Q.1 What is the primary role of a plasmid vector in genetic engineering?
To provide a source of energy for the host cell
To replicate autonomously and carry foreign DNA into a host cell
To act as a catalyst for biochemical reactions
To degrade unwanted RNA molecules
Explanation - Plasmid vectors are circular DNA molecules that can replicate independently of the chromosome and are used to introduce foreign genes into a host.
Correct answer is: To replicate autonomously and carry foreign DNA into a host cell
Q.2 Which of the following is a common selectable marker used in bacterial vectors?
Green fluorescent protein (GFP)
Ampicillin resistance (bla)
Luciferase
β‑galactosidase (lacZ)
Explanation - The bla gene confers resistance to ampicillin, allowing only transformed bacteria to grow on media containing the antibiotic.
Correct answer is: Ampicillin resistance (bla)
Q.3 A cosmid vector is best described as:
A plasmid that contains a bacteriophage λ cos site
A viral particle used for gene delivery in mammals
A linear DNA fragment that cannot replicate in bacteria
A synthetic RNA molecule used for silencing
Explanation - Cosmids combine features of plasmids and bacteriophage λ, allowing them to carry larger DNA fragments (up to ~45 kb) thanks to the cos site.
Correct answer is: A plasmid that contains a bacteriophage λ cos site
Q.4 Which viral vector is most commonly used for stable gene integration in mammalian cells?
Adenovirus
Lentivirus
Influenza virus
Bacteriophage M13
Explanation - Lentiviral vectors can integrate their genome into dividing and non‑dividing mammalian cells, providing long‑term expression.
Correct answer is: Lentivirus
Q.5 In a cloning vector, the multiple cloning site (MCS) is:
A region that codes for antibiotic resistance
A sequence that enhances transcription of inserted genes
A short stretch containing many unique restriction sites
A promoter that drives high expression in eukaryotes
Explanation - The MCS provides numerous restriction enzyme sites to facilitate insertion of foreign DNA fragments.
Correct answer is: A short stretch containing many unique restriction sites
Q.6 Which of the following is NOT a characteristic of a high‑copy‑number plasmid?
It produces many copies per cell
It often carries a strong origin of replication like pUC
It is ideal for cloning large genomic fragments (>100 kb)
It can lead to a higher yield of recombinant protein
Explanation - High‑copy plasmids usually have small size limits (<10 kb). Large fragments require low‑copy or specialized vectors like BACs.
Correct answer is: It is ideal for cloning large genomic fragments (>100 kb)
Q.7 What is the purpose of a promoter in an expression vector?
To replicate the vector in the host cell
To provide a site for restriction enzyme cutting
To initiate transcription of the cloned gene
To confer antibiotic resistance
Explanation - Promoters are DNA sequences recognized by RNA polymerase to start transcription of downstream genes.
Correct answer is: To initiate transcription of the cloned gene
Q.8 Which of these vectors is specifically designed for cloning and maintaining large pieces of DNA (100–300 kb) in bacteria?
BAC (Bacterial Artificial Chromosome)
pBR322 plasmid
M13 phage vector
pUC19 plasmid
Explanation - BACs can accommodate large DNA inserts and replicate at low copy number in E. coli, making them suitable for large‑scale cloning.
Correct answer is: BAC (Bacterial Artificial Chromosome)
Q.9 A shuttle vector:
Can replicate in two different host species
Transfers DNA between mitochondria and nucleus
Is used only in plant transformation
Contains only viral elements
Explanation - Shuttle vectors have origins of replication functional in multiple hosts, such as both E. coli and yeast.
Correct answer is: Can replicate in two different host species
Q.10 Which enzyme is commonly used to create blunt ends on DNA fragments before ligation?
EcoRI
Taq polymerase
DNA polymerase I
DNA polymerase I Klenow fragment
Explanation - The Klenow fragment possesses 5'→3' polymerase and 3'→5' exonuclease activity, useful for filling in overhangs to produce blunt ends.
Correct answer is: DNA polymerase I Klenow fragment
Q.11 Which of the following vectors is a bacteriophage that can display peptides on its coat proteins?
M13 filamentous phage
λ phage
T4 phage
ΦX174
Explanation - M13 phage is used for phage display, where foreign peptides are fused to its coat protein pIII or pVIII.
Correct answer is: M13 filamentous phage
Q.12 What does the term 'transduction' refer to in the context of viral vectors?
Transfer of DNA between bacteria via pili
Direct uptake of naked DNA by cells
Transfer of genetic material by a virus
Insertion of DNA into the mitochondrial genome
Explanation - Transduction is the process by which viruses deliver genetic material into host cells, a key mechanism for viral vectors.
Correct answer is: Transfer of genetic material by a virus
Q.13 In a eukaryotic expression vector, the polyadenylation signal is required for:
Initiating transcription
Stabilizing mRNA and facilitating export from the nucleus
Increasing plasmid copy number
Providing antibiotic resistance
Explanation - The poly(A) signal signals cleavage and addition of a poly(A) tail, which protects mRNA and assists nuclear export.
Correct answer is: Stabilizing mRNA and facilitating export from the nucleus
Q.14 Which of the following is a feature of a lentiviral vector that makes it safer for laboratory use?
It contains all viral genes required for replication
It is replication‑defective and requires helper plasmids
It integrates randomly without any control
It cannot infect non‑dividing cells
Explanation - Lentiviral vectors are engineered to lack essential genes for replication, requiring separate helper plasmids for production, reducing biosafety risks.
Correct answer is: It is replication‑defective and requires helper plasmids
Q.15 A YAC (Yeast Artificial Chromosome) is primarily used for:
Cloning small DNA fragments (<5 kb)
Expression of bacterial proteins in yeast
Cloning very large DNA fragments (up to 1 Mb)
Transfection of mammalian cells
Explanation - YACs can maintain DNA inserts of up to a megabase, making them valuable for genome mapping and large‑scale cloning.
Correct answer is: Cloning very large DNA fragments (up to 1 Mb)
Q.16 Which element in a vector ensures that the inserted gene is transcribed only in a specific tissue type?
Constitutive promoter
Tissue‑specific promoter
Origin of replication
Multiple cloning site
Explanation - A tissue‑specific promoter drives gene expression only in the target tissue, allowing controlled expression patterns.
