Free Biotechnology MCQs with Answers

51. The enzyme used in PCR to synthesize DNA is

• A. DNA polymerase I
• B. Taq polymerase
• C. RNA polymerase
• D. Reverse transcriptase

Explanation: Taq polymerase (from Thermus aquaticus) is heat-stable and used in PCR to withstand denaturation temperatures.

52. Gel electrophoresis separates DNA by

• A. Sequence
• B. Size
• C. Charge only
• D. GC content

Explanation: DNA fragments are separated by size (smaller fragments move faster) through an agarose gel matrix.

53. Insulin for diabetes treatment is now produced using

• A. Pig pancreas
• B. Human cadavers
• C. Recombinant bacteria
• D. Synthetic chemistry only

Explanation: Human insulin is produced by recombinant DNA technology using E. coli or yeast with the human insulin gene.

54. DNA ligase is used to

• A. Cut DNA
• B. Join DNA fragments
• C. Copy DNA
• D. Separate DNA strands

Explanation: DNA ligase seals nicks in DNA by forming phosphodiester bonds, joining DNA fragments together.

55. cDNA is synthesized from

• A. DNA template
• B. RNA template
• C. Protein template
• D. Lipid template

Explanation: Complementary DNA (cDNA) is synthesized from mRNA using reverse transcriptase; it lacks introns.

56. Stem cells that can form any cell type are called

• A. Multipotent
• B. Pluripotent
• C. Unipotent
• D. Differentiated

Explanation: Pluripotent stem cells (e.g., embryonic stem cells) can differentiate into any of the three germ layers.