Electrophoresis is an important topic for students preparing for Biology, Biotechnology, Microbiology, and various competitive exams such as NEET, CUET, NET, and GATE. Questions based on electrophoresis are frequently asked in objective exams, making this topic highly scoring.
In this blog post, we provide a well-structured collection of Electrophoresis MCQ Questions designed to help students understand key concepts clearly and practice exam-oriented questions. This content is specially created for students and competitive exam aspirants to improve accuracy and confidence.
Electrophoresis MCQ Questions with Answers
1. Electrophoresis is a technique used for:
- A. Separation of cells based on size
- B. Separation of molecules based on electric charge
- C. Separation of molecules based on boiling point
- D. Separation of gases
Explanation: Electrophoresis separates charged molecules by applying an electric field, causing them to migrate based on charge and size.
2. Which biomolecule is most commonly separated using electrophoresis?
- A. Lipids
- B. Carbohydrates
- C. Proteins and nucleic acids
- D. Vitamins
Explanation: Electrophoresis is widely used to separate proteins and nucleic acids like DNA and RNA.
3. In agarose gel electrophoresis, DNA moves towards which electrode?
- A. Cathode
- B. Anode
- C. Neutral point
- D. Depends on size only
Explanation: DNA is negatively charged, so it migrates towards the positively charged anode.
4. Which matrix is commonly used for DNA electrophoresis?
- A. Polyacrylamide gel
- B. Agarose gel
- C. Starch gel
- D. Cellulose acetate
Explanation: Agarose gel is most commonly used for separating DNA fragments.
5. SDS-PAGE is mainly used for the separation of:
- A. DNA fragments
- B. RNA molecules
- C. Proteins based on size
- D. Lipids
Explanation: SDS-PAGE separates proteins primarily according to their molecular weight.
6. What is the role of buffer in electrophoresis?
- A. To stain the gel
- B. To maintain pH and conduct current
- C. To harden the gel
- D. To break DNA
Explanation: Buffer maintains a stable pH and allows electric current to flow during electrophoresis.
7. Which dye is commonly used to visualize DNA in gels?
- A. Methylene blue
- B. Ethidium bromide
- C. Safranin
- D. Crystal violet
Explanation: Ethidium bromide intercalates with DNA and fluoresces under UV light.
8. Which factor does NOT affect the rate of migration in electrophoresis?
- A. Size of molecule
- B. Charge of molecule
- C. Shape of molecule
- D. Color of molecule
Explanation: Migration depends on size, charge, and shape, not on color.
9. Polyacrylamide gel electrophoresis (PAGE) is best suited for:
- A. Large DNA fragments
- B. Very small DNA and proteins
- C. Whole cells
- D. Lipoproteins only
Explanation: PAGE provides high resolution and is ideal for small DNA fragments and proteins.
10. The movement of molecules in electrophoresis occurs due to:
- A. Gravity
- B. Diffusion
- C. Electric field
- D. Centrifugal force
Explanation: Charged molecules migrate through the medium under the influence of an electric field.
11. The principle of electrophoresis is based on:
- A. Capillary action
- B. Movement of charged particles in an electric field
- C. Osmosis
- D. Sedimentation
Explanation: Electrophoresis works on the movement of charged molecules when an electric field is applied.
12. Which component gives uniform negative charge to proteins in SDS-PAGE?
- A. Agarose
- B. SDS
- C. Glycine
- D. Tris buffer
Explanation: SDS (Sodium dodecyl sulfate) binds to proteins and provides a uniform negative charge.
13. Which buffer is commonly used in agarose gel electrophoresis?
- A. TAE or TBE
- B. PBS
- C. Saline
- D. Acetate only
Explanation: TAE and TBE buffers are commonly used to maintain pH and conductivity.
14. What happens if the voltage is too high during electrophoresis?
- A. Faster and clearer bands
- B. No movement of samples
- C. Smiling or distorted bands
- D. Gel becomes thicker
Explanation: Excess voltage can cause overheating and distortion of bands known as smiling effect.
