1What is the primary basis of biotechnology as a field?
Discussion on thrust research area- Biotechnology
Easy
A.Design of mechanical engines
B.Study of only non-living chemical reactions
C.Analysis of geological rock formations
D.Use of living organisms or their systems to develop products
Correct Answer: Use of living organisms or their systems to develop products
Explanation:
Biotechnology uses living organisms, cells, or biological systems to create useful products and processes.
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2Which color of biotechnology is associated with medical and pharmaceutical applications?
Discussion on thrust research area- Biotechnology
Easy
A.Blue biotechnology
B.Green biotechnology
C.White biotechnology
D.Red biotechnology
Correct Answer: Red biotechnology
Explanation:
Red biotechnology refers to the medical and pharmaceutical sector, including drugs and vaccines.
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3Which color of biotechnology deals with agriculture and crops?
Discussion on thrust research area- Biotechnology
Easy
A.Blue biotechnology
B.Red biotechnology
C.Green biotechnology
D.White biotechnology
Correct Answer: Green biotechnology
Explanation:
Green biotechnology is applied to agricultural processes such as developing improved crops.
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4A thrust research area in a field refers to:
Discussion on thrust research area- Biotechnology
Easy
A.An outdated topic no longer studied
B.A priority area receiving focused attention and funding
C.A subject unrelated to the field
D.A purely theoretical concept with no application
Correct Answer: A priority area receiving focused attention and funding
Explanation:
A thrust area is a high-priority research domain that receives concentrated resources and effort.
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5Genetic engineering primarily involves:
Discussion on thrust research area- Biotechnology
Easy
A.Direct manipulation of an organism's genes
B.Measurement of soil pH
C.Study of animal behavior only
D.Design of computer hardware
Correct Answer: Direct manipulation of an organism's genes
Explanation:
Genetic engineering is the direct alteration of an organism's DNA to achieve desired traits.
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6Which of the following is a major thrust area in modern biotechnology?
Discussion on thrust research area- Biotechnology
Easy
A.Genomics and gene sequencing
B.Mechanical clock repair
C.Manual pottery making
D.Traditional glass blowing
Correct Answer: Genomics and gene sequencing
Explanation:
Genomics is a leading thrust area, focusing on sequencing and analyzing entire genomes.
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7The full form of DNA is:
Discussion on thrust research area- Biotechnology
Easy
A.Deoxyribonucleic acid
B.Dinucleic acid
C.Double nucleotide acid
D.Deoxyribose amino acid
Correct Answer: Deoxyribonucleic acid
Explanation:
DNA stands for deoxyribonucleic acid, the molecule carrying genetic instructions.
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8PCR technique is used mainly to:
Discussion on thrust research area- Biotechnology
Easy
A.Generate electricity
B.Purify drinking water
C.Measure blood pressure
D.Amplify specific DNA sequences
Correct Answer: Amplify specific DNA sequences
Explanation:
PCR (Polymerase Chain Reaction) amplifies targeted DNA segments into many copies.
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9Which thrust area focuses on producing biofuels from biological sources?
Discussion on thrust research area- Biotechnology
Easy
A.Astronomy
B.Nuclear physics
C.Metallurgy
D.Bioenergy biotechnology
Correct Answer: Bioenergy biotechnology
Explanation:
Bioenergy biotechnology develops fuels like bioethanol and biodiesel from biological materials.
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10CRISPR-Cas9 is best known as a tool for:
Discussion on thrust research area- Biotechnology
Easy
A.Water filtration
B.Signal transmission
C.Gene editing
D.Metal cutting
Correct Answer: Gene editing
Explanation:
CRISPR-Cas9 is a widely used technology for precise editing of genes.
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11Blue biotechnology is associated with:
Discussion on thrust research area- Biotechnology
Easy
A.Marine and aquatic organisms
B.Coal mining
C.Desert plant farming
D.Space exploration
Correct Answer: Marine and aquatic organisms
Explanation:
Blue biotechnology focuses on marine and aquatic resources for products and processes.
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12A vaccine works primarily by:
Discussion on thrust research area- Biotechnology
Easy
A.Replacing damaged bones
B.Stimulating the immune system to build protection
C.Directly killing all body cells
D.Cooling the body temperature
Correct Answer: Stimulating the immune system to build protection
Explanation:
Vaccines train the immune system to recognize and defend against specific pathogens.
