Q.1 What does DNA stand for?
Deoxyribonucleic Acid
Dicarboxylic Nitrogenous Acid
Dihydroxy Nucleotide Alkane
Dideoxyribose Nucleic Acid
Explanation - DNA is the abbreviation for Deoxyribonucleic Acid, the molecule that carries genetic information.
Correct answer is: Deoxyribonucleic Acid
Q.2 Which of the following is the basic unit of heredity?
Chromosome
Gene
Nucleus
Plasmid
Explanation - A gene is a segment of DNA that encodes a functional product, typically a protein, and is the basic unit of heredity.
Correct answer is: Gene
Q.3 What is the role of a restriction enzyme in genetic engineering?
To copy DNA fragments
To cut DNA at specific sequences
To join DNA fragments together
To amplify RNA
Explanation - Restriction enzymes recognize specific DNA sequences and cleave the DNA at or near these sites, enabling manipulation of DNA fragments.
Correct answer is: To cut DNA at specific sequences
Q.4 Which of the following vectors is commonly used to clone large DNA fragments?
Plasmid
Bacteriophage
Cosmid
Yeast artificial chromosome (YAC)
Explanation - YACs can carry large inserts (up to 1 Mb), making them suitable for cloning large DNA fragments.
Correct answer is: Yeast artificial chromosome (YAC)
Q.5 Polymerase Chain Reaction (PCR) is used to:
Sequence entire genomes
Amplify a specific DNA segment
Introduce genes into cells
Separate proteins by size
Explanation - PCR uses repeated cycles of denaturation, annealing, and extension to exponentially amplify a target DNA region.
Correct answer is: Amplify a specific DNA segment
Q.6 What is a plasmid?
A type of virus
A circular DNA molecule in bacteria
A protein that binds DNA
A lipid membrane
Explanation - Plasmids are small, circular, double‑stranded DNA molecules that replicate independently of chromosomal DNA in bacteria.
Correct answer is: A circular DNA molecule in bacteria
Q.7 In the context of genetic engineering, ‘transformation’ refers to:
The process of converting RNA to DNA
The uptake of foreign DNA by a cell
The editing of a gene using CRISPR
The transcription of DNA into RNA
Explanation - Transformation is the process by which a cell takes up extracellular DNA and incorporates it into its genome.
Correct answer is: The uptake of foreign DNA by a cell
Q.8 Which of the following is a key component of a CRISPR‑Cas9 system?
Guide RNA
RNA polymerase
DNA ligase
Reverse transcriptase
Explanation - The guide RNA directs the Cas9 nuclease to the specific DNA sequence to be cut.
Correct answer is: Guide RNA
Q.9 What is the main purpose of a selectable marker gene in a cloning vector?
To increase DNA replication speed
To identify cells that have taken up the vector
To cause cells to fluoresce
To degrade unwanted DNA
Explanation - Selectable markers, such as antibiotic resistance genes, allow researchers to select for cells that have successfully incorporated the vector.
Correct answer is: To identify cells that have taken up the vector
Q.10 Which technique is used to separate DNA fragments based on size?
Southern blotting
Gel electrophoresis
Northern blotting
Chromatography
Explanation - Gel electrophoresis moves DNA fragments through a gel matrix under an electric field, separating them by size.
Correct answer is: Gel electrophoresis
Q.11 What does the term ‘gene expression’ refer to?
The number of genes in a genome
The process of DNA replication
The transcription and translation of a gene into a functional product
The mutation rate of a gene
Explanation - Gene expression encompasses both transcription of DNA into RNA and translation of RNA into a protein or functional RNA molecule.
Correct answer is: The transcription and translation of a gene into a functional product
Q.12 Which organism is most commonly used as a host for recombinant DNA experiments?
Saccharomyces cerevisiae
Escherichia coli
Arabidopsis thaliana
Drosophila melanogaster
Explanation - E. coli grows quickly, is easy to manipulate, and is the standard bacterial host for cloning DNA.
Correct answer is: Escherichia coli
Q.13 The term ‘GMO’ stands for:
Genetically Modified Organism
Gene-Mapped Organism
Genome-Mutated Organism
General Molecular Organism
Explanation - A GMO is an organism whose genetic material has been altered using genetic engineering techniques.
Correct answer is: Genetically Modified Organism
Q.14 Which of the following enzymes is used to join DNA fragments together?
DNA polymerase
RNA polymerase
DNA ligase
Helicase
Explanation - DNA ligase catalyzes the formation of phosphodiester bonds between adjacent nucleotides, sealing nicks in the DNA backbone.
Correct answer is: DNA ligase
Q.15 In a DNA sequencing reaction, the chain‑terminating nucleotides are:
dNTPs
ddNTPs
rNTPs
cNTPs
Explanation - Dideoxynucleotides (ddNTPs) lack a 3'‑OH group, causing termination of DNA synthesis at the incorporated base.
Correct answer is: ddNTPs
Q.16 What is a ‘promoter’ in a gene?
