Q.1 What is the primary purpose of CRISPR-Cas9 technology in medicine?
To sequence DNA from a single cell
To edit specific genes in a living organism
To amplify viral proteins
To produce synthetic vaccines
Explanation - CRISPR-Cas9 is a gene‑editing tool that allows precise modifications to the genome, enabling correction of disease‑causing mutations.
Correct answer is: To edit specific genes in a living organism
Q.2 Which molecular technique is commonly used to detect viral RNA in a patient’s blood sample?
Enzyme‑linked immunosorbent assay (ELISA)
Polymerase chain reaction (PCR)
Gram staining
Western blotting
Explanation - PCR amplifies nucleic acids, allowing detection of even tiny amounts of viral RNA in clinical samples.
Correct answer is: Polymerase chain reaction (PCR)
Q.3 A monoclonal antibody that binds to the HIV envelope protein is best used for which purpose?
As a diagnostic reagent
As a vaccine candidate
As a drug delivery system
As a gene editing tool
Explanation - Monoclonal antibodies can mimic the immune response and are often developed as vaccine components against viruses like HIV.
Correct answer is: As a vaccine candidate
Q.4 Which of the following is NOT an application of recombinant DNA technology?
Production of human insulin
Creation of transgenic crops
Synthesis of antibiotics in bacteria
Extraction of DNA from fossils
Explanation - Recombinant DNA involves combining DNA from different sources; extracting ancient DNA is a paleogenetic activity, not recombinant.
Correct answer is: Extraction of DNA from fossils
Q.5 Why are plasmids preferred vectors for cloning genes in bacterial expression systems?
They are large and carry many genes
They can replicate independently of the host chromosome
They integrate into the host genome
They are resistant to antibiotics
Explanation - Plasmids can autonomously replicate within bacteria, allowing multiple copies of the inserted gene for protein production.
Correct answer is: They can replicate independently of the host chromosome
Q.6 What is the role of the protein p53 in cancer biology?
Promotes cell division
Induces DNA repair and apoptosis
Encodes a viral capsid
Synthesizes ATP
Explanation - p53 acts as a tumor suppressor by detecting DNA damage and initiating repair or programmed cell death.
Correct answer is: Induces DNA repair and apoptosis
Q.7 Which method is used to quantify the amount of RNA in a sample?
Spectrophotometry at 260 nm
Flow cytometry
Mass spectrometry
Southern blot
Explanation - RNA absorbs UV light at 260 nm, and measuring absorbance provides a quick estimate of RNA concentration.
Correct answer is: Spectrophotometry at 260 nm
Q.8 The term 'bioreactor' most closely refers to:
A device that amplifies DNA sequences
An incubator for growing microorganisms under controlled conditions
A chemical reactor producing plastic
A microscope for observing cells
Explanation - Bioreactors maintain optimal temperature, pH, and nutrient supply to grow cells or produce biologics.
Correct answer is: An incubator for growing microorganisms under controlled conditions
Q.9 Which of the following is a direct application of molecular biology in personalized medicine?
Standardized drug dosage for all patients
Genetic testing to tailor drug therapy
Using generic vaccines for all diseases
Treating infections with antibiotics only
Explanation - Personalized medicine uses a patient’s genetic profile to select the most effective drugs with minimal side effects.
Correct answer is: Genetic testing to tailor drug therapy
Q.10 How does an ELISA test detect the presence of a pathogen?
By amplifying its genetic material
By using labeled antibodies that bind to the pathogen’s antigens
By culturing the pathogen on selective media
By measuring the pathogen’s metabolic activity
Explanation - ELISA relies on antigen–antibody interactions with enzymatic or fluorescent labels to produce a measurable signal.
Correct answer is: By using labeled antibodies that bind to the pathogen’s antigens
Q.11 What is the main advantage of using viral vectors for gene therapy?
They can carry large amounts of DNA
They have high infection efficiency in target cells
They do not integrate into the host genome
They are inexpensive to produce
Explanation - Viral vectors efficiently deliver therapeutic genes into target cells, overcoming cellular uptake barriers.
Correct answer is: They have high infection efficiency in target cells
Q.12 The process of turning a specific DNA sequence into an mRNA transcript is called:
Translation
Transcription
Replication
Recombination
Explanation - Transcription is the synthesis of RNA from a DNA template by RNA polymerase.
Correct answer is: Transcription
Q.13 Which of these is a type of bioinformatics tool used to align multiple protein sequences?
BLAST
PCR
Microarray
Western blot
Explanation - BLAST (Basic Local Alignment Search Tool) aligns sequences to find similarities and functional annotations.
Correct answer is: BLAST
Q.14 Which cell component is the site of ribosomal RNA (rRNA) transcription?
Mitochondria
Nucleolus
Cytosol
Endoplasmic reticulum
Explanation - The nucleolus is a sub‑nuclear structure where ribosomal RNA genes are transcribed and ribosome assembly initiates.
Correct answer is: Nucleolus
Q.15 What is the primary purpose of a restriction enzyme in molecular cloning?
To amplify DNA
To cut DNA at specific recognition sites
To synthesize new proteins
To label DNA with fluorescent tags
Explanation - Restriction enzymes recognize specific short DNA sequences and create double‑strand breaks, facilitating cloning.
Correct answer is: To cut DNA at specific recognition sites
Q.16 Which technique would you use to separate proteins based on their isoelectric point?
SDS‑PAGE
Isoelectric focusing (IEF)
Affinity chromatography
Gel electrophoresis
Explanation - IEF separates proteins according to the pH at which they carry no net charge (isoelectric point).
Correct answer is: Isoelectric focusing (IEF)
Q.17 In vaccine development, why are attenuated viruses preferred for some vaccines?
They are easier to grow in culture
They replicate without causing disease
They do not require adjuvants
They are cheaper to manufacture
Explanation - Attenuated viruses elicit strong immune responses but have reduced pathogenicity, offering long‑lasting immunity.
Correct answer is: They replicate without causing disease
Q.18 Which of the following is a key feature of mRNA vaccines?
They integrate into the host genome
They use lipid nanoparticles for delivery
They are made from live viruses
They contain bacterial plasmids
Explanation - mRNA vaccines are encapsulated in lipid nanoparticles to protect the RNA and facilitate cellular uptake.
Correct answer is: They use lipid nanoparticles for delivery
Q.19 What is the function of the 'green fluorescent protein' (GFP) in molecular biology experiments?
To inhibit DNA replication
To serve as a fluorescent marker for gene expression
To catalyze protein synthesis
To bind antibodies in ELISA
Explanation - GFP fluoresces green when exposed to blue light, allowing researchers to visualize gene expression in living cells.
Correct answer is: To serve as a fluorescent marker for gene expression
Q.20 What is a primary safety concern when handling recombinant proteins in a lab?
They can spontaneously combust
They may trigger allergic reactions
They are always radioactive
They degrade instantly in air
Explanation - Recombinant proteins can be immunogenic, causing allergic or immune responses if not handled properly.
Correct answer is: They may trigger allergic reactions
Q.21 Which of the following best describes the term 'biomarker'?
