2025
CHEM LAB
Micropipette and Gel Electrophoresis Study
Guide| Exam Style Questions and Verified
Answers| updated for 2025/26
Questions and Correct Answers
1. What does the plunger do?
✅Correct Answer: Makes the micropipette draw up or eject liquid.
Rationale: The plunger is pressed to the first stop to create a vacuum for
drawing liquid into the pipette tip and to the second stop to expel the liquid,
ensuring accurate liquid handling.
2. What does the adjustment knob do?
✅Correct Answer: Changes the volume that the micropipette will measure.
Rationale: The adjustment knob allows the user to set the desired volume within
the micropipette’s range, ensuring precise measurement for dispensing.
3. Micropipettes measure volumes of liquid using what measurement?
✅Correct Answer: Microliters (μl).
Rationale: Micropipettes are designed for precise handling of small liquid
volumes, measured in microliters (one-millionth of a liter), ideal for laboratory
applications.
4. Why should you press the plunger down to the second stop when expelling
liquid from a micropipette?
✅Correct Answer: To ensure all liquid in the tip is expelled.
Rationale: Pressing to the second stop fully dispenses the liquid, preventing
residual liquid from remaining in the tip, which ensures accurate delivery.
5. Unknown molecules migrated to position A, B, and C. What conclusion can
you draw from these results?
✅Correct Answer: The molecules in position A are positively charged, the
molecules in position B are neutral, and the molecules in position C are
, 2025
CHEM LAB
negatively charged.
Rationale: In gel electrophoresis, molecules migrate based on charge: positively
charged toward the cathode, negatively charged toward the anode, and neutral
molecules remain near the starting point.
6. What is a volume window?
✅Correct Answer: Displays the volume that the micropipette is set to measure.
Rationale: The volume window shows the set volume, allowing the user to
confirm the micropipette’s measurement setting for accuracy.
7. Range of P2?
✅Correct Answer: 0.1-2 μl.
Rationale: A P2 micropipette is designed for very small volumes, ranging from
0.1 to 2 microliters, suitable for precise tasks in molecular biology.
8. Gel electrophoresis works by what principles?
✅Correct Answer: Sorting molecules by size and charge.
Rationale: Gel electrophoresis separates molecules based on their size (smaller
molecules move faster through the gel) and charge (molecules move toward the
opposite electrode).
9. If a student ended up with less liquid than they intended to measure, what
might have gone wrong?
✅Correct Answer: They may have drawn up the sample too quickly and had air
bubbles in the liquid.
Rationale: Drawing liquid too quickly can introduce air bubbles, which displace
liquid and reduce the measured volume, leading to inaccuracy.
10. Range of P1000?
✅Correct Answer: 200-1000 μl.
Rationale: A P1000 micropipette handles larger volumes, from 200 to 1000
microliters, suitable for tasks requiring bigger liquid amounts.
CHEM LAB
Micropipette and Gel Electrophoresis Study
Guide| Exam Style Questions and Verified
Answers| updated for 2025/26
Questions and Correct Answers
1. What does the plunger do?
✅Correct Answer: Makes the micropipette draw up or eject liquid.
Rationale: The plunger is pressed to the first stop to create a vacuum for
drawing liquid into the pipette tip and to the second stop to expel the liquid,
ensuring accurate liquid handling.
2. What does the adjustment knob do?
✅Correct Answer: Changes the volume that the micropipette will measure.
Rationale: The adjustment knob allows the user to set the desired volume within
the micropipette’s range, ensuring precise measurement for dispensing.
3. Micropipettes measure volumes of liquid using what measurement?
✅Correct Answer: Microliters (μl).
Rationale: Micropipettes are designed for precise handling of small liquid
volumes, measured in microliters (one-millionth of a liter), ideal for laboratory
applications.
4. Why should you press the plunger down to the second stop when expelling
liquid from a micropipette?
✅Correct Answer: To ensure all liquid in the tip is expelled.
Rationale: Pressing to the second stop fully dispenses the liquid, preventing
residual liquid from remaining in the tip, which ensures accurate delivery.
5. Unknown molecules migrated to position A, B, and C. What conclusion can
you draw from these results?
✅Correct Answer: The molecules in position A are positively charged, the
molecules in position B are neutral, and the molecules in position C are
, 2025
CHEM LAB
negatively charged.
Rationale: In gel electrophoresis, molecules migrate based on charge: positively
charged toward the cathode, negatively charged toward the anode, and neutral
molecules remain near the starting point.
6. What is a volume window?
✅Correct Answer: Displays the volume that the micropipette is set to measure.
Rationale: The volume window shows the set volume, allowing the user to
confirm the micropipette’s measurement setting for accuracy.
7. Range of P2?
✅Correct Answer: 0.1-2 μl.
Rationale: A P2 micropipette is designed for very small volumes, ranging from
0.1 to 2 microliters, suitable for precise tasks in molecular biology.
8. Gel electrophoresis works by what principles?
✅Correct Answer: Sorting molecules by size and charge.
Rationale: Gel electrophoresis separates molecules based on their size (smaller
molecules move faster through the gel) and charge (molecules move toward the
opposite electrode).
9. If a student ended up with less liquid than they intended to measure, what
might have gone wrong?
✅Correct Answer: They may have drawn up the sample too quickly and had air
bubbles in the liquid.
Rationale: Drawing liquid too quickly can introduce air bubbles, which displace
liquid and reduce the measured volume, leading to inaccuracy.
10. Range of P1000?
✅Correct Answer: 200-1000 μl.
Rationale: A P1000 micropipette handles larger volumes, from 200 to 1000
microliters, suitable for tasks requiring bigger liquid amounts.