A region that codes for protein
A sequence where RNA polymerase binds to initiate transcription
A DNA segment that terminates transcription
A protein that degrades mRNA
Explanation - Promoters are DNA regions upstream of a gene that recruit RNA polymerase and transcription factors to start transcription.
Correct answer is: A sequence where RNA polymerase binds to initiate transcription
Q.17 Which of the following best describes a ‘knock‑out’ mouse?
A mouse with an extra copy of a gene
A mouse in which a specific gene has been inactivated
A mouse that expresses a fluorescent protein
A mouse that is resistant to antibiotics
Explanation - Knock‑out mice have targeted gene deletions, allowing researchers to study gene function by observing resulting phenotypes.
Correct answer is: A mouse in which a specific gene has been inactivated
Q.18 What is the main advantage of using a viral vector for gene therapy?
It can replicate indefinitely in the patient
It can deliver large DNA fragments easily
It has high efficiency in delivering genes into target cells
It does not trigger any immune response
Explanation - Viral vectors have evolved mechanisms to enter cells efficiently, making them powerful tools for delivering therapeutic genes.
Correct answer is: It has high efficiency in delivering genes into target cells
Q.19 In the context of CRISPR, what does “Cas9” refer to?
A guide RNA molecule
A DNA polymerase
An RNA‑guided endonuclease
A transcription factor
Explanation - Cas9 is a nuclease that, guided by a complementary RNA, creates double‑strand breaks at specific genomic locations.
Correct answer is: An RNA‑guided endonuclease
Q.20 Which of the following is NOT a typical step in the recombinant DNA cloning process?
Isolation of DNA fragment
Insertion into a vector
Transformation of host cells
Protein purification from plasmid
Explanation - Protein purification is downstream of expression; the cloning steps involve DNA manipulation and introduction into a host.
Correct answer is: Protein purification from plasmid
Q.21 A “silencer” element in a gene’s regulatory region:
Enhances transcription
Blocks transcription
Initiates DNA replication
Promotes mRNA splicing
Explanation - Silencer sequences bind repressor proteins that reduce or prevent transcription of the downstream gene.
Correct answer is: Blocks transcription
Q.22 Which of the following best describes a “synthetic biology” approach?
Studying natural gene functions only
Designing and constructing new biological parts and systems
Sequencing genomes of extinct species
Observing microbial behavior in natural habitats
Explanation - Synthetic biology aims to engineer biological components that do not exist in nature, often using standardized parts.
Correct answer is: Designing and constructing new biological parts and systems
Q.23 In gene therapy, “in vivo” delivery means:
Delivery into cultured cells outside the body
Delivery directly into the patient’s body
Delivery into animal models only
Delivery using plant cells
Explanation - In vivo gene therapy introduces genetic material directly into the patient's tissues, unlike ex vivo approaches which modify cells outside the body first.
Correct answer is: Delivery directly into the patient’s body
Q.24 What is the purpose of a “multiple cloning site” (MCS) in a plasmid vector?
To provide a high‑copy origin of replication
To encode a selectable marker
To offer several unique restriction sites for inserting DNA
To produce a fluorescent protein
Explanation - An MCS contains many restriction enzyme recognition sites, allowing flexible insertion of DNA fragments.
Correct answer is: To offer several unique restriction sites for inserting DNA
Q.25 Which of the following statements about RNA interference (RNAi) is true?
It enhances translation of target mRNA
It degrades DNA directly
It uses small RNAs to silence gene expression post‑transcriptionally
It inserts new genes into the genome
Explanation - RNAi employs siRNA or miRNA molecules to bind complementary mRNA and trigger its degradation or translational repression.
Correct answer is: It uses small RNAs to silence gene expression post‑transcriptionally
Q.26 Which method is most commonly used to introduce DNA into plant cells?
Electroporation
Microinjection
Agrobacterium‑mediated transformation
Liposome fusion
Explanation - Agrobacterium tumefaciens naturally transfers DNA (T‑DNA) into plant genomes, making it a preferred tool for plant genetic engineering.
Correct answer is: Agrobacterium‑mediated transformation
Q.27 A “reporter gene” is used in molecular biology to:
Select for antibiotic resistance
Report the activity of a regulatory element by producing an easily measurable product
Repair damaged DNA
Encode a structural protein
Explanation - Reporter genes such as lacZ, GFP, or luciferase generate detectable signals that indicate promoter or enhancer activity.
Correct answer is: Report the activity of a regulatory element by producing an easily measurable product
Q.28 Which of the following is a potential risk associated with the release of GMOs into the environment?
Increased biodiversity
Horizontal gene transfer to wild relatives
Reduced crop yield
Higher mutation rates in humans
Explanation - GMOs can potentially transfer engineered genes to related wild species, which may affect ecosystems and biodiversity.
Correct answer is: Horizontal gene transfer to wild relatives
Q.29 What does the term “codon bias” refer to?
Preference for certain codons over others in a genome
Mutation rate of codons
The ability of codons to bind proteins
The number of codons in a gene
Explanation - Codon bias describes the non‑random usage of synonymous codons, often reflecting tRNA abundance and influencing translation efficiency.