A biological molecule that indicates a disease state
A type of laboratory glassware
An instrument that measures voltage
A process for gene sequencing
Explanation - Biomarkers are measurable indicators (like proteins or nucleic acids) that reflect normal or pathogenic biological processes.
Correct answer is: A biological molecule that indicates a disease state
Q.22 How does a 'polymerase chain reaction' (PCR) amplify DNA?
By adding more primers to a solution
By using heat to denature DNA, then cooling for primers to bind, and an enzyme to extend the strand
By using light to break DNA strands
By injecting DNA into a living cell
Explanation - PCR cycles through denaturation, annealing, and extension steps, exponentially amplifying the target DNA segment.
Correct answer is: By using heat to denature DNA, then cooling for primers to bind, and an enzyme to extend the strand
Q.23 What is the role of a promoter region in a plasmid used for protein expression?
To restrict plasmid replication
To initiate transcription of the inserted gene
To provide antibiotic resistance
To encode the protein itself
Explanation - The promoter is a DNA sequence recognized by RNA polymerase that starts transcription of the gene of interest.
Correct answer is: To initiate transcription of the inserted gene
Q.24 Which type of chromatography is used to purify antibodies based on their affinity for a specific antigen?
Ion exchange chromatography
Size exclusion chromatography
Affinity chromatography
Thin layer chromatography
Explanation - Affinity chromatography employs a ligand that specifically binds the target protein, allowing selective purification.
Correct answer is: Affinity chromatography
Q.25 The 'mRNA vaccine' platform was most notably used in which disease outbreak?
HIV
Influenza
COVID‑19
Zika virus
Explanation - mRNA vaccines (Pfizer‑BioNTech and Moderna) were rapidly deployed during the COVID‑19 pandemic.
Correct answer is: COVID‑19
Q.26 Which of the following is a function of heat shock proteins (HSPs) in cells?
To degrade misfolded proteins
To act as transcription factors
To catalyze DNA replication
To serve as cell surface receptors
Explanation - HSPs act as molecular chaperones, helping refold or target misfolded proteins for degradation.
Correct answer is: To degrade misfolded proteins
Q.27 What is the main advantage of using a cell‑free protein synthesis system?
It requires living cells for expression
It allows rapid protein production without culturing cells
It can replicate DNA autonomously
It eliminates the need for ribosomes
Explanation - Cell‑free systems use lysates containing all necessary components for translation, speeding up protein synthesis.
Correct answer is: It allows rapid protein production without culturing cells
Q.28 In molecular diagnostics, what does a 'Ct value' represent?
The concentration of DNA in a sample
The cycle threshold at which fluorescence is detected in PCR
The size of a DNA fragment
The number of plasmid copies
Explanation - Ct (cycle threshold) indicates the PCR cycle at which the fluorescence signal crosses the detection threshold.
Correct answer is: The cycle threshold at which fluorescence is detected in PCR
Q.29 Which of the following is a key benefit of using biopharmaceuticals over conventional drugs?
Lower cost of production
Higher oral bioavailability
Specific targeting with fewer side effects
No requirement for clinical trials
Explanation - Biopharmaceuticals often act on specific molecular targets, reducing off‑target effects compared to small molecules.
Correct answer is: Specific targeting with fewer side effects
Q.30 What does the term 'in silico' refer to in molecular biology research?
Experiments performed in living organisms
Computational simulations and modeling
Laboratory assays in test tubes
Clinical trials in patients
Explanation - In silico studies involve computer‑based simulations to predict molecular interactions and properties.
Correct answer is: Computational simulations and modeling
Q.31 Which of the following is a characteristic of a 'fusion protein'?
It contains two protein domains linked together
It is a synthetic DNA sequence
It is a type of RNA polymerase
It cannot be expressed in bacteria
Explanation - Fusion proteins combine two distinct proteins to create a single, multifunctional molecule.
Correct answer is: It contains two protein domains linked together
Q.32 Why are 'synthetic promoters' used in engineered gene circuits?
To avoid natural gene regulation entirely
To provide predictable and tunable expression levels
To increase the size of plasmids
To inhibit plasmid replication
Explanation - Synthetic promoters allow precise control over the timing and amount of gene expression in synthetic biology.
Correct answer is: To provide predictable and tunable expression levels
Q.33 Which molecular method can quantify the amount of a specific DNA sequence in a sample?
Northern blot
Real‑time PCR (qPCR)
Gram staining
Electron microscopy
Explanation - qPCR measures the accumulation of PCR product in real time, allowing quantitative determination of the target.
Correct answer is: Real‑time PCR (qPCR)
Q.34 What is a common use of aptamers in diagnostics?
As RNA-based antibiotics
As small molecules that inhibit enzymes
As synthetic DNA or RNA ligands that bind specific proteins
As fluorescent dyes
Explanation - Aptamers can bind target proteins with high affinity, making them useful in sensing and purification.
Correct answer is: As synthetic DNA or RNA ligands that bind specific proteins
Q.35 Which of these best describes an 'oncogene'?
A gene that repairs DNA damage
A gene that promotes cell death
A gene that, when overactive, can cause cancer
A gene that encodes a structural protein
Explanation - Oncogenes are mutated or overexpressed genes that drive uncontrolled cell proliferation.
Correct answer is: A gene that, when overactive, can cause cancer
Q.36 In protein engineering, what is the purpose of site‑directed mutagenesis?
To delete large genomic regions
To introduce specific amino‑acid changes at defined positions
To synthesize proteins directly in vitro
To measure protein folding rates
Explanation - Site‑directed mutagenesis allows precise changes to a protein’s sequence to alter function or stability.
Correct answer is: To introduce specific amino‑acid changes at defined positions
Q.37 What does 'RNA interference' (RNAi) primarily do?
Enhances gene transcription
Silences gene expression by degrading mRNA
Encodes new proteins
Stabilizes mRNA molecules
Explanation - RNAi uses small interfering RNAs to target and degrade complementary mRNA, reducing protein production.
Correct answer is: Silences gene expression by degrading mRNA
Q.38 Which of the following is NOT an advantage of using viral vectors for delivering therapeutic genes?
High transduction efficiency
Large packaging capacity for all genes
Ability to integrate into host genome (for some vectors)
Potential for immune responses
Explanation - Viral vectors have limited packaging capacity; for example, AAV can carry ~4.7 kb.
Correct answer is: Large packaging capacity for all genes
Q.39 A 'biomaterial scaffold' used in tissue engineering is designed to:
Act as a drug delivery system only
Serve as a temporary structure that supports cell growth
Produce proteins directly
Detect pathogens in the bloodstream
Explanation - Scaffolds provide a 3D framework for cells to attach, proliferate, and differentiate into functional tissues.
Correct answer is: Serve as a temporary structure that supports cell growth
Q.40 Which type of vaccine uses a genetically engineered version of a virus that cannot replicate?
Live attenuated
Inactivated
Subunit
Virus‑like particle (VLP) vaccine
Explanation - VLPs mimic the structure of viruses but lack genetic material, making them safe yet immunogenic.