Correct answer is: Tissue‑specific promoter
Q.17 The 'origin of replication' (ori) in a plasmid vector determines:
Which antibiotic the vector is resistant to
The host range of the vector
How many copies of the plasmid are maintained per cell
The size of DNA that can be inserted
Explanation - Different ori sequences confer high or low copy numbers, influencing plasmid abundance in the host.
Correct answer is: How many copies of the plasmid are maintained per cell
Q.18 Which of the following is NOT a method of introducing vectors into bacterial cells?
Electroporation
Heat shock transformation
Microinjection
Conjugation
Explanation - Microinjection is used for eukaryotic cells; bacteria are typically transformed by electroporation, heat shock, or conjugation.
Correct answer is: Microinjection
Q.19 A reporter gene in a vector is used to:
Provide antibiotic resistance
Facilitate plasmid replication
Indicate successful expression of the cloned gene
Increase plasmid stability
Explanation - Reporter genes (e.g., GFP, luciferase) produce measurable signals that confirm gene expression.
Correct answer is: Indicate successful expression of the cloned gene
Q.20 Which viral vector is known for delivering genes to the respiratory epithelium but typically does not integrate into the host genome?
Adenovirus
Lentivirus
Retrovirus
Herpes simplex virus
Explanation - Adenoviral vectors remain episomal and are efficient for transient expression, especially in airway tissues.
Correct answer is: Adenovirus
Q.21 In a bacterial expression vector, the ribosome binding site (RBS) is also called:
Shine‑Dalgarno sequence
Kozak sequence
TATA box
Poly‑A tail
Explanation - The Shine‑Dalgarno sequence aligns the ribosome with the start codon in prokaryotes.
Correct answer is: Shine‑Dalgarno sequence
Q.22 Which of the following best describes a 'conditional' expression vector?
A vector that expresses a gene only in the presence of an inducer
A vector that can replicate only at certain temperatures
A vector that contains a fluorescent marker
A vector that cannot be transferred between species
Explanation - Conditional vectors use inducible promoters (e.g., lac, arabinose) to control gene expression timing.
Correct answer is: A vector that expresses a gene only in the presence of an inducer
Q.23 What is the main advantage of using a ‘self‑splicing intron’ in a vector designed for expression in eukaryotes?
It enhances plasmid replication
It removes the need for a promoter
It allows correct mRNA processing without external splicing factors
It confers antibiotic resistance
Explanation - Self‑splicing introns can excise themselves from pre‑mRNA, ensuring proper mRNA maturation in the host.
Correct answer is: It allows correct mRNA processing without external splicing factors
Q.24 Which of the following vectors is most appropriate for stable integration of a transgene into the plant genome?
Ti plasmid‑derived binary vector
Adenoviral vector
M13 phage vector
BAC
Explanation - Ti (tumor‑inducing) plasmid vectors, used in Agrobacterium‑mediated transformation, integrate DNA into plant genomes.
Correct answer is: Ti plasmid‑derived binary vector
Q.25 The presence of which sequence in a vector enables it to be packaged into bacteriophage particles for phage display?
Cos site
oriV
MCS
SV40 origin
Explanation - The cos (cohesive end) site is required for λ phage DNA packaging; in phage display vectors, it ensures encapsidation.
Correct answer is: Cos site
Q.26 Which of the following is a key safety feature of third‑generation lentiviral vectors?
Inclusion of the full viral genome
Deletion of the U3 region in the 3' LTR
Use of a strong viral promoter
Retention of the env gene
Explanation - Third‑generation vectors have a self‑inactivating (SIN) LTR where the U3 promoter is removed, reducing the risk of activating host genes.
Correct answer is: Deletion of the U3 region in the 3' LTR
Q.27 A vector containing the gene for green fluorescent protein (GFP) under a CMV promoter is most suitable for:
Selection in bacteria
Transient expression in mammalian cells
Stable integration in yeast
Cloning large genomic DNA
Explanation - The CMV promoter drives strong, transient expression in mammalian cells, and GFP provides an easy visual read‑out.
Correct answer is: Transient expression in mammalian cells
Q.28 What is the function of a 'terminator' sequence in a bacterial expression vector?
To start transcription
To end transcription and release the RNA transcript
To replicate the plasmid
To confer antibiotic resistance
Explanation - Terminator sequences signal RNA polymerase to stop transcription and release the mRNA.
Correct answer is: To end transcription and release the RNA transcript
Q.29 Which of the following vectors is most appropriate for expressing a toxic protein in E. coli?
High‑copy plasmid with strong promoter
Low‑copy plasmid with tightly regulated inducible promoter
Cosmid vector
Phage λ vector
Explanation - Low copy number reduces basal expression, and an inducible promoter allows expression only when needed, minimizing toxicity.
Correct answer is: Low‑copy plasmid with tightly regulated inducible promoter
Q.30 A vector that contains a chloramphenicol resistance gene (cat) is used to select for:
Yeast transformants
Mammalian cells
Bacterial colonies
Plant cells
Explanation - The cat gene provides resistance to chloramphenicol, allowing selection of transformed bacteria.
Correct answer is: Bacterial colonies
Q.31 The term 'payload' in the context of a viral vector refers to:
The capsid proteins
The genetic material carried by the vector
The host cell receptors
The replication machinery
Explanation - Payload is the therapeutic or reporter gene inserted into the viral genome for delivery.
Correct answer is: The genetic material carried by the vector
Q.32 Which of the following is a typical feature of a bacterial expression vector for producing recombinant proteins?
A eukaryotic polyadenylation signal
A ribosome binding site upstream of the gene
A nuclear localization signal
A chloroplast transit peptide
Explanation - Prokaryotic translation requires a Shine‑Dalgarno (RBS) sequence to recruit ribosomes.
Correct answer is: A ribosome binding site upstream of the gene
Q.33 Which of the following vectors is designed to replicate in both E. coli and mammalian cells?
pUC19
pBR322
pGL3
pCMV‑SV40
Explanation - pCMV‑SV40 contains an SV40 origin allowing replication in mammalian cells and a bacterial origin for propagation in E. coli.
