Chapter 11: Biotechnology – Principles and Processes – MCQs
🟢 Part 1: Biotechnology – Principles and Processes (Q1–Q25)
Q1. The first step in recombinant DNA technology is usually
a) Ligation
b) Isolation of DNA
c) Transformation
d) Screening
Answer: b) Isolation of DNA
Explanation: Pure, intact DNA from source and vector is needed before cutting and joining.
Q2. Which enzyme joins DNA fragments to form phosphodiester bonds?
a) Restriction endonuclease
b) DNA polymerase I
c) DNA ligase
d) Reverse transcriptase
Answer: c) DNA ligase
Explanation: Ligase seals nicks and covalently links DNA fragments.
Q3. Restriction endonucleases recognize and cut
a) Random sequences
b) Palindromic sequences
c) Only single-stranded DNA
d) RNA–DNA hybrids
Answer: b) Palindromic sequences
Explanation: Most Type II enzymes bind specific palindromic sites producing sticky/blunt ends.
Q4. The discovery of restriction enzymes is credited to
a) Boyer and Cohen
b) Arber, Smith, and Nathans
c) Fleming
d) Kary Mullis
Answer: b) Arber, Smith, and Nathans
Explanation: They explained restriction–modification systems; Nobel Prize (1978).
Q5. The multiple cloning site (MCS) in a plasmid is designed to
a) Initiate replication
b) Provide numerous unique restriction sites
c) Confer antibiotic resistance only
d) Help in transcription termination
Answer: b) Provide numerous unique restriction sites
Explanation: MCS enables easy insertion using different enzymes without disrupting essentials.
Q6. In pBR322, ampR and tetR genes are used as
a) Origins of replication
b) Reporter genes
c) Selectable markers
d) Promoters
Answer: c) Selectable markers
Explanation: Resistance to ampicillin/tetracycline helps select transformants.
Q7. The ori sequence in a vector is required for
a) Selection of clones
b) Initiation of replication
c) Protein expression
d) Cell lysis
Answer: b) Initiation of replication
Explanation: ori determines copy number and replication in host.
Q8. Competency in E. coli can be induced by
a) Phenol treatment
b) CaCl₂ followed by heat shock
c) SDS treatment
d) Incubation at 4°C only
Answer: b) CaCl₂ followed by heat shock
Explanation: Calcium chloride neutralizes charge; heat shock drives DNA into cells.
Q9. Electroporation introduces DNA by
a) Phage infection
b) Creating transient pores with electric pulses
c) Chemical precipitation
d) Microinjection
Answer: b) Creating transient pores with electric pulses
Explanation: High-voltage pulses allow DNA entry into cells.
Q10. Which enzyme synthesizes DNA from an RNA template to make cDNA?
a) DNA pol I
b) RNA pol II
c) Reverse transcriptase
d) Ligase
Answer: c) Reverse transcriptase
Explanation: Converts mRNA → cDNA for cloning of expressed genes.
Q11. PCR requires a thermostable DNA polymerase such as
a) DNA pol I
b) Taq polymerase
c) Reverse transcriptase
d) RNA polymerase
Answer: b) Taq polymerase
Explanation: Taq withstands repeated denaturation at ~94–95°C.
Q12. Correct order in a PCR cycle is
a) Denaturation → Extension → Annealing
b) Annealing → Denaturation → Extension
c) Denaturation → Annealing → Extension
d) Extension → Denaturation → Annealing
Answer: c) Denaturation → Annealing → Extension
Explanation: Standard cycle: 94–95°C, then 50–65°C, then 72°C.
Q13. Agarose gel electrophoresis separates DNA fragments primarily by
a) Charge only
b) Shape only
c) Size (length)
d) GC content
Answer: c) Size (length)
Explanation: Smaller fragments migrate faster through the gel matrix.
Q14. Ethidium bromide in gel electrophoresis is used to
a) Cut DNA
b) Visualize DNA under UV
c) Stain proteins
d) Precipitate DNA
Answer: b) Visualize DNA under UV
Explanation: Intercalates into DNA; fluoresces to reveal bands.