Correct answer is: Preference for certain codons over others in a genome
Q.30 In the context of gene cloning, “blue‑white screening” relies on which enzyme?
β‑galactosidase
Lactase
Amylase
Lipase
Explanation - The lacZ gene encodes β‑galactosidase; insertion of DNA disrupts its activity, resulting in white colonies on X‑gal plates, while non‑recombinant colonies remain blue.
Correct answer is: β‑galactosidase
Q.31 What is a “haploid” organism?
An organism with two sets of chromosomes
An organism with one set of chromosomes
An organism that reproduces asexually
An organism lacking mitochondria
Explanation - Haploid cells contain a single copy of each chromosome (n), typical of gametes in many species.
Correct answer is: An organism with one set of chromosomes
Q.32 Which of the following best describes an “operon”?
A single gene encoding multiple proteins
A cluster of genes under the control of a single promoter
A DNA region that codes for ribosomal RNA
A protein complex involved in DNA repair
Explanation - Operons, common in prokaryotes, consist of multiple structural genes regulated together by a single promoter and operator.
Correct answer is: A cluster of genes under the control of a single promoter
Q.33 Which of the following is NOT a type of nucleic acid?
DNA
RNA
tRNA
tDNA
Explanation - tDNA is not a recognized nucleic acid; the main types are DNA, RNA (including mRNA, tRNA, rRNA).
Correct answer is: tDNA
Q.34 The enzyme reverse transcriptase is used to:
Synthesize DNA from an RNA template
Cut DNA at specific sites
Ligate DNA fragments
Separate DNA strands
Explanation - Reverse transcriptase synthesizes complementary DNA (cDNA) from an RNA template, a key step in retroviral replication and cDNA library construction.
Correct answer is: Synthesize DNA from an RNA template
Q.35 What is the purpose of a “terminator” sequence in a transcription unit?
To start transcription
To end transcription
To enhance translation
To bind ribosomes
Explanation - Terminator sequences signal RNA polymerase to stop transcription and release the newly synthesized RNA.
Correct answer is: To end transcription
Q.36 Which of the following best describes a “knock‑in” mouse?
A mouse with a gene deletion
A mouse with an extra copy of a gene inserted at a specific locus
A mouse that expresses a fluorescent marker randomly
A mouse that is resistant to antibiotics
Explanation - Knock‑in mice have targeted insertion of a transgene at a defined genomic location, allowing controlled expression studies.
Correct answer is: A mouse with an extra copy of a gene inserted at a specific locus
Q.37 In the context of DNA sequencing, the Sanger method utilizes:
Fluorescently labeled ddNTPs
RNA polymerase
DNA ligase
Topoisomerase
Explanation - Sanger sequencing incorporates chain‑terminating ddNTPs labeled with different fluorophores to read DNA sequence after electrophoresis.
Correct answer is: Fluorescently labeled ddNTPs
Q.38 What is the main function of a “riboswitch”?
To catalyze peptide bond formation
To regulate gene expression in response to small molecules
To splice introns from pre‑mRNA
To replicate DNA
Explanation - Riboswitches are RNA elements that change conformation upon binding a ligand, thereby influencing transcription or translation.
Correct answer is: To regulate gene expression in response to small molecules
Q.39 Which of these is a common selectable marker for yeast cloning vectors?
Ampicillin resistance
Kanamycin resistance
URA3 gene
Chloramphenicol resistance
Explanation - URA3 complements uracil auxotrophy in Saccharomyces cerevisiae, allowing growth on media lacking uracil.
Correct answer is: URA3 gene
Q.40 The term “epigenetics” refers to:
Changes in DNA sequence
Heritable changes in gene expression without altering DNA sequence
The study of viruses
The process of DNA replication
Explanation - Epigenetic mechanisms (DNA methylation, histone modification) can regulate gene activity across cell generations without changing the underlying DNA.
Correct answer is: Heritable changes in gene expression without altering DNA sequence
Q.41 Which of the following best describes the function of a “vector” in genetic engineering?
A molecule that cuts DNA
A vehicle used to deliver foreign DNA into a host cell
A protein that translates mRNA
A cellular organelle that stores DNA
Explanation - Vectors (plasmids, viruses, etc.) carry and introduce the desired genetic material into target cells.
Correct answer is: A vehicle used to deliver foreign DNA into a host cell
Q.42 In a gene expression study, “qPCR” stands for:
Quantitative Polymerase Chain Reaction
Quick Protein Coding Ratio
Quaternary Protein Chromatography
Qualified Primer Collection
Explanation - qPCR quantifies the amount of a specific DNA (or cDNA) in real‑time, often used to measure gene expression levels.
Correct answer is: Quantitative Polymerase Chain Reaction
Q.43 Which of the following is an example of a non‑viral gene delivery method?
