8667639
Description
Flashcards by Alice Hathaway, updated more than 1 year ago
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Created by Alice Hathaway
about 7 years ago
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| Question | Answer |
| Biodiversity | Relates to a range of habitats from a small (local) habitat to the Earth |
| Habitat | A place where organisms live |
| Species Richness | A measure of the number of different species in a community |
| Community | All the different species living in a habitat |
| What is Random Sampling? | A method of collecting data on species richness |
| Why is it "Random"? | To reduce any bias |
| How does it remove bias? | Reduces the amount of human involvement in the process |
| What is the first step in a method of random sampling? | Divide the area the samples are taken from by placing 2 large tape measures at right angles at 1 corner (like an axis) |
| Step 2 | Use a random number generator to select a coordinate for how far you will go along the X tape and another for the Y coordinate |
| Why is a random number generator used? | Prevent bias |
| Step 3 | Place the corner of the quadrat at the point where the 2 coordinates intersect |
| How is this quadrat used? (Step 4) | COUNT THE NUMBER OF EACH SPECIES PRESENT WITHIN IT |
| How can the effect of chance be reduced? | Use a large sample size Use statistics to analyse the data |
| How does increasing the sample size decrease the effect of chance? | More data collected means a larger probability the sample reflects the true population. Increases the RELIABILITY of the mean |
| What is the ideal sample size? | 10% |
| How does data analysis with statistics reduce effect of chance? | Determine to what extent chance had on results |
| What are methods of statistical analysis? | Calculate a standard deviation T-test Correlation coefficient Chi-squared |
| Index of diversity | A relationship between the number of species in a community and the number of individuals in each species |
| How is index of diversity calculated? | |
| What is D? | Index of Diversity |
| What is N? | Total number of organisms of ALL species |
| What is n? | Total number of organisms of each species/ |
| How does agriculture or deforestation impact on species diversity? | Species richness is reduced e.g. monocrop Use of techniques e.g. herbicides to kill weeds/ ploughing LESS VARIETY OF FOOD SOURCES FEWER HABITATS AND NICHES |
| How could a farmer increase diversity or species richness through conservation? | Grow a variety of crops Plant hedges around fields MORE VARIETY OF FOOD SOURCES MORE HABITATS AND NICHES |
| Why is it more useful to calculate index if diversity than just number of species? | Index of diversity measures number of species and number of individuals within each species Some species are only found in small numbers |
| Suggest a explanation for relationship between the idea of diversity for an animal (birds) and structural diversity for plants? | More structural diversity in plants provides more variety of food sources and more habitats and niches Birds feed/ nest at different heights (Aka link specifically to the animal) |
| What is shown by a higher index of diversity? | There are more different alleles therefore higher stability so more likely to survive environmental change |
| Why is index diversity better than just the number of species present? | This measures both the number of species and individuals within the species Some species may only be found in small numbers |
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