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13Bioinformatics is the field that combines biology with:
Discussion on thrust research area- Biotechnology
Easy
A.Computer science and data analysis
B.Textile weaving
C.Road construction
D.Mechanical welding
Correct Answer: Computer science and data analysis
Explanation:
Bioinformatics uses computational tools to store, analyze, and interpret biological data.
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14Recombinant DNA technology allows scientists to:
Discussion on thrust research area- Biotechnology
Easy
A.Combine DNA from different sources
B.Detect earthquakes
C.Refine crude oil
D.Measure atmospheric pressure
Correct Answer: Combine DNA from different sources
Explanation:
Recombinant DNA technology joins DNA from different organisms to create new gene combinations.
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15Stem cell research is important mainly because stem cells can:
Discussion on thrust research area- Biotechnology
Easy
A.Emit visible light
B.Convert directly into metals
C.Store electrical charge
D.Develop into many different cell types
Correct Answer: Develop into many different cell types
Explanation:
Stem cells are valued for their ability to differentiate into various specialized cell types.
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16White biotechnology is primarily applied in:
Discussion on thrust research area- Biotechnology
Easy
A.Volcano monitoring
B.Industrial processes and manufacturing
C.Weather forecasting
D.Deep space missions
Correct Answer: Industrial processes and manufacturing
Explanation:
White biotechnology uses biological systems for industrial production, such as enzymes and biofuels.
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17A genetically modified organism (GMO) is one whose:
Discussion on thrust research area- Biotechnology
Easy
A.Diet has been changed naturally
B.Genetic material has been artificially altered
C.Habitat has been relocated
D.Body has been physically painted
Correct Answer: Genetic material has been artificially altered
Explanation:
A GMO has its genetic material modified using genetic engineering techniques.
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18Bioremediation uses living organisms mainly to:
Discussion on thrust research area- Biotechnology
Easy
A.Melt frozen glaciers
B.Build tall skyscrapers
C.Clean up environmental pollutants
D.Increase noise pollution
Correct Answer: Clean up environmental pollutants
Explanation:
Bioremediation employs microbes or plants to break down and remove contaminants from the environment.
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19Fermentation in biotechnology is commonly used to produce:
Discussion on thrust research area- Biotechnology
Easy
A.Glass windows
B.Plastic pipes
C.Steel beams
D.Antibiotics and alcohol
Correct Answer: Antibiotics and alcohol
Explanation:
Fermentation by microorganisms is used to produce products like antibiotics, alcohol, and enzymes.
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20Tissue culture in biotechnology refers to growing cells or tissues:
Discussion on thrust research area- Biotechnology
Easy
A.Only inside living animals
B.In an artificial nutrient medium
C.Inside metal containers without nutrients
D.In dry desert soil
Correct Answer: In an artificial nutrient medium
Explanation:
Tissue culture involves growing cells, tissues, or organs in a sterile artificial nutrient medium.
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21A research team wants to correct a single point mutation in a patient's genome with minimal off-target effects and without introducing double-strand breaks. Which gene-editing approach is most appropriate?
Discussion on thrust research area- Biotechnology
Medium
A.Base editing
B.RNA interference
C.Random transposon mutagenesis
D.Zinc finger nuclease knockout
Correct Answer: Base editing
Explanation:
Base editors convert one nucleotide to another without creating double-strand breaks, making them ideal for precise correction of point mutations with reduced off-target damage.
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22In a monoclonal antibody production process, a scientist observes low product titer despite high cell viability. Which upstream parameter should be optimized first to improve specific productivity?
Discussion on thrust research area- Biotechnology
Medium
A.Culture feeding and nutrient supplementation
B.Vial fill volume during packaging
C.Column chromatography resin type
D.Final formulation buffer pH
Correct Answer: Culture feeding and nutrient supplementation
Explanation:
Titer depends on upstream culture conditions. Optimizing feeding strategy sustains cell metabolism and boosts specific productivity, whereas chromatography, buffer, and fill relate to downstream/formulation steps.