Lentiviral vector
Adenoviral vector
Liposome‑mediated transfection
Retroviral vector
Explanation - Liposomes are synthetic vesicles that encapsulate DNA and fuse with cell membranes to deliver genetic material without using viruses.
Correct answer is: Liposome‑mediated transfection
Q.44 The term “genome editing” most accurately describes:
Sequencing an organism’s DNA
Removing all non‑coding DNA
Precise modification of DNA sequences at specific loci
Amplifying a gene using PCR
Explanation - Genome editing technologies (CRISPR, TALENs, ZFNs) enable targeted changes such as insertions, deletions, or base substitutions.
Correct answer is: Precise modification of DNA sequences at specific loci
Q.45 Which of the following best defines a “synthetic promoter”?
A promoter naturally found in bacteria
A promoter created by assembling DNA elements to achieve desired expression levels
A promoter that cannot be bound by RNA polymerase
A promoter that only works in plant cells
Explanation - Synthetic promoters are engineered sequences designed to provide predictable and tunable transcriptional activity.
Correct answer is: A promoter created by assembling DNA elements to achieve desired expression levels
Q.46 What is the primary purpose of a “codon optimization” process when expressing a gene in a heterologous host?
To change the amino acid sequence of the protein
To increase mRNA stability and translation efficiency
To remove introns
To add a fluorescent tag
Explanation - Codon optimization replaces rare codons with those preferred by the host organism, improving translation rates without altering the protein sequence.
Correct answer is: To increase mRNA stability and translation efficiency
Q.47 In bacterial transformation, the “competent” state refers to:
Cells that are actively dividing
Cells that have been chemically or electrically treated to take up DNA
Cells that have integrated plasmid DNA into the chromosome
Cells that produce antibiotics
Explanation - Competent cells are made capable of binding and internalizing extracellular DNA, often via calcium chloride treatment or electroporation.
Correct answer is: Cells that have been chemically or electrically treated to take up DNA
Q.48 Which of the following is NOT a typical characteristic of a good genetic marker?
Clear phenotypic expression
Low mutation rate
High background expression in all tissues
Ease of detection
Explanation - A good marker should have low background to allow easy distinction between transformed and non‑transformed cells.
Correct answer is: High background expression in all tissues
Q.49 What does the term “horizontal gene transfer” describe?
Transfer of genes from parent to offspring
Transfer of genes between unrelated species
Transfer of genes from mitochondria to nucleus
Transfer of genes during meiosis
Explanation - Horizontal gene transfer involves movement of genetic material across species boundaries, common among bacteria via transformation, transduction, or conjugation.
Correct answer is: Transfer of genes between unrelated species
Q.50 In a DNA microarray experiment, the intensity of a spot primarily reflects:
The number of cells in the sample
The amount of hybridized cDNA corresponding to a particular gene
The length of the DNA fragment
The temperature during hybridization
Explanation - Higher fluorescence intensity indicates greater expression of the gene represented by that spot on the microarray.
Correct answer is: The amount of hybridized cDNA corresponding to a particular gene
Q.51 Which of the following best describes the role of “splicing” in eukaryotic gene expression?
Removal of introns from pre‑mRNA
Addition of a 5' cap
Synthesis of tRNA
Replication of DNA
Explanation - Splicing excises non‑coding introns from the primary transcript, joining exons to produce mature mRNA.
Correct answer is: Removal of introns from pre‑mRNA
Q.52 What is the primary advantage of using a “self‑splicing intron” in a vector?
It reduces vector size
It allows the intron to be removed without requiring host splicing machinery
It increases antibiotic resistance
It enhances plasmid replication
Explanation - Self‑splicing introns can catalyze their own excision, ensuring correct mRNA processing even in hosts lacking the necessary splicing factors.
Correct answer is: It allows the intron to be removed without requiring host splicing machinery
Q.53 Which of the following describes “gene silencing” by RNA interference?
Insertion of a transgene into the genome
Methylation of promoter DNA
Degradation of target mRNA by siRNA
Amplification of the gene by PCR
Explanation - siRNA guides the RNA‑induced silencing complex (RISC) to complementary mRNA, leading to its cleavage and reduced protein production.
Correct answer is: Degradation of target mRNA by siRNA
Q.54 In the context of biotechnology, “bioreactor” is primarily used for:
Sequencing DNA
Culturing cells or microorganisms under controlled conditions for product synthesis
Measuring electrical activity of neurons
Analyzing protein structures
Explanation - Bioreactors provide optimal conditions (pH, temperature, oxygen) for large‑scale production of biologics such as proteins or metabolites.
Correct answer is: Culturing cells or microorganisms under controlled conditions for product synthesis
Q.55 Which of the following is a major ethical concern surrounding human germline editing?
High cost of reagents
Potential off‑target mutations affecting future generations
Difficulty in delivering CRISPR components
Low efficiency of editing
Explanation - Germline edits are heritable; unintended off‑target changes could propagate, raising significant ethical and safety issues.
Correct answer is: Potential off‑target mutations affecting future generations
Q.56 Which of the following best explains the principle of “synthetic lethal screening” in cancer genetics?