Q15. The Ti plasmid used in plant genetic engineering is naturally found in
a) Rhizobium leguminosarum
b) Agrobacterium tumefaciens
c) E. coli
d) Bacillus subtilis
Answer: b) Agrobacterium tumefaciens
Explanation: Disarmed Ti vectors deliver T-DNA into plant genomes.
Q16. Blue–white screening in vectors uses disruption of
a) lacI
b) lacZ (α-complementation)
c) tetR
d) araC
Answer: b) lacZ (α-complementation)
Explanation: Inserts disrupt lacZα → white colonies (recombinants); blue = non-recombinants.
Q17. A genomic library contains
a) Only expressed genes
b) Only mitochondrial DNA
c) Entire genome fragments cloned
d) Only promoter regions
Answer: c) Entire genome fragments cloned
Explanation: Represents all DNA sequences of an organism.
Q18. A cDNA library is preferred over genomic library for eukaryotic gene expression in bacteria because
a) cDNA has introns
b) cDNA lacks introns
c) cDNA is larger
d) cDNA contains promoters
Answer: b) cDNA lacks introns
Explanation: Bacteria cannot splice introns; cDNA from mRNA is intron-free.
Q19. Which is not a typical feature of an ideal cloning vector?
a) ori
b) Selectable marker
c) Multiple cloning site
d) Large genome size
Answer: d) Large genome size
Explanation: Vectors should be small for easy manipulation and high copy number.
Q20. The process of introducing recombinant plasmid into a host cell is
a) Transduction
b) Transformation
c) Conjugation
d) Translation
Answer: b) Transformation
Explanation: Uptake of naked DNA/plasmid by competent cells.
Q21. In bioreactors, agitation and aeration are mainly for
a) Maintaining pH only
b) Mixing and oxygen transfer
c) Sterilization
d) Downstream processing
Answer: b) Mixing and oxygen transfer
Explanation: Ensures homogeneous nutrients and adequate dissolved O₂ for aerobic cultures.
Q22. A sparger in a stirred-tank bioreactor is used to
a) Control temperature
b) Introduce sterile air bubbles
c) Measure pH
d) Harvest biomass
Answer: b) Introduce sterile air bubbles
Explanation: Enhances gas–liquid mass transfer.
Q23. “Downstream processing” refers to
a) Fermentation setup
b) Recovery and purification of product
c) Vector construction
d) Cell line maintenance
Answer: b) Recovery and purification of product
Explanation: Includes filtration, chromatography, formulation of the final product.
Q24. The first recombinant DNA was created by Cohen and Boyer using
a) Ti plasmid and yeast
b) pSC101 plasmid and E. coli DNA
c) λ phage only
d) BACs with human DNA
Answer: b) pSC101 plasmid and E. coli DNA
Explanation: They ligated foreign DNA into plasmid and transformed E. coli (1973).
Q25. Which statement about Type II restriction endonucleases is true?
a) Cut at random sites far from recognition sequence
b) Require ATP and cut RNA
c) Recognize specific palindromes and cut at/near those sites
d) Only methylate DNA
Answer: c) Recognize specific palindromes and cut at/near those sites
Explanation: Type II enzymes are precise tools for cloning; methylases are separate.
🟢 Part 2: Biotechnology – Principles and Processes (Q26–Q50)
Q26. Which of the following is an example of a cloning vector?
a) pBR322
b) pUC19
c) λ phage
d) All of these
Answer: d) All of these
Explanation: Plasmids (pBR322, pUC19) and bacteriophage λ are widely used vectors in cloning.
Q27. Which selectable marker is present in pBR322?
a) Kanamycin resistance
b) Ampicillin and tetracycline resistance
c) Chloramphenicol resistance only
d) Neomycin resistance
Answer: b) Ampicillin and tetracycline resistance
Explanation: ampR and tetR are used to identify recombinants in pBR322.
