Q.1 What is the primary function of the cell membrane?
To produce energy for the cell
To store genetic information
To regulate the movement of molecules in and out of the cell
To synthesize proteins
Explanation - The cell membrane (plasma membrane) controls what enters and leaves the cell, maintaining homeostasis.
Correct answer is: To regulate the movement of molecules in and out of the cell
Q.2 Which organelle contains ribosomes and is the site of protein synthesis?
Mitochondria
Golgi apparatus
Endoplasmic reticulum
Nucleus
Explanation - The rough endoplasmic reticulum, studded with ribosomes, is where proteins are synthesized.
Correct answer is: Endoplasmic reticulum
Q.3 In cell culture, what is the purpose of a growth medium?
To provide a surface for cells to stick to
To supply nutrients and maintain pH
To sterilize the culture
To change the cell’s DNA
Explanation - Growth medium supplies essential nutrients, electrolytes, and buffering agents to keep cells alive.
Correct answer is: To supply nutrients and maintain pH
Q.4 Which technique is used to observe live cells in a petri dish?
Transmission electron microscopy
Light microscopy
X-ray diffraction
Fluorescence in situ hybridization
Explanation - Light microscopy allows real‑time observation of living cells without the need for electron beams.
Correct answer is: Light microscopy
Q.5 What is the role of ATP in a cell?
To store genetic information
To act as a messenger between cells
To provide energy for biochemical reactions
To form the cell wall
Explanation - ATP is the universal energy currency, fueling processes like muscle contraction and active transport.
Correct answer is: To provide energy for biochemical reactions
Q.6 Which of the following is NOT a type of cell culture?
Monolayer culture
Suspension culture
Biofilm culture
DNA culture
Explanation - DNA culture is not a recognized cell culture method; the others involve cells grown under various conditions.
Correct answer is: DNA culture
Q.7 What is the main difference between prokaryotic and eukaryotic cells?
Prokaryotes have a nucleus
Eukaryotes contain organelles
Prokaryotes are larger
Eukaryotes lack DNA
Explanation - Eukaryotic cells have membrane‑bound organelles, whereas prokaryotes do not.
Correct answer is: Eukaryotes contain organelles
Q.8 Which device measures the impedance of a cell culture to infer cell health?
Spectrophotometer
Cytometer
Impedance analyzer
Oscilloscope
Explanation - Impedance analyzers detect changes in electrical properties that correlate with cell proliferation and viability.
Correct answer is: Impedance analyzer
Q.9 What does the term 'serum' refer to in cell culture media?
A type of growth factor
The liquid part of blood rich in proteins
A buffer solution
A type of plasticware
Explanation - Serum supplies growth factors, hormones, and attachment proteins necessary for cell growth.
Correct answer is: The liquid part of blood rich in proteins
Q.10 Which cellular structure is responsible for detoxifying harmful substances?
Nucleus
Mitochondria
Ribosome
Lysosome
Explanation - Lysosomes contain enzymes that break down waste materials and cellular debris.
Correct answer is: Lysosome
Q.11 How does a pipette help in cell culture?
It sterilizes the medium
It measures cell density
It transfers precise volumes of liquid
It provides electrical stimulation
Explanation - Pipettes are essential for accurately dispensing media, reagents, and cells.
Correct answer is: It transfers precise volumes of liquid
Q.12 Which of the following is a marker used to identify stem cells?
CD4
CD34
CD45
CD8
Explanation - CD34 is commonly used as a surface marker for hematopoietic stem cells.
Correct answer is: CD34
Q.13 What is the purpose of using antibiotics in cell culture?
To provide nutrients
To increase cell growth rate
To prevent bacterial contamination
To change the cell's DNA
Explanation - Antibiotics kill or inhibit bacteria that may contaminate the culture.
Correct answer is: To prevent bacterial contamination
Q.14 Which technique is used to isolate specific cell populations by their surface proteins?
PCR
Flow cytometry
Western blot
ELISA
Explanation - Flow cytometry can sort cells based on fluorescently labeled antibodies against surface markers.
Correct answer is: Flow cytometry
Q.15 What is the key advantage of 3‑D cell culture over 2‑D monolayer culture?
Higher throughput
Simpler imaging
Closer mimicry of tissue architecture
Lower cost
Explanation - 3‑D cultures form structures that resemble in‑vivo tissues, providing more relevant biology.
