Q.1 What is the primary purpose of a genetic toggle switch in synthetic biology?
To amplify electrical signals in a circuit
To enable reversible switching between two gene expression states
To increase the speed of DNA replication
To provide resistance to antibiotics
Explanation - A genetic toggle switch consists of two mutually repressing genes, allowing the system to stably exist in either of two states until an external stimulus flips it.
Correct answer is: To enable reversible switching between two gene expression states
Q.2 Which of the following components is NOT typically part of a synthetic gene circuit?
Promoter
Repressor protein
Transistor
Reporter gene
Explanation - Transistors are electronic components; synthetic gene circuits use biological parts such as promoters, repressors, and reporters.
Correct answer is: Transistor
Q.3 In a repressilator, how many genes are usually arranged in a feedback loop to produce oscillations?
Two
Three
Four
Five
Explanation - The classic repressilator consists of three genes that each repress the next, creating a cyclic negative feedback loop that generates oscillations.
Correct answer is: Three
Q.4 Which modeling framework is most commonly used for describing the dynamics of synthetic biological circuits?
Finite element analysis
Ordinary differential equations (ODEs)
Monte Carlo simulation
Fourier transform
Explanation - ODEs capture the continuous change of concentrations of biomolecules over time and are standard for modeling gene circuit dynamics.
Correct answer is: Ordinary differential equations (ODEs)
Q.5 What does the term ‘orthogonal’ refer to in the context of synthetic biology parts?
Components that operate independently of the host’s native machinery
Components that are physically perpendicular
Components that produce light
Components that enhance electrical conductivity
Explanation - Orthogonal parts function without cross‑talk with endogenous cellular processes, allowing predictable behavior.
Correct answer is: Components that operate independently of the host’s native machinery
Q.6 Which of the following best describes a ‘biosensor’ built using synthetic biology?
A device that converts light into electricity
A living cell that produces a measurable output in response to a specific chemical
A metal electrode that detects pH changes
A computer algorithm that predicts protein folding
Explanation - Synthetic biosensors employ engineered cells that generate signals such as fluorescence when they detect a target molecule.
Correct answer is: A living cell that produces a measurable output in response to a specific chemical
Q.7 In the context of systems biotechnology, what does the term ‘metabolic flux analysis’ (MFA) aim to quantify?
The electrical resistance of a cell membrane
The rate at which metabolites flow through metabolic pathways
The number of genes in a genome
The speed of RNA polymerase transcription
Explanation - MFA uses isotopic labeling and mathematical modeling to estimate the flow of metabolites through a network, informing pathway engineering.
Correct answer is: The rate at which metabolites flow through metabolic pathways
Q.8 Which of the following is a common chassis organism for synthetic biology applications?
Escherichia coli
Homo sapiens
Canis lupus
Agaricus bisporus
Explanation - E. coli is well‑characterized, easy to manipulate, and widely used as a host for engineered genetic constructs.
Correct answer is: Escherichia coli
Q.9 What role does a ‘ribosome binding site’ (RBS) play in a synthetic gene construct?
It determines where transcription starts
It recruits RNA polymerase to DNA
It initiates translation by aligning ribosomes with the start codon
It degrades mRNA after transcription
Explanation - The RBS is a sequence upstream of the start codon that helps the ribosome bind and begin protein synthesis.
Correct answer is: It initiates translation by aligning ribosomes with the start codon
Q.10 Which of the following techniques is used to integrate a synthetic pathway into the genome of a host organism?
Electrophoresis
CRISPR‑Cas9 mediated genome editing
Western blotting
Spectrophotometry
Explanation - CRISPR‑Cas9 enables precise insertion of DNA sequences into specific genomic loci, facilitating stable expression of synthetic pathways.
Correct answer is: CRISPR‑Cas9 mediated genome editing
Q.11 In a synthetic biology project, why might a researcher use a ‘deadman switch’?
To ensure the system continues operating indefinitely
To cause cell death if a containment condition fails
To increase the speed of DNA replication
To amplify the signal from a promoter
Explanation - A deadman switch is a safety mechanism that triggers cell death when a required condition (e.g., presence of a specific molecule) is not met, preventing uncontrolled spread.
Correct answer is: To cause cell death if a containment condition fails
Q.12 Which of the following best describes a ‘modular’ approach in synthetic biology?
Using interchangeable biological parts that can be combined in different configurations
Building circuits only with electronic components
Studying only natural gene networks
Focusing on single‑gene mutations
Explanation - Modularity allows standardized parts (promoters, RBSs, coding sequences, terminators) to be mixed‑and‑matched to create diverse functions.
Correct answer is: Using interchangeable biological parts that can be combined in different configurations
Q.13 What does the abbreviation ‘iGEM’ stand for?
International Gene Engineering Marathon
Integrated Genetic Engineering Model
International Genetically Engineered Machine
Innovative Genome Editing Method
Explanation - iGEM is a worldwide synthetic biology competition that encourages students to build and test engineered biological systems.
Correct answer is: International Genetically Engineered Machine
Q.14 In the context of synthetic and systems biotechnology, a ‘flux balance analysis’ (FBA) model primarily assumes which of the following?
All reactions proceed at their maximum possible rates
The system is in a steady state with no accumulation of metabolites
Enzyme concentrations are unlimited
Temperature is constant across the cell
Explanation - FBA computes feasible flux distributions under the steady‑state assumption (dC/dt = 0 for each metabolite).