Correct answer is: Virus‑like particle (VLP) vaccine
Q.41 In the context of DNA sequencing, what does 'next‑generation sequencing' (NGS) enable?
Sequencing one DNA molecule at a time
Parallel sequencing of millions of DNA fragments
Sequencing only RNA molecules
Sequencing DNA without reagents
Explanation - NGS technologies can generate massive amounts of sequence data in a single run, revolutionizing genomics.
Correct answer is: Parallel sequencing of millions of DNA fragments
Q.42 What is the purpose of adding a 'stop codon' during gene synthesis?
To prevent the ribosome from translating into the vector backbone
To increase transcription levels
To allow unlimited translation
To silence the gene
Explanation - A stop codon signals termination of translation, ensuring only the intended protein is produced.
Correct answer is: To prevent the ribosome from translating into the vector backbone
Q.43 Which of the following best describes 'gene therapy'?
Using drugs to treat genetic disorders
Replacing faulty genes with correct copies
Removing all genes from a cell
Sequencing the entire genome
Explanation - Gene therapy introduces functional genes into a patient’s cells to compensate for defective genes.
Correct answer is: Replacing faulty genes with correct copies
Q.44 Why is a 'negative control' used in PCR reactions?
To confirm that the primers are working
To ensure that no contamination leads to false‑positive results
To measure the amount of target DNA
To speed up the amplification process
Explanation - Negative controls contain no template DNA, verifying that any amplification is not due to contamination.
Correct answer is: To ensure that no contamination leads to false‑positive results
Q.45 What is a primary advantage of using 'phage display' for antibody discovery?
It allows direct sequencing of human genomes
It produces antibodies in large quantities without cells
It displays peptides or proteins on bacteriophage surfaces for high‑throughput screening
It eliminates the need for immunization
Explanation - Phage display presents a library of peptides on phage coats, enabling rapid identification of binding partners.
Correct answer is: It displays peptides or proteins on bacteriophage surfaces for high‑throughput screening
Q.46 Which enzyme is used to join two DNA fragments in a process called 'ligation'?
DNA polymerase
DNA ligase
RNA polymerase
Helicase
Explanation - DNA ligase catalyzes the formation of phosphodiester bonds between DNA fragments, sealing nicks.
Correct answer is: DNA ligase
Q.47 What is the main reason for using antibiotic resistance genes in plasmid vectors?
To allow selection of successfully transformed cells
To increase plasmid copy number
To suppress host cell growth
To prevent plasmid replication
Explanation - Antibiotic resistance markers enable only transformed cells to grow in antibiotic-containing media.
Correct answer is: To allow selection of successfully transformed cells
Q.48 In protein purification, what is the role of a 'capture ligand' in a chromatography column?
To wash away impurities
To bind the target protein selectively
To change the pH of the buffer
To degrade unwanted proteins
Explanation - Capture ligands specifically interact with the protein of interest, allowing selective retention and elution.
Correct answer is: To bind the target protein selectively
Q.49 Which of the following is a key feature of 'mRNA‑based therapeutics' other than vaccines?
They are permanently integrated into the genome
They can transiently produce proteins for a short period
They rely on ribosome‑binding proteins
They are produced only in bacterial cells
Explanation - mRNA therapeutics provide temporary protein expression without altering the host DNA.
Correct answer is: They can transiently produce proteins for a short period
Q.50 What does 'insertional mutagenesis' involve?
Inserting a gene into the genome to disrupt an existing gene
Removing a gene from the genome
Deleting a plasmid from a bacterial culture
Changing the amino acid sequence of a protein
Explanation - Insertional mutagenesis disrupts gene function by inserting foreign DNA, often used to identify gene function.
Correct answer is: Inserting a gene into the genome to disrupt an existing gene
Q.51 Which technique is best for separating proteins based on charge?
Affinity chromatography
Ion‑exchange chromatography
Size exclusion chromatography
Reverse‑phase HPLC
Explanation - Ion‑exchange chromatography separates proteins by their net charge at a given pH.
Correct answer is: Ion‑exchange chromatography
Q.52 In a typical 'Western blot' procedure, what is the purpose of the blocking step?
To prevent non‑specific antibody binding
To fix the proteins onto the membrane
To wash away unbound primary antibodies
To cut the membrane into strips
Explanation - Blocking agents occupy remaining binding sites on the membrane, reducing background signal.
Correct answer is: To prevent non‑specific antibody binding
Q.53 Which of these is a common source of recombinant protein expressed in mammalian cells?
Bacterial plasmids
Yeast expression vectors
Insect virus vectors
Mammalian expression plasmids with a CMV promoter
Explanation - The CMV promoter drives high expression in mammalian cells for recombinant protein production.
Correct answer is: Mammalian expression plasmids with a CMV promoter
Q.54 What is the primary benefit of using 'single‑cell RNA sequencing' (scRNA‑seq)?
To analyze DNA mutations in a population
To profile gene expression at the individual cell level
To sequence proteins directly
To amplify whole genomes
Explanation - scRNA‑seq reveals heterogeneity within cell populations by measuring mRNA from single cells.
Correct answer is: To profile gene expression at the individual cell level
Q.55 Which of these is a characteristic of a 'transient transfection' in cell culture?
Stable integration into the host genome
Temporary expression of the transgene
Permanent gene expression
Use of viral vectors only
Explanation - Transient transfection results in short‑term expression without genomic integration.
Correct answer is: Temporary expression of the transgene
Q.56 Why is 'glycosylation' important for therapeutic antibodies?
It determines their color
It affects their stability, efficacy, and immune recognition
It makes them fluorescent
It prevents them from binding antigens
Explanation - Glycosylation patterns influence antibody half‑life, potency, and clearance from the body.
Correct answer is: It affects their stability, efficacy, and immune recognition
Q.57 In the production of biopharmaceuticals, what is the purpose of a 'fermentation process'?
To chemically synthesize proteins
To grow microbial cultures in large bioreactors for protein production
To purify DNA sequences
To sequence genomes of patients
Explanation - Fermentation allows large‑scale cultivation of cells that express the desired protein.
Correct answer is: To grow microbial cultures in large bioreactors for protein production
Q.58 Which of the following is a feature of 'aptamer‑based biosensors'?
They are made from proteins only
They use synthetic nucleic acid sequences that bind specific targets
They cannot detect small molecules
They require radioactive labeling
Explanation - Aptamers are nucleic acid molecules selected for high affinity to a target, enabling biosensing.
Correct answer is: They use synthetic nucleic acid sequences that bind specific targets
Q.59 What does the term 'translational control' refer to?
Regulation of gene transcription
Control of mRNA degradation only
Regulation of protein synthesis from mRNA
Inhibition of DNA replication
Explanation - Translational control modulates how efficiently ribosomes produce proteins from mRNA.
Correct answer is: Regulation of protein synthesis from mRNA
Q.60 In a typical 'Southern blot', which type of nucleic acid is being detected?
Proteins
RNA
DNA
Lipids
Explanation - Southern blotting uses labeled DNA probes to detect specific DNA sequences.
Correct answer is: DNA
Q.61 What is the main function of an 'antigen‑presenting cell' in immunotherapy?