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23A biotech firm develops a Bt cotton variety expressing the cry1Ac gene. What is the primary agricultural advantage this confers?
Discussion on thrust research area- Biotechnology
Medium
A.Tolerance to soil salinity
B.Increased seed oil content
C.Resistance to specific insect pests
D.Resistance to fungal blight
Correct Answer: Resistance to specific insect pests
Explanation:
The cry1Ac gene encodes a Bt toxin lethal to certain lepidopteran larvae, providing built-in insect pest resistance and reducing chemical pesticide use.
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24During PCR optimization, non-specific bands appear on the gel. Increasing which parameter is most likely to improve amplification specificity?
Discussion on thrust research area- Biotechnology
Medium
A.Annealing temperature
B.Number of cycles
C. concentration
D.Template concentration
Correct Answer: Annealing temperature
Explanation:
Raising the annealing temperature increases primer-template stringency, reducing mispriming and non-specific bands. Higher cycles, template, or often worsen non-specific products.
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25A metabolic engineer wants a microbe to overproduce a target amino acid. Which strategy would most directly increase flux toward the product?
Discussion on thrust research area- Biotechnology
Medium
A.Using a smaller inoculum size
B.Knocking out competing branch-point pathways
C.Reducing the fermenter working volume
D.Lowering the incubation temperature to
Correct Answer: Knocking out competing branch-point pathways
Explanation:
Eliminating competing pathways redirects carbon and precursor flux toward the desired product, a core metabolic engineering strategy. The other options do not redirect metabolic flux.
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26A vaccine developer chooses an mRNA platform over a traditional inactivated-virus platform for a rapidly mutating pathogen. What is the main reason for this choice?
Discussion on thrust research area- Biotechnology
Medium
A.Guaranteed lifelong immunity
B.Rapid redesign and manufacturing turnaround
C.Elimination of any need for clinical trials
D.No need for cold-chain storage
Correct Answer: Rapid redesign and manufacturing turnaround
Explanation:
mRNA platforms allow the antigen sequence to be quickly updated and manufactured, ideal for fast-evolving pathogens. They still require cold storage and clinical testing.
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27In a bioremediation project, engineers deploy microbes to degrade oil spills. Which term best describes enhancing native microbial activity by adding nutrients?
Discussion on thrust research area- Biotechnology
Medium
A.Bioleaching
B.Biostimulation
C.Biomagnification
D.Bioaugmentation
Correct Answer: Biostimulation
Explanation:
Biostimulation adds nutrients or electron acceptors to boost native microbial degradation. Bioaugmentation adds external microbes, while the other terms describe unrelated processes.
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28A researcher fuses a target protein's gene to a GFP gene to study its cellular location. This is an example of which technique?
Discussion on thrust research area- Biotechnology
Medium
A.Southern blotting
B.Reporter gene tagging
C.Restriction fragment length polymorphism
D.Site-directed mutagenesis
Correct Answer: Reporter gene tagging
Explanation:
Fusing a gene to GFP creates a fluorescent reporter that reveals protein localization in living cells, a standard reporter-tagging approach.
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29A CAR-T cell therapy is being designed to target cancer cells. What component of the CAR gives it antigen specificity?
Discussion on thrust research area- Biotechnology
Medium
A.Transmembrane hinge region
B.Single-chain variable fragment (scFv)
C.Costimulatory 4-1BB domain
D.CD3 signaling domain
Correct Answer: Single-chain variable fragment (scFv)
Explanation:
The scFv, derived from an antibody, recognizes the tumor antigen and confers target specificity. The signaling and costimulatory domains drive T-cell activation, not specificity.
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30In an industrial fermentation, dissolved oxygen drops sharply during exponential growth. What is the most appropriate immediate corrective action?
Discussion on thrust research area- Biotechnology
Medium
A.Lower the temperature setpoint
B.Add more carbon source
C.Increase agitation and aeration rate
D.Reduce the stirrer speed
Correct Answer: Increase agitation and aeration rate
Explanation:
High oxygen demand during exponential growth lowers dissolved oxygen. Increasing agitation and aeration raises oxygen transfer to meet demand; reducing stirring or adding carbon worsens it.
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31A plant biotechnologist regenerates whole plants from a single somatic cell in culture. This demonstrates which cellular property?