Correct answer is: The system is in a steady state with no accumulation of metabolites
Q.15 Which fluorescent protein is most commonly used as a reporter in synthetic biology circuits?
Hemoglobin
GFP (Green Fluorescent Protein)
Myosin
Cytochrome c
Explanation - GFP emits green fluorescence when excited, allowing easy, non‑invasive monitoring of gene expression.
Correct answer is: GFP (Green Fluorescent Protein)
Q.16 What is a key advantage of using a cell‑free transcription‑translation (TX‑TL) system for prototyping synthetic circuits?
It eliminates the need for DNA
It provides a rapid, controllable environment without living cells
It increases the mutation rate of DNA
It allows direct measurement of electrical currents
Explanation - Cell‑free systems allow quick testing of genetic designs in vitro, avoiding the complexities of cellular metabolism.
Correct answer is: It provides a rapid, controllable environment without living cells
Q.17 Which of the following is a common metric used to assess the performance of a synthetic gene circuit?
Signal‑to‑noise ratio
Thermal conductivity
Magnetic permeability
Dielectric constant
Explanation - Signal‑to‑noise ratio quantifies how distinguishable the intended output is from background variability.
Correct answer is: Signal‑to‑noise ratio
Q.18 In systems biology, the term ‘omics’ refers to:
The study of electrical circuits
High‑throughput comprehensive analyses of biological molecules (e.g., genomics, proteomics)
Measurement of mechanical properties of cells
Design of synthetic polymers
Explanation - ‘Omics’ disciplines generate large datasets that can be integrated to model whole‑cell behavior.
Correct answer is: High‑throughput comprehensive analyses of biological molecules (e.g., genomics, proteomics)
Q.19 Which of the following best describes a ‘kill switch’ in engineered microbes?
A genetic circuit that triggers cell death under specific conditions
A device that turns off an electrical power supply
A promoter that enhances transcription
A protein that accelerates DNA replication
Explanation - Kill switches improve biosafety by ensuring engineered organisms cannot survive outside defined environments.
Correct answer is: A genetic circuit that triggers cell death under specific conditions
Q.20 What does the term ‘chassis’ refer to in synthetic biology?
The metal frame of a bioreactor
The host organism that carries engineered genetic parts
The software used for data analysis
The power supply for a laboratory instrument
Explanation - A chassis provides the cellular machinery needed for expression of synthetic constructs.
Correct answer is: The host organism that carries engineered genetic parts
Q.21 Which computational tool is widely used for designing DNA parts and checking for restriction sites?
MATLAB
SnapGene
AutoCAD
LabVIEW
Explanation - SnapGene allows visualization, editing, and verification of DNA sequences, including restriction enzyme analysis.
Correct answer is: SnapGene
Q.22 In a synthetic metabolic pathway, the term ‘flux bottleneck’ refers to:
A step that limits the overall throughput of the pathway
A gene that is overexpressed
A region of DNA with high GC content
A protein that fluoresces brightly
Explanation - Identifying bottlenecks helps engineers target enzymes for overexpression or engineering to improve product yields.
Correct answer is: A step that limits the overall throughput of the pathway
Q.23 Which of the following is NOT a standard biological part in the BioBrick format?
Promoter
Ribosome Binding Site
Terminator
Diode
Explanation - Diodes are electronic components; BioBrick parts are biological sequences such as promoters, RBSs, coding regions, and terminators.
Correct answer is: Diode
Q.24 What is the main advantage of using a ‘constitutive promoter’ in a synthetic circuit?
It turns on gene expression only in response to an inducer
It provides a constant level of transcription regardless of environmental conditions
It degrades mRNA quickly
It blocks translation
Explanation - Constitutive promoters drive steady gene expression, useful when a constant output is required.
Correct answer is: It provides a constant level of transcription regardless of environmental conditions
Q.25 Which method can be used to measure the concentration of a metabolite produced by an engineered pathway?
Western blotting
Gas chromatography–mass spectrometry (GC‑MS)
Electrocardiography
X‑ray diffraction
Explanation - GC‑MS separates and identifies small molecules, making it suitable for quantifying metabolic products.
Correct answer is: Gas chromatography–mass spectrometry (GC‑MS)
Q.26 In the design of a synthetic quorum‑sensing system, which molecule typically acts as the signaling autoinducer?
cAMP
N‑acyl‑homoserine lactone (AHL)
ATP
Glucose
Explanation - AHLs are common autoinducers in Gram‑negative bacteria used to coordinate population‑level responses.
Correct answer is: N‑acyl‑homoserine lactone (AHL)
Q.27 Which of the following best explains why synthetic biologists use insulated promoters?
To prevent transcriptional read‑through from neighboring genes
To increase the voltage across a membrane
To enhance the magnetic field in a cell
To reduce the size of the DNA construct
Explanation - Insulated promoters contain terminators and other elements that block interference from upstream or downstream transcription.
Correct answer is: To prevent transcriptional read‑through from neighboring genes
Q.28 What is the purpose of a ‘reporter assay’ in synthetic biology?
To measure the electrical resistance of a circuit
To assess the activity of a genetic element by linking it to a detectable output
To calculate the mass of a protein
To determine the pH of a solution
Explanation - Reporter assays couple promoters or other parts to a measurable signal (e.g., fluorescence) to quantify their function.
Correct answer is: To assess the activity of a genetic element by linking it to a detectable output
Q.29 Which of the following best describes a ‘synthetic riboswitch’?