Correct answer is: pCMV‑SV40
Q.34 A plasmid that contains the 'sacB' gene is used for counter‑selection because sacB makes cells:
Resistant to kanamycin
Sensitive to sucrose
Fluorescent under UV light
Able to grow at high temperature
Explanation - Expression of sacB in many bacteria is lethal on sucrose, allowing selection against cells retaining the plasmid.
Correct answer is: Sensitive to sucrose
Q.35 In a dual‑promoter vector, the two promoters are usually arranged:
In tandem, driving expression of two separate genes
Back‑to‑back, controlling the same gene
One inside the other
Only one active at a time
Explanation - Dual‑promoter vectors allow independent expression of two genes placed downstream of each promoter.
Correct answer is: In tandem, driving expression of two separate genes
Q.36 Which of the following is a common method for verifying that a vector contains the correct insert?
Southern blotting
PCR amplification of the insert region
Gel electrophoresis of the whole plasmid only
Measuring cell growth rate
Explanation - PCR with primers flanking the insertion site quickly confirms presence and size of the insert.
Correct answer is: PCR amplification of the insert region
Q.37 A vector containing the 'lacZ' gene for blue/white screening is used to:
Select for antibiotic resistance
Identify colonies that have taken up the vector with an insert
Measure fluorescence intensity
Detect RNA levels
Explanation - Insertional inactivation of lacZ prevents blue color on X‑gal plates, resulting in white colonies indicating successful cloning.
Correct answer is: Identify colonies that have taken up the vector with an insert
Q.38 Which type of vector is best suited for delivering small interfering RNAs (siRNAs) into mammalian cells?
Adenoviral vector
Plasmid vector with a U6 promoter
Cosmid vector
BAC
Explanation - The U6 promoter drives strong transcription of short RNAs like siRNAs in mammalian cells.
Correct answer is: Plasmid vector with a U6 promoter
Q.39 In the context of vector design, 'codon optimization' refers to:
Changing the vector backbone to increase copy number
Altering the DNA sequence of a gene to match host codon usage without changing the protein
Adding extra restriction sites
Inserting a promoter from a different organism
Explanation - Codon optimization improves translation efficiency by using codons preferred by the host organism.
Correct answer is: Altering the DNA sequence of a gene to match host codon usage without changing the protein
Q.40 Which of the following vectors would you use to express a membrane protein that requires post‑translational modifications?
pET bacterial expression vector
Baculovirus expression vector
M13 phage vector
pUC19 plasmid
Explanation - Baculovirus vectors infect insect cells that can perform eukaryotic post‑translational modifications needed for membrane proteins.
Correct answer is: Baculovirus expression vector
Q.41 The presence of a 'T7 promoter' in a plasmid is most useful when:
The host cells produce T7 RNA polymerase
The plasmid is to be used in yeast
The vector must replicate in mammalian cells
The gene is to be expressed constitutively in all bacteria
Explanation - T7 promoter requires T7 RNA polymerase, typically provided by a specialized E. coli strain (e.g., BL21(DE3)).
Correct answer is: The host cells produce T7 RNA polymerase
Q.42 Which vector component ensures that a recombinant gene is transcribed in the correct orientation?
Multiple cloning site
Origin of replication
Antibiotic resistance gene
Polyadenylation signal
Explanation - The MCS is flanked by restriction sites arranged so that the insert can be ligated in the proper direction relative to the promoter.
Correct answer is: Multiple cloning site
Q.43 A vector that contains an 'IRES' (internal ribosome entry site) is designed to:
Allow simultaneous translation of two open reading frames from one mRNA
Increase plasmid copy number
Enable integration into the host genome
Provide antibiotic resistance
Explanation - IRES elements recruit ribosomes internally, permitting bicistronic expression from a single transcript.
Correct answer is: Allow simultaneous translation of two open reading frames from one mRNA
Q.44 Which of the following is a reason to use a low‑copy‑number plasmid for cloning genomic DNA fragments?
Higher plasmid yield per cell
Reduced metabolic burden and increased stability of large inserts
Stronger expression of the cloned gene
Simpler antibiotic selection
Explanation - Low copy number reduces stress on the host and helps maintain large or unstable DNA fragments.
Correct answer is: Reduced metabolic burden and increased stability of large inserts
Q.45 In a virus‑based vector, the term 'pseudotyping' refers to:
Using a non‑functional viral genome
Replacing the native envelope protein with one from another virus
Removing all viral genes
Inserting a reporter gene
Explanation - Pseudotyping changes tropism and can improve safety or targeting of viral vectors.
Correct answer is: Replacing the native envelope protein with one from another virus
Q.46 Which of these vectors is most commonly used for the production of recombinant antibodies in CHO cells?
pCMV‑based mammalian expression vector
BAC vector
pBR322 plasmid
M13 phage vector
Explanation - CMV promoter drives high expression in CHO cells, making it suitable for antibody production.
Correct answer is: pCMV‑based mammalian expression vector
Q.47 What is the purpose of a 'selection marker' in a cloning vector?
To increase the size of the vector
To allow identification of cells that have taken up the vector
To promote plasmid replication
To enhance transcriptional activity
Explanation - Selection markers (e.g., antibiotic resistance) let researchers isolate transformed cells by applying selective pressure.
Correct answer is: To allow identification of cells that have taken up the vector
Q.48 A vector that contains a 'T2A' peptide sequence between two coding regions is used to:
Fuse the two proteins into a single polypeptide
Enable ribosomal skipping, producing two separate proteins from one transcript
Increase plasmid stability
Target the protein to mitochondria
Explanation - The 2A peptide causes a 'ribosomal skip' resulting in cleavage between the two proteins during translation.
Correct answer is: Enable ribosomal skipping, producing two separate proteins from one transcript
Q.49 Which of the following is true about a 'gateway' recombination cloning system?
It uses type II restriction enzymes
It relies on site‑specific recombination using att sites
It requires high‑temperature annealing
It only works in yeast
Explanation - Gateway cloning uses attB, attP, attL, and attR recombination sites for efficient DNA transfer without restriction enzymes.
Correct answer is: It relies on site‑specific recombination using att sites
Q.50 When designing a vector for gene therapy, why is it important to use a 'self‑inactivating' (SIN) LTR?