Q28. Which is NOT a feature of a good vector?
a) Origin of replication
b) Selectable marker
c) Small size
d) Multiple introns
Answer: d) Multiple introns
Explanation: Vectors must be intron-free and small for easy manipulation and replication.
Q29. A bacteriophage vector capable of cloning large DNA fragments is
a) Cosmid
b) pUC19
c) pBR322
d) Plasmid
Answer: a) Cosmid
Explanation: Cosmids combine features of plasmids and λ phage, carrying larger DNA inserts.
Q30. The lacZ gene encodes
a) β-galactosidase
b) DNA ligase
c) RNA polymerase
d) Amylase
Answer: a) β-galactosidase
Explanation: Enzyme hydrolyzes lactose into glucose + galactose; used in blue–white screening.
Q31. In blue–white screening, blue colonies indicate
a) Successful recombinants
b) Non-recombinants with intact lacZ
c) DNA ligation
d) Transformation success
Answer: b) Non-recombinants with intact lacZ
Explanation: X-gal is cleaved by β-galactosidase, producing blue colonies; white = recombinants.
Q32. Which technique is used to introduce DNA into plant cells?
a) Microinjection
b) Gene gun (biolistics)
c) Electroporation
d) All of these
Answer: d) All of these
Explanation: Different methods are applied: gene gun for plants, electroporation for protoplasts, microinjection in cells.
Q33. Which is a disarmed vector used for gene transfer in plants?
a) pUC19
b) λ phage
c) Ti plasmid of Agrobacterium
d) F-plasmid
Answer: c) Ti plasmid of Agrobacterium
Explanation: Modified (disarmed) Ti plasmid delivers foreign genes into plants without causing disease.
Q34. Which is NOT an application of PCR?
a) DNA amplification
b) Disease diagnosis
c) Gene cloning
d) Protein sequencing directly
Answer: d) Protein sequencing directly
Explanation: PCR amplifies DNA but cannot directly sequence proteins.
Q35. Which of the following steps in PCR requires primers?
a) Denaturation
b) Annealing
c) Extension
d) Digestion
Answer: b) Annealing
Explanation: Primers bind to template DNA during annealing to initiate DNA synthesis.
Q36. Thermostable DNA polymerase was originally isolated from
a) Thermus aquaticus
b) Agrobacterium tumefaciens
c) E. coli
d) Streptomyces
Answer: a) Thermus aquaticus
Explanation: Taq polymerase functions at high temperature, essential for PCR.
Q37. The transformation efficiency is the measure of
a) Rate of plasmid replication
b) Frequency of cells transformed by plasmid DNA
c) DNA ligation success
d) Stability of recombinant DNA
Answer: b) Frequency of cells transformed by plasmid DNA
Explanation: High efficiency means more cells incorporate plasmid DNA successfully.
Q38. Which technique is used to transfer genes into animal cells?
a) Microinjection
b) Liposome-mediated transfer
c) Electroporation
d) All of these
Answer: d) All of these
Explanation: Multiple physical and chemical methods are used in animal genetic engineering.
Q39. The first recombinant DNA molecule was constructed using
a) pBR322
b) pSC101
c) λ phage
d) BAC
Answer: b) pSC101
Explanation: Cohen and Boyer used plasmid pSC101 and DNA ligase for first recombinant DNA (1973).
Q40. DNA is generally cut at specific sites using
a) Exonucleases
b) Restriction endonucleases
c) Ligases
d) RNA polymerases
Answer: b) Restriction endonucleases
Explanation: These enzymes cut DNA at specific palindromic sequences.
Q41. Blunt ends are generated by
a) EcoRI
b) HindIII
c) SmaI
d) BamHI
Answer: c) SmaI
Explanation: SmaI produces blunt ends, while EcoRI and BamHI produce sticky ends.
Q42. Which is a palindromic sequence?
a) GAATTC (EcoRI site)
b) AAAAAA
c) ATGCAT
d) Both a and c
Answer: d) Both a and c
Explanation: Palindromes read the same in 5’→3’ and 3’→5’; GAATTC and ATGCAT are examples.