A DNA sequence that binds proteins
An RNA element that changes conformation upon binding a small molecule to regulate translation
A protein that transports ions across membranes
A lipid that forms vesicles
Explanation - Synthetic riboswitches enable ligand‑dependent control of gene expression at the translational level.
Correct answer is: An RNA element that changes conformation upon binding a small molecule to regulate translation
Q.30 In a synthetic biology context, the term ‘load’ usually refers to:
The electrical current drawn by a device
The demand placed on cellular resources (e.g., ribosomes, ATP) by an introduced circuit
The weight of a petri dish
The amount of light entering a spectrophotometer
Explanation - High genetic load can reduce host growth and affect circuit performance, so engineers aim to minimize it.
Correct answer is: The demand placed on cellular resources (e.g., ribosomes, ATP) by an introduced circuit
Q.31 Which of the following is an example of a ‘dynamic’ synthetic circuit?
A constitutive expression system
A circuit that produces oscillations over time
A plasmid that never replicates
A gene that is always silent
Explanation - Dynamic circuits change their output over time, such as oscillators or pulse generators.
Correct answer is: A circuit that produces oscillations over time
Q.32 What is the purpose of using a ‘strong terminator’ downstream of a gene in a synthetic construct?
To increase transcription initiation
To halt transcription and prevent read‑through into downstream sequences
To enhance ribosome binding
To degrade the mRNA quickly
Explanation - A strong terminator ensures that RNA polymerase stops at the intended location, providing insulation between genetic parts.
Correct answer is: To halt transcription and prevent read‑through into downstream sequences
Q.33 Which of the following best describes the concept of ‘design‑build‑test‑learn’ (DBTL) in synthetic biology?
A linear manufacturing process for electronic chips
An iterative workflow that cycles through designing, constructing, testing, and refining biological systems
A method for measuring voltage in cells
A technique for sequencing genomes
Explanation - DBTL accelerates development by incorporating data from each test back into the design phase.
Correct answer is: An iterative workflow that cycles through designing, constructing, testing, and refining biological systems
Q.34 When engineering a pathway for production of a non‑native compound, why is it often necessary to knock out competing native pathways?
To reduce the cell’s ability to divide
To divert precursor metabolites toward the desired product and increase yield
To make the cell more electrically conductive
To increase the cell’s size
Explanation - Eliminating competing pathways minimizes loss of substrates and improves the efficiency of the engineered route.
Correct answer is: To divert precursor metabolites toward the desired product and increase yield
Q.35 Which of the following statements about ‘CRISPRi’ (CRISPR interference) is true?
It creates double‑strand breaks in DNA
It uses a dead Cas9 protein to block transcription without cutting DNA
It integrates new genes into the genome
It enhances the speed of ribosome movement
Explanation - CRISPRi represses gene expression by sterically hindering RNA polymerase binding or elongation.
Correct answer is: It uses a dead Cas9 protein to block transcription without cutting DNA
Q.36 In a synthetic circuit, a ‘feed‑forward loop’ is a network motif where:
A gene directly regulates itself
A regulator controls a target gene both directly and indirectly through an intermediate
All genes are expressed at the same time
The circuit produces only a single output
Explanation - Feed‑forward loops can generate precise timing, pulse generation, or noise filtering in gene networks.
Correct answer is: A regulator controls a target gene both directly and indirectly through an intermediate
Q.37 Which of the following is a common challenge when scaling up a synthetic biological production process from the lab to an industrial bioreactor?
Maintaining consistent temperature only
Ensuring the engineered pathway remains stable and high‑yielding under large‑scale conditions
Keeping the bioreactor dark
Reducing the amount of water used
Explanation - Scale‑up can introduce stresses, oxygen gradients, and mutations that affect circuit performance; stability engineering is essential.
Correct answer is: Ensuring the engineered pathway remains stable and high‑yielding under large‑scale conditions
Q.38 Which of the following is a typical use for a synthetic biology platform in the field of medicine?
Creating renewable energy from solar panels
Engineering bacteria to produce therapeutic proteins or deliver drugs in situ
Designing faster computer processors
Building stronger concrete
Explanation - Engineered microbes can be programmed to sense disease markers and release treatments directly at the site.
Correct answer is: Engineering bacteria to produce therapeutic proteins or deliver drugs in situ
Q.39 What is a ‘plasmid copy number’ and why does it matter in synthetic circuit design?
The number of plasmids per cell; it influences gene dosage and expression level
The number of genes on a chromosome; it determines cell size
The number of electrons transferred per second; it affects conductivity
The number of ribosomes in a cell; it determines protein synthesis speed
Explanation - High‑copy plasmids can boost expression but increase metabolic burden; low‑copy plasmids reduce burden but may give weaker signals.
Correct answer is: The number of plasmids per cell; it influences gene dosage and expression level
Q.40 Which of the following is a characteristic of a ‘digital’ synthetic gene circuit?
It produces a continuous gradient of output
It yields discrete ON/OFF states, similar to binary logic
It changes the color of the cell membrane
It reduces the cell’s ATP production
Explanation - Digital circuits are designed to give clear high (ON) or low (OFF) outputs, facilitating logic operations in cells.
Correct answer is: It yields discrete ON/OFF states, similar to binary logic
Q.41 In metabolic engineering, what does the term ‘heterologous expression’ refer to?
Expression of a gene in its native organism
Expression of a gene from one organism in a different host organism
Expression of RNA without translation
Expression of proteins only in the presence of light
Explanation - Heterologous expression allows production of enzymes or pathways not naturally present in the host.