To produce antibodies
To display processed antigens on MHC molecules to activate T cells
To secrete cytokines only
To kill cancer cells directly
Explanation - APCs present antigens to T cells, initiating adaptive immune responses.
Correct answer is: To display processed antigens on MHC molecules to activate T cells
Q.62 Which of these is a direct application of CRISPR technology in agriculture?
Sequencing crops for sale
Editing plant genomes to increase yield or disease resistance
Producing pharmaceutical proteins in plants
Creating synthetic DNA strands for storage
Explanation - CRISPR is used to introduce targeted mutations in crops for improved traits.
Correct answer is: Editing plant genomes to increase yield or disease resistance
Q.63 What does 'DNA microarray' allow researchers to measure?
Protein folding rates
Gene expression levels across thousands of genes simultaneously
Cell membrane potential
Enzyme kinetics
Explanation - Microarrays contain probes for many genes, enabling simultaneous analysis of expression patterns.
Correct answer is: Gene expression levels across thousands of genes simultaneously
Q.64 Which of the following best describes a 'pharmaceutical grade recombinant protein'?
Produced in any cell line with no purification
Purified to meet stringent purity, safety, and potency standards for clinical use
Only used in research laboratories
Made from synthetic peptides only
Explanation - Pharmaceutical grade requires rigorous quality controls to ensure patient safety.
Correct answer is: Purified to meet stringent purity, safety, and potency standards for clinical use
Q.65 Why is 'polymerase chain reaction' (PCR) often coupled with gel electrophoresis?
To purify the PCR product
To separate and visualize DNA fragments by size
To amplify RNA directly
To detect proteins
Explanation - Gel electrophoresis resolves PCR products, confirming the expected amplicon size.
Correct answer is: To separate and visualize DNA fragments by size
Q.66 What is the primary advantage of 'in vitro transcription' (IVT) in generating RNA for vaccines?
It allows immediate translation in vivo
It bypasses the need for ribosomes
It produces large quantities of RNA quickly and without living cells
It automatically creates lipid nanoparticles
Explanation - IVT uses purified enzymes and templates to synthesize RNA in a test tube.
Correct answer is: It produces large quantities of RNA quickly and without living cells
Q.67 Which enzyme is responsible for removing RNA primers during DNA replication?
DNA ligase
DNA polymerase I
RNA polymerase
Helicase
Explanation - DNA polymerase I has 5’→3’ exonuclease activity that removes RNA primers.
Correct answer is: DNA polymerase I
Q.68 In gene therapy, what is the main difference between 'ex vivo' and 'in vivo' approaches?
Ex vivo targets only viral genes
Ex vivo modifies cells outside the body before re‑implantation
In vivo uses only bacterial vectors
In vivo requires cell culture
Explanation - Ex vivo therapy modifies cells outside the patient, whereas in vivo delivers the gene directly to tissues.
Correct answer is: Ex vivo modifies cells outside the body before re‑implantation
Q.69 Which of these is a typical use of a 'luciferase reporter assay'?
To detect antibiotic resistance
To measure promoter activity through bioluminescence
To sequence DNA fragments
To purify proteins
Explanation - Luciferase emits light when its gene is expressed, indicating promoter strength.
Correct answer is: To measure promoter activity through bioluminescence
Q.70 What is a key benefit of using 'CRISPRi' over CRISPR‑Cas9 in gene silencing?
It permanently deletes the target gene
It uses a dead Cas9 to block transcription without cutting DNA
It produces more off‑target effects
It requires viral vectors only
Explanation - CRISPRi employs a nuclease‑dead Cas9 fused to a repressor domain to inhibit gene expression.
Correct answer is: It uses a dead Cas9 to block transcription without cutting DNA
Q.71 What is the main role of a 'heat shock protein 70' (HSP70) during cellular stress?
To degrade proteins
To assist in refolding denatured proteins and prevent aggregation
To act as a transcription factor
To break DNA strands
Explanation - HSP70 binds unfolded proteins, aiding in proper folding and preventing aggregation.
Correct answer is: To assist in refolding denatured proteins and prevent aggregation
Q.72 Which of the following best describes 'gene editing' versus 'gene therapy'?
Gene editing changes DNA sequence; gene therapy adds functional genes without altering the genome
Gene editing is only for plants; gene therapy is for animals
Gene editing uses antibiotics; gene therapy uses viruses
They are the same process
Explanation - Editing directly modifies the genome, while therapy typically introduces new genes.
Correct answer is: Gene editing changes DNA sequence; gene therapy adds functional genes without altering the genome
Q.73 Why are 'induced pluripotent stem cells' (iPSCs) significant in biotechnology?
They are naturally resistant to viruses
They can be derived from adult cells and differentiate into many cell types for therapy and research
They produce large amounts of insulin
They are used to grow bacteria
Explanation - iPSCs allow patient‑specific cell generation for regenerative medicine and disease modeling.
Correct answer is: They can be derived from adult cells and differentiate into many cell types for therapy and research
Q.74 What is the purpose of 'selection markers' in plasmid construction?
To increase plasmid copy number
To facilitate the identification of cells that have taken up the plasmid
To suppress gene expression
To degrade unwanted DNA fragments
Explanation - Markers (e.g., antibiotic resistance) enable researchers to select transformed cells.
Correct answer is: To facilitate the identification of cells that have taken up the plasmid
Q.75 Which technique is used to identify protein–protein interactions in living cells?
Co‑immunoprecipitation (Co‑IP)
DNA sequencing
Gram staining
PCR
Explanation - Co‑IP isolates protein complexes, revealing interacting partners.
Correct answer is: Co‑immunoprecipitation (Co‑IP)
Q.76 What is a common application of 'in silico docking' studies?
Predicting the 3D structure of a DNA molecule
Designing primers for PCR
Simulating how a drug candidate binds to a target protein
Measuring protein concentration
Explanation - Docking predicts binding modes and affinities, guiding drug design.
Correct answer is: Simulating how a drug candidate binds to a target protein
Q.77 Which of the following is NOT a typical step in a standard protein purification workflow?
Cell lysis
Chromatographic separation
DNA sequencing
Buffer exchange
Explanation - Protein purification involves physical separation, not DNA sequencing.
Correct answer is: DNA sequencing
Q.78 What is the main purpose of a 'stop‑signal' in a ribozyme‑based gene expression system?
To terminate translation early
To prevent transcription of downstream genes
To enhance DNA replication
To increase ribosomal binding
Explanation - Stop signals can terminate transcription or translation to regulate gene expression.
Correct answer is: To prevent transcription of downstream genes
Q.79 In the context of gene therapy, what does 'viral tropism' refer to?
The preference of a virus for specific host cell types
The rate at which a virus replicates
The ability of a virus to integrate into the host genome
The color change in infected cells
Explanation - Viral tropism determines which cells or tissues a vector can efficiently infect.
Correct answer is: The preference of a virus for specific host cell types
Q.80 Which of the following best describes a 'nanoparticle vaccine'?
