Grade 9-12 Performance Task
Developed by: New York State Education Department (NYSED)
University of Buffalo and NORC (1991)
Introduction:
This laboratory test presents tasks and lists materials.
You will be asked to follow different procedures provided to solve
the several tasks. You will be askd to have your worked checked
by your teacher (or test administrator) several times. After being
checked, continue with the next procedure. You will have a total
of 40 minutes to complete this test. Record your answers in the
test booklet.
Materials:
- Compound light microscope
- Glass microscope slide
- Plastic cover slips
- Dropper bottle with water
- Pieces of onion bulb
- Forceps
- Paper towel or tissue
- Prepared slide of colored threads
- Transparent plastic metric ruler
- Prepared slides of onion epidermis cells.
Please contact your test administrator if you need a review of
the procedure for operating a microscope.
Procedure A:
- Using the materials at the station, prepare a wet mount
slide of onion epidermis tissue.
- When finished, raise your hand to have your wet mount
slide examined by the teacher. Do NOT place this
slide on the microscope.
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Do not write in the boxes below
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Procedure B:
- At your station is a prepared slide labelled "Colored
Threads." On the line at the right, write the number
that is on the slide.
- Focus on the colored threads under low power. Raise
your hand to have the teacher examine your results.
- Where the threads cross, identify which color thread is
on top of the others. Write your answer on the line at right.
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Procedure C:
- Focus the slide of the colored threads under high
power. Raise your hand to have the teacher examine your
results.
Remove the slide from the stage.
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Procedure D:
- Adjust the microscope so that it is set for 100X magnification.
- Using the metric ruler, measure the diameter of the 100X field
of view in millimeters.
Diameter of the field of view at 100X magnification
= ____________ millimeters
- Calculate the diameter of the 100X field of view in micrometers.
One millimeter is equal to 1000 micrometers.
Diameter of the field of view at 100X magnification
= ____________ micrometers
- View the prepared slide of onion cells at 100X magnification
and determine the average length of a single onion cell in micrometers.
Show and/or explain how you calculated the length
of a single onion cell (in micro-meters) in the box below.
Length of a single onion cell in micrometers =
_____________ micrometers
- Change to high power and record the high power magnification
that you will use below.
High power magnification that you used = ______________
X
- As magnification increases, the diameter of the field view decreases.
Calculate the diameter of the high power field that you are using.
Express your answer in micrometers.
Show and/or explain how you calculated the diameter
of the field of view at high power (in micrometers) in the box
below.
Diameter of the field of view at high power =
______________ micrometers.
- View the prepared slide of onion cells at high power and determine
the approximate diameter of a single onion cell nucleus in micrometers.
Show and/or explain how you calculated the approximate
diameter of a single onion cell nucleus (in micrometers) in
the box below.
Approximate diameter of a single onion cell nucleus
= ______________ micrometers
Your test booklet will be collected at the end of 40 minutes.
If you finish early, please wait at this station.
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