Correct answer is: Expression of a gene from one organism in a different host organism
Q.42 Which of the following is NOT a typical output measured in a synthetic biosensor assay?
Fluorescence intensity
Electrical current
Colorimetric change
Magnetization of the cell
Explanation - Biosensors commonly use fluorescence, luminescence, color change, or electrochemical signals—not magnetic properties.
Correct answer is: Magnetization of the cell
Q.43 When designing a synthetic pathway for biofuel production, why might a researcher choose a thermophilic host organism?
Thermophiles grow faster at room temperature
Higher temperatures can increase reaction rates and reduce contamination
Thermophiles have larger genomes for more genes
Thermophiles emit light for easy detection
Explanation - Thermophilic hosts operate at elevated temperatures, which can improve enzyme kinetics and limit growth of unwanted microbes.
Correct answer is: Higher temperatures can increase reaction rates and reduce contamination
Q.44 Which of the following best defines ‘synthetic lethality’ in the context of engineered microbes?
A pair of genes where loss of either is viable, but loss of both is lethal
A gene that causes the cell to glow
A mutation that makes cells resistant to antibiotics
A circuit that produces excess ATP
Explanation - Synthetic lethality can be exploited for safety switches, where two redundant essential functions are engineered to fail only under specific conditions.
Correct answer is: A pair of genes where loss of either is viable, but loss of both is lethal
Q.45 In a synthetic gene circuit, a ‘delay element’ is used to:
Increase the speed of transcription
Introduce a timed lag between input and output, shaping dynamic response
Reduce the length of DNA
Make the circuit produce more proteins per minute
Explanation - Delay elements (e.g., RNA degradation tags, slow promoters) help generate pulses, oscillations, or filter noise.
Correct answer is: Introduce a timed lag between input and output, shaping dynamic response
Q.46 Which analytical method is most suitable for quantifying a fluorescent reporter protein in a cell population?
Flow cytometry
Gel electrophoresis
Nuclear magnetic resonance (NMR)
X‑ray crystallography
Explanation - Flow cytometry measures fluorescence intensity of individual cells rapidly, giving population‑level data.
Correct answer is: Flow cytometry
Q.47 What does the ‘Hill coefficient’ indicate in the context of a synthetic transcriptional regulator’s response curve?
The maximum fluorescence intensity
The degree of cooperativity in ligand binding
The number of plasmids per cell
The length of the promoter sequence
Explanation - A higher Hill coefficient (>1) signifies cooperative binding, leading to steeper response curves.
Correct answer is: The degree of cooperativity in ligand binding
Q.48 Which of the following is a common strategy to reduce metabolic burden when expressing a large synthetic pathway?
Using high‑copy plasmids for all genes
Balancing expression levels by using promoters of varying strengths
Increasing the temperature to 50 °C
Adding extra ribosomes to the cell
Explanation - Tuning promoter strengths helps distribute resources evenly, minimizing stress on the host.
Correct answer is: Balancing expression levels by using promoters of varying strengths
Q.49 Which of the following best describes the purpose of a ‘library’ of genetic parts in synthetic biology?
A collection of electronic components
A curated set of interchangeable DNA sequences that can be assembled in many combinations
A list of antibiotics
A database of animal species
Explanation - Part libraries enable rapid design and testing of diverse genetic constructs.
Correct answer is: A curated set of interchangeable DNA sequences that can be assembled in many combinations
Q.50 In the context of systems biotechnology, what is a ‘genome‑scale metabolic model’ (GSMM)?
A model that predicts the electrical activity of a cell
A computational reconstruction of all metabolic reactions encoded by an organism’s genome
A diagram of the cell’s structural proteins
A map of neuronal connections
Explanation - GSMMs integrate genomic data with stoichiometry to simulate cellular metabolism at the whole‑cell level.
Correct answer is: A computational reconstruction of all metabolic reactions encoded by an organism’s genome
Q.51 Which of the following is a primary advantage of using a ‘cell‑surface display’ system for enzyme engineering?
Enzymes are secreted into the medium, making purification easier
Enzymes are anchored on the cell surface, allowing direct access to substrates without cell lysis
Enzymes become fluorescent
Enzymes gain resistance to high temperatures
Explanation - Surface display enables whole‑cell biocatalysis and facilitates screening of enzyme variants.
Correct answer is: Enzymes are anchored on the cell surface, allowing direct access to substrates without cell lysis
Q.52 Which of the following is an example of a ‘non‑model organism’ that has been engineered for production of a valuable chemical?
Saccharomyces cerevisiae
Pseudomonas putida
Escherichia coli
Bacillus subtilis
Explanation - P. putida is not a traditional model organism but has been engineered for bioremediation and production of aromatic compounds.
Correct answer is: Pseudomonas putida
Q.53 What is the main purpose of using a ‘dual‑reporter system’ in a synthetic circuit experiment?
To increase the brightness of fluorescence
To simultaneously monitor two different outputs, allowing normalization and detection of circuit behavior
To reduce the size of the plasmid
To make the cells magnetic
Explanation - Dual reporters (e.g., GFP and RFP) help control for variability and provide internal standards.
Correct answer is: To simultaneously monitor two different outputs, allowing normalization and detection of circuit behavior
Q.54 Which of the following best explains why a synthetic biologist might use a ‘split‑protein’ design?