Identifying genes that cause cell death when overexpressed
Finding gene pairs where loss of either alone is tolerated, but loss of both is lethal
Screening for drugs that increase cell proliferation
Measuring DNA replication speed
Explanation - Synthetic lethality exploits vulnerabilities in cancer cells by targeting a gene that becomes essential only when another gene is already mutated.
Correct answer is: Finding gene pairs where loss of either alone is tolerated, but loss of both is lethal
Q.57 The “Golden Gate” cloning method utilizes which feature of type IIS restriction enzymes?
They cut within their recognition site
They generate blunt ends
They cut outside their recognition site, producing custom overhangs
They only cut methylated DNA
Explanation - Type IIS enzymes enable seamless assembly of multiple DNA fragments in a defined order without leaving scar sequences.
Correct answer is: They cut outside their recognition site, producing custom overhangs
Q.58 In a gene drive system, the engineered gene is:
Silenced after one generation
Propagated through a population at higher than Mendelian rates
Only expressed in males
Removed by natural selection quickly
Explanation - Gene drives bias inheritance so that the engineered trait spreads rapidly through a population, potentially overriding wild‑type alleles.
Correct answer is: Propagated through a population at higher than Mendelian rates
Q.59 Which of the following technologies enables the detection of single‑molecule DNA modifications without amplification?
Sanger sequencing
Nanopore sequencing
PCR
Southern blotting
Explanation - Nanopore platforms read native DNA strands, detecting base modifications (e.g., methylation) directly as the molecule passes through the pore.
Correct answer is: Nanopore sequencing
Q.60 The term “orthogonal” in synthetic biology refers to:
Components that function independently of the host’s native systems
Genes that are highly expressed
DNA sequences that are identical across species
Proteins that bind to multiple promoters
Explanation - Orthogonal parts avoid cross‑talk with endogenous cellular pathways, ensuring predictable behavior of engineered circuits.
Correct answer is: Components that function independently of the host’s native systems
Q.61 Which of the following best describes a “metagenomic” approach?
Sequencing the genome of a single cultured bacterium
Studying gene expression in a model organism
Analyzing DNA extracted directly from environmental samples containing mixed microbial communities
Cloning a gene into a plasmid
Explanation - Metagenomics bypasses the need for culturing, allowing the study of genetic material from complex ecosystems.
Correct answer is: Analyzing DNA extracted directly from environmental samples containing mixed microbial communities
Q.62 In a CRISPR interference (CRISPRi) system, the Cas9 protein is modified to:
Cut DNA at target sites
Bind DNA without cutting, blocking transcription
Integrate new DNA sequences
Degrade RNA molecules
Explanation - Dead Cas9 (dCas9) lacks nuclease activity and can sterically hinder RNA polymerase, repressing gene expression.
Correct answer is: Bind DNA without cutting, blocking transcription
Q.63 Which of the following is a typical characteristic of a “constitutive promoter”?
Active only under specific environmental conditions
Produces a constant level of transcription regardless of conditions
Requires an inducer molecule to function
Is only found in viruses
Explanation - Constitutive promoters drive continuous gene expression, unlike inducible promoters which respond to stimuli.
Correct answer is: Produces a constant level of transcription regardless of conditions
Q.64 Which of the following enzymes is essential for the ligation step in Gibson Assembly?
T5 exonuclease
DNA polymerase I
DNA ligase
RNase H
Explanation - Gibson Assembly uses T5 exonuclease, DNA polymerase, and DNA ligase; ligase seals nicks between overlapping fragments.
Correct answer is: DNA ligase
Q.65 A “phage display” library is primarily used to:
Identify protein–protein interactions
Sequence entire genomes
Clone large DNA fragments
Measure enzyme activity
Explanation - Phage display presents peptides or proteins on the surface of bacteriophages, enabling selection of binders to target molecules.
Correct answer is: Identify protein–protein interactions
Q.66 Which of the following best describes “synthetic lethality” as a therapeutic strategy in cancer?
Targeting a gene that is already mutated in cancer cells, causing cell death only when combined with another defect
Using antibiotics to kill cancer cells
Activating oncogenes to trigger immune response
Inhibiting all DNA repair pathways
Explanation - Synthetic lethal drugs exploit cancer‑specific genetic lesions, sparing normal cells that lack the complementary mutation.
Correct answer is: Targeting a gene that is already mutated in cancer cells, causing cell death only when combined with another defect
Q.67 Which of the following is a typical application of a “biosensor” in genetic engineering?
Detecting the presence of a specific DNA sequence by producing a measurable signal
Amplifying RNA
Sequencing proteins
Culturing bacteria
Explanation - Genetically engineered biosensors couple a recognition element (e.g., promoter) to a reporter, generating a signal when the target is present.
Correct answer is: Detecting the presence of a specific DNA sequence by producing a measurable signal
Q.68 In the context of CRISPR, what does “PAM” stand for and why is it important?
