Problem: What are the basic parts of a
cell you are going to look at in this lab is from the aquatic plant Elodea. Like any complex cell, it
has the basic organelles. You will not
see the nucleus with the DNA in this lab, but the cell wall and chloroplasts
will be very obvious. The chloroplasts
are the site for photosynthesis in the cell; they contain chlorophyll, which
traps sunlight and thus enables the cell to combine carbon dioxide and water to
make glucose (a simple carbohydrate with the formula C6H12O6).
You will be:
at a cell under a microscope at both low (100X) and high power (400X).
a diagram of the cell at each magnification.
(with names and arrows) the high power diagram with the parts you see
(cell wall and chloroplast).
to each drawing a title and the magnification.
the diameter of the field of the low power magnification with a ruler and
converting to microns (1 mm = 1000 microns).
the length and width of the plant cell.
After answering the pre-lab questions, have your group give
the teacher a small slip of paper with your group number and the name of the
microscope part that you use to adjust light. Then begin the procedure.
Plant Cell - page 301 in the new light green version
Microscope Parts and Use – page 831
in the light green version
carry the microscope with 2 hands.
in high power, only use the fine adjustment knob.
sit the microscope near the edge of the table.
pull out an electrical plug by the cord.
- Why do
plant cells need a cell wall?
high power, we use the long high power objective to view the slide. How much does this lens magnify the
object? How much does it magnify when combined with the eyepiece?
many microns wide is your pencil?
in the blank: When the microscope is in high power, only use the _______
to focus the slide.
Materials: (per group)
Sprig of Elodea
- Always begin with your microscope in
the lowest magnification.
- Make a
wet mount of an Elodea leaf on a microscope slide. (See page 831.)
on the microscope stage with the leaf centered over the hole in the stage.
with the course adjustment knob. If in 40X (with the 4X objective down),
increase to low power. (Revolve the 10X objective in place over the leaf
until it clicks into place. Focus again.)
- In the
data section of your lab, draw a circle with a 12 cm diameter.
2 – 3 cells in the circle such that the cells you draw are in the same
proportion to the circle as the actual cells are to the lit up field you
are looking at.
rotate the high power objective into place, and then focus using ONLY the
fine adjustment knob.
2-3 cells under this magnification in a similar circle, and label the cell
parts that you see.
to low power (100X), and remove and clean up the slide and cover slip.
a transparent or translucent ruler on the stage, and focus on the
in millimeters the diameter of the visible field (the lit-up circle area).
the diameter to microns using the formula above.
the length and width of a plant cell in microns from the known diameter.
Microscope to the lowest power, turn off the light, and cover it.
Data: (This section should include the 2
circular field diagrams, the measurement, and the estimates.)
mm ________ microns
Estimated Cell Length _______________ Estimated Cell
What you should see:
|Chloroplasts in the Cytoplasm
||Cell Wall around each cell
Post-Lab Questions: (Answer each in a
1. How big is a plant cell?
2. How would humans be different if we had cell walls around
3. How many molecules of C02 does it take to make
1 molecule of glucose in the chloroplast? Explain
how you got this answer.
4. Bonus Questions:
How many plant cells placed end to end would be 1 cm long?
(In your conclusion,
you should briefly summarize the problem and what you did. Then answer the
problem referring to the data.)