To create a protein that can be reconstituted only when two separate parts interact, enabling conditional activity
To make the protein larger
To increase the rate of transcription
To change the protein’s color
Explanation - Split‑protein systems provide control, as activity is restored only when both fragments are brought together (e.g., by a ligand).
Correct answer is: To create a protein that can be reconstituted only when two separate parts interact, enabling conditional activity
Q.55 In synthetic biology, a ‘biobrick’ is:
A metallic component used in bioreactors
A standardized DNA part with defined flanking sequences for easy assembly
A type of bacteria that lives in bricks
A protein that binds to brick-shaped molecules
Explanation - Biobricks follow the RFC 10 standard, allowing parts to be combined using restriction enzyme cloning.
Correct answer is: A standardized DNA part with defined flanking sequences for easy assembly
Q.56 Which of the following is a typical reason to employ a ‘synthetic promoter library’?
To vary the strength of transcription across many levels for fine‑tuning gene expression
To increase the temperature tolerance of the host
To make the DNA sequence shorter
To change the cell’s shape
Explanation - Promoter libraries provide a range of transcriptional outputs, enabling precise control of circuit dynamics.
Correct answer is: To vary the strength of transcription across many levels for fine‑tuning gene expression
Q.57 What does the term ‘chassis engineering’ refer to in synthetic biology?
Modifying the host organism’s genome to improve compatibility with synthetic parts
Designing the outer case of a bioreactor
Creating new electronic components
Building a physical robot to handle cells
Explanation - Chassis engineering optimizes the host’s metabolism, reduces background activity, and enhances stability of engineered constructs.
Correct answer is: Modifying the host organism’s genome to improve compatibility with synthetic parts
Q.58 Which of the following is NOT a typical element of a synthetic ‘logic gate’ implemented in a cell?
Promoter
Repressor
AND/OR logic defined by transcriptional regulation
Capacitor
Explanation - Capacitors are electronic components; cellular logic gates rely on transcriptional regulators and promoters.
Correct answer is: Capacitor
Q.59 Why is it often necessary to include a ‘selection marker’ on a plasmid used for synthetic biology experiments?
To allow the host cells to glow under UV light
To enable growth of only those cells that have successfully taken up the plasmid (e.g., antibiotic resistance)
To increase the plasmid size
To change the cell’s pH
Explanation - Selection markers (antibiotic resistance genes) ensure that only transformed cells survive under selective conditions.
Correct answer is: To enable growth of only those cells that have successfully taken up the plasmid (e.g., antibiotic resistance)
Q.60 In the context of synthetic biology, ‘orthogonal ribosomes’ are used to:
Translate a specific set of mRNAs without interfering with the host’s native translation
Increase the electrical conductivity of the cell membrane
Pump protons across the membrane
Generate light inside the cell
Explanation - Orthogonal ribosome–mRNA pairs enable dedicated translation of synthetic genes, reducing cross‑talk.
Correct answer is: Translate a specific set of mRNAs without interfering with the host’s native translation
Q.61 Which of the following best describes a ‘synthetic pathway’ for the production of a bio‑derived polymer?
A natural route found in wild‑type organisms
A designed set of enzymatic steps introduced into a host to convert simple feedstocks into the polymer
A method of polymerizing plastics chemically
A process that uses only physical forces
Explanation - Synthetic pathways are engineered to channel metabolites toward non‑native products, such as polyhydroxyalkanoates.
Correct answer is: A designed set of enzymatic steps introduced into a host to convert simple feedstocks into the polymer
Q.62 Which of the following is an advantage of using ‘RNA‑based regulation’ (e.g., ribozymes, aptamers) over protein‑based regulation in synthetic circuits?
RNA regulators are always faster to evolve
RNA regulators can function without consuming cellular resources for translation
RNA regulators are more stable than proteins
RNA regulators do not interact with metabolites
Explanation - RNA‑based control uses existing transcripts, reducing the metabolic load of producing additional proteins.
Correct answer is: RNA regulators can function without consuming cellular resources for translation
Q.63 Which of the following best characterizes the concept of ‘systems biotechnology’?
The study of electronic circuits in biological systems
The integration of systems biology data with engineering principles to design and optimize biological production platforms
The use of microscopes to view cells
The construction of large‑scale mechanical devices for biology
Explanation - Systems biotechnology leverages holistic models and high‑throughput data to guide rational engineering of microbes and cells.
Correct answer is: The integration of systems biology data with engineering principles to design and optimize biological production platforms
Q.64 What is the main function of a ‘terminator’ in a synthetic transcription unit?
To start transcription
To stop transcription and release the RNA polymerase
To enhance translation initiation
To degrade the plasmid
Explanation - Terminators signal the end of transcription, preventing read‑through and ensuring proper mRNA termination.
Correct answer is: To stop transcription and release the RNA polymerase
Q.65 In a CRISPR‑based gene activation system (CRISPRa), what is the role of a catalytically dead Cas9 (dCas9) fused to an activation domain?
To cut DNA at the target site
To bind a promoter region and recruit transcriptional machinery, enhancing gene expression
To degrade mRNA
To inhibit ribosome binding
Explanation - dCas9 lacks nuclease activity but can be guided to DNA, where an activation domain up‑regulates transcription.
Correct answer is: To bind a promoter region and recruit transcriptional machinery, enhancing gene expression
Q.66 Which of the following is a typical challenge when using high‑throughput DNA synthesis for creating large libraries of synthetic parts?