Q43. Gene cloning in eukaryotes often uses vectors called
a) Cosmids
b) Artificial chromosomes (YACs, BACs)
c) Plasmids only
d) Episomes
Answer: b) Artificial chromosomes (YACs, BACs)
Explanation: These vectors can carry very large DNA inserts for genomic projects.
Q44. Which is the first step in gene transfer into plants using Agrobacterium?
a) T-DNA integration
b) Wounding of plant tissue
c) Expression of foreign gene
d) Vector selection
Answer: b) Wounding of plant tissue
Explanation: Agrobacterium infects wounded plant tissues, transferring T-DNA into the genome.
Q45. Microinjection involves
a) Electric pulses
b) Direct injection of DNA into nucleus
c) Use of viral vectors
d) RNA probes
Answer: b) Direct injection of DNA into nucleus
Explanation: A fine glass needle injects DNA directly into animal cell nucleus.
Q46. Which of the following is NOT a method of introducing foreign DNA into a host?
a) Liposome-mediated transfer
b) Biolistics
c) Electroporation
d) Respiration
Answer: d) Respiration
Explanation: Respiration is a metabolic process, not a method of DNA delivery.
Q47. DNA fragments can be visualized in agarose gels because of
a) Radiolabels
b) Ethidium bromide/fluorescent dyes
c) Autoradiography only
d) Protein staining
Answer: b) Ethidium bromide/fluorescent dyes
Explanation: EtBr intercalates DNA, fluoresces under UV light.
Q48. Which process involves introducing foreign DNA into bacterial cells using bacteriophages?
a) Transformation
b) Conjugation
c) Transduction
d) Transcription
Answer: c) Transduction
Explanation: Bacteriophages act as vectors to deliver DNA into bacteria.
Q49. The host organism widely used in rDNA technology is
a) Bacillus subtilis
b) Agrobacterium tumefaciens
c) Escherichia coli
d) Pseudomonas putida
Answer: c) Escherichia coli
Explanation: E. coli is easy to manipulate, grows rapidly, and is well studied.
Q50. Which technique allows separation of DNA fragments according to size in an electric field?
a) PCR
b) Electroporation
c) Gel electrophoresis
d) Northern blotting
Answer: c) Gel electrophoresis
Explanation: DNA fragments migrate through agarose gel depending on size and charge.
🟢 Part 3: Biotechnology – Principles and Processes (Q51–Q75)
Q51. Which type of endonucleases cut DNA at specific recognition sequences?
a) Type I
b) Type II
c) Type III
d) Exonucleases
Answer: b) Type II
Explanation: Type II restriction enzymes recognize specific palindromic sequences and cut at/near them, widely used in rDNA technology.
Q52. Which restriction enzyme produces sticky ends?
a) EcoRI
b) SmaI
c) HindII
d) AluI
Answer: a) EcoRI
Explanation: EcoRI cuts between G and A in GAATTC, producing sticky overhangs.
Q53. Which is used for the amplification of a specific DNA sequence?
a) PCR
b) Blotting
c) Electrophoresis
d) Hybridization
Answer: a) PCR
Explanation: Polymerase Chain Reaction amplifies specific DNA sequences exponentially.
Q54. Which of the following is NOT required for PCR?
a) DNA template
b) RNA polymerase
c) DNA primers
d) Taq polymerase
Answer: b) RNA polymerase
Explanation: PCR needs DNA template, primers, nucleotides, and thermostable DNA polymerase.
Q55. The main application of Southern blotting is to detect
a) Specific RNA sequences
b) Specific DNA sequences
c) Specific proteins
d) Specific lipids
Answer: b) Specific DNA sequences
Explanation: Southern blotting uses DNA probes to identify complementary DNA fragments.
Q56. Northern blotting is used for the detection of
a) DNA
b) RNA
c) Proteins
d) Carbohydrates
Answer: b) RNA
Explanation: Northern blotting identifies and studies specific RNA transcripts.
