File : THESIS.pdf - Universitas Muhammadiyah Malang

Drawing
conclusions
Suggesting
improvements
3 marks
3 marks
Manipulation, measurement and observation
Successful collection of data and
observations Candidates should be able
to:
• set up apparatus correctly;
• follow instructions given in the form of written instructions or diagrams;
• use their apparatus to collect an appropriate quantity of data or
observations, including subtle differences in colour or other properties of
materials;
• make measurements using millimetre scales, graticules, protractors,
stopwatches, balances, measuring cylinders, syringes, thermometers,
and other common laboratory apparatus.
Candidates will be expected to use light microscopes. They should be
able to place the slide on the stage, arrange the lighting appropriately and
focus on the specimen at both low- power (X10, sometimes described as 16
mm or 2/3”) and high-power (X40, or 4 mm or 1/6”) using a microscope with a
graticule fitted into the eyepiece.
Decisions relating to measurements or observations
Candidates should be able to:
• decide how many tests, measurements or observations to perform;
• make measurements or observations that span the largest possible
range within the limits either of the equipment provided or of the
instructions given;
• make quantitative measurements or qualitative observations that are
appropriately distributed within this range;
• decide how long to leave experiments running before making readings.
• replicate readings or observations as necessary;
• make and record sufficient, accurate measurements and observations.
Candidates may need to choose how many tests, measurements and
observations can be made in the time available. In some experiments a
regularly-spaced set of measurements will be appropriate. For other
experiments, such as those requiring the peak value of a curved graph
to be determined, it may be appropriate for the measurements to be
concentrated in one part of the range investigated. Candidates will be
expected to be able to identify the most appropriate distribution of values.
In qualitative experiments, precise descriptions and comparisons of colour or
other observations are expected.
In experiments, such as those involving enzymes:
initial rate of reaction may be measured (in which case
measurements should be conducted as quickly as practicable),
the rate of reaction might be expected to be constant over several
minutes, or colour changes may take several minutes to occur, in
which case leaving the experiment to run for as long as possible
may be appropriate,
an end point is being sought, in which case, candidates should
expect to run the experiment until the end point is achieved or the
time runs out.
Repeated readings of particular quantities are often necessary in
biology, where experimental errors and variation in the activity of
biological materials are large and an average value would be more
representative. Individual readings or observations should be repeated where
they appear to be anomalous. It may be necessary for the candidate to
decide how many times to let something that is repetitious occur before
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