Discussion on thrust research area- Biotechnology
Medium
A.Pluripotency
B.Senescence
C.Totipotency
D.Apoptosis
Correct Answer: Totipotency
Explanation:
Totipotency is the ability of a single cell to divide and differentiate into an entire organism, the basis of plant tissue-culture regeneration.
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32A diagnostic lab needs to detect a specific pathogen's RNA quantitatively in patient samples. Which technique is most suitable?
Discussion on thrust research area- Biotechnology
Medium
A.Gel electrophoresis
B.Gram staining
C.ELISA for antibodies
D.RT-qPCR
Correct Answer: RT-qPCR
Explanation:
RT-qPCR reverse-transcribes RNA and quantifies it in real time, enabling sensitive detection of pathogen RNA. The other methods detect proteins, size, or morphology, not RNA quantity.
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33A synthetic biology team wants tunable control over a gene's expression level in E. coli. Which element should they modify?
Discussion on thrust research area- Biotechnology
Medium
A.Ribosome binding site strength
B.Plasmid backbone color
C.Origin of replication
D.Antibiotic resistance marker
Correct Answer: Ribosome binding site strength
Explanation:
Ribosome binding site strength directly tunes translation efficiency and protein output. The origin and resistance marker control replication and selection, not expression level.
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34In stem cell research, induced pluripotent stem cells (iPSCs) are created from adult cells. Which set of factors is classically used for reprogramming?
Discussion on thrust research area- Biotechnology
Medium
A.Oct4, Sox2, Klf4, c-Myc
B.Insulin, glucagon, leptin
C.IL-2, IL-6, TNF-
D.p53, Rb, PTEN
Correct Answer: Oct4, Sox2, Klf4, c-Myc
Explanation:
The Yamanaka factors Oct4, Sox2, Klf4, and c-Myc reprogram differentiated cells into pluripotent stem cells. The others are hormones, tumor suppressors, or cytokines.
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35A biofuel researcher engineers algae to accumulate more lipids for biodiesel. Limiting which nutrient commonly triggers lipid accumulation?
Discussion on thrust research area- Biotechnology
Medium
A.Carbon dioxide
B.Light
C.Nitrogen
D.Water
Correct Answer: Nitrogen
Explanation:
Nitrogen starvation shifts algal metabolism toward lipid (triacylglycerol) storage, a widely used strategy to boost biodiesel feedstock.
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36A protein purification workflow uses a His-tagged recombinant protein. Which chromatography method exploits this tag?
Discussion on thrust research area- Biotechnology
Medium
A.Ion exchange chromatography
B.Size exclusion chromatography
C.Immobilized metal affinity chromatography (IMAC)
D.Reverse-phase chromatography
Correct Answer: Immobilized metal affinity chromatography (IMAC)
Explanation:
His-tags bind immobilized or ions in IMAC, allowing selective purification. The other methods separate by size or charge, not tag affinity.
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37A team studies gene function by silencing an mRNA transcript without altering the genome. Which technology fits this requirement?
Discussion on thrust research area- Biotechnology
Medium
A.Chemical mutagenesis
B.CRISPR knockout
C.RNA interference (RNAi)
D.Homologous recombination
Correct Answer: RNA interference (RNAi)
Explanation:
RNAi uses small RNAs to degrade or block target mRNA, silencing gene expression post-transcriptionally without changing the DNA sequence.
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38In next-generation sequencing, a researcher reports coverage for a genome. What does this value indicate?
Discussion on thrust research area- Biotechnology
Medium
A.Each base is sequenced on average 30 times
B.The error rate is 30 per million bases
C.The genome is 30 megabases long
D.30% of reads passed quality filtering
Correct Answer: Each base is sequenced on average 30 times
Explanation:
Coverage (depth) of means each nucleotide is read about 30 times on average, improving confidence in base calls and variant detection.
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39A tissue engineer designs a scaffold for growing cartilage. Which scaffold property is most critical for supporting cell infiltration and nutrient exchange?
Discussion on thrust research area- Biotechnology
Medium
A.Magnetic responsiveness
B.Interconnected porosity
C.High electrical conductivity
D.Bright coloration
Correct Answer: Interconnected porosity
Explanation:
Interconnected pores allow cells to migrate inward and permit nutrient and waste exchange, essential for viable tissue formation on scaffolds.
