
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What is species diversity? |
-the number of different species and the abundance of each species within a community |
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What does a higher species diversity of plants and trees in an area mean? |
-they higher the species diversity of insects, animals and birds because there are more habitats and a larger/more varied food source |
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What can be diversity be measured for? |
-to help us monitor ecosystems and identify areas where it has been dramatically reduced |
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What is the problem with just counting the number of different species? |
-it does not take into account the population size of each species: species that are in a community in very small numbers shouldn't be treated the same as those with bigger populations |
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What do you need to know to work out the species diversity? |
-N=the total number of organisms of all species -n=the total number of organisms in each species |
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Why does deforestation decrease species diversity? |
-it directly reduces the number of trees and sometimes the number of different tree species -it also destroys habitats, some species could lose their shelter and food source-these species will probs die or are forced to migrate to another suitable area, reducing diversity -the migration of organisms into increasingly smaller areas of remaining forest may temporarily increase species diversity in those areas |
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With agriculture, how does woodland clearance and hedgerow removal reduce diversity? |
-for the same reasons as deforestation |
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With agriculture, how does monoculture reduce diversity? |
-this is when farmers grow fields containing only one type of plant -a single type of plant will support fewer species |
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With agriculture, how do pesticides reduce diversity? |
--they are chemicals which kill organisms that feed on crops -reduces diversity by directly killing the pest, also any species that feed on the pests will losse a food source, so their numbers could decrease too |
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With agriculture, how do herbicides reduce diversity? |
-there are chemicals that kill unwanted plants -this reduces plants diversity and could reduce the number of organisms that feed on the weeds |
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What are the benefits of deforestation? |
-wood and land for homes to be built -local areas become more developed by attracting businesses |
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What are the risk of deforestation? |
-diversity is reduced-species could become extinct -less co2 is stored bc there are fewer trees which contributes to climate change -many medicines come from organisms found in rainforests-possible future discoveries are lost -natural beauty is lost |
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What are the benefits of agriculture? |
-more food can be produced -food is cheaper to produce, so food prices are lower -local areas become more developed by attracting businesses |
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What are the risks of agriculture? |
-diversity is reduced-bc of monoculture, woodland and hedgerow clearance etc -natural beauty is lost |