Protein‑Associated Motif; it recruits RNA polymerase
Protospacer Adjacent Motif; required for Cas9 binding and cleavage
Promoter Activation Marker; initiates transcription
Poly‑A Modulation; stabilizes mRNA
Explanation - PAM is a short DNA sequence downstream of the target site; Cas9 recognizes PAM to bind and cut adjacent DNA.
Correct answer is: Protospacer Adjacent Motif; required for Cas9 binding and cleavage
Q.69 Which of the following statements about “RNA vaccines” is correct?
They integrate into the host genome
They deliver mRNA encoding antigenic proteins that are translated in host cells
They require viral vectors for delivery
They are ineffective against viral infections
Explanation - RNA vaccines introduce mRNA that cells translate into viral proteins, eliciting an immune response without altering DNA.
Correct answer is: They deliver mRNA encoding antigenic proteins that are translated in host cells
Q.70 What is the main function of a “terminator” in a prokaryotic transcription unit?
To initiate transcription
To cause RNA polymerase to detach from DNA
To enhance ribosome binding
To splice introns
Explanation - Terminator sequences signal the end of transcription, leading to release of the newly synthesized RNA.
Correct answer is: To cause RNA polymerase to detach from DNA
Q.71 Which of the following is a primary advantage of using “baculovirus” vectors for protein expression?
They replicate in bacterial cells
They enable high‑level expression of eukaryotic proteins with proper folding and post‑translational modifications
They are resistant to all antibiotics
They integrate into the host genome permanently
Explanation - Baculovirus infection of insect cells provides a eukaryotic environment for complex protein expression.
Correct answer is: They enable high‑level expression of eukaryotic proteins with proper folding and post‑translational modifications
Q.72 In the context of gene regulation, what does the term “inducible promoter” mean?
A promoter that is always active
A promoter that becomes active only in the presence of a specific inducer molecule
A promoter that inhibits transcription
A promoter that is located in the mitochondria
Explanation - Inducible promoters allow controlled gene expression; an external compound (e.g., IPTG) triggers transcription.
Correct answer is: A promoter that becomes active only in the presence of a specific inducer molecule
Q.73 Which of the following best defines “synthetic lethality” in the context of CRISPR screens?
A phenotype where loss of a single gene leads to cell death
A situation where simultaneous disruption of two non‑essential genes results in cell death
The process of integrating a synthetic gene into the genome
A method for measuring transcription levels
Explanation - Synthetic lethal interactions are identified by CRISPR screens that knock out gene pairs to find combinations lethal to cells, useful for drug target discovery.
Correct answer is: A situation where simultaneous disruption of two non‑essential genes results in cell death
Q.74 What is the main purpose of adding a “poly‑A tail” to eukaryotic mRNA?
To promote nuclear export and stability of the mRNA
To initiate transcription
To bind ribosomes directly
To encode amino acids
Explanation - The poly‑A tail protects mRNA from degradation and assists in translation initiation.
Correct answer is: To promote nuclear export and stability of the mRNA
Q.75 In the context of genome editing, “base editors” are designed to:
Create double‑strand breaks
Introduce specific nucleotide conversions without double‑strand breaks
Delete large chromosomal regions
Insert whole genes
Explanation - Base editors couple a deaminase to a dead Cas9, enabling precise point mutations while avoiding DSBs.
Correct answer is: Introduce specific nucleotide conversions without double‑strand breaks
Q.76 Which of the following best explains why a “high‑copy number plasmid” is useful for protein production?
It reduces the metabolic burden on the host
It ensures many copies of the gene, leading to high protein yield
It integrates into the host chromosome
It provides resistance to all antibiotics
Explanation - High‑copy plasmids replicate to large numbers per cell, increasing transcription of the cloned gene and thus protein production.
Correct answer is: It ensures many copies of the gene, leading to high protein yield
Q.77 Which of the following is a common method for confirming successful insertion of a DNA fragment into a plasmid?
Southern blotting
PCR amplification of the insert region
Northern blotting
ELISA
Explanation - Colony PCR using primers flanking the insertion site quickly verifies presence and size of the inserted fragment.
Correct answer is: PCR amplification of the insert region
Q.78 The “RNA‑seq” technique is primarily used to:
Sequence genomic DNA
Quantify and profile the transcriptome
Detect protein–protein interactions
Measure lipid composition
Explanation - RNA‑seq converts RNA to cDNA and sequences it, providing genome‑wide expression data and discovery of novel transcripts.
Correct answer is: Quantify and profile the transcriptome
Q.79 In a bacterial operon, the “operator” region functions as:
A promoter for RNA polymerase binding
A binding site for repressor proteins that block transcription
A site for ribosome attachment
A terminator sequence
Explanation - The operator is where repressors bind to inhibit transcription of downstream genes in the operon.
Correct answer is: A binding site for repressor proteins that block transcription
Q.80 Which of the following best describes a “phagemid”?
A plasmid that can be packaged into bacteriophage particles for infection
A viral genome that integrates into the host chromosome
A linear DNA molecule used in cloning
A protein that binds DNA
Explanation - Phagemids combine plasmid replication origins with a phage packaging signal, enabling efficient transduction of the plasmid into bacteria.