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40A pharmaceutical company produces human insulin using recombinant E. coli. Why must the bacterial system be carefully engineered for this human protein?
Discussion on thrust research area- Biotechnology
Medium
A.Bacteria destroy all foreign proteins instantly
B.Bacteria cannot replicate plasmid DNA
C.Bacteria lack machinery for some post-translational modifications
D.Bacteria cannot grow in liquid culture
Correct Answer: Bacteria lack machinery for some post-translational modifications
Explanation:
Prokaryotes lack certain modification systems (e.g., glycosylation) and proper disulfide-bond formation, so processes are engineered to yield correctly folded, active human insulin.
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41A CRISPR-Cas9 experiment targeting a disease locus shows high on-target editing but unacceptable off-target cleavage. Which strategy provides the most mechanistically sound reduction in off-target activity without reducing on-target efficiency below usable levels?
Discussion on thrust research area- Biotechnology
Hard
A.Removing the PAM-proximal seed region requirement from guide design
B.Using high-fidelity Cas9 variants (e.g., SpCas9-HF1 or eSpCas9) that weaken non-specific DNA contacts
C.Increasing the concentration of wild-type Cas9 ribonucleoprotein delivered to cells
D.Extending the sgRNA spacer to 25 nt to increase total binding energy
Correct Answer: Using high-fidelity Cas9 variants (e.g., SpCas9-HF1 or eSpCas9) that weaken non-specific DNA contacts
Explanation:
High-fidelity variants introduce mutations that reduce non-specific DNA backbone contacts, raising the specificity threshold so mismatched sites are rejected while true targets are still cleaved. Higher enzyme dose worsens off-target activity, and longer/altered guides typically reduce efficiency or specificity.
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42In metabolic engineering of E. coli for a heterologous pathway, flux is limited by an intermediate that is toxic at high concentration. Which control strategy best balances yield and viability?
Discussion on thrust research area- Biotechnology
Hard
A.Lowering culture temperature permanently to slow all metabolism
B.Deleting all competing pathways to force flux through the target route
C.A dynamic sensor-regulator that couples downstream enzyme expression to intermediate concentration
D.Constitutive maximal overexpression of every pathway enzyme simultaneously
Correct Answer: A dynamic sensor-regulator that couples downstream enzyme expression to intermediate concentration
Explanation:
Dynamic regulation (metabolite-responsive biosensors driving downstream enzymes) autonomously drains the toxic intermediate as it accumulates, preventing buildup while sustaining flux. Static maximal overexpression or blunt deletions ignore the dynamic nature of toxicity.
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43A monoclonal antibody produced in CHO cells shows batch-to-batch variation in efficacy traced to glycosylation. Which factor is the primary critical quality attribute driving antibody-dependent cellular cytotoxicity (ADCC)?
Discussion on thrust research area- Biotechnology
Hard
A.Number of disulfide bonds in the hinge region
B.Total protein concentration in the final formulation
C.Isoelectric point of the light chain
D.Core fucosylation level of the Fc N-glycan
Correct Answer: Core fucosylation level of the Fc N-glycan
Explanation:
Afucosylated antibodies bind FcγRIIIa with much higher affinity, dramatically enhancing ADCC. This is why afucosylation is a targeted glycoengineering strategy. The other attributes affect stability or charge but not ADCC potency directly.
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44In an RNA-seq differential expression study with only 3 replicates per condition, which statistical concern is most critical to address for valid conclusions?
Discussion on thrust research area- Biotechnology
Hard
A.Increasing sequencing depth to compensate for low replicate number
B.Reporting only fold-change without any p-values
C.Using raw read counts without any normalization
D.Multiple testing correction combined with shrinkage estimation of dispersion
Correct Answer: Multiple testing correction combined with shrinkage estimation of dispersion
Explanation:
With thousands of genes tested, false discovery control (e.g., Benjamini-Hochberg) is essential, and low replicate counts require shrinkage of gene-wise dispersion estimates (as in DESeq2/edgeR) for reliable variance. Deeper sequencing cannot substitute for biological replication.
