Doing a brilliant A2 Biology Coursework in Ecology.
The A2 coursework builds on what you did at AS, but with some added twists:
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all your marks must come from one investigation (no pick & choose!),
you need to state a proper hypothesis,
you must use a correct statistical test for the higher marks,
you must bring together relevant concepts from different topics for a new skill ‘E’.
Follow these guidelines step-by step, & keep thinking …
What you must do
Explanation / example
criterion
Research the idea you have
been given.
Find out:
 General info about your species,
 Info about the habitat,
 What abiotic factors affect your species,
 What biotic interactions may affect it.
 Sketch the graph you would like at the end,
with labelled axes (units!) for your input &
output variables.
 Sketch a results table for the right data, and
 Choose the right statistical test NOW!
 Jot down all other variables you will need to
take into account, and
 Jot down key points of your method
Your H1 should be simple, clear and testable:
 it should state how the input variable will
affect the output variable.
 Eg: ‘dogwhelks will require more force to
dislodge them on shores more exposed to wave
action’
 the H0 (neutral, not opposite to H1) will be
used as the basis for your stats test.
Take care that
 all the information is relevant to your
investigation, and you say how it is relevant
 you include concepts from other areas; e.g.
temperature needs controlling because it
affects enzymes & therefore …
 The most likely ‘other areas’ are: osmosis (re
salinity), enzymes (re temperature / pH),
respiration (via enzymes), photosynthesis (re
light intensity).
 you present you ideas clearly and logically,
using technical terms where appropriate
E
Think backwards to clarify your
ideas!
Don’t skimp this stage or you’ll
regret it later (e.g. when 10 hours
worth of data can’t be put into a
statistical test!)
Write your hypothesis (H1) and
a null hypothesis (H0).
Write an introduction, giving
the background information you
are using in planning your
investigation.
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Write your method
Collect your data…
… but don’t stop thinking now!
Briefly discuss the precautions
taken while collecting data
Prepare your data
Plot a graph before doing the
stats
Describe the pattern / trend
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 Use numbered steps,
 Use the future (impersonal) tense, e.g.:
‘50 dogwhelks will be chosen …’
 Work individually, under supervision
 Give clear details of method, apparatus &
precautions (as if someone else had to follow
your plan)
 Explain your choice of technique
 Explain any necessary preliminary checks
(e.g. for quadrat size, No of stations, etc)
 Say how you will minimise the effect of each
of the ‘other factors’ (&/or measure them for
later discussion)
 Say what data you will collect: how many
samples, what units …
 Say what stats test you will use and why you
chose it (re type of data)
 Any other analysis – e.g. graphs?
 Use a proper table, with headers & units
 Always keep & work from your raw data –
copying it usually introduces errors
Look at the data as you collect it:
 Does it look consistent?
o If not, can you improve anything?
 Do you need to
o
sample more areas, or
o
fewer areas more thoroughly?
o
take some extra repeats?
 Is another factor affecting your results?
o
can you improve your method?
o
can you measure it?
 Don’t be afraid to stop collecting data if it
looks highly significant already and you have a
good sample size!
I.e.: say what you were able to do (and could not
do) to ensure reliable data.
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Do the totals, averages, percentages
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Give an example of your working
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Use units, signs (+/-) and sensible
accuracy
e.g. don’t give the average force to
remove a whelk as 15.6723639 N!
A simple graph (bar, line, or scatter) will give you
a ‘feel’ for your results and what they show
You will be less likely to believe a daft stats
result if you know what the graph shows!
Most studies show some trend: even if it is ‘non-
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shown by your graph
Now that evil statistical test!
But you chose the right test at
the start, and you’ve got your
Numerical Techniques book, so
it will be a doddle!
Write a conclusion.
Just the evaluation left…
 State all the main
limitations of your method.
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Assess the likely effects of
each limitation on your data.
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Assess the overall validity
of the data
You’ve finished!
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significant’ it is still a trend!
Do consider the details, as well as the basic ‘up’
or ‘down’ – this is A2, after all!
Either do it long-hand, and show the steps, or use
a stats pack and state:
 exactly what test you did, on what package,
 the formula for the test
 what data you entered (totals, %, etc)
 how many degrees of freedom,
 the value for the statistic (e.g. t=3.145)
 the p-value (e.g. p<0.001)
 what the p-value means for your H0 & H1
(‘rejected’ or ‘supported’ not ‘proved’)
This must be clearly based on your results, graph,
and statistics.
 Summarise what you have found out.
 In detail, say how this relates to your
hypothesis, and
 Explain your results using the biological
ideas in your introduction (& any others?)
… but it’s not like GCSE.
 This means the main unavoidable
limitations inherent in doing it this way (e.g.
‘the shores differed in aspect as well as
exposure to wave action’; but no marks for
‘human error’, ‘out of time’ ‘a sheep ate my
data’, etc)
 How is the accuracy, or overall reliability
likely to have been affected? E.g.: ‘whelks on
the S-facing shore may be warmed by the sun,
respire faster & thus hold on tighter, but the
trend still held for 10 that were in complete
shade on this shore…’
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For each limitation, explain whether it
would undermine the overall conclusion.
 Don’t be too harsh on yourself – most
studies should still be valid, and limitations
are unlikely to overturn highly significant
results.
 Round it off with a sentence giving your
verdict on the validity of your study.
The End.
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