Q57. Western blotting is used for detecting
a) DNA
b) RNA
c) Proteins
d) Carbohydrates
Answer: c) Proteins
Explanation: Western blotting uses antibodies to detect specific proteins.
Q58. Which of the following vectors is used to clone large fragments of DNA?
a) Plasmids
b) BACs (Bacterial Artificial Chromosomes)
c) Cosmids
d) YACs (Yeast Artificial Chromosomes)
Answer: d) YACs (Yeast Artificial Chromosomes)
Explanation: YACs can carry inserts up to 1 Mb, used for cloning very large DNA fragments.
Q59. Which of the following enzymes is used in recombinant DNA technology to seal nicks?
a) DNA polymerase
b) DNA ligase
c) Restriction enzyme
d) RNA polymerase
Answer: b) DNA ligase
Explanation: DNA ligase seals nicks between DNA fragments by forming phosphodiester bonds.
Q60. A genomic library contains
a) cDNA only
b) Expressed sequences only
c) Whole genome fragments cloned into vectors
d) Only mitochondrial DNA
Answer: c) Whole genome fragments cloned into vectors
Explanation: Genomic library represents all DNA sequences of an organism.
Q61. Which is true about cDNA library?
a) Made from mRNA
b) Contains introns
c) Larger than genomic library
d) Contains entire genome
Answer: a) Made from mRNA
Explanation: cDNA is made by reverse transcriptase from mRNA, hence intron-free.
Q62. The enzyme used for complementary DNA synthesis is
a) RNA polymerase
b) DNA ligase
c) Reverse transcriptase
d) DNA polymerase I
Answer: c) Reverse transcriptase
Explanation: Converts RNA into complementary DNA (cDNA).
Q63. Which term describes the ability of a cell to develop into a whole plant?
a) Pluripotency
b) Multipotency
c) Totipotency
d) Unipotency
Answer: c) Totipotency
Explanation: Plant cells exhibit totipotency — ability of a single cell to regenerate an entire organism.
Q64. In electrophoresis, smaller DNA fragments move
a) Slower than larger fragments
b) Faster than larger fragments
c) At the same rate
d) Not at all
Answer: b) Faster than larger fragments
Explanation: DNA fragments migrate through agarose gel inversely proportional to their size.
Q65. Ethidium bromide is used in electrophoresis because it
a) Cuts DNA
b) Visualizes DNA under UV light
c) Binds proteins
d) Removes RNA
Answer: b) Visualizes DNA under UV light
Explanation: EtBr intercalates DNA and fluoresces under UV, making DNA bands visible.
Q66. The primary function of ori in plasmid vectors is
a) Antibiotic resistance
b) Origin of replication
c) Transcription initiation
d) Gene expression
Answer: b) Origin of replication
Explanation: ori ensures replication and copy number of plasmid DNA inside the host.
Q67. Which of the following is an example of an expression vector?
a) pUC19
b) pBR322
c) pET series plasmids
d) Cosmid
Answer: c) pET series plasmids
Explanation: Expression vectors like pET plasmids are used for high-level protein expression.
Q68. Which selectable marker is used in plant transformation vectors?
a) Antibiotic resistance genes
b) Herbicide resistance genes
c) Both a and b
d) Ribosomal RNA genes
Answer: c) Both a and b
Explanation: Selectable markers allow identification of transformed cells in plants (e.g., kanamycin resistance).
Q69. The enzyme alkaline phosphatase is used in cloning to
a) Cut DNA at specific sites
b) Prevent self-ligation of vectors
c) Amplify DNA
d) Repair DNA
Answer: b) Prevent self-ligation of vectors
Explanation: Removes phosphate groups at 5′ ends, preventing vector recircularization.
Q70. Which type of ends generated by restriction enzymes are easier to ligate?
a) Sticky ends
b) Blunt ends
c) Both equally
d) None
Answer: a) Sticky ends
Explanation: Overhanging bases allow hydrogen bonding, making ligation more efficient.