Limited availability of electricity
Errors (mutations) introduced during synthesis that require verification
Inability to store DNA at low temperatures
Excessive magnetic fields
Explanation - Synthesis errors can lead to non‑functional parts; sequencing and error‑correction steps are essential.
Correct answer is: Errors (mutations) introduced during synthesis that require verification
Q.67 Which of the following best describes a ‘synthetic operon’?
A cluster of engineered genes transcribed together from a single promoter, mimicking natural operons
A set of electronic components controlling a circuit
A single gene with multiple promoters
A group of proteins that form a membrane channel
Explanation - Synthetic operons allow coordinated expression of multiple enzymes or regulators.
Correct answer is: A cluster of engineered genes transcribed together from a single promoter, mimicking natural operons
Q.68 What is a primary reason to employ a ‘dynamic control system’ (e.g., feedback regulation) in a production strain?
To keep the pathway permanently off
To adjust enzyme levels in response to metabolite concentrations, improving yield and preventing toxicity
To make the cells change color
To increase the cell’s size
Explanation - Dynamic regulation can balance pathway flux, avoid buildup of intermediates, and enhance overall productivity.
Correct answer is: To adjust enzyme levels in response to metabolite concentrations, improving yield and preventing toxicity
Q.69 Which of the following is a common metric used to evaluate the efficiency of a synthetic pathway for chemical production?
Voltage across the cell membrane
Yield (g product per g substrate) and productivity (g/L·h)
Number of chromosomes
Length of the DNA sequence
Explanation - Yield and productivity quantify how much product is generated from feedstock and how fast, reflecting process performance.
Correct answer is: Yield (g product per g substrate) and productivity (g/L·h)
Q.70 Which of the following best explains why a synthetic biologist might use a ‘dual‑input AND gate’ in a microbial sensor?
To ensure the output is produced only when two specific environmental signals are present simultaneously
To double the fluorescence intensity
To make the cell divide faster
To increase the temperature of the culture
Explanation - An AND gate requires both inputs to be high, providing specificity and reducing false‑positive responses.
Correct answer is: To ensure the output is produced only when two specific environmental signals are present simultaneously
Q.71 In the context of synthetic biology safety, what does the term ‘biocontainment’ refer to?
Physical barriers preventing lab access
Genetic strategies that limit the survival or spread of engineered organisms outside controlled environments
Using thicker petri dishes
Storing cells at low temperatures
Explanation - Biocontainment includes kill switches, auxotrophies, and dependency on synthetic nutrients to prevent environmental release.
Correct answer is: Genetic strategies that limit the survival or spread of engineered organisms outside controlled environments
Q.72 Which of the following is a common approach to increase the stability of a plasmid in a host without using antibiotics?
Increasing the temperature of the culture
Using a toxin‑antitoxin (addiction) system that kills cells losing the plasmid
Adding extra sugars to the medium
Shaking the culture faster
Explanation - Addiction systems create a selective pressure for plasmid retention without external antibiotics.
Correct answer is: Using a toxin‑antitoxin (addiction) system that kills cells losing the plasmid
Q.73 What is the primary purpose of a ‘metabolic model validation’ step in systems biotechnology?
To confirm that the computational predictions match experimental measurements of fluxes or growth rates
To adjust the pH of the culture medium
To change the color of the cells
To increase the speed of DNA replication
Explanation - Validation ensures that the model accurately reflects real cellular behavior before using it for design decisions.
Correct answer is: To confirm that the computational predictions match experimental measurements of fluxes or growth rates
Q.74 Which of the following best defines a ‘synthetic minimal genome’ project?
Sequencing the smallest possible natural genome
Designing and constructing a genome that contains only the essential genes required for life
Deleting all DNA from a cell
Creating a genome that can only produce fluorescent proteins
Explanation - Minimal genome efforts aim to reduce genomic complexity, providing a clean chassis for synthetic biology.
Correct answer is: Designing and constructing a genome that contains only the essential genes required for life
Q.75 In a synthetic pathway for producing a terpene, which enzyme class is typically responsible for the final cyclization step?
Kinases
Terpene synthases
Polymerases
Ligases
Explanation - Terpene synthases catalyze the formation of cyclic terpene structures from linear precursors.
Correct answer is: Terpene synthases
Q.76 Which of the following is an example of an ‘all‑osteric’ regulatory mechanism used in synthetic circuits?
A protein that changes conformation upon binding a small molecule, altering its DNA‑binding activity
A promoter that is always on
A ribosome that translates faster at high temperature
A cell wall that becomes rigid
Explanation - Allosteric regulation involves ligand‑induced structural changes that modify protein function, useful for sensor designs.
Correct answer is: A protein that changes conformation upon binding a small molecule, altering its DNA‑binding activity
Q.77 What does the term ‘flux balance analysis (FBA)’ assume about metabolite concentrations in a cell?
All metabolites are at equilibrium
Metabolite concentrations change rapidly over time
The system is at steady‑state (net accumulation is zero)
Metabolites are only present in the extracellular medium
Explanation - FBA uses mass‑balance constraints (S·v = 0) to compute feasible flux distributions under steady‑state conditions.
Correct answer is: The system is at steady‑state (net accumulation is zero)
Q.78 Which of the following best describes a ‘synthetic genetic circuit’ that functions as a ‘memory device’?
A circuit that only produces a transient pulse
A circuit that can retain a state (ON or OFF) after the initial stimulus is removed
A circuit that continuously oscillates
A circuit that degrades all its components quickly
Explanation - Memory devices use bistable switches or recombinase-based systems to store information in DNA or epigenetic states.
