19.5 investigating populations Flashcards Preview

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Flashcards in 19.5 investigating populations Deck (12):

what are the 2 ways to sample?

1. random
2. systematic (transect)


how do you sample at random?

1. 2 numbered axis can be laid out over the sample area
2. generate random numbers to provide co-ordinates for areas to study


how do you sample systematically?

samples are taken at regular intervals along a transect


what are the 2 types of quadrat?

1. frame
2. point


what are the things to consider when using a quadrat?

- size of quadrat
- number of samples being taken in the area
- position of each quadrat


what is the mean density equation?

total number of individuals counted/ number of quadrat X area of quadrat


why are the numbers generated in a random sampling done at random?

remove bias


why are more samples better than taking few sample?

more reliable


describe the process of mark- release- recapture

1. set of animals are caught and then marked
2. released back into the community
3. after a specified length of time, the community is revisited ad the same number or individuals is caught again
4. number of marked individuals is counted


estimated population size equation

total number of individuals in 1st sample X total number of individuals in 2nd sample/ number of marked individuals recaptured


assumptions in the mark- release- recapture method

- no births and deaths
- mark is not lost or rubbed off
- mark is not toxic nor does it make the individuals more conspicuous to predators
- define boundary so no immigration or emigration
- marked individual released distribute themselves evenly and have sufficient time to do so
- proportion marked to unmarked in the 2nd sample is the same as the proportion of marked and unmarked individuals in the population as a whole


in which sampling technique do you use quadrats?

random sampling