Correct answer is: Closer mimicry of tissue architecture
Q.16 Which electrical property of a cell is measured by impedance spectroscopy?
Color
Size
Surface charge
Membrane capacitance
Explanation - Impedance spectroscopy detects changes in membrane capacitance related to cell health and proliferation.
Correct answer is: Membrane capacitance
Q.17 In cell culture, what does 'passaging' mean?
Adding more nutrients
Replacing the medium with fresh medium
Detaching cells and re‑seeding them at a lower density
Changing the temperature
Explanation - Passaging removes confluent cells and transfers them to new vessels to maintain growth.
Correct answer is: Detaching cells and re‑seeding them at a lower density
Q.18 Which molecule is a common component of cell culture medium to stabilize pH?
Tris
Glucose
DNA
Lactate
Explanation - Tris buffer maintains the pH of the medium in physiological range.
Correct answer is: Tris
Q.19 What does the abbreviation 'DMEM' stand for in cell culture?
Dulbecco’s Modified Eagle Medium
Divalent Metal Electron Medium
Densified Medium for Endothelial Mammals
Dibasic Medium for Epithelial Mammals
Explanation - DMEM is a widely used basal medium enriched with nutrients for mammalian cells.
Correct answer is: Dulbecco’s Modified Eagle Medium
Q.20 Which of the following is a characteristic of cancer cell lines?
Limited replicative lifespan
Strict adherence to cell cycle checkpoints
Unlimited proliferative potential
Inability to grow in vitro
Explanation - Cancer cells bypass senescence and can divide indefinitely in culture.
Correct answer is: Unlimited proliferative potential
Q.21 Which enzyme is typically used to detach adherent cells from culture plates?
Trypsin
Lysine
DNA polymerase
RNAse
Explanation - Trypsin cleaves proteins on the cell surface, allowing cells to detach.
Correct answer is: Trypsin
Q.22 What does the term 'MOI' refer to in viral transduction of cells?
Multiplicity of Infection
Molecular Oligomer Index
Maximum Oligomer Input
Minimum Operational Index
Explanation - MOI is the ratio of viral particles to target cells during infection.
Correct answer is: Multiplicity of Infection
Q.23 Which technique is used to measure DNA content per cell?
Flow cytometry with propidium iodide
Transmission electron microscopy
Northern blotting
Western blotting
Explanation - PI intercalates into DNA, allowing cell cycle analysis by flow cytometry.
Correct answer is: Flow cytometry with propidium iodide
Q.24 Which of the following best describes the 'stemness' of stem cells?
The ability to differentiate into all cell types
The ability to produce energy rapidly
The ability to secrete hormones
The ability to form a rigid extracellular matrix
Explanation - 'Stemness' refers to unlimited self‑renewal and multipotency/differentiation potential.
Correct answer is: The ability to differentiate into all cell types
Q.25 What is a common method to quantify protein concentration in a cell lysate?
BCA assay
PCR
ELISA
Western blot
Explanation - The bicinchoninic acid (BCA) assay provides a colorimetric readout of total protein.
Correct answer is: BCA assay
Q.26 In tissue engineering, which material is frequently used as a scaffold for cell growth?
Polyethylene
Collagen
Silicon
Glass
Explanation - Collagen offers a natural extracellular matrix mimic for cells to adhere to.
Correct answer is: Collagen
Q.27 Which parameter is monitored to assess cell viability using impedance-based systems?
Color change
Resistance and reactance
Temperature shift
pH decrease
Explanation - Cell coverage alters the impedance (resistance and reactance) measured across electrodes.
Correct answer is: Resistance and reactance
Q.28 Which type of cell culture requires a gas mixture of 5% CO₂ and 95% air?
Microbial culture
Mammalian cell culture
Plant cell culture
Bacterial culture
Explanation - CO₂ levels help maintain bicarbonate buffer equilibrium in mammalian media.
Correct answer is: Mammalian cell culture
Q.29 What does the term 'autophagy' refer to in cells?
Cell division
Cell death via apoptosis
The self‑digestion of cellular components
Protein synthesis
Explanation - Autophagy is a survival mechanism where cells degrade damaged organelles.
Correct answer is: The self‑digestion of cellular components
Q.30 Which instrument can be used to apply controlled mechanical strain to cultured cells?