Correct answer is: A circuit that can retain a state (ON or OFF) after the initial stimulus is removed
Q.79 In the design of a synthetic pathway for producing an amino acid, why might a researcher overexpress a transporter gene?
To increase the import of precursor substrates or export of the product, alleviating toxicity
To make the cell change color
To increase the rate of DNA replication
To decrease the cell’s ATP levels
Explanation - Transporters can improve substrate uptake or product secretion, enhancing overall production efficiency.
Correct answer is: To increase the import of precursor substrates or export of the product, alleviating toxicity
Q.80 Which of the following best illustrates the concept of ‘systems‑level optimization’ in synthetic biotechnology?
Tuning a single promoter for higher expression
Simultaneously adjusting multiple pathway enzymes, host metabolism, and regulatory circuits based on model predictions
Changing the temperature of the incubator
Adding more agar to plates
Explanation - Systems‑level optimization integrates multi‑scale data to achieve balanced, high‑performance production.
Correct answer is: Simultaneously adjusting multiple pathway enzymes, host metabolism, and regulatory circuits based on model predictions
Q.81 Which of the following is a commonly used reporter gene for detecting gene expression in anaerobic bacteria?
GFP
mCherry
lacZ (β‑galactosidase)
luciferase
Explanation - β‑galactosidase activity can be measured colorimetrically under anaerobic conditions where fluorescent proteins may not fold properly.
Correct answer is: lacZ (β‑galactosidase)
Q.82 What is the main function of a ‘synthetic ribosome binding site (RBS) calculator’?
To predict the strength of translation initiation based on RBS sequence
To calculate the electrical resistance of a cell
To estimate the weight of a plasmid
To determine the optimal temperature for growth
Explanation - RBS calculators estimate translation rates, helping designers choose sequences that give desired protein levels.
Correct answer is: To predict the strength of translation initiation based on RBS sequence
Q.83 In a synthetic biology project, why might a researcher use a ‘split‑intein’ system?
To separate DNA strands during replication
To covalently join two protein fragments after translation, enabling conditional protein assembly
To increase the speed of transcription
To change the cell’s shape
Explanation - Split‑inteins mediate protein splicing, allowing modular assembly of functional proteins only when both parts are present.
Correct answer is: To covalently join two protein fragments after translation, enabling conditional protein assembly
Q.84 Which of the following best describes the purpose of a ‘metabolite sensor’ in a dynamic pathway control system?
To detect the concentration of a key intermediate and adjust enzyme expression accordingly
To measure the temperature of the culture
To record the cell’s lineage
To change the cell’s shape
Explanation - Metabolite sensors provide feedback that can up‑ or down‑regulate pathway enzymes, maintaining optimal flux.
Correct answer is: To detect the concentration of a key intermediate and adjust enzyme expression accordingly
Q.85 Which of the following is a typical characteristic of a ‘high‑throughput’ synthetic biology workflow?
Testing one construct at a time
Automation, parallel cloning, and rapid screening of large libraries of designs
Manually pipetting each reaction
Using only glassware
Explanation - High‑throughput pipelines employ robotics and multiplexed assays to accelerate design–build–test cycles.
Correct answer is: Automation, parallel cloning, and rapid screening of large libraries of designs
Q.86 What is the main advantage of using a ‘modular cloning (MoClo)’ system over traditional restriction enzyme cloning?
It allows scar‑less assembly of multiple DNA parts in a single reaction
It eliminates the need for DNA altogether
It requires no enzymes
It makes DNA invisible
Explanation - MoClo uses Type IIS restriction enzymes to create seamless junctions, enabling rapid construction of complex circuits.
Correct answer is: It allows scar‑less assembly of multiple DNA parts in a single reaction
Q.87 In a synthetic biology context, which of the following best defines a ‘chassis‑dependent’ phenotype?
A trait that appears only when a specific host organism is used
A property that is independent of the host
A color change in the medium
A change in the temperature of the incubator
Explanation - Chassis‑dependent phenotypes arise from interactions between the engineered construct and host‑specific physiology.
Correct answer is: A trait that appears only when a specific host organism is used
Q.88 Which of the following is a common method for verifying that a synthetic pathway has been successfully integrated into the genome?
PCR screening followed by sequencing of the integration site
Measuring the pH of the culture broth
Observing colony morphology
Weighing the petri dish
Explanation - PCR amplifies the target region to confirm correct insertion, and sequencing validates the exact DNA sequence.
Correct answer is: PCR screening followed by sequencing of the integration site
Q.89 Why might a synthetic biologist incorporate a ‘ribosome‑binding site (RBS) spacer’ of varying length upstream of the start codon?
To alter the distance between the RBS and start codon, fine‑tuning translation initiation efficiency
To change the DNA’s color
To increase the cell’s resistance to antibiotics
To modify the cell’s membrane potential
Explanation - Spacer length influences ribosome access and can modulate protein expression levels.
Correct answer is: To alter the distance between the RBS and start codon, fine‑tuning translation initiation efficiency
Q.90 Which of the following best describes the purpose of a ‘synthetic gene circuit’ that implements a ‘pulse generator’?
To maintain constant high expression
To produce a brief, transient burst of gene expression in response to a stimulus
To permanently silence a gene
To change the cell’s shape
Explanation - Pulse generators create timed expression windows, useful for applications requiring short‑lived signals.