A vaccine that uses whole virus particles
A vaccine encapsulating antigens in nanoparticles for enhanced delivery
A vaccine that only contains antigens from bacteria
A vaccine that uses only RNA molecules
Explanation - Nanoparticle platforms protect antigens and improve uptake by antigen‑presenting cells.
Correct answer is: A vaccine encapsulating antigens in nanoparticles for enhanced delivery
Q.81 What is the main function of a 'linker peptide' in a fusion protein?
To cleave the fusion protein into two parts
To provide flexibility and prevent steric hindrance between domains
To increase the size of the protein
To act as a fluorescent tag
Explanation - Linkers maintain proper folding and function of each domain in a fusion protein.
Correct answer is: To provide flexibility and prevent steric hindrance between domains
Q.82 Which of the following is a key feature of 'antibody‑drug conjugates' (ADCs)?
They use DNA to target cancer cells
They combine a monoclonal antibody with a cytotoxic drug to deliver the drug specifically to cancer cells
They are used only for viral infections
They cannot be administered intravenously
Explanation - ADCs harness antibody specificity to target and kill tumor cells while sparing healthy tissue.
Correct answer is: They combine a monoclonal antibody with a cytotoxic drug to deliver the drug specifically to cancer cells
Q.83 What does 'PCR‑based genotyping' involve?
Sequencing the entire genome
Amplifying specific DNA regions to identify genetic variants
Measuring protein concentrations
Testing for antibiotic resistance only
Explanation - Genotyping uses PCR to amplify target loci for SNP or mutation detection.
Correct answer is: Amplifying specific DNA regions to identify genetic variants
Q.84 Which of the following is a main challenge when delivering gene therapies to the brain?
The blood–brain barrier limits vector entry
Neurons cannot be transduced
The brain has no DNA
All viral vectors are ineffective
Explanation - The BBB restricts many therapeutic agents from reaching CNS tissues.
Correct answer is: The blood–brain barrier limits vector entry
Q.85 What is the role of an 'internal ribosome entry site' (IRES) in an expression vector?
To terminate transcription
To allow cap‑independent initiation of translation from a downstream open reading frame
To degrade mRNA
To act as a promoter
Explanation - IRES elements enable translation of multiple proteins from a single mRNA.
Correct answer is: To allow cap‑independent initiation of translation from a downstream open reading frame
Q.86 Which of these is an advantage of using 'cell‑free synthetic biology' platforms?
They require living organisms for production
They allow rapid prototyping of genetic circuits without culturing cells
They cannot produce proteins
They are always more cost‑effective than cell‑based systems
Explanation - Cell‑free systems enable quick testing of genetic designs in vitro.
Correct answer is: They allow rapid prototyping of genetic circuits without culturing cells
Q.87 What is the main use of a 'dual‑promoter' vector?
To express two genes simultaneously from a single plasmid
To inhibit transcription of a gene
To provide antibiotic resistance
To increase plasmid copy number
Explanation - Dual‑promoter vectors drive expression of two separate genes in one construct.
Correct answer is: To express two genes simultaneously from a single plasmid
Q.88 In a 'gene knock‑in' experiment, what is achieved?
The removal of an existing gene
Insertion of a new gene at a specific genomic location
Deletion of the entire genome
Overexpression of a random gene
Explanation - Knock‑in adds a gene at a defined locus, often to restore function or introduce a reporter.
Correct answer is: Insertion of a new gene at a specific genomic location
Q.89 Which technique is commonly used to quantify protein concentrations in a mixture?
Bicinchoninic acid (BCA) assay
DNA ladder
Gram staining
Electroencephalography (EEG)
Explanation - BCA assay detects protein by forming a colored complex with Cu²⁺ ions.
Correct answer is: Bicinchoninic acid (BCA) assay
Q.90 What does the term 'biosensor' refer to in biotechnology?
A device that produces biological waste
A system that integrates a biological component to detect analytes and produce a measurable signal
A type of vaccine
A microscope slide
Explanation - Biosensors combine biology with electronics to detect molecules like glucose or toxins.
Correct answer is: A system that integrates a biological component to detect analytes and produce a measurable signal
Q.91 In the context of 'antibody engineering', what is a 'Fab fragment'?
A full antibody molecule
The antigen‑binding fragment of an antibody
The constant region only
A small peptide used as a drug
Explanation - Fab fragments retain the antigen‑binding domain and are used for diagnostics or therapy.
Correct answer is: The antigen‑binding fragment of an antibody
Q.92 Which of the following is a main benefit of using a 'bioluminescent reporter gene'?
It requires radioactive labeling
It allows real‑time, non‑invasive monitoring of gene expression in living organisms
It can only be used in vitro
It is a type of DNA polymerase
Explanation - Bioluminescent reporters emit light, enabling imaging in living cells or animals.
Correct answer is: It allows real‑time, non‑invasive monitoring of gene expression in living organisms
Q.93 What is a typical use of 'flow cytometry' in molecular biology?
To amplify DNA
To analyze and sort cells based on fluorescent markers
To measure protein mass
To sequence RNA
Explanation - Flow cytometry counts and sorts cells using fluorescently labeled antibodies or dyes.
Correct answer is: To analyze and sort cells based on fluorescent markers
Q.94 Which of these is a critical parameter in designing a CRISPR guide RNA?
Length of the PAM sequence
Target DNA GC content near the PAM
Presence of methylated cytosines in the guide
Color of the guide RNA
Explanation - Guide RNA effectiveness depends on target sequence compatibility, including GC content and PAM presence.
Correct answer is: Target DNA GC content near the PAM
Q.95 In a 'Western blot', which of the following steps follows the transfer of proteins onto a membrane?
Electrophoresis
Blocking
PCR
DNA extraction
Explanation - After transfer, the membrane is blocked to prevent nonspecific antibody binding.
Correct answer is: Blocking
Q.96 What is the purpose of a 'vector backbone' in a plasmid construct?
To carry the gene of interest
To provide replication and selection features
To encode the antibiotic
To act as a fluorescent reporter
Explanation - The backbone contains origins of replication and selection markers essential for plasmid maintenance.
Correct answer is: To provide replication and selection features
Q.97 Which of the following describes 'RNA‑seq'?
Sequencing of DNA strands in a sample
Sequencing of the complete RNA content of a cell or tissue
Amplification of RNA to measure its quantity
Sequencing of protein sequences
Explanation - RNA‑seq provides transcriptome profiles, revealing gene expression levels.
Correct answer is: Sequencing of the complete RNA content of a cell or tissue
Q.98 Which of the following best characterizes a 'bacterial artificial chromosome' (BAC)?
A small plasmid used in mammalian cells
A large plasmid capable of carrying DNA fragments up to 300 kb
A viral vector that only infects bacteria
A type of ribosome
Explanation - BACs are used to clone large genomic fragments for functional studies.
Correct answer is: A large plasmid capable of carrying DNA fragments up to 300 kb
Q.99 What is a key feature of 'DNA‑based vaccines'?
They encode the antigen as a DNA plasmid that is taken up by host cells
They contain live viruses
They rely on bacterial toxins as adjuvants
They are delivered orally only
Explanation - DNA vaccines rely on plasmids that enter cells and produce antigenic proteins internally.
