AP Lab 02 - Biology Lab Skills

Name: ______________________________ AP Biology – Lab 02
Table 7: Mass of water volumes measured using a 10 mL glass pipette.
Volume of
water (mL)
10.0
10.0
10.0
10.0
10.0
Mean
Values:
Expected mass
of water added
in this step (g)
Measured mass
of water added
in this step (g)
+ / – Error (g) Percent Error
Using a Micropipette
THE SOLUTIONS FOR THIS PART OF THE LAB ARE COLORED WATER. THE SAFETY
PRECAUTIONS LISTED BELOW ARE TO PREVENT DAMAGE TO THE MICROPIPETTE.
NEVER SET THE MICROPIPETTE TO A VOLUME BEYOND ITS RANGE.
NEVER ATTEMPT TO USE THE PIPETTE WITHOUT A TIP IN PLACE.
NEVER LAY DOWN A PIPETTE THAT HAS A FILLED TIP.
NEVER LET THE PLUNGER SNAP BACK AFTER WITHDRAWING OR EJECTING FLUID.
1. Take a large-range micropipette (100 L—1000 L). Rotate the control button to the
minimum (100) and maximum (1000) values – do not exceed these values! Notice the
change in the plunger length as the volume is changed.
2. Push the micropipette end firmly in the proper size tip.
3. While withdrawing or expelling fluid, always hold the vessel at nearly eye-level. It is
important that you watch while you pipette.
4. Hold the pipette in a vertical position when filling.
5. To draw fluid, depress the button to the first stop, and hold in this position. Then, dip the
tip into the solution to be pipetted, and draw the fluid into the tip by gradually releasing the
plunger.
6. Slide the tip out along the inside wall of the reagent tube to dislodge any excess fluid
adhering to the outside of the tip.
7. To withdraw the sample, touch the pipette tip to the inside wall of the reaction tube into
which you wish to empty the sample. This creates a capillary effect which helps draw fluid
out of the tip.
8. Slowly depress the button to the first stop. Then press on to the second stop to blow out
the last bit of fluid. Hold the button down in the second position.
9. Slide the pipette out of the reagent tube with the button depressed to the second stop to
avoid sucking any liquid back into the tip.
10. To eject the tip, depress the separate thumb button to ‗launch‘ tip into a waste jar.
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