Correct answer is: A plasmid that can be packaged into bacteriophage particles for infection
Q.81 Which of the following is a primary advantage of using a “dual‑reporter” system in gene expression studies?
It allows simultaneous monitoring of two independent transcriptional events
It doubles the fluorescence intensity
It eliminates the need for a promoter
It reduces the size of the plasmid
Explanation - Dual‑reporter constructs (e.g., GFP + RFP) enable internal normalization and comparison of expression under different conditions.
Correct answer is: It allows simultaneous monitoring of two independent transcriptional events
Q.82 In the context of synthetic biology, “CRISPRa” is used to:
Create double‑strand DNA breaks
Activate transcription of target genes without cutting DNA
Delete large genomic regions
Sequence DNA
Explanation - CRISPR activation (CRISPRa) uses dCas9 fused to transcriptional activators to up‑regulate gene expression.
Correct answer is: Activate transcription of target genes without cutting DNA
Q.83 Which of the following best defines “gene drive” technology?
A method to silence genes permanently
A technique to ensure a genetic trait is inherited by >50% of offspring, spreading through a population rapidly
A system for cloning large genomic regions
A way to measure gene expression levels
Explanation - Gene drives bias inheritance, allowing engineered genes to propagate through a population faster than traditional Mendelian inheritance.
Correct answer is: A technique to ensure a genetic trait is inherited by >50% of offspring, spreading through a population rapidly
Q.84 What is the primary function of a “ribosome binding site (RBS)” in a prokaryotic expression vector?
To initiate DNA replication
To recruit RNA polymerase
To align the ribosome for translation initiation
To terminate transcription
Explanation - The RBS (Shine‑Dalgarno sequence) pairs with the 16S rRNA, positioning the ribosome at the start codon.
Correct answer is: To align the ribosome for translation initiation
Q.85 Which of the following is a common method for delivering CRISPR components into mammalian cells?
Electroporation of plasmid DNA
Agrobacterium infection
Transformation of yeast
Bacteriophage infection
Explanation - Electroporation creates temporary pores in the cell membrane, allowing plasmids encoding CRISPR components to enter mammalian cells efficiently.
Correct answer is: Electroporation of plasmid DNA
Q.86 In the context of molecular cloning, “blunt‑end cloning” differs from “sticky‑end cloning” because:
It uses restriction enzymes that leave overhangs
It does not require compatible overhangs, allowing any DNA ends to be ligated
It only works with RNA molecules
It requires a special type of ligase
Explanation - Blunt‑end ligation joins DNA fragments with flush ends, but generally has lower efficiency compared to sticky‑end ligation.
Correct answer is: It does not require compatible overhangs, allowing any DNA ends to be ligated
Q.87 Which of the following best describes the purpose of a “selection marker” in a cloning vector?
To increase plasmid copy number
To facilitate detection of successful transformants
To promote transcription of the insert
To degrade host DNA
Explanation - Selection markers (e.g., antibiotic resistance genes) allow growth of only those cells that have taken up the vector.
Correct answer is: To facilitate detection of successful transformants
Q.88 What does the term “synthetic gene circuit” refer to?
A naturally occurring metabolic pathway
An engineered network of genes and regulatory elements that perform logical functions
A DNA fragment that cannot be transcribed
A sequence of introns only
Explanation - Synthetic gene circuits mimic electronic circuits, using promoters, repressors, and activators to process inputs and generate outputs.
Correct answer is: An engineered network of genes and regulatory elements that perform logical functions
Q.89 Which of the following best explains why “codon usage bias” can affect heterologous protein expression?
Rare codons may stall ribosomes due to low tRNA abundance, reducing translation efficiency
It changes the amino acid sequence of the protein
It leads to DNA degradation
It prevents transcription initiation
Explanation - When a gene uses codons that are rare in the host, translation can be inefficient, lowering protein yield.
Correct answer is: Rare codons may stall ribosomes due to low tRNA abundance, reducing translation efficiency
Q.90 Which of the following is a key limitation of using viral vectors for gene therapy?
Inability to infect dividing cells
Potential for insertional mutagenesis and immune responses
Lack of ability to carry large DNA fragments
Low transduction efficiency
Explanation - Viral vectors can integrate into the host genome, possibly disrupting genes, and may provoke immune reactions.
Correct answer is: Potential for insertional mutagenesis and immune responses
Q.91 In a CRISPR‑Cas12a system, the guide RNA differs from Cas9 in that it:
Is longer and requires a tracrRNA
Is shorter and does not require a separate tracrRNA
Binds double‑stranded RNA
Does not require a PAM sequence
Explanation - Cas12a (Cpf1) uses a single crRNA that is shorter than the combined crRNA‑tracrRNA of Cas9, simplifying the system.
Correct answer is: Is shorter and does not require a separate tracrRNA
Q.92 Which of the following best describes the purpose of a “ribosome profiling” technique?
