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Cambridge International AS and A Level Biology 9700 syllabus Practical assessment
Light microscope and photomicrographs
Manipulation, measurement and observation (MMO)
These marks are awarded for two strands of skills:
• Making decisions about measurements or observations
• Successfully collecting data and observations.
Making decisions about measurements or observations
This strand requires the use of a light microscope and photomicrographs.
Candidates should decide how to:
• Set up a light microscope to view and observe specimens, in order to make either plan diagrams to
show tissue distribution or to draw cells to include only the observable features
• Draw the distribution of different tissues in plant and animal specimens and label the drawings
appropriately
• Correctly identify cells and label the structures of cells
• Stain and make a slide of cells
• Calibrate an eyepiece graticule using a stage micrometer
• Obtain actual sizes of tissues or cells using a calibrated eyepiece graticule, by measuring the tissues or
cells to obtain a mean measurement, using the correct units for microscopy (μm)
• Estimate the number of cells or cell organelles in a whole slide or field of view using a sample or using a
grid.
Successfully collecting data and observations
This strand requires the use of a light microscope and prepared slides and photomicrographs.
Candidates should be able to collect:
• Observations by drawing the distribution of tissues in a specimen, as plan diagrams, with no cells drawn
and correct proportions of layers of tissues
• Observations by drawing the observable features of cells in a specimen showing:
– the correct shapes
– the thicknesses of cell walls (which are drawn with two lines with a third line between adjacent
cells)
– the relative sizes (using (uncalibrated) eyepiece graticule scale)
– observable cell contents only
• Correct measurements of tissue layers or cells, including:
– using a calibrated eyepiece graticule
– using scale bars
– appropriate magnification
• Correct observations from specimens, including numbers of cells or cell organelles, using sampling or a
grid or tally counts or numbers of stained to non-stained cells
• Similarities and differences between two specimens using only their observable features.
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