To increase viral particle production
To prevent transcription from the LTR after integration, reducing activation of nearby genes
To enhance antibiotic resistance
To enable replication in bacteria
Explanation - SIN LTRs lack promoter activity after integration, lowering the risk of insertional mutagenesis.
Correct answer is: To prevent transcription from the LTR after integration, reducing activation of nearby genes
Q.51 A 'phagemid' is a hybrid vector that combines features of:
Plasmids and bacteriophage M13
Cosmids and BACs
Adenovirus and retrovirus
Yeast and plant plasmids
Explanation - Phagemids replicate as plasmids in bacteria but can be packaged into M13 phage particles for display or ssDNA production.
Correct answer is: Plasmids and bacteriophage M13
Q.52 Which of the following vectors would be most suitable for expressing a secreted protein in mammalian cells?
A vector lacking a signal peptide
A vector containing a signal peptide sequence upstream of the gene
A vector with a bacterial promoter only
A vector with a chloroplast transit peptide
Explanation - Signal peptides direct nascent proteins to the secretory pathway, resulting in secretion outside the cell.
Correct answer is: A vector containing a signal peptide sequence upstream of the gene
Q.53 The use of a 'riboswitch' in a vector allows:
Antibiotic resistance
Conditional regulation of gene expression by a small molecule ligand
Replication in yeast
Integration into the host genome
Explanation - Riboswitches are RNA elements that change conformation upon ligand binding, influencing transcription or translation.
Correct answer is: Conditional regulation of gene expression by a small molecule ligand
Q.54 A 'BAC' vector typically contains which of the following origins of replication?
pUC origin
F plasmid origin (oriF)
ColE1 origin
SV40 origin
Explanation - BACs use the low‑copy F plasmid origin to maintain large inserts with high stability.
Correct answer is: F plasmid origin (oriF)
Q.55 In gene therapy, an 'AAV' vector is preferred for long‑term expression because:
It integrates randomly into the host genome
It remains largely episomal and elicits low immune responses
It replicates autonomously in the host cell
It has a large cargo capacity (>10 kb)
Explanation - AAV vectors persist as episomes, provide long‑term expression, and are less immunogenic compared with many other viral vectors.
Correct answer is: It remains largely episomal and elicits low immune responses
Q.56 Which of the following statements about the 'Cre‑loxP' system in vectors is correct?
It is used for antibiotic selection
It allows site‑specific recombination to delete or invert DNA segments
It promotes plasmid replication
It enhances transcriptional activity
Explanation - Cre recombinase recognizes loxP sites and can excise or invert DNA flanked by these sites, enabling conditional gene manipulation.
Correct answer is: It allows site‑specific recombination to delete or invert DNA segments
Q.57 A vector designed to express a protein with a C‑terminal His‑tag is primarily used for:
Fluorescence microscopy
Affinity purification of the protein
Increasing transcriptional efficiency
Targeting the protein to mitochondria
Explanation - His‑tags bind nickel or cobalt resin, enabling purification of the recombinant protein via immobilized metal affinity chromatography (IMAC).
Correct answer is: Affinity purification of the protein
Q.58 Which of the following is a major limitation of using plasmid vectors for in vivo gene delivery in humans?
High immunogenicity
Inability to replicate in host cells
Very low transfection efficiency and rapid degradation
Requirement for viral packaging
Explanation - Plasmids are often degraded by nucleases and have poor cellular uptake, limiting their use for direct in vivo delivery.
Correct answer is: Very low transfection efficiency and rapid degradation
Q.59 A vector containing the 'Tn5' transposase system is used for:
High‑copy plasmid replication
Random insertion of the transgene into the host genome
Virus packaging
RNA interference
Explanation - Tn5 transposase mediates cut‑and‑paste transposition, enabling stable integration of DNA into the host genome.
Correct answer is: Random insertion of the transgene into the host genome
Q.60 Which of the following vectors would be best for expressing a protein that requires glycosylation?
Bacterial plasmid
Yeast expression vector
Plant chloroplast vector
M13 phage vector
Explanation - Yeast can perform many eukaryotic post‑translational modifications, including N‑linked glycosylation.
Correct answer is: Yeast expression vector
Q.61 In a vector, the 'terminator' for eukaryotic transcription is usually derived from:
Bacterial rRNA operon
SV40 polyadenylation signal
Lac operon
ColE1 origin
Explanation - SV40 poly(A) signal provides proper transcription termination and polyadenylation in many mammalian expression vectors.
Correct answer is: SV40 polyadenylation signal
Q.62 Which of the following is a characteristic of a 'minicircle' DNA vector?
It contains bacterial backbone sequences for selection
It is a small, supercoiled DNA lacking bacterial origin and antibiotic markers
It is integrated into the host genome
It requires a viral capsid for delivery
Explanation - Minicircles are produced by removing bacterial backbone sequences, resulting in higher transgene expression and lower immunogenicity.
Correct answer is: It is a small, supercoiled DNA lacking bacterial origin and antibiotic markers
Q.63 The purpose of adding an 'insulator' sequence (e.g., cHS4) to a vector is to:
Increase plasmid copy number
Prevent interaction between the transgene and surrounding chromatin after integration
Enhance antibiotic resistance
Promote viral packaging
Explanation - Insulators block enhancer or silencer effects from neighboring genomic elements, stabilizing transgene expression.
Correct answer is: Prevent interaction between the transgene and surrounding chromatin after integration
Q.64 Which of the following vectors is commonly used for CRISPR‑Cas9 genome editing in mammalian cells?
pUC19
pSpCas9(BB)-2A‑GFP (PX458)
M13 phage vector
BAC
Explanation - PX458 carries Cas9, a guide RNA scaffold, and GFP for selection, making it a popular CRISPR delivery vector.
Correct answer is: pSpCas9(BB)-2A‑GFP (PX458)
Q.65 A vector that contains a 'FRT' site is designed for use with which recombinase system?
Cre‑loxP
Flp‑FRT
PhiC31‑attB
Lambda‑Red
Explanation - Flp recombinase recognizes FRT (Flippase Recognition Target) sites for site‑specific recombination.