15. Which substance is used as a tracking dye in electrophoresis?
- A. Bromophenol blue
- B. Ethanol
- C. Phenol
- D. Acetic acid
Explanation: Bromophenol blue is commonly used to monitor the progress of electrophoresis.
16. Native PAGE differs from SDS-PAGE because it separates proteins based on:
- A. Size only
- B. Charge only
- C. Size, charge, and shape
- D. Hydrophobicity
Explanation: Native PAGE maintains protein structure, so separation depends on size, charge, and shape.
17. What is the purpose of a molecular weight marker?
- A. To stain DNA
- B. To compare sizes of molecules
- C. To increase voltage
- D. To solidify gel
Explanation: Molecular weight markers help estimate the size of separated molecules.
18. Which electrophoresis technique is used for separation of serum proteins?
- A. Agarose gel electrophoresis
- B. Paper electrophoresis
- C. Capillary electrophoresis
- D. All of the above
Explanation: All listed techniques can be used for serum protein separation.
19. Electrophoresis is widely used in forensic science mainly for:
- A. Blood grouping
- B. DNA fingerprinting
- C. Drug synthesis
- D. Vaccine preparation
Explanation: DNA electrophoresis is a key step in DNA fingerprinting in forensics.
20. Increasing gel concentration will result in:
- A. Faster migration of large molecules
- B. Slower migration of large molecules
- C. No effect on migration
- D. Denaturation of DNA
Explanation: Higher gel concentration reduces pore size, slowing the movement of large molecules.
21. Which electrophoresis technique separates molecules in a capillary tube?
- A. Agarose gel electrophoresis
- B. PAGE
- C. Capillary electrophoresis
- D. Paper electrophoresis
Explanation: Capillary electrophoresis uses narrow capillary tubes for high-resolution separation.
22. Which molecule moves fastest in agarose gel electrophoresis?
- A. Larger DNA fragments
- B. Smaller DNA fragments
- C. Circular DNA only
- D. Protein molecules
Explanation: Smaller DNA fragments migrate faster through the gel pores.
23. Which staining method is safer alternative to ethidium bromide?
- A. Crystal violet
- B. SYBR Green
- C. Safranin
- D. Methylene blue
Explanation: SYBR Green is a safer fluorescent dye for DNA visualization.
24. Which factor determines direction of migration in electrophoresis?
- A. Molecular weight
- B. Electric charge
- C. Gel concentration
- D. Temperature
Explanation: Charged molecules move towards the opposite electrode based on their charge.
25. Which electrophoresis is used to study enzyme activity?
- A. SDS-PAGE
- B. Native PAGE
- C. Agarose gel electrophoresis
- D. Paper electrophoresis
Explanation: Native PAGE preserves enzyme structure and activity.
26. Which component forms the gel matrix in PAGE?
- A. Agarose
- B. Starch
- C. Polyacrylamide
- D. Cellulose
Explanation: Polyacrylamide forms a fine mesh suitable for protein separation.
27. What is the purpose of loading buffer?
- A. To stain DNA
- B. To increase sample density and track migration
- C. To polymerize gel
- D. To break proteins
Explanation: Loading buffer helps samples sink into wells and track progress.
28. Which electrophoresis method uses filter paper as support medium?
- A. Agarose gel electrophoresis
- B. PAGE
- C. Paper electrophoresis
- D. Capillary electrophoresis
Explanation: Paper electrophoresis uses filter paper as the supporting medium.
29. Which electrophoresis technique has highest resolution?
- A. Agarose gel electrophoresis
- B. Paper electrophoresis
- C. Capillary electrophoresis
- D. Starch gel electrophoresis
Explanation: Capillary electrophoresis provides very high resolution and speed.