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45A biosensor uses an aptamer that undergoes conformational change upon target binding. The measured dissociation constant is nM. At a target concentration of nM, what approximate fraction of aptamer is bound at equilibrium?
Discussion on thrust research area- Biotechnology
Hard
A.Approximately
B.Approximately
C.Approximately
D.Approximately
Correct Answer: Approximately
Explanation:
Fraction bound , i.e. about . Since target concentration is well below , only a small fraction is bound.
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46In developing an mRNA vaccine, why is incorporation of N1-methylpseudouridine instead of uridine a critical innovation?
Discussion on thrust research area- Biotechnology
Hard
A.It eliminates the need for a lipid nanoparticle delivery system
B.It reduces innate immune activation and increases translation of the mRNA
C.It increases the melting temperature of the mRNA duplex for storage
D.It allows the mRNA to integrate stably into the host genome
Correct Answer: It reduces innate immune activation and increases translation of the mRNA
Explanation:
Modified nucleosides like N1-methylpseudouridine evade RNA sensors (e.g., TLRs, RIG-I), reducing type I interferon responses that otherwise degrade mRNA and suppress translation, thereby boosting antigen expression. mRNA does not integrate and still requires delivery vehicles.
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47A fed-batch bioreactor exhibits declining productivity late in culture despite adequate nutrients. Metabolic analysis shows lactate and ammonia accumulation. Which intervention most directly addresses the underlying cause?
Discussion on thrust research area- Biotechnology
Hard
A.Doubling the dissolved oxygen setpoint above saturation
B.Adding more antifoam to reduce surface bubbling
C.Controlled glucose feeding to limit overflow metabolism and byproduct formation
D.Increasing agitation speed to maximize shear on cells
Correct Answer: Controlled glucose feeding to limit overflow metabolism and byproduct formation
Explanation:
Lactate and ammonia accumulate from overflow metabolism when glucose is abundant. Restricting glucose via controlled feeding shifts cells toward oxidative metabolism, reducing toxic byproducts. Excess DO or shear can harm cells; antifoam addresses a different problem.
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48In a genome-wide association study (GWAS), a SNP reaches . With independent tests and a genome-wide significance threshold of , how should this result be interpreted?
Discussion on thrust research area- Biotechnology
Hard
A.Genome-wide significant and ready for clinical application
B.Significant only if the sample size exceeds one million individuals
C.Not genome-wide significant; likely a false positive requiring replication
D.Definitively causal for the phenotype under study
Correct Answer: Not genome-wide significant; likely a false positive requiring replication
Explanation:
The p-value () does not pass the Bonferroni-derived genome-wide threshold (). Even if it did, association is not causation and replication is required. GWAS hits are typically tag SNPs, not proven causal variants.
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49A synthetic biology team designs a toggle switch with two mutually repressing genes. For robust bistability, which parameter condition is most essential?
Discussion on thrust research area- Biotechnology
Hard
A.Sufficiently high cooperativity (Hill coefficient ) in the repression functions
B.Absence of any leaky basal transcription from either promoter
C.Identical promoter strengths for both genes at all times
D.Equal and low degradation rates of both repressor proteins
Correct Answer: Sufficiently high cooperativity (Hill coefficient ) in the repression functions
Explanation:
Bistability in a mutual-repression toggle requires ultrasensitivity, achieved when the Hill coefficient exceeds 1 (cooperative repression). Without sufficient nonlinearity the system has a single stable state. Symmetric parameters help but are not strictly required for bistability.
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50In CAR-T cell therapy, tonic (antigen-independent) signaling causes premature T-cell exhaustion. Which design change most effectively mitigates this without abolishing antigen-specific activation?
Discussion on thrust research area- Biotechnology
Hard
A.Increasing the affinity of the scFv for its target antigen
B.Removing the CD3ζ signaling domain entirely
C.Switching the costimulatory domain from CD28 to 4-1BB (CD137)
D.Using a shorter hinge region regardless of antigen epitope location
Correct Answer: Switching the costimulatory domain from CD28 to 4-1BB (CD137)
Explanation:
4-1BB costimulation promotes memory phenotype and reduces exhaustion associated with the strong, sustained signaling of CD28-based CARs. Higher affinity can worsen tonic signaling, and removing CD3ζ eliminates activation entirely.