Correct answer is: Flp‑FRT
Q.66 Which of the following is a typical feature of a vector used for producing recombinant viral vaccines?
A bacterial origin of replication only
An attenuated viral backbone with an inserted antigen gene
A chloroplast transit peptide
A high‑copy number plasmid origin
Explanation - Viral vaccine vectors are engineered viruses (often attenuated) that carry a foreign antigen gene for immune stimulation.
Correct answer is: An attenuated viral backbone with an inserted antigen gene
Q.67 In the context of gene vectors, the term 'payload capacity' refers to:
The amount of antibiotic the host can tolerate
The maximum size of foreign DNA that can be packaged
The replication speed of the vector
The number of selectable markers
Explanation - Payload capacity defines how large an insert a vector can carry while remaining functional.
Correct answer is: The maximum size of foreign DNA that can be packaged
Q.68 Which of the following vectors would be most appropriate for a high‑throughput screening of promoter activity in mammalian cells?
A luciferase reporter plasmid with a multiple cloning site upstream of the luciferase gene
A plasmid containing a bacterial origin and ampicillin resistance only
A cosmid vector for large genomic fragments
A yeast shuttle vector
Explanation - Luciferase reporters enable quantitative measurement of promoter strength in mammalian cells.
Correct answer is: A luciferase reporter plasmid with a multiple cloning site upstream of the luciferase gene
Q.69 A 'dual‑selection' vector contains:
Two different antibiotic resistance genes
One promoter and two terminators
A bacterial origin and a eukaryotic origin
Two multiple cloning sites
Explanation - Dual‑selection allows growth on two different antibiotics, increasing stringency and enabling co‑selection of multiple constructs.
Correct answer is: Two different antibiotic resistance genes
Q.70 The primary reason for adding a 'Kozak sequence' upstream of a eukaryotic coding sequence is to:
Enhance ribosome binding and translation initiation
Provide an origin of replication
Give antibiotic resistance
Enable site‑specific recombination
Explanation - The Kozak consensus sequence (GCCACCaugG) improves translation efficiency in eukaryotes.
Correct answer is: Enhance ribosome binding and translation initiation
Q.71 Which of the following vectors is commonly used for producing recombinant proteins in insect cells?
pFastBac (baculovirus expression vector)
pBR322
M13 phage vector
pUC19
Explanation - pFastBac is a baculovirus-based vector that enables high‑level protein expression in insect cell lines.
Correct answer is: pFastBac (baculovirus expression vector)
Q.72 When using a plasmid vector with an 'oriT' (origin of transfer), what process does this enable?
Replication in mammalian cells
Conjugative transfer of the plasmid between bacteria
Integration into the host genome
High‑level expression of the transgene
Explanation - oriT is required for mobilization of plasmids during bacterial conjugation.
Correct answer is: Conjugative transfer of the plasmid between bacteria
Q.73 A vector that incorporates a 'Tet‑On' system provides:
Constitutive expression of the gene
Repression of gene expression in the presence of tetracycline
Inducible expression of the gene when tetracycline or doxycycline is added
Deletion of the gene after induction
Explanation - Tet‑On switches activate transcription only after addition of the tetracycline analog.
Correct answer is: Inducible expression of the gene when tetracycline or doxycycline is added
Q.74 Which of the following statements about 'viral pseudotyping' is FALSE?
It can alter the host range of a viral vector
It involves swapping the envelope protein of the virus
It always increases the vector's genome size
It is used to improve safety or targeting
Explanation - Pseudotyping changes only the envelope protein; it does not necessarily change the genome size.
Correct answer is: It always increases the vector's genome size
Q.75 In a cloning workflow, after ligation of the insert into a vector, which step is most commonly performed to verify successful cloning?
Transformation into competent cells followed by colony PCR or restriction analysis
Direct sequencing of the ligation mixture
Western blot of bacterial lysates
Measuring growth rate of transformed cells
Explanation - Colony PCR or restriction digests after transformation confirm presence and orientation of the insert.
Correct answer is: Transformation into competent cells followed by colony PCR or restriction analysis
Q.76 A vector containing the 'hCMV' promoter is typically used for:
Strong, constitutive expression in a wide range of mammalian cells
Selective growth of bacteria in high‑salt media
Replication in yeast only
Inducible expression in response to IPTG
Explanation - The human cytomegalovirus (hCMV) immediate‑early promoter drives high-level expression in many mammalian cell types.
Correct answer is: Strong, constitutive expression in a wide range of mammalian cells
Q.77 Which of the following is an advantage of using a 'self‑replicating RNA' vector (e.g., replicon) for vaccine delivery?
It integrates into the host genome
It produces high levels of antigen without DNA integration
It requires a viral capsid for entry
It confers antibiotic resistance to host cells
Explanation - Self‑replicating RNA replicons amplify in the cytoplasm, yielding strong antigen expression while remaining non‑integrative.
Correct answer is: It produces high levels of antigen without DNA integration
Q.78 In a vector map, the region labeled 'oriV' refers to:
Origin of replication for viral packaging
Origin of replication for the vector in bacteria
Origin of replication for the vector in mammalian cells
Origin of replication for yeast
Explanation - oriV is the viral origin of replication required for replication of the vector genome inside a virus‑producing cell.
Correct answer is: Origin of replication for viral packaging
Q.79 Which of the following best describes the function of a 'ribosomal binding site' (RBS) in a prokaryotic expression vector?
It initiates transcription
It recruits the ribosome to the start codon for translation
It provides antibiotic resistance
It acts as a terminator
Explanation - The RBS (Shine‑Dalgarno sequence) aligns the ribosome with the start codon, facilitating translation initiation.
Correct answer is: It recruits the ribosome to the start codon for translation
Q.80 A vector designed to produce a protein with a C‑terminal FLAG tag is useful for:
Fluorescence microscopy
Affinity purification and detection using anti‑FLAG antibodies
Increasing transcriptional activity
Targeting the protein to mitochondria
Explanation - FLAG tags enable specific detection and purification with anti‑FLAG antibodies.
Correct answer is: Affinity purification and detection using anti‑FLAG antibodies
Q.81 Which of the following is true about a 'phage display' vector?
