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Slide 1

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Biology Unit 4
Try to pass this time…read more

Slide 2

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First there are a few definitions you need to
· Habitat ­ the place where an organism
· Popl ­ all the organisms of in species
· Community ­ all the organisms living in a
· Ecosystem ­ all the interacting biotic and
abiotic factors in a ecosystem
· Abiotic ­ non-living factors (pH)
· Biotic ­ living factors (predation)…read more

Slide 3

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· The niche a species occupies includes its
biotic interactions and its abiotic
· Every species has its own niche there's no
· If two species do occupy the same niche
then one will out compete the other as its
better adapted…read more

Slide 4

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Investigating Popl
· First chose an area to sample, it should be
relatively small
· Samples need to be chosen at random to avoid any
bias, you can do this by creating a grid a using a
random no. generator such as a calculator or bingo
machine to get co-ordinates
· Repeat the process until you get a running mean as
this gives you a reliable estimate for the whole
area…read more

Slide 5

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Pitfall and Pooters
Pitfall traps are steep sided containers sunk in a hole,
insects and bugs fall in but cant get out, allowing for
mark-release-re capture method
Pooters are jars with two tubes sticking out one with
a mesh covering, the idea is that you suck in one end
and collect all the lil insects up the other saving you
from swallowing them thou is the handy bit of mesh,
however it can take a very long time to collect are
large enough sample…read more

Slide 6

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· Capture a sample of a species using an appropriate
· Count and mark them in such a way that wont
affect them
· Release the sample
· Wait a given period of time and then recatch and
count the sample
· Use this equation to estimate Popl size
· (1st*2nd) / marked in 2nd
· This will only work if you assume there is no
migration, births, deaths within Popl…read more

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Slide 9

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Slide 10

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You are actually amazing! Thank you! 

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