Incubator
Mechanical stretcher
Spectrophotometer
Micropipette
Explanation - Stretchers apply cyclic strain to mimic physiological mechanical forces on cells.
Correct answer is: Mechanical stretcher
Q.31 Which of the following best defines a 'bioreactor'?
A device that sterilizes cell culture
A vessel that supports large‑scale cell cultivation with controlled conditions
An imaging system for cells
A type of cell line
Explanation - Bioreactors allow precise control over temperature, pH, oxygen, and nutrient supply.
Correct answer is: A vessel that supports large‑scale cell cultivation with controlled conditions
Q.32 Which molecule is commonly used as a marker for apoptosis detection via flow cytometry?
Annexin V
CD34
GFP
FITC
Explanation - Annexin V binds phosphatidylserine exposed on the outer leaflet during early apoptosis.
Correct answer is: Annexin V
Q.33 Which method allows high‑throughput screening of drug effects on cell viability?
Western blot
MTT assay
Microscopy
DNA sequencing
Explanation - MTT measures metabolic activity and can be performed in 96‑ or 384‑well plates.
Correct answer is: MTT assay
Q.34 In a co‑culture system, two cell types are grown together. What is the main advantage of this system?
Simplified data collection
Increased cell density
Mimicking cell–cell interactions
Lower cost
Explanation - Co‑culture allows studying intercellular communication in a controlled environment.
Correct answer is: Mimicking cell–cell interactions
Q.35 Which electrical parameter is most directly influenced by the cell membrane potential?
Impedance magnitude
Medium pH
Temperature
Light absorption
Explanation - Membrane potential changes affect the capacitive component of impedance.
Correct answer is: Impedance magnitude
Q.36 What is the primary function of a feeder layer in stem cell culture?
To provide nutrients
To absorb waste products
To secrete extracellular matrix and growth factors
To generate electrical signals
Explanation - Feeder cells support stem cells by producing signals that maintain pluripotency.
Correct answer is: To secrete extracellular matrix and growth factors
Q.37 Which of the following best describes an 'organ-on-a-chip' device?
A miniature organ built in a lab
A microfluidic platform mimicking organ physiology
An implantable artificial organ
A 3‑D printed organ model
Explanation - Organ‑on‑a‑chip uses microfluidics to replicate the micro‑environment of a specific organ.
Correct answer is: A microfluidic platform mimicking organ physiology
Q.38 What is the role of extracellular matrix (ECM) components in cell culture?
To provide nutrients
To act as a scaffold for adhesion and signaling
To increase temperature
To sterilize the culture
Explanation - ECM components like collagen and fibronectin mediate cell attachment and biochemical signaling.
Correct answer is: To act as a scaffold for adhesion and signaling
Q.39 Which technique is used to track cell migration over time?
Scratch wound assay
Western blotting
DNA sequencing
ELISA
Explanation - A scratch is made in a cell monolayer, and cell movement into the gap is monitored.
Correct answer is: Scratch wound assay
Q.40 What does 'CRISPR‑Cas9' primarily allow researchers to do in cell biology?
Stain cells for microscopy
Edit genes with high precision
Measure electrical impedance
Quantify protein expression
Explanation - CRISPR‑Cas9 is a genome‑editing tool that can knock out or modify specific genes.
Correct answer is: Edit genes with high precision
Q.41 Which of the following is a key benefit of using induced pluripotent stem cells (iPSCs) in research?
They are cheaper than other cell types
They can differentiate into any cell type
They grow in any medium without supplements
They have no ethical concerns
Explanation - iPSCs can give rise to almost any specialized cell, providing a versatile model.
Correct answer is: They can differentiate into any cell type
Q.42 Which imaging modality can visualize subcellular organelles in living cells without fixation?
Confocal microscopy
Transmission electron microscopy
Cryo‑EM
Atomic force microscopy
Explanation - Confocal microscopy provides optical sectioning with fluorescent labels in living cells.
Correct answer is: Confocal microscopy
Q.43 In microfluidic cell culture, what is a primary advantage over traditional dishes?
Higher throughput
Greater ease of imaging
Lower fluid shear stress
Simplified reagent use
Explanation - Microfluidics enables parallel processing of many small experiments.
Correct answer is: Higher throughput
Q.44 Which technique is used to quantify cytokine secretion in a cell culture supernatant?
