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15 Cards in this Set
- Front
- Back
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Environment |
The conditions surrounding an organism including all biotic and abiotic factors |
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Habitat |
The particular place where a community of organisms is found |
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Niche |
The precise way an organism fits into its environment is its ecological niche. It includes where it lives and what it does there. Organisms are adapted to the biotic and abiotic factors of their niche |
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Biotic factors |
Living factors |
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Abiotic factors |
Factors due to physical (non-living) or climatic features of the enivornment |
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Quadrat |
Clearly defined area inside which organisms are sampled. The organisms present are identified and then their abundance is measured. |
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Percentage cover |
Estimate area of a quadrat that a species covers. Easy to get data as individual plants do not need to be counted. Less useful in overlying layers of plants. |
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Frequency |
Work out percentage of a total number of quadrats the species occurs in. Useful for plants such as grass which are difficult to count. Gives no information on density of species present. |
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Random sampling |
Quadrats should be placed at random to ensure that they are not biased and are representative |
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How to random sample |
Arrange two measuring tapes at right angles to form a grid. Select pairs of numbers from a table of random numbers Use the random numbers as coordinates of the points to place the quadrats. |
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Transect |
A line across an area along which organisms are sampled. Line transect- organisms touching the lines are sampled Belt transect- Quadrats are used to sample a belt along the transect. Transects involve systematic sampling and are useful to study changes in the distribution of a species. |
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Mark-release-recapture |
Used in estimating mobile species such as animals.
Population size= (number in first sample x number in second sample) / number of marked individuals in the second sample |
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Mark-release-recapture assumptions |
Proportion of marked to unmarked individuals in the second sample is the same as the proportion of the population as a whole. Marked animals have enough time to mix evenly No immigration or emigration has occurred in the population Population does not change significantly due to births and deaths between samples. Marking is not toxic and does not make the animal more likely to be killed by predators Mark is not lost or rubbed off |
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Analysis of data |
Normal distribution- gives a bell shaped curve on a graph. The mean, median and mode have the same value Standard deviation- measures how spread out the data is around the mean Statistical tests- are used to assess the probability whether variations in data are due to chance or are caused by a specific factor i.e. Significant or not significant |
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Significant |
Means there is less than 5% that the variation in the data is due to chance. i.e there must be something causing it |