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51A protein engineering effort uses directed evolution. After several rounds, fitness plateaus below the target. Which explanation and remedy is most consistent with fitness-landscape theory?
Discussion on thrust research area- Biotechnology
Hard
A.Random mutations always improve fitness, so more rounds guarantee success
B.The population is trapped in a local optimum; increasing mutational diversity or recombination can enable escape
C.Selection pressure was too weak; it should simply be increased indefinitely
D.The protein has reached its physical maximum activity and cannot improve
Correct Answer: The population is trapped in a local optimum; increasing mutational diversity or recombination can enable escape
Explanation:
Fitness plateaus often reflect local optima on a rugged landscape. Increasing diversity (higher mutation rate, larger libraries) or recombination (DNA shuffling) allows exploration of new regions to escape the local peak. Simply raising selection stringency cannot cross fitness valleys.
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52In single-cell RNA sequencing, a 'batch effect' between two samples processed on different days obscures biological signal. Which approach best corrects this while preserving true biological variation?
Discussion on thrust research area- Biotechnology
Hard
A.Removing all genes that differ between the two batches from the analysis
B.Integration methods that align shared cell states while retaining condition-specific differences (e.g., mutual nearest neighbors)
C.Merging the raw count matrices without any correction
D.Analyzing each batch entirely separately and never comparing them
Correct Answer: Integration methods that align shared cell states while retaining condition-specific differences (e.g., mutual nearest neighbors)
Explanation:
Integration algorithms (MNN, Harmony, Seurat CCA) identify corresponding cell populations across batches and correct technical offsets while preserving genuine biological differences. Deleting variable genes or ignoring batches loses information or leaves confounding intact.
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53A recombinant protein forms inclusion bodies in E. coli. Which combination of interventions is most likely to increase soluble yield of correctly folded protein?
Discussion on thrust research area- Biotechnology
Hard
A.Maximizing inducer concentration to drive the strongest expression
B.Using a stronger promoter with a high copy-number plasmid only
C.Increasing growth temperature to accelerate folding kinetics
D.Lowering induction temperature and co-expressing molecular chaperones
Correct Answer: Lowering induction temperature and co-expressing molecular chaperones
Explanation:
Reduced temperature slows translation, allowing proper folding, and chaperones assist folding of nascent chains, both reducing aggregation into inclusion bodies. Stronger/maximal expression typically worsens misfolding and inclusion body formation.
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54In an enzyme kinetics assay, adding a compound decreases but leaves unchanged. What type of inhibition is this, and what does it imply mechanistically?
Discussion on thrust research area- Biotechnology
Hard
A.Non-competitive inhibition; the inhibitor binds a site distinct from the active site regardless of substrate binding
B.Competitive inhibition; the inhibitor competes directly for the active site
C.Uncompetitive inhibition; the inhibitor binds only the enzyme-substrate complex
D.Substrate inhibition; excess substrate blocks catalysis at high concentration
Correct Answer: Non-competitive inhibition; the inhibitor binds a site distinct from the active site regardless of substrate binding
Explanation:
Classic non-competitive inhibition lowers (fewer functional enzyme molecules) but leaves unchanged because the inhibitor binds equally to free enzyme and ES complex at an allosteric site. Competitive inhibition raises ; uncompetitive lowers both.
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55A gene therapy uses AAV vectors, but pre-existing neutralizing antibodies limit efficacy in a subset of patients. Which strategy addresses this specific barrier most directly?
Discussion on thrust research area- Biotechnology
Hard
A.Using an alternative AAV serotype or engineered capsid that evades existing antibodies
B.Switching the promoter from a tissue-specific to a ubiquitous one
C.Increasing the transgene size to exceed the packaging limit
D.Reducing the vector dose to below the immunogenic threshold
Correct Answer: Using an alternative AAV serotype or engineered capsid that evades existing antibodies
Explanation:
Neutralizing antibodies are capsid-specific, so an alternative serotype or capsid engineered to escape recognition restores transduction. Dose reduction lowers efficacy, promoter choice affects expression not neutralization, and exceeding packaging limits breaks the vector.