To map the positions of ribosomes on mRNAs genome‑wide, revealing translation rates
To identify DNA binding sites of transcription factors
To sequence the entire genome
To detect protein–protein interactions
Explanation - Ribosome profiling (Ribo‑seq) captures ribosome-protected mRNA fragments, providing a snapshot of translation activity.
Correct answer is: To map the positions of ribosomes on mRNAs genome‑wide, revealing translation rates
Q.93 Which of the following is a common method for generating a “knock‑in” cell line using CRISPR technology?
Homology‑directed repair (HDR) with a donor template
Non‑homologous end joining (NHEJ) without a template
Random integration of plasmid DNA
RNA interference
Explanation - HDR uses a repair template with desired modifications flanked by homology arms to introduce precise changes.
Correct answer is: Homology‑directed repair (HDR) with a donor template
Q.94 What is the main advantage of using a “self‑replicating RNA” (replicon) vector for vaccine development?
It integrates into the host genome
It can amplify within cells, leading to higher antigen expression without DNA intermediates
It requires no delivery vehicle
It produces long‑lasting immunity without boosters
Explanation - Self‑replicating RNA replicons replicate intracellularly, boosting protein production while avoiding genomic integration.
Correct answer is: It can amplify within cells, leading to higher antigen expression without DNA intermediates
Q.95 In a “split‑intein” system used for protein engineering, the purpose of the intein is to:
Bind DNA promoters
Catalyze protein splicing, joining two separate polypeptide fragments
Degrade mRNA
Facilitate protein export from the cell
Explanation - Inteins can self‑splice, allowing two halves of a protein expressed separately to be ligated post‑translationally.
Correct answer is: Catalyze protein splicing, joining two separate polypeptide fragments
Q.96 Which of the following best describes the principle behind “fluorescence‑activated cell sorting (FACS)” in genetic engineering workflows?
Separating cells based on size only
Sorting cells expressing a fluorescent reporter, allowing enrichment of transfected cells
Measuring DNA sequencing quality
Amplifying RNA from single cells
Explanation - FACS uses lasers to detect fluorescence, enabling isolation of cells that express a reporter gene indicating successful modification.
Correct answer is: Sorting cells expressing a fluorescent reporter, allowing enrichment of transfected cells
Q.97 Which of the following statements about “prime editing” is correct?
It creates double‑strand breaks to insert large DNA fragments
It uses a reverse transcriptase fused to a nickase Cas9 to directly write new genetic information without DSBs
It relies on RNA interference to silence genes
It only works in bacterial cells
Explanation - Prime editing combines a Cas9 nickase with a reverse transcriptase and a pegRNA to install targeted edits without double‑strand breaks.
Correct answer is: It uses a reverse transcriptase fused to a nickase Cas9 to directly write new genetic information without DSBs
Q.98 In the context of gene regulation, an “enhancer” functions by:
Blocking RNA polymerase binding
Increasing transcription from a promoter, often over long distances
Terminating transcription
Splicing introns
Explanation - Enhancers are DNA elements that can boost transcription when bound by activator proteins, even if located far from the promoter.
Correct answer is: Increasing transcription from a promoter, often over long distances
Q.99 Which of the following is a typical feature of a “landing pad” in genome engineering?
A pre‑engineered genomic site that enables precise insertion of transgenes via recombinase‑mediated cassette exchange
A sequence that blocks transcription
A region that encodes antibiotic resistance
A viral integration site
Explanation - Landing pads provide a defined locus for consistent transgene integration, improving reproducibility.
Correct answer is: A pre‑engineered genomic site that enables precise insertion of transgenes via recombinase‑mediated cassette exchange
Q.100 Which of the following best explains why “codon optimization” is often required when expressing a human gene in a bacterial system?
Bacteria cannot transcribe human promoters
Human genes contain introns that bacteria cannot process
Bacterial tRNA pools differ, so optimizing codons improves translation efficiency
Human genes are too long for bacterial replication
Explanation - Replacing rare human codons with those preferred by the bacterial host enhances protein production.
Correct answer is: Bacterial tRNA pools differ, so optimizing codons improves translation efficiency
Q.101 In the context of metabolic engineering, which strategy is most commonly used to increase the yield of a desired product?
Knocking out competing pathways
Increasing the number of ribosomes
Using high‑temperature growth conditions
Adding more antibiotics
Explanation - Removing or down‑regulating enzymes that divert precursors toward side products redirects flux toward the target metabolite.
Correct answer is: Knocking out competing pathways
Q.102 Which of the following best describes a “synthetic chromosome” in yeast?
A naturally occurring chromosome with many mutations
A chromosome built from scratch using synthesized DNA fragments, designed to function in yeast
A viral genome integrated into the yeast nucleus
A plasmid that replicates like a chromosome
Explanation - Synthetic yeast chromosomes (e.g., Sc2.0 project) are designed and assembled de novo, allowing genome‑wide engineering.
Correct answer is: A chromosome built from scratch using synthesized DNA fragments, designed to function in yeast