Correct answer is: To produce a brief, transient burst of gene expression in response to a stimulus
Q.91 In a synthetic biology workflow, what is the role of ‘DNA part annotation’?
Adding descriptive metadata (function, origin, standards) to each part to facilitate sharing and reuse
Changing the color of DNA
Increasing the size of the plasmid
Measuring the pH of the solution
Explanation - Proper annotation ensures parts can be identified, compared, and assembled reliably by different labs.
Correct answer is: Adding descriptive metadata (function, origin, standards) to each part to facilitate sharing and reuse
Q.92 Which of the following is a typical outcome when a synthetic pathway imposes a high metabolic burden on the host cell?
Increased growth rate
Reduced cell fitness and slower growth
Higher fluorescence without any cost
Immediate cell death
Explanation - Heavy resource consumption diverts ATP, ribosomes, and precursors, often slowing growth.
Correct answer is: Reduced cell fitness and slower growth
Q.93 What is the main benefit of using a ‘synthetic auxotrophy’ as a biocontainment strategy?
The engineered organism can only survive when supplied with a synthetic nutrient not found in the environment
It makes the organism glow
It increases the organism’s speed
It changes the organism’s DNA to a different species
Explanation - Auxotrophic dependencies restrict growth outside controlled conditions, enhancing safety.
Correct answer is: The engineered organism can only survive when supplied with a synthetic nutrient not found in the environment
Q.94 In the context of synthetic biology, what does the term ‘chassis‑agnostic’ mean?
The design works across multiple host organisms without major redesign
It only works in one specific organism
It requires a specific temperature
It depends on a particular plasmid backbone
Explanation - Chassis‑agnostic parts are portable and functional in diverse microbial hosts.
Correct answer is: The design works across multiple host organisms without major redesign
Q.95 Which of the following best describes an ‘engineered biosynthetic cluster’?
A set of contiguous genes assembled to produce a natural product or novel compound
A group of electrical components on a circuit board
A collection of antibiotics
A set of DNA primers used for PCR
Explanation - Biosynthetic clusters encode enzymes for stepwise assembly of complex molecules, often transferred and optimized in heterologous hosts.
Correct answer is: A set of contiguous genes assembled to produce a natural product or novel compound
Q.96 Which analytical technique is most suitable for measuring intracellular concentrations of a small‑molecule metabolite in engineered bacteria?
Liquid chromatography–mass spectrometry (LC‑MS)
Western blotting
Electrophoretic mobility shift assay
Polyacrylamide gel electrophoresis
Explanation - LC‑MS separates metabolites and provides sensitive quantification based on mass/charge ratios.
Correct answer is: Liquid chromatography–mass spectrometry (LC‑MS)
Q.97 What is the primary purpose of a ‘synthetic promoter library’ with graded strengths?
To provide a range of transcriptional outputs for fine‑tuning gene expression levels
To make cells resistant to antibiotics
To change the color of colonies
To increase the size of the genome
Explanation - Graded promoters enable systematic optimization of pathway enzyme levels for balanced flux.
Correct answer is: To provide a range of transcriptional outputs for fine‑tuning gene expression levels
Q.98 Which of the following is a typical method for removing an unwanted plasmid after genome integration?
Applying a high temperature shock
Using a counter‑selection marker (e.g., sacB) that kills cells retaining the plasmid in the presence of sucrose
Changing the pH of the medium
Adding extra glucose
Explanation - Counter‑selection allows for positive selection of cells that have lost the plasmid after recombination.
Correct answer is: Using a counter‑selection marker (e.g., sacB) that kills cells retaining the plasmid in the presence of sucrose
Q.99 In a synthetic biology course, students are often asked to build a ‘genetic AND gate’ using which two basic components?
Two promoters and one repressor
Two repressors that each inhibit a common promoter, requiring both to be inactive for expression
One ribosome and one ATP molecule
Two plasmids and one antibiotic
Explanation - An AND gate can be constructed where only when both inputs are present (e.g., inactivating both repressors) does the output promoter become active.
Correct answer is: Two repressors that each inhibit a common promoter, requiring both to be inactive for expression
Q.100 Which of the following best explains why a synthetic biologist would use a ‘constitutive degradation tag’ (e.g., ssrA) on a protein?
To increase the half‑life of the protein
To ensure rapid turnover, enabling tighter dynamic control of protein levels
To make the protein fluorescent
To change the protein’s charge
Explanation - Degradation tags target proteins for proteolysis, allowing fast response to regulatory signals.
Correct answer is: To ensure rapid turnover, enabling tighter dynamic control of protein levels
Q.101 What is the primary purpose of using ‘computational protein design’ in synthetic biotechnology?
To predict DNA sequences that will fold into desired shapes
To engineer enzymes with altered substrate specificity or improved stability for new pathways
To calculate the voltage across a cell membrane
To design the layout of a laboratory
Explanation - In silico protein engineering accelerates the creation of tailored catalysts for synthetic routes.
Correct answer is: To engineer enzymes with altered substrate specificity or improved stability for new pathways
Q.102 Which of the following is a key consideration when choosing a host organism for large‑scale production of a synthetic natural product?
The host’s native ability to synthesize the product
Growth rate, genetic tractability, tolerance to product toxicity, and availability of precursor metabolites
The color of the host’s colonies
The host’s resistance to UV light
Explanation - These factors determine the feasibility and efficiency of industrial-scale bioproduction.
Correct answer is: Growth rate, genetic tractability, tolerance to product toxicity, and availability of precursor metabolites