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56In a proteomics experiment using label-free quantification, low-abundance proteins are inconsistently detected across runs ('missing values'). Which handling strategy risks introducing the least bias?
Discussion on thrust research area- Biotechnology
Hard
A.Replacing all missing values with zero before statistical testing
B.Discarding any protein with a single missing value across all runs
C.Distinguishing missing-not-at-random from missing-at-random and imputing accordingly
D.Replacing missing values with the global mean of all proteins
Correct Answer: Distinguishing missing-not-at-random from missing-at-random and imputing accordingly
Explanation:
Missing values in MS often reflect below-detection-limit (MNAR) rather than random loss (MAR); appropriate imputation (e.g., left-censored for MNAR, KNN for MAR) minimizes bias. Zero-filling or global-mean imputation distorts distributions, and aggressive filtering loses real signal.
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57A biofuel project engineers algae for enhanced lipid accumulation. Nitrogen starvation boosts lipid content but halts growth. Which engineering approach best resolves this growth-vs-lipid tradeoff?
Discussion on thrust research area- Biotechnology
Hard
A.Decoupling lipid biosynthesis from stress by overexpressing key lipogenic regulators under nutrient-replete conditions
B.Permanently maintaining nitrogen starvation to maximize lipid fraction
C.Increasing light intensity far beyond the photosynthetic saturation point
D.Deleting all photosynthesis genes to redirect carbon to lipids
Correct Answer: Decoupling lipid biosynthesis from stress by overexpressing key lipogenic regulators under nutrient-replete conditions
Explanation:
Engineering constitutive expression of lipid-pathway regulators (e.g., DGAT, transcription factors) lets cells accumulate lipids while still growing under replete nutrients, breaking the growth-lipid antagonism. Sustained starvation sacrifices biomass; removing photosynthesis eliminates the carbon source.
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58In a phylogenetic analysis, two genes give conflicting tree topologies for the same set of species. Which explanation should be evaluated first before concluding the species tree is wrong?
Discussion on thrust research area- Biotechnology
Hard
A.The species definitely evolved twice independently by convergence
B.The sequencing was contaminated in all samples equally
C.Molecular clocks never apply to any protein-coding genes
D.Incomplete lineage sorting or horizontal gene transfer causing gene-tree/species-tree discordance
Correct Answer: Incomplete lineage sorting or horizontal gene transfer causing gene-tree/species-tree discordance
Explanation:
Gene trees can differ from the species tree due to biological processes like incomplete lineage sorting, horizontal gene transfer, or hidden paralogy. These are the standard first explanations for discordance, not immediately assuming a wrong species tree or contamination.
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59A downstream purification uses affinity chromatography with a His-tag. The eluted protein co-purifies with a persistent contaminant. Which follow-up step is most rational to identify and remove it?
Discussion on thrust research area- Biotechnology
Hard
A.Add an orthogonal polishing step such as size-exclusion or ion-exchange chromatography
B.Elute at a much lower pH to denature the target protein
C.Remove the His-tag from the construct and skip affinity purification
D.Increase imidazole in the wash buffer to M for all steps
Correct Answer: Add an orthogonal polishing step such as size-exclusion or ion-exchange chromatography
Explanation:
Contaminants co-eluting on affinity resin (often native His-rich proteins or nonspecific binders) are best removed by an orthogonal separation exploiting a different property (size or charge). Extreme imidazole/pH can strip or denature the target, and removing the tag defeats the capture strategy.
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60In designing an antibody-drug conjugate (ADC), the drug-to-antibody ratio (DAR) is a critical parameter. Why is a very high DAR (e.g., ) often counterproductive?
Discussion on thrust research area- Biotechnology
Hard
A.It reduces pharmacokinetic stability and increases aggregation and clearance, lowering efficacy
B.It eliminates the need for a cleavable linker between drug and antibody
C.It always increases target selectivity and reduces off-target toxicity
D.It guarantees higher tumor penetration due to increased hydrophilicity
Correct Answer: It reduces pharmacokinetic stability and increases aggregation and clearance, lowering efficacy
Explanation:
High DAR increases hydrophobicity, promoting aggregation and faster plasma clearance, which paradoxically reduces delivered payload and efficacy despite more drug per antibody. Optimal DAR (often ~3-4) balances potency and stability.
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