30. Which buffer component maintains pH in electrophoresis?
- A. SDS
- B. Tris
- C. Agarose
- D. Ethidium bromide
Explanation: Tris helps maintain stable pH during electrophoresis.
31. Which electrophoresis separates DNA fragments differing by a single base pair?
- A. Agarose gel electrophoresis
- B. SDS-PAGE
- C. Denaturing PAGE
- D. Paper electrophoresis
Explanation: Denaturing PAGE offers very high resolution for small DNA fragments.
32. What causes band broadening in electrophoresis?
- A. Uniform voltage
- B. Diffusion and overheating
- C. Proper buffer
- D. Correct gel concentration
Explanation: Diffusion and excessive heat can spread bands and reduce resolution.
33. Which electrophoresis technique is fastest?
- A. Paper electrophoresis
- B. Agarose gel electrophoresis
- C. Capillary electrophoresis
- D. Starch gel electrophoresis
Explanation: Capillary electrophoresis allows rapid separation due to high voltage.
34. Which electrophoresis is commonly used in clinical laboratories?
- A. Agarose gel electrophoresis
- B. Serum protein electrophoresis
- C. SDS-PAGE
- D. DNA electrophoresis
Explanation: Serum protein electrophoresis is widely used for clinical diagnosis.
35. Which parameter increases migration speed?
- A. Lower voltage
- B. Higher gel concentration
- C. Higher voltage
- D. Larger molecules
Explanation: Higher voltage increases electric force, speeding migration.
36. Which electrophoresis separates isoenzymes?
- A. SDS-PAGE
- B. Native PAGE
- C. Agarose gel electrophoresis
- D. Capillary electrophoresis
Explanation: Native PAGE preserves charge and structure, useful for isoenzymes.
37. Which molecule does NOT undergo electrophoresis?
- A. DNA
- B. RNA
- C. Proteins
- D. Neutral molecules
Explanation: Only charged molecules migrate in an electric field.
38. Which electrophoresis is used for hemoglobin variants?
- A. Paper electrophoresis
- B. Agarose gel electrophoresis
- C. SDS-PAGE
- D. Both A and B
Explanation: Paper and agarose gel electrophoresis are used for hemoglobin variants.
39. Which electrophoresis technique uses discontinuous buffer system?
- A. Agarose gel electrophoresis
- B. SDS-PAGE
- C. Paper electrophoresis
- D. Capillary electrophoresis
Explanation: SDS-PAGE uses stacking and resolving gels with different buffers.
40. The stacking gel in SDS-PAGE is used to:
- A. Separate proteins by size
- B. Concentrate proteins into sharp bands
- C. Stain proteins
- D. Polymerize acrylamide
Explanation: Stacking gel aligns proteins into thin bands before separation.
41. Which chemical initiates polymerization in polyacrylamide gel?
- A. SDS
- B. TEMED
- C. Tris
- D. Glycine
Explanation: TEMED catalyzes free radical formation to initiate acrylamide polymerization.
42. Which compound provides free radicals for PAGE polymerization?
- A. APS
- B. SDS
- C. Tris-HCl
- D. Agarose
Explanation: Ammonium persulfate (APS) generates free radicals needed for gel formation.
43. Which electrophoresis separates DNA by size and conformation?
- A. Agarose gel electrophoresis
- B. SDS-PAGE
- C. Isoelectric focusing
- D. Paper electrophoresis
Explanation: Agarose gels can resolve DNA based on size and structural conformation.
44. Which technique separates proteins based on isoelectric point?
- A. SDS-PAGE
- B. Agarose gel electrophoresis
- C. Isoelectric focusing
- D. Native PAGE
Explanation: Isoelectric focusing separates proteins according to their isoelectric point (pI).
45. In isoelectric focusing, proteins stop migrating when:
- A. Voltage is removed
- B. They reach the anode
- C. Net charge becomes zero
- D. Gel pores block them
Explanation: Proteins stop at their pI where net charge is zero.