It integrates into the host genome permanently
It expresses foreign peptides on the surface of phage particles
It is used to replicate large genomic DNA fragments
It confers resistance to ampicillin
Explanation - Phage display vectors fuse foreign peptide sequences to phage coat proteins, allowing selection of binding partners.
Correct answer is: It expresses foreign peptides on the surface of phage particles
Q.82 The presence of an 'attB' site in a donor plasmid is required for:
Restriction enzyme cloning
Site‑specific recombination with an integrase in the host genome
Replication in yeast
Antibiotic selection
Explanation - attB sites recombine with attP sites in the host genome via integrase enzymes (e.g., phiC31) for stable integration.
Correct answer is: Site‑specific recombination with an integrase in the host genome
Q.83 A vector that contains a 'CMV‑IE' promoter and a 'bGH' polyadenylation signal is best suited for:
Expression in bacterial cells
Transient expression in mammalian cells
Stable integration in plant chloroplasts
Replication in yeast
Explanation - Both CMV‑IE promoter and bovine growth hormone (bGH) polyA signal function efficiently in mammalian cells for strong transient expression.
Correct answer is: Transient expression in mammalian cells
Q.84 Which of the following vectors would be most appropriate for delivering a large (150 kb) genomic region into mammalian cells?
AAV vector
BAC vector modified with a mammalian origin of replication
pUC19 plasmid
M13 phage vector
Explanation - BACs can accommodate large inserts; adding a mammalian origin allows replication in mammalian cells.
Correct answer is: BAC vector modified with a mammalian origin of replication
Q.85 The use of a 'self‑cleaving 2A peptide' between two coding sequences in a vector results in:
A single fused protein
Two separate proteins generated from one transcript
Enhanced transcriptional termination
Increased plasmid copy number
Explanation - 2A peptides cause ribosome skipping, producing two distinct proteins from a single open reading frame.
Correct answer is: Two separate proteins generated from one transcript
Q.86 A vector with an 'SV40 origin of replication' is primarily used for:
Replication in bacterial cells
Replication in mammalian cells (e.g., COS‑7)
Packaging into bacteriophage particles
Integration into plant chloroplasts
Explanation - The SV40 ori allows episomal replication in mammalian cells that express the SV40 large T antigen.
Correct answer is: Replication in mammalian cells (e.g., COS‑7)
Q.87 Which vector component determines the host range (i.e., which organisms the vector can replicate in)?
Multiple cloning site
Origin of replication
Promoter strength
Polyadenylation signal
Explanation - Different origins of replication are recognized by specific host replication machinery, defining host range.
Correct answer is: Origin of replication
Q.88 A vector that includes a 'Woodchuck hepatitis virus post‑transcriptional regulatory element' (WPRE) is intended to:
Increase transcriptional termination efficiency
Enhance nuclear export and translation of the transgene mRNA
Provide antibiotic resistance
Facilitate viral packaging
Explanation - WPRE improves mRNA stability and export, leading to higher protein expression.
Correct answer is: Enhance nuclear export and translation of the transgene mRNA
Q.89 The term 'episomal' in the context of vector biology means:
The vector integrates into the host genome
The vector replicates independently as a separate DNA molecule
The vector cannot be replicated
The vector is only active in prokaryotes
Explanation - Episomal vectors exist extrachromosomally and replicate without integration.
Correct answer is: The vector replicates independently as a separate DNA molecule
Q.90 Which of the following is a key advantage of using a 'binary vector system' in Agrobacterium‑mediated plant transformation?
It allows simultaneous expression of two different genes in bacteria
It separates the virulence genes from the T‑DNA region, improving safety and flexibility
It provides higher copy number in E. coli
It eliminates the need for selectable markers
Explanation - Binary vectors contain the T‑DNA (with gene of interest) on a small plasmid, while vir genes are on a separate helper plasmid, enhancing safety.
Correct answer is: It separates the virulence genes from the T‑DNA region, improving safety and flexibility
Q.91 A vector that includes a 'loxP‑flanked' stop cassette upstream of a gene is used to:
Enable constitutive expression of the gene
Allow conditional activation of the gene after Cre recombination
Increase plasmid stability
Provide resistance to tetracycline
Explanation - The stop cassette blocks transcription; Cre recombinase removes it, activating downstream gene expression.
Correct answer is: Allow conditional activation of the gene after Cre recombination
Q.92 Which of the following vectors would be most suitable for delivering a gene to the central nervous system via intrathecal injection?
Adenoviral vector
AAV vector with a neuronal tropic capsid
Plasmid DNA alone
M13 phage vector
Explanation - AAV vectors can be engineered with capsids that preferentially transduce neurons, providing efficient CNS delivery.
Correct answer is: AAV vector with a neuronal tropic capsid
Q.93 The presence of a 'KpnI' site within the MCS of a vector is useful because:
It provides antibiotic resistance
It allows directional cloning of inserts cut with compatible ends
It serves as an origin of replication
It terminates transcription
Explanation - Using two different restriction sites (e.g., KpnI and XhoI) enables orientation‑specific insertion of the DNA fragment.
Correct answer is: It allows directional cloning of inserts cut with compatible ends
Q.94 Which of the following statements about 'self‑amplifying mRNA' (saRNA) vectors is correct?
They integrate into the host genome
They replicate in the nucleus using host DNA polymerases
They contain viral replicase genes that amplify the RNA in the cytoplasm
They require bacterial transformation for production
Explanation - saRNA vectors encode replicase proteins (e.g., from alphaviruses) that copy the RNA, boosting antigen expression without DNA intermediates.
Correct answer is: They contain viral replicase genes that amplify the RNA in the cytoplasm
Q.95 A vector engineered to contain a 'CMV‑IE enhancer' upstream of a minimal promoter is designed to:
Reduce transcriptional activity
Provide tissue‑specific expression
Increase transcriptional activity in many cell types
Enable replication in bacteria only
Explanation - The CMV‑IE enhancer boosts promoter activity, leading to higher expression across a broad range of cell types.
Correct answer is: Increase transcriptional activity in many cell types
Q.96 Which of the following vectors is most appropriate for expressing a gene in chloroplasts of plants?
Nuclear binary vector
Chloroplast transformation vector containing the psbA promoter and flanking chloroplast DNA sequences
AAV vector
Bacterial plasmid with ColE1 origin
Explanation - Chloroplast vectors have promoters and homologous regions specific for chloroplast integration and expression.