Western blot
ELISA
Flow cytometry
PCR
Explanation - ELISA uses antibodies to detect and quantify soluble cytokines.
Correct answer is: ELISA
Q.45 What is the primary role of a perfusion bioreactor in cell culture?
To sterilize the medium
To continuously supply fresh medium while removing waste
To increase cell density by adding more cells
To provide electrical stimulation
Explanation - Perfusion bioreactors maintain optimal growth conditions over long periods.
Correct answer is: To continuously supply fresh medium while removing waste
Q.46 Which parameter is NOT typically monitored in a 3‑D spheroid culture?
Size and shape
Nutrient gradient
Ambient light intensity
Cell viability
Explanation - Light intensity is irrelevant; nutrient gradients and viability are key metrics.
Correct answer is: Ambient light intensity
Q.47 What does the term 'autocrine signaling' mean?
Cell signals to neighboring cells
Cell signals to itself
Signal across the entire organism
Signal mediated by the bloodstream
Explanation - Autocrine signaling involves a cell secreting a factor that binds back to its own receptors.
Correct answer is: Cell signals to itself
Q.48 Which of the following best describes 'electrospinning' in tissue engineering?
A technique to deposit nanoparticles on cells
A method to produce nanofiber scaffolds by applying high voltage
A process to create microfluidic channels
A way to sterilize culture dishes
Explanation - Electrospinning creates fibrous mats resembling the natural ECM.
Correct answer is: A method to produce nanofiber scaffolds by applying high voltage
Q.49 In electrical impedance spectroscopy, which frequency range is most sensitive to cell adhesion events?
0.1–1 Hz
10–100 Hz
1–10 kHz
100–1000 kHz
Explanation - Low‑frequency impedance is influenced by cell‑cell and cell‑substrate interactions.
Correct answer is: 10–100 Hz
Q.50 Which type of biosensor can detect changes in impedance due to cell proliferation?
Glucose meter
Impedimetric cell sensor
Spectrophotometer
Thermocouple
Explanation - Impedimetric sensors measure electrical impedance changes as cells grow.
Correct answer is: Impedimetric cell sensor
Q.51 What is the main purpose of using a 'suspension culture' for blood cells?
To grow cells on a surface
To maintain cells in a fluid environment mimicking blood flow
To create a solid scaffold
To remove nutrients
Explanation - Suspension cultures allow hematopoietic cells to remain free‑floating in media.
Correct answer is: To maintain cells in a fluid environment mimicking blood flow
Q.52 Which technique allows real‑time monitoring of electrical activity in cultured cardiomyocytes?
Patch‑clamp recording
Impedance spectroscopy
Western blot
ELISA
Explanation - Patch‑clamp measures ion currents across the cell membrane.
Correct answer is: Patch‑clamp recording
Q.53 Which device is commonly used for cryopreservation of cell lines?
CO₂ incubator
Dry ice
Liquid nitrogen freezer
Microwave
Explanation - Liquid nitrogen provides temperatures (~‑196 °C) that halt cellular metabolism.
Correct answer is: Liquid nitrogen freezer
Q.54 In biophotonics, what is the principle behind using near‑infrared light for cellular imaging?
It damages DNA
It penetrates deeper with less scattering
It increases temperature
It is absorbed by the medium
Explanation - Near‑infrared light has better tissue penetration and lower phototoxicity.
Correct answer is: It penetrates deeper with less scattering
Q.55 What is the main advantage of using 3‑D bioprinting for tissue engineering?
Simpler equipment
Lower material costs
Precise spatial placement of cells and ECM components
Faster cell growth
Explanation - Bioprinting allows complex architectures that mimic native tissues.
Correct answer is: Precise spatial placement of cells and ECM components
Q.56 Which of the following best explains the concept of 'cellular senescence'?
Cells divide indefinitely
Cells stop dividing but remain metabolically active
Cells undergo programmed death
Cells become cancerous
Explanation - Senescence is a permanent growth arrest while the cell remains viable.
Correct answer is: Cells stop dividing but remain metabolically active
Q.57 In a 3‑D culture, what role does oxygen diffusion play?
It is irrelevant
It creates gradients that affect cell differentiation
It sterilizes the culture
It enhances media viscosity
Explanation - Oxygen gradients in 3‑D constructs influence cell fate decisions.