Correct answer is: They encode the antigen as a DNA plasmid that is taken up by host cells
Q.100 Which technique is used to measure the kinetic rate of a protein–ligand interaction?
Mass spectrometry
Surface plasmon resonance (SPR)
Gel electrophoresis
PCR
Explanation - SPR monitors binding events in real time, providing association and dissociation rates.
Correct answer is: Surface plasmon resonance (SPR)
Q.101 What does 'RNA interference' (RNAi) rely on to silence gene expression?
Small interfering RNAs that guide the RNA‑induced silencing complex to target mRNA
Large proteins that bind to DNA
Deletion of genes
Chemical inhibitors of DNA replication
Explanation - siRNAs form complexes that degrade complementary mRNA, reducing protein output.
Correct answer is: Small interfering RNAs that guide the RNA‑induced silencing complex to target mRNA
Q.102 Which of the following is a major advantage of 'microfluidic devices' in molecular biology?
They eliminate the need for a microscope
They allow rapid, high‑throughput processing of small sample volumes
They can sequence genomes without reagents
They are used only in physics
Explanation - Microfluidics miniaturize assays, saving reagents and enabling parallel analyses.
Correct answer is: They allow rapid, high‑throughput processing of small sample volumes
Q.103 What is a common method to deliver CRISPR components in vivo?
Electroporation
Lipid nanoparticles
Heat shock
Microinjection into eggs
Explanation - LNPs protect nucleic acids and facilitate cellular uptake for systemic delivery.
Correct answer is: Lipid nanoparticles
Q.104 In gene therapy, what is the significance of using a 'self‑inactivating (SIN) lentiviral vector'?
It cannot integrate into host DNA
It reduces the risk of insertional mutagenesis by disabling promoter activity after integration
It has a larger packaging capacity
It is cheaper to produce
Explanation - SIN vectors remove viral enhancers, lowering oncogenic potential.
Correct answer is: It reduces the risk of insertional mutagenesis by disabling promoter activity after integration
Q.105 Which of the following best describes a 'DNA origami' technique?
Using DNA to fold proteins into functional shapes
Using long single‑stranded DNA to fold into precise nanostructures with short staple strands
Sequencing DNA to determine its length
Amplifying DNA to high quantities
Explanation - DNA origami designs nanostructures by base‑pairing staple strands to a long scaffold.
Correct answer is: Using long single‑stranded DNA to fold into precise nanostructures with short staple strands
Q.106 Which of the following is a hallmark of a 'biobricks' system?
Random DNA fragments inserted into plasmids
Standardized biological parts with defined overhangs for modular assembly
Large, unmodified plasmids
Only eukaryotic DNA sequences
Explanation - Biobricks provide a library of parts that can be assembled via standardized restriction sites.
Correct answer is: Standardized biological parts with defined overhangs for modular assembly
Q.107 What is the primary purpose of using a 'negative stain' in electron microscopy?
To enhance contrast by surrounding the sample with heavy metal salts
To fix the sample permanently
To prevent evaporation
To stain the DNA
Explanation - Negative staining increases image contrast for small biomolecules like viruses.
Correct answer is: To enhance contrast by surrounding the sample with heavy metal salts
Q.108 In a 'dual‑color immunofluorescence' experiment, what does each color typically represent?
The same protein at two different time points
Different cell organelles or proteins being co‑localised
Two different samples mixed together
The same antibody in two forms
Explanation - Dual colours allow simultaneous detection of two distinct targets in one sample.
Correct answer is: Different cell organelles or proteins being co‑localised
Q.109 What is the role of 'beta‑galactosidase' in a bacterial reporter system?
To catalyze DNA replication
To produce a measurable color change when its substrate is present
To bind RNA
To degrade antibiotics
Explanation - Beta‑galactosidase converts X‑gal into a blue product, indicating promoter activity.
Correct answer is: To produce a measurable color change when its substrate is present
Q.110 Which of these is a common method to assess the purity of a plasmid DNA preparation?
Measuring absorbance at 260/280 nm
Running a western blot
Using a mass spectrometer
Measuring pH of the solution
Explanation - 260/280 ratio indicates protein contamination in nucleic acid samples.
Correct answer is: Measuring absorbance at 260/280 nm
Q.111 What does 'bioinformatics' primarily involve?
Experimental wet‑lab techniques
Computational analysis of biological data
Chemical synthesis of drugs
Microscopy imaging
Explanation - Bioinformatics uses algorithms to interpret biological datasets like genomes and proteomes.
Correct answer is: Computational analysis of biological data
Q.112 Which of the following best describes 'RNA‑based therapeutics' besides vaccines?
RNA molecules that encode toxins
Messenger RNA (mRNA) that codes for therapeutic proteins or regulatory RNAs like siRNA
Only small RNAs used in research
Large plasmid DNA
Explanation - RNA therapeutics include mRNA, siRNA, and antisense oligonucleotides for disease treatment.
Correct answer is: Messenger RNA (mRNA) that codes for therapeutic proteins or regulatory RNAs like siRNA
Q.113 Which of these is NOT a characteristic of a 'promoter' in eukaryotic gene expression?
Contains a TATA box
Functions as a binding site for RNA polymerase II
Determines the start codon
Regulates transcription initiation
Explanation - Promoters control transcription initiation; the start codon is part of the coding sequence.
Correct answer is: Determines the start codon
Q.114 What is a key benefit of 'cell‑surface display' of proteins?
It eliminates the need for purification
It allows high‑throughput screening of protein–protein interactions on living cells
It increases the size of the protein
It reduces expression levels
Explanation - Display systems present proteins on the cell surface for rapid binding assays.
Correct answer is: It allows high‑throughput screening of protein–protein interactions on living cells
Q.115 In 'molecular cloning', what is the purpose of using a 'heat‑shock' step during bacterial transformation?
To denature plasmid DNA
To increase membrane permeability, allowing plasmid uptake
To kill bacteria
To activate restriction enzymes
Explanation - Heat shock temporarily disrupts the bacterial membrane, facilitating plasmid entry.
Correct answer is: To increase membrane permeability, allowing plasmid uptake
Q.116 Which of the following best describes a 'CRISPR‑Cas12a' system?
A DNA‑based gene silencing method
A variant of CRISPR that generates staggered DNA cuts and can be used for base editing
A tool for amplifying RNA
An ancient viral enzyme
Explanation - Cas12a creates sticky ends and is employed in precise genome editing.
Correct answer is: A variant of CRISPR that generates staggered DNA cuts and can be used for base editing
Q.117 Which of the following is a common feature of 'synthetic biology' in medicine?
Using only natural biological components
Designing novel genetic circuits to produce therapeutic compounds
Avoiding any computational modeling
Limiting to bacterial systems only
Explanation - Synthetic biology constructs engineered pathways for drug or protein production.
Correct answer is: Designing novel genetic circuits to produce therapeutic compounds
Q.118 What is the primary goal of 'pharmacogenomics'?