Correct answer is: Chloroplast transformation vector containing the psbA promoter and flanking chloroplast DNA sequences
Q.97 In the context of a vector, a 'poly‑A tail' is added to:
DNA during replication
mRNA during processing to stabilize it and aid nuclear export
Proteins to facilitate folding
The plasmid backbone for stability
Explanation - The poly‑A tail is a post‑transcriptional modification that protects mRNA and assists in translation.
Correct answer is: mRNA during processing to stabilize it and aid nuclear export
Q.98 Which of the following is a typical use of a 'reporter gene' such as luciferase in a vector?
To confer antibiotic resistance
To provide a visual read‑out of gene expression levels
To increase plasmid copy number
To serve as a replication origin
Explanation - Reporter genes generate measurable signals (luminescence, fluorescence) that indicate transcriptional activity.
Correct answer is: To provide a visual read‑out of gene expression levels
Q.99 A vector containing a 'circularized single‑strand DNA' (ssDNA) is typically derived from:
M13 phage
Adenovirus
BAC
Cosmid
Explanation - M13 phage produces circular ssDNA, which can be used as a template for mutagenesis or sequencing.
Correct answer is: M13 phage
Q.100 The main advantage of using a 'dual‑promoter' vector for co‑expression of a gene and a selectable marker is:
Both genes are expressed at the same high level from a single promoter
Each gene can be regulated independently, allowing separate control of expression and selection
The vector size is reduced
It eliminates the need for antibiotic selection
Explanation - Dual promoters enable distinct transcriptional control of the transgene and the selection marker.
Correct answer is: Each gene can be regulated independently, allowing separate control of expression and selection
Q.101 Which of the following is a characteristic of a 'retroviral vector' used for gene delivery?
It can infect non‑dividing cells efficiently
It remains episomal and does not integrate
It integrates preferentially into transcriptionally active regions of the genome
It has a large payload capacity (>30 kb)
Explanation - Retroviruses integrate into the host genome, often favoring active transcription units.
Correct answer is: It integrates preferentially into transcriptionally active regions of the genome
Q.102 A vector that contains a 'copper‑inducible promoter' would be most useful in which experimental scenario?
Studying gene function in response to metal stress
Achieving constitutive expression in all cells
Producing recombinant protein in yeast without induction
Integrating DNA into the host genome
Explanation - Copper‑inducible promoters activate transcription only upon copper addition, enabling controlled expression under metal‑stress conditions.
Correct answer is: Studying gene function in response to metal stress
Q.103 The 'pUC' series of plasmids are popular cloning vectors because they:
Contain a high‑copy origin of replication and lacZα for blue/white screening
Are derived from viral genomes
Integrate into the host chromosome
Contain a eukaryotic origin of replication
Explanation - pUC plasmids have the pMB1 high‑copy ori and lacZα fragment for blue/white colony screening.
Correct answer is: Contain a high‑copy origin of replication and lacZα for blue/white screening
Q.104 In a vector, the 'poly‑A signal' is required for:
Initiation of transcription
Termination of transcription and addition of a poly‑A tail
Replication of the plasmid
Antibiotic resistance
Explanation - The poly‑A signal signals cleavage of the pre‑mRNA and polyadenylation, essential for stable mRNA.
Correct answer is: Termination of transcription and addition of a poly‑A tail
Q.105 Which of the following vector features is essential for ensuring that a transgene is secreted from mammalian cells?
A strong bacterial promoter
A signal peptide sequence at the N‑terminus
An origin of replication
A selectable marker
Explanation - Signal peptides direct nascent proteins into the secretory pathway, resulting in secretion.
Correct answer is: A signal peptide sequence at the N‑terminus
Q.106 A 'phagemid' vector is most useful for:
Generating single‑stranded DNA for mutagenesis
Integrating into the host genome
High‑level expression of membrane proteins in bacteria
Providing antibiotic resistance in mammalian cells
Explanation - Phagemids can be rescued as ssDNA when infected with helper phage, facilitating mutagenesis and sequencing.
Correct answer is: Generating single‑stranded DNA for mutagenesis
Q.107 Which of the following is a key benefit of using a 'minicircle' DNA vector over a conventional plasmid for gene therapy?
Higher bacterial copy number
Reduced immunogenicity and higher transgene expression due to lack of bacterial backbone
Ability to integrate into the host genome
Inclusion of a viral capsid
Explanation - Minicircles lack bacterial sequences that can trigger immune responses, leading to better expression in vivo.
Correct answer is: Reduced immunogenicity and higher transgene expression due to lack of bacterial backbone
Q.108 The purpose of an 'IRES' (internal ribosome entry site) in a bicistronic vector is to:
Allow translation of a second open reading frame from the same mRNA
Increase plasmid replication speed
Provide antibiotic resistance
Terminate transcription
Explanation - IRES enables ribosomes to initiate translation internally, permitting expression of two proteins from one transcript.
Correct answer is: Allow translation of a second open reading frame from the same mRNA
Q.109 Which of the following vectors is typically employed for delivering a gene to dividing and non‑dividing cells with long‑term expression?
Lentiviral vector
Adenoviral vector
M13 phage vector
pUC19 plasmid
Explanation - Lentiviruses can transduce both dividing and non‑dividing cells and integrate into the genome, ensuring durable expression.
Correct answer is: Lentiviral vector
Q.110 A vector designed with a 'Tet‑repressor binding site' upstream of the promoter will:
Activate transcription when tetracycline is absent
Repress transcription in the presence of tetracycline
Constitutively express the gene
Integrate into the host genome
Explanation - In the Tet‑off system, the Tet repressor binds the operator and blocks transcription; tetracycline removal allows expression.
Correct answer is: Activate transcription when tetracycline is absent
Q.111 Which of the following is a typical characteristic of a 'viral envelope protein' used for pseudotyping?
It determines the vector's replication speed
It dictates the cell tropism and entry pathway of the viral vector
It confers antibiotic resistance
It acts as a transcription factor
Explanation - Envelope proteins interact with cellular receptors, influencing which cell types the virus can infect.