Q71. The enzyme HindII was the first restriction endonuclease discovered. It cuts DNA at
a) Specific 6 bp recognition sites
b) Random sequences
c) GC-rich regions only
d) Palindrome of 4 bp
Answer: a) Specific 6 bp recognition sites
Explanation: HindII was the first discovered enzyme cutting DNA at defined sites.
Q72. Which organism provides the natural plasmid Ti used in plant transformation?
a) Escherichia coli
b) Agrobacterium tumefaciens
c) Rhizobium leguminosarum
d) Bacillus thuringiensis
Answer: b) Agrobacterium tumefaciens
Explanation: Ti plasmid naturally transfers T-DNA into plant cells.
Q73. Which is NOT a cloning host used in biotechnology?
a) E. coli
b) Yeast
c) Mammalian cells
d) Red blood cells
Answer: d) Red blood cells
Explanation: RBCs lack nucleus/DNA, hence cannot serve as cloning hosts.
Q74. The term “recombinant DNA” means
a) DNA isolated from bacteria
b) DNA with identical repeats
c) DNA molecule with combined sequences from different sources
d) DNA made of only RNA
Answer: c) DNA molecule with combined sequences from different sources
Explanation: Recombinant DNA combines genetic material from two or more organisms.
Q75. The technique used to separate DNA based on density gradient centrifugation is
a) CsCl density gradient method
b) Electrophoresis
c) PCR
d) Blotting
Answer: a) CsCl density gradient method
Explanation: DNA separates according to buoyant density in CsCl gradients, used for purity testing.
🟢 Part 4: Biotechnology – Principles and Processes (Q76–Q100)
Q76. Which enzyme is used to cut DNA at specific sites?
a) Ligase
b) Polymerase
c) Restriction endonuclease
d) Topoisomerase
Answer: c) Restriction endonuclease
Explanation: Restriction enzymes recognize palindromic sequences and cut DNA precisely.
Q77. The first recombinant DNA molecule was created in
a) 1928
b) 1973
c) 1953
d) 1983
Answer: b) 1973
Explanation: Stanley Cohen and Herbert Boyer made the first rDNA using E. coli plasmid pSC101.
Q78. Which type of DNA ends produced by restriction enzymes are most suitable for cloning?
a) Sticky ends
b) Blunt ends
c) Both equally
d) Random breaks
Answer: a) Sticky ends
Explanation: Sticky ends form hydrogen bonds, ensuring easier ligation with complementary sequences.
Q79. The principle of gel electrophoresis depends on
a) Size and charge of molecules
b) GC content
c) pH of solution only
d) Shape of molecules only
Answer: a) Size and charge of molecules
Explanation: DNA moves toward the positive electrode; smaller fragments move faster.
Q80. The enzyme Taq polymerase was isolated from
a) Agrobacterium tumefaciens
b) Thermus aquaticus
c) E. coli
d) Pseudomonas putida
Answer: b) Thermus aquaticus
Explanation: A thermostable polymerase used in PCR.
Q81. Which of the following is an essential requirement for PCR?
a) Primers
b) DNA polymerase
c) dNTPs
d) All of these
Answer: d) All of these
Explanation: PCR requires primers, template DNA, nucleotides, and DNA polymerase.
Q82. In blue–white screening, white colonies represent
a) Non-recombinants
b) Recombinants
c) Both
d) None
Answer: b) Recombinants
Explanation: Insert disrupts lacZ gene → β-galactosidase not formed → colonies remain white.
Q83. Which is a selectable marker in bacteria?
a) GFP gene
b) Antibiotic resistance gene
c) lac operon
d) ori
Answer: b) Antibiotic resistance gene
Explanation: Confers resistance to antibiotics, allowing selection of transformants.
Q84. Which of the following is NOT a method of introducing foreign DNA?
a) Biolistics
b) Electroporation
c) Respiration
d) Microinjection
Answer: c) Respiration
Explanation: Respiration is a metabolic process, not a DNA transfer method.