To discover new antibiotics
To study the genetic basis of drug response and tailor treatments to individual patients
To sequence all human genomes
To develop new surgical techniques
Explanation - Pharmacogenomics links genetics with drug efficacy and safety.
Correct answer is: To study the genetic basis of drug response and tailor treatments to individual patients
Q.119 Which of the following is an application of 'enzyme immobilization' in biotechnology?
Increasing enzyme turnover for industrial biocatalysis
Sequencing DNA strands
Producing antibiotics
Measuring gene expression
Explanation - Immobilized enzymes can be reused and have enhanced stability in industrial processes.
Correct answer is: Increasing enzyme turnover for industrial biocatalysis
Q.120 What is the main function of a 'tag' added to a recombinant protein?
To prevent the protein from folding
To facilitate purification, detection, or purification of the protein
To change the protein’s primary structure
To inhibit gene expression
Explanation - Tags like His or FLAG allow easy purification or detection via specific antibodies.
Correct answer is: To facilitate purification, detection, or purification of the protein
Q.121 Which of these is a key advantage of 'cell‑free protein synthesis' over cell‑based expression?
Requires living organisms for growth
Allows rapid synthesis without culturing cells
Cannot produce functional proteins
Is slower than cell‑based systems
Explanation - Cell‑free systems bypass cell growth, enabling fast protein production.
Correct answer is: Allows rapid synthesis without culturing cells
Q.122 What is the role of 'optogenetics' in molecular biology?
Using light to control the activity of proteins in living cells
Sequencing genomes using light sensors
Generating heat shock proteins
Creating DNA mutations via light exposure
Explanation - Optogenetics harnesses light‑responsive proteins to modulate cellular functions precisely.
Correct answer is: Using light to control the activity of proteins in living cells
Q.123 Which of the following best describes 'bioprinting'?
Printing books about biology
3D printing of living cells and biomaterials to create tissues or organs
Printing DNA sequences
Printing pharmaceutical drugs directly onto skin
Explanation - Bioprinting layers living cells to produce complex tissue constructs.
Correct answer is: 3D printing of living cells and biomaterials to create tissues or organs
Q.124 What is a major consideration when designing a 'CRISPR guide RNA' to minimize off‑target effects?
Using as many mismatches as possible
Choosing guide sequences with high specificity and low similarity to other genomic regions
Including repetitive sequences
Avoiding GC‑rich regions
Explanation - Specific guides reduce unintended binding and cleavage elsewhere in the genome.
Correct answer is: Choosing guide sequences with high specificity and low similarity to other genomic regions
Q.125 Which technique is used to isolate 'extracellular vesicles' from cell culture media?
Ultracentrifugation
PCR
Gel electrophoresis
Microscopy
Explanation - High‑speed centrifugation separates vesicles by size and density.
Correct answer is: Ultracentrifugation
Q.126 In a 'dual‑promoter' vector, why might researchers choose two different promoters?
To express two genes at identical levels
To control expression timing or levels of each gene independently
To increase plasmid size
To ensure both genes are silent
Explanation - Different promoters allow distinct expression patterns for multiple genes.
Correct answer is: To control expression timing or levels of each gene independently
Q.127 Which of the following is a primary application of 'gene editing in livestock'?
Improving crop yields
Reducing disease susceptibility and enhancing growth traits
Sequencing human genomes
Developing new antibiotics
Explanation - Gene editing modifies livestock genomes for better health and productivity.
Correct answer is: Reducing disease susceptibility and enhancing growth traits
Q.128 What is the primary use of a 'polyethylene glycol' (PEG) in recombinant protein production?
As a fluorescent dye
To precipitate proteins and aid purification
To act as a detergent
To stabilize DNA
Explanation - PEG reduces protein solubility, allowing selective precipitation.
Correct answer is: To precipitate proteins and aid purification
Q.129 Which of these is a common strategy for enhancing the immunogenicity of a subunit vaccine?
Using a live, attenuated virus
Adding an adjuvant like aluminum salts
Removing all glycosylation sites
Increasing the amount of antigen to the maximum
Explanation - Adjuvants boost the immune response to subunit antigens.
Correct answer is: Adding an adjuvant like aluminum salts
Q.130 In 'protein microarray' technology, what is typically spotted onto the array surface?
Whole organisms
Protein or peptide probes
Cells
Nucleic acids only
Explanation - Microarrays can detect interactions between proteins and various ligands.
Correct answer is: Protein or peptide probes
Q.131 What does 'GFP tagging' enable researchers to observe in living cells?
Gene expression levels in vitro
Real‑time protein localization and dynamics
Cell membrane potential
DNA replication fidelity
Explanation - GFP fusion proteins fluoresce, allowing live‑cell imaging of protein movement.
Correct answer is: Real‑time protein localization and dynamics
Q.132 Which of the following is NOT a characteristic of a 'phage display library'?
Thousands to billions of unique peptides displayed on phage surface
Use of bacterial hosts for production
Direct selection of binders to a target
Requirement for viral replication within mammalian cells
Explanation - Phage display is performed in bacteria, not mammalian systems.
Correct answer is: Requirement for viral replication within mammalian cells
Q.133 In a 'CRISPR‑Cas13' system, which nucleic acid is targeted?
DNA
RNA
Proteins
Lipids
Explanation - Cas13 is an RNA‑guided RNA‑seeking nuclease used for RNA editing or knockdown.
Correct answer is: RNA
Q.134 What is a common application of a 'nanoparticle‑based drug delivery system'?
Direct DNA sequencing
Targeted delivery of chemotherapeutic agents to tumor cells
Amplifying PCR reactions
Measuring protein concentration
Explanation - Nanoparticles can encapsulate drugs and deliver them selectively, reducing side effects.
Correct answer is: Targeted delivery of chemotherapeutic agents to tumor cells
Q.135 Which technique is used to identify the presence of specific DNA fragments after PCR?
Gel electrophoresis
Western blotting
Northern blotting
Mass spectrometry
Explanation - Gel electrophoresis separates DNA fragments by size, confirming PCR products.
Correct answer is: Gel electrophoresis
Q.136 What is the main purpose of using 'temperature‑sensitive plasmids' in research?
To ensure plasmid replication at all temperatures
To control plasmid replication based on temperature shifts
To increase antibiotic resistance
To produce proteins at high temperatures only
Explanation - Temperature‑sensitive plasmids allow researchers to modulate plasmid maintenance.
Correct answer is: To control plasmid replication based on temperature shifts
Q.137 Which of the following is a key step in a typical 'Western blot' protocol?
DNA extraction
Protein transfer from gel to membrane
RNA isolation
PCR amplification
Explanation - Transferring proteins onto a membrane is essential for antibody probing in Western blots.
Correct answer is: Protein transfer from gel to membrane
Q.138 Which of the following best describes a 'theranostic' agent?
A compound used only for imaging
A compound that provides both therapeutic and diagnostic functions
A molecule that degrades proteins
A vaccine that only diagnoses disease
Explanation - Theranostics combine treatment and diagnostic imaging into a single agent.
Correct answer is: A compound that provides both therapeutic and diagnostic functions
Q.139 What does the 'T7 promoter' control in an expression vector?