Correct answer is: It dictates the cell tropism and entry pathway of the viral vector
Q.112 In a gene‑editing vector, the presence of a 'sgRNA scaffold' is required for:
Providing antibiotic resistance
Guiding the Cas9 nuclease to the target DNA sequence
Increasing plasmid copy number
Terminating transcription
Explanation - The single‑guide RNA (sgRNA) combines a targeting sequence with a scaffold that binds Cas9, directing it to the specific genomic site.
Correct answer is: Guiding the Cas9 nuclease to the target DNA sequence
Q.113 A 'synthetic insulator' placed between a promoter and a transgene is used to:
Increase the rate of plasmid replication
Prevent transcriptional interference from neighboring genomic elements after integration
Enhance antibiotic resistance
Enable viral packaging
Explanation - Insulators block enhancer/silencer effects, stabilizing transgene expression regardless of integration site.
Correct answer is: Prevent transcriptional interference from neighboring genomic elements after integration
Q.114 Which vector component is responsible for allowing a gene to be expressed in both bacterial and mammalian cells?
Dual origins of replication (bacterial ori and SV40 ori)
A bacterial promoter
A chloroplast transit peptide
A yeast selectable marker
Explanation - Having both bacterial and mammalian origins enables replication in bacteria and episomal maintenance in mammalian cells.
Correct answer is: Dual origins of replication (bacterial ori and SV40 ori)
Q.115 The 'Cre‑loxP' system is commonly employed in vectors for:
Selective antibiotic resistance
Site‑specific recombination to delete or invert DNA segments
Replication in yeast
Increasing plasmid copy number
Explanation - Cre recombinase recognizes loxP sites and mediates recombination, allowing conditional gene modifications.
Correct answer is: Site‑specific recombination to delete or invert DNA segments
Q.116 A vector that includes a 'bacterial promoter' but no eukaryotic promoter will:
Express the gene efficiently in mammalian cells
Express the gene only in bacterial hosts
Integrate into the plant genome
Produce a viral capsid
Explanation - Bacterial promoters are recognized only by prokaryotic RNA polymerases; they are inactive in eukaryotic cells.
Correct answer is: Express the gene only in bacterial hosts
Q.117 Which of the following best describes the purpose of a 'multiple cloning site' (MCS) placed downstream of a promoter?
To provide an antibiotic resistance gene
To enable insertion of a gene in the correct orientation for transcription
To act as an origin of replication
To terminate transcription
Explanation - The MCS contains several unique restriction sites that allow cloning of a gene downstream of the promoter in the proper direction.
Correct answer is: To enable insertion of a gene in the correct orientation for transcription
Q.118 A vector containing the 'EF1α' promoter is typically used for:
Transient high‑level expression in bacterial cells
Stable, moderate‑level expression in a wide range of mammalian cell types
Expression in plant chloroplasts
Replication in yeast only
Explanation - The human elongation factor 1 alpha promoter provides strong, constitutive expression across many mammalian cells.
Correct answer is: Stable, moderate‑level expression in a wide range of mammalian cell types
Q.119 In a viral vector, the term 'gag' refers to:
A gene encoding the viral capsid proteins
A selectable marker gene
An origin of replication
A promoter element
Explanation - The gag (group‑specific antigen) gene encodes structural proteins that form the viral core.
Correct answer is: A gene encoding the viral capsid proteins
Q.120 A vector designed to produce a protein with a 'C‑terminal Myc tag' would be primarily used for:
Purifying the protein via nickel affinity chromatography
Detecting the protein with anti‑Myc antibodies in Western blots
Targeting the protein to the mitochondria
Increasing transcriptional activity
Explanation - Myc tags are short peptide epitopes recognized by specific antibodies, facilitating detection and immunoprecipitation.
Correct answer is: Detecting the protein with anti‑Myc antibodies in Western blots
Q.121 Which vector element ensures that a transgene is transcribed only after integration into the host genome?
A viral origin of replication
A promoter that is active only in the context of chromatin (e.g., endogenous promoter)
A bacterial origin of replication
An antibiotic resistance gene
Explanation - Certain promoters require chromatin environment for activity; they become functional only after integration.
Correct answer is: A promoter that is active only in the context of chromatin (e.g., endogenous promoter)
Q.122 Which of the following is a typical feature of an 'AAV' vector that distinguishes it from adenoviral vectors?
Large packaging capacity (>20 kb)
Ability to replicate autonomously in host cells
Predominantly episomal persistence with low immunogenicity
Presence of a viral capsid protein gene
Explanation - AAV vectors remain mostly episomal and elicit minimal immune responses compared with adenoviral vectors.
Correct answer is: Predominantly episomal persistence with low immunogenicity
Q.123 A vector that includes a 'CAG promoter' combines elements from:
Cytomegalovirus, chicken β‑actin, and rabbit β‑globin
Chloroplast, Arabidopsis, and Giardia
Calcium‑activated and glucocorticoid promoters
Cysteine‑rich and GTPase domains
Explanation - The CAG promoter fuses CMV enhancer with chicken β‑actin promoter and rabbit β‑globin intron for strong ubiquitous expression.
Correct answer is: Cytomegalovirus, chicken β‑actin, and rabbit β‑globin
Q.124 Which of the following best explains why a 'self‑inactivating' (SIN) lentiviral vector is considered safer for gene therapy?
It cannot enter host cells
It lacks the viral envelope gene, preventing reinfection
Its LTR promoter activity is disabled after integration, reducing the risk of activating nearby oncogenes
It does not integrate into the genome
Explanation - SIN vectors delete the U3 region in the LTR, preventing transcription from the LTR and lowering insertional mutagenesis risk.
Correct answer is: Its LTR promoter activity is disabled after integration, reducing the risk of activating nearby oncogenes
Q.125 The 'pBR322' plasmid is historically significant because it was the first:
Plasmid to contain a multiple cloning site
Vector to incorporate an antibiotic resistance marker for selection
Vector to contain a eukaryotic promoter
Phage‑derived vector used in mammalian cells
Explanation - pBR322 introduced tetracycline and ampicillin resistance genes, enabling antibiotic selection of transformed bacteria.
Correct answer is: Vector to incorporate an antibiotic resistance marker for selection