Correct answer is: It creates gradients that affect cell differentiation
Q.58 Which measurement is commonly used to assess the stiffness of a hydrogel scaffold?
Optical density
Rheometry
pH meter
Thermocouple
Explanation - Rheometry provides elastic modulus values indicating material stiffness.
Correct answer is: Rheometry
Q.59 What is the primary function of a 'cytokine array' in cell biology?
To sequence DNA
To profile multiple cytokines simultaneously
To measure electrical impedance
To image cells
Explanation - Cytokine arrays detect the presence of many signaling proteins at once.
Correct answer is: To profile multiple cytokines simultaneously
Q.60 Which of the following is a key consideration when scaling up cell culture from flasks to bioreactors?
Ambient light
Oxygen transfer rate
Ambient noise level
Room temperature only
Explanation - Large‑scale cultures need sufficient oxygen delivery to all cells.
Correct answer is: Oxygen transfer rate
Q.61 What is 'electrochemical impedance spectroscopy' primarily used for in cell culture?
Measuring temperature
Assessing cell membrane integrity and viability
Sequencing DNA
Imaging cell nuclei
Explanation - EIS detects changes in impedance due to membrane damage or cell death.
Correct answer is: Assessing cell membrane integrity and viability
Q.62 Which type of sensor is suitable for detecting metabolic waste in real‑time during cell culture?
pH sensor
Glucose sensor
Oxygen sensor
All of the above
Explanation - pH, glucose, and oxygen levels all indicate metabolic activity in culture.
Correct answer is: All of the above
Q.63 Which of the following is a characteristic of a 'biocompatible' material?
It dissolves rapidly in water
It causes severe immune responses
It does not provoke a significant biological reaction when in contact with tissues
It is metallic
Explanation - Biocompatibility refers to a material's safety and non‑toxicity in biological systems.
Correct answer is: It does not provoke a significant biological reaction when in contact with tissues
Q.64 In the context of electrical stimulation of cells, what is a 'pulse width'?
The duration of the electrical pulse
The frequency of pulses
The voltage amplitude
The number of pulses per second
Explanation - Pulse width determines how long each electrical burst lasts, influencing cell responses.
Correct answer is: The duration of the electrical pulse
Q.65 Which component is essential for forming a 'tight junction' between epithelial cells?
Actin filaments
Claudins
Mitochondria
Ribosomes
Explanation - Claudins are integral proteins that seal intercellular gaps in tight junctions.
Correct answer is: Claudins
Q.66 What is the advantage of using microelectrode arrays (MEAs) for neural cultures?
They provide optical images
They record electrical activity from multiple neurons simultaneously
They stain the cells
They deliver nutrients
Explanation - MEAs capture action potentials across an array of electrodes.
Correct answer is: They record electrical activity from multiple neurons simultaneously
Q.67 Which of the following is a common marker for endothelial cells?
VE‑cadherin
Sox2
Nanog
Oct4
Explanation - VE‑cadherin is specifically expressed in vascular endothelial cells.
Correct answer is: VE‑cadherin
Q.68 In a 'split‑well' experiment, what does 'splitting' refer to?
Dividing the media into two
Transferring part of a cell culture to a new well to reduce density
Adding a split of nutrients
Halving the incubation time
Explanation - Splitting maintains optimal growth by preventing over‑confluence.
Correct answer is: Transferring part of a cell culture to a new well to reduce density
Q.69 Which property of a cell membrane allows it to be selectively permeable?
Its rigidity
Its lipid bilayer with embedded proteins
Its high protein content
Its crystalline structure
Explanation - The lipid bilayer acts as a barrier, while proteins facilitate selective transport.
Correct answer is: Its lipid bilayer with embedded proteins
Q.70 What is the function of the 'extracellular matrix' in organoids?
To provide nutrients
To act as a scaffold and provide biochemical cues
To generate electrical signals
To stain cells for imaging
Explanation - ECM components support 3‑D organization and guide differentiation.
Correct answer is: To act as a scaffold and provide biochemical cues
Q.71 Which method is most suitable for detecting changes in cell morphology under electrical stimulation?
Live‑cell confocal microscopy
PCR
Western blot
Flow cytometry
Explanation - Live imaging captures real‑time morphological changes during stimulation.
Correct answer is: Live‑cell confocal microscopy
Q.72 In cell culture, what is a 'feeder-free' system?