The transcription of the gene by T7 RNA polymerase
The replication of the plasmid
The selection of antibiotic resistance
The packaging of viral capsids
Explanation - The T7 promoter is recognized by T7 RNA polymerase for strong transcription in vitro and in bacteria.
Correct answer is: The transcription of the gene by T7 RNA polymerase
Q.140 Which of these is NOT a common method for purifying recombinant antibodies?
Protein A affinity chromatography
Ion exchange chromatography
Gel electrophoresis
Size exclusion chromatography
Explanation - Gel electrophoresis is not typically used for large‑scale antibody purification.
Correct answer is: Gel electrophoresis
Q.141 What is a primary benefit of using 'synthetic biology' to produce antibiotics?
It eliminates the need for bacterial cultures
It allows engineered microbial strains to produce novel or improved antibiotic compounds
It reduces the cost of sequencing
It avoids using any enzymes
Explanation - Synthetic biology designs pathways to yield new antibiotics or enhance yield.
Correct answer is: It allows engineered microbial strains to produce novel or improved antibiotic compounds
Q.142 Which of the following is a typical application of a 'CRISPR activation (CRISPRa)' system?
Knocking out genes
Enhancing gene transcription without cutting DNA
Deleting entire chromosomes
Sequencing DNA
Explanation - CRISPRa uses a catalytically inactive Cas9 fused to activation domains to upregulate genes.
Correct answer is: Enhancing gene transcription without cutting DNA
Q.143 What is the primary purpose of 'beta‑lactamase' in bacterial resistance?
To degrade antibiotics by breaking the beta‑lactam ring
To synthesize DNA
To bind antibodies
To phosphorylate proteins
Explanation - Beta‑lactamase hydrolyzes the β‑lactam ring of penicillins and cephalosporins.
Correct answer is: To degrade antibiotics by breaking the beta‑lactam ring
Q.144 In 'optogenetic therapy', light is used to control:
DNA replication
Enzyme activity or ion channel opening in specific cells
RNA splicing
Protein degradation
Explanation - Light‑responsive proteins can regulate neuronal firing or gene expression in targeted cells.
Correct answer is: Enzyme activity or ion channel opening in specific cells
Q.145 Which of the following is an example of a 'biomimetic material' used in tissue engineering?
Polystyrene
Hydrogel mimicking extracellular matrix
Silicone rubber
Plastic packaging
Explanation - Hydrogels replicate the natural extracellular environment, promoting cell growth.
Correct answer is: Hydrogel mimicking extracellular matrix
Q.146 What is the role of a 'signal peptide' in recombinant protein design?
To anchor the protein to the cell membrane
To direct the protein to the secretory pathway
To degrade the protein after translation
To make the protein fluorescent
Explanation - Signal peptides guide nascent polypeptides into the endoplasmic reticulum for secretion.
Correct answer is: To direct the protein to the secretory pathway
Q.147 Which technique is most appropriate for detecting protein‑protein interactions in vivo?
Co‑immunoprecipitation
Yeast two‑hybrid
Proximity ligation assay (PLA)
PCR
Explanation - PLA detects interactions inside cells with high specificity using antibody proximity.
Correct answer is: Proximity ligation assay (PLA)
Q.148 What is the main function of the 'reverse transcription' step in RT‑PCR?
To amplify DNA directly
To convert mRNA into complementary DNA (cDNA)
To degrade RNA
To sequence DNA
Explanation - Reverse transcription produces cDNA from RNA templates for subsequent PCR amplification.
Correct answer is: To convert mRNA into complementary DNA (cDNA)
Q.149 What is a common use of a 'bioluminescent enzyme' in a clinical assay?
To generate heat for cell culture
To produce light as a readout of enzymatic activity for diagnostic purposes
To synthesize antibodies
To fragment DNA
Explanation - Bioluminescence provides a sensitive signal in diagnostic tests like ELISA variants.
Correct answer is: To produce light as a readout of enzymatic activity for diagnostic purposes
Q.150 Which of these is a primary advantage of 'enzyme‑linked immunosorbent assay (ELISA)'?
It detects protein–DNA interactions only
It provides quantitative measurement of antigen or antibody concentrations in samples
It can only detect nucleic acids
It requires live cells
Explanation - ELISA uses antibodies and enzyme labels for sensitive, quantitative detection.
Correct answer is: It provides quantitative measurement of antigen or antibody concentrations in samples
Q.151 What is the role of a 'glycosyltransferase' in protein production?
To attach sugar moieties to proteins during post‑translational modification
To cleave glycosidic bonds in carbohydrates
To polymerize DNA strands
To degrade proteins
Explanation - Glycosyltransferases add sugars to proteins, affecting stability and function.
Correct answer is: To attach sugar moieties to proteins during post‑translational modification
Q.152 What is a primary feature of 'CRISPR‑Cas9 base editors'?
They cause double‑strand breaks for large deletions
They directly convert one DNA base to another without cutting the DNA backbone
They function only in bacteria
They are used for RNA sequencing
Explanation - Base editors fuse a deaminase to Cas9 nickase, enabling precise base changes.
Correct answer is: They directly convert one DNA base to another without cutting the DNA backbone
Q.153 Which of the following best describes a 'phage display library'?
A collection of bacterial plasmids for antibiotic resistance
A library of peptides displayed on phage surfaces for selecting binders
A set of mammalian expression constructs
A database of genomic sequences
Explanation - Phage display allows high‑throughput screening of peptide or protein ligands.
Correct answer is: A library of peptides displayed on phage surfaces for selecting binders
Q.154 What is the purpose of using a 'heat‑shock' step during bacterial transformation?
To denature plasmid DNA
To increase membrane permeability, allowing plasmid uptake
To kill bacteria
To activate restriction enzymes
Explanation - Heat shock temporarily disrupts the bacterial membrane, facilitating plasmid entry.
Correct answer is: To increase membrane permeability, allowing plasmid uptake
Q.155 Which of the following is NOT an advantage of using a 'synthetic gene circuit' for therapeutic purposes?
Precise control of gene expression
Ability to program cellular behavior
Increased off‑target effects
Integration of multiple inputs for complex responses
Explanation - Synthetic circuits are designed to minimize unintended interactions, not increase them.
Correct answer is: Increased off‑target effects
Q.156 What is the main reason for using a 'fluorescence‑activated cell sorter (FACS)' in a molecular biology lab?
To amplify DNA
To sort and analyze cells based on fluorescent labeling
To sequence proteins
To measure enzyme activity
Explanation - FACS separates cells according to fluorescence intensity, enabling population analyses.
Correct answer is: To sort and analyze cells based on fluorescent labeling
Q.157 Which of these is a key application of 'microRNA' (miRNA) in medicine?
Acting as a structural component of ribosomes
Regulating gene expression post‑transcriptionally and serving as diagnostic biomarkers
Encoding enzymes for DNA replication
Serving as a vaccine vector
Explanation - miRNAs bind mRNAs to suppress translation or promote degradation.
Correct answer is: Regulating gene expression post‑transcriptionally and serving as diagnostic biomarkers