Q85. Biolistics (gene gun) is mainly used for
a) Animal cells
b) Plant cells
c) Bacterial cells
d) Fungal cells
Answer: b) Plant cells
Explanation: DNA-coated microparticles are shot into plant cells.
Q86. The T-DNA region of Ti plasmid integrates into
a) Animal genome
b) Plant genome
c) Bacterial genome
d) Viral genome
Answer: b) Plant genome
Explanation: Agrobacterium transfers T-DNA into wounded plant cells, integrating into host DNA.
Q87. A good cloning vector must have
a) Origin of replication
b) Selectable marker
c) Multiple cloning site
d) All of these
Answer: d) All of these
Explanation: ori, markers, and MCS are essential features of an ideal vector.
Q88. Which method is used to introduce DNA into animal cells using lipids?
a) Microinjection
b) Liposome-mediated transfer
c) Electroporation
d) Biolistics
Answer: b) Liposome-mediated transfer
Explanation: Liposomes fuse with cell membranes, releasing DNA inside.
Q89. Which blotting technique is used for protein detection?
a) Southern
b) Northern
c) Western
d) Eastern
Answer: c) Western
Explanation: Western blotting detects proteins using specific antibodies.
Q90. The term “downstream processing” refers to
a) Gene transfer
b) Purification of product
c) Transformation
d) DNA replication
Answer: b) Purification of product
Explanation: Involves extraction, purification, and formulation of desired product.
Q91. Which enzyme was first discovered as a restriction endonuclease?
a) EcoRI
b) HindII
c) BamHI
d) PstI
Answer: b) HindII
Explanation: HindII was the first restriction enzyme discovered (1970).
Q92. The first genetically engineered product approved for human use was
a) Human insulin
b) Interferon
c) Human growth hormone
d) Antibiotics
Answer: a) Human insulin
Explanation: Recombinant human insulin (Humulin) was the first FDA-approved biopharmaceutical.
Q93. Plasmid pBR322 was developed by
a) Boyer and Cohen
b) Bolivar and Rodriguez
c) Watson and Crick
d) Arber and Nathans
Answer: b) Bolivar and Rodriguez
Explanation: pBR322 was created in 1977; name comes from their initials.
Q94. Which of the following is a viral vector used in gene transfer?
a) pBR322
b) Cosmid
c) λ phage
d) BAC
Answer: c) λ phage
Explanation: Bacteriophage λ is a widely used viral vector in cloning.
Q95. Which is NOT an application of recombinant DNA technology?
a) Production of antibiotics
b) Production of insulin
c) Gene therapy
d) Production of antibiotics through fermentation only
Answer: d) Production of antibiotics through fermentation only
Explanation: Traditional fermentation (like penicillin) is not rDNA-based; other options are.
Q96. Which technique is used to separate DNA fragments by size?
a) PCR
b) Gel electrophoresis
c) Blotting
d) Hybridization
Answer: b) Gel electrophoresis
Explanation: Smaller DNA fragments migrate faster through agarose gel.
Q97. Which of the following is NOT a common host for cloning?
a) E. coli
b) Yeast
c) Mammalian cells
d) Mature red blood cells
Answer: d) Mature red blood cells
Explanation: RBCs lack a nucleus and DNA, hence cannot be used.
Q98. Microinjection is used to
a) Insert DNA into animal cells directly
b) Insert DNA into plant chloroplasts
c) Sequence DNA
d) Amplify DNA
Answer: a) Insert DNA into animal cells directly
Explanation: Fine needles inject DNA into nucleus of animal cells.
Q99. Restriction enzymes cut DNA at sites that are usually
a) Palindromic sequences
b) Random sequences
c) Promoter sequences
d) Centromeric DNA
Answer: a) Palindromic sequences
Explanation: Recognition sites are palindromes, same sequence read in both directions.
Q100. Which is considered the “workhorse” of biotechnology as a cloning host?
a) Yeast
b) E. coli
c) Agrobacterium
d) Bacillus
Answer: b) E. coli
Explanation: E. coli is widely used due to its rapid growth, easy handling, and well-characterized genetics.
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