46. Which electrophoresis combines isoelectric focusing and SDS-PAGE?
- A. Native PAGE
- B. Two-dimensional electrophoresis
- C. Capillary electrophoresis
- D. Agarose gel electrophoresis
Explanation: 2D electrophoresis separates proteins by pI and then by molecular weight.
47. Which buffer system is used in SDS-PAGE?
- A. Tris-Glycine
- B. TAE
- C. TBE
- D. PBS
Explanation: Tris-Glycine buffer system is standard for SDS-PAGE.
48. Which molecule gives blue color to loading dye?
- A. Xylene cyanol
- B. Bromophenol blue
- C. Coomassie blue
- D. Both A and B
Explanation: Bromophenol blue and xylene cyanol are common tracking dyes.
49. Which stain is commonly used for proteins in PAGE?
- A. Ethidium bromide
- B. SYBR Green
- C. Coomassie Brilliant Blue
- D. Safranin
Explanation: Coomassie Brilliant Blue binds to proteins for visualization.
50. Silver staining is preferred because it is:
- A. Cheaper
- B. Faster
- C. Highly sensitive
- D. Non-toxic
Explanation: Silver staining can detect very low amounts of protein.
51. Which electrophoresis is used for separation of RNA?
- A. Agarose gel electrophoresis
- B. SDS-PAGE
- C. Paper electrophoresis
- D. Native PAGE
Explanation: Agarose gels are commonly used for RNA separation (often under denaturing conditions).
52. Which agent is added to denature RNA during electrophoresis?
- A. SDS
- B. Formaldehyde
- C. Tris
- D. Glycine
Explanation: Formaldehyde keeps RNA denatured to separate by size.
53. Which electrophoresis technique uses pH gradient?
- A. SDS-PAGE
- B. Agarose gel electrophoresis
- C. Isoelectric focusing
- D. Paper electrophoresis
Explanation: Isoelectric focusing establishes a stable pH gradient.
54. Which electrophoresis is best for separating large DNA fragments (>20 kb)?
- A. Agarose gel electrophoresis
- B. PAGE
- C. Pulsed-field gel electrophoresis
- D. Capillary electrophoresis
Explanation: PFGE separates very large DNA fragments by changing electric field direction.
55. In PFGE, DNA migration is achieved by:
- A. Constant electric field
- B. Alternating electric fields
- C. Magnetic field
- D. Centrifugation
Explanation: Alternating fields allow reorientation of large DNA molecules.
56. Which electrophoresis is commonly used in proteomics?
- A. Agarose gel electrophoresis
- B. Native PAGE
- C. Two-dimensional electrophoresis
- D. Paper electrophoresis
Explanation: 2D electrophoresis resolves complex protein mixtures in proteomics.
57. Which factor reduces overheating during electrophoresis?
- A. Higher voltage
- B. Lower buffer volume
- C. Cooling system
- D. Higher gel concentration
Explanation: Cooling dissipates heat generated by electric current.
58. Which electrophoresis is suitable for charged small ions?
- A. Agarose gel electrophoresis
- B. Capillary electrophoresis
- C. SDS-PAGE
- D. Starch gel electrophoresis
Explanation: Capillary electrophoresis efficiently separates small charged ions.
59. Which electrophoresis technique requires UV detection?
- A. DNA agarose gel electrophoresis
- B. Paper electrophoresis
- C. Native PAGE
- D. Starch gel electrophoresis
Explanation: DNA stained with fluorescent dyes is visualized under UV light.
60. The main advantage of electrophoresis is:
- A. Low resolution
- B. High specificity and resolution
- C. High cost
- D. Complex procedure
Explanation: Electrophoresis provides high-resolution separation of biomolecules.
We hope these Electrophoresis MCQ Questions help you strengthen your preparation and improve your understanding of the topic. Regular practice of MCQs is essential to perform well in competitive examinations.
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