A culture without any cells or matrices
A system that does not require feeder cells for stem cell maintenance
A culture that uses only feeder cells
A system that feeds cells automatically
Explanation - Feeder‑free systems rely on defined media and coatings rather than support cells.
Correct answer is: A system that does not require feeder cells for stem cell maintenance
Q.73 Which type of electric field is typically used to align cells during fabrication of tissue scaffolds?
DC electric field
AC electric field
Magnetic field
Sound wave
Explanation - AC fields can orient cells and fibers without causing electrolysis.
Correct answer is: AC electric field
Q.74 What is the main purpose of a 'sterile filtration' step before adding a growth factor to cell culture?
To heat‑sterilize the solution
To remove particulates and potential microbes
To adjust pH
To dissolve the growth factor
Explanation - Filter sterilization ensures the solution is free of contaminants.
Correct answer is: To remove particulates and potential microbes
Q.75 Which of the following describes 'mechanotransduction' in cells?
Conversion of light signals into electrical currents
Conversion of mechanical stimuli into biochemical signals
Synthesis of mechanical proteins
Translocation of DNA
Explanation - Mechanotransduction translates physical forces into cellular responses.
Correct answer is: Conversion of mechanical stimuli into biochemical signals
Q.76 In a 'dual‑layer' culture system, what advantage does it provide?
Simpler imaging
Single cell type growth
Mimicking layered tissue structures like skin
Reduced media usage
Explanation - Dual layers allow distinct cell populations to interact in a stratified manner.
Correct answer is: Mimicking layered tissue structures like skin
Q.77 Which of the following is an example of a 'soft lithography' technique used for cell culture?
Photolithography
Nanoimprinting
Soft lithography using PDMS molds
Chemical vapor deposition
Explanation - Soft lithography creates flexible patterns for guiding cell growth.
Correct answer is: Soft lithography using PDMS molds
Q.78 What is the role of 'matrix metalloproteinases (MMPs)' in tissue engineering?
They synthesize collagen
They degrade ECM components to allow cell migration
They provide electrical conductivity
They store energy
Explanation - MMPs remodel the scaffold, facilitating cell movement and integration.
Correct answer is: They degrade ECM components to allow cell migration
Q.79 Which measurement is critical for ensuring the viability of a cryopreserved cell batch?
Temperature of the freezer
Post‑thaw cell viability percentage
Ambient light levels
Number of freeze cycles
Explanation - Assessing viability ensures that cells recover after cryopreservation.
Correct answer is: Post‑thaw cell viability percentage
Q.80 In the context of bioelectricity, what does a 'potentiostat' control?
The temperature of the culture
The electrical potential applied between electrodes
The pH of the medium
The illumination intensity
Explanation - A potentiostat maintains a set voltage to drive electrochemical reactions.
Correct answer is: The electrical potential applied between electrodes
Q.81 Which parameter is NOT affected by cell confluency?
Metabolic rate
Medium pH
Electrical impedance
Ambient temperature
Explanation - Confluency influences cellular metabolism but not room temperature.
Correct answer is: Ambient temperature
Q.82 Which imaging technique can detect fluorescently labeled intracellular calcium dynamics?
Fluorescence microscopy
X‑ray crystallography
Mass spectrometry
NMR spectroscopy
Explanation - Calcium indicators fluoresce when bound to calcium, allowing live imaging.
Correct answer is: Fluorescence microscopy
Q.83 In a bioreactor, what is the main purpose of a 'shear‑stabilized' design?
To increase nutrient mixing
To reduce mechanical stress on cells
To enhance oxygen transfer
To lower temperature
Explanation - Shear‑stabilized reactors protect fragile cells from shear forces.
Correct answer is: To reduce mechanical stress on cells
Q.84 Which of the following best describes the 'Seahorse XF Analyzer'?
A device that measures electrical impedance
A tool for measuring oxygen consumption rate and extracellular acidification
A spectrophotometer for DNA
A microscope for sub‑nanometer resolution
Explanation - Seahorse assays profile cellular metabolism in real‑time.
Correct answer is: A tool for measuring oxygen consumption rate and extracellular acidification
Q.85 What does the term 'biorecognition' refer to in biosensor design?
The electrical signal generation
The specific interaction between the target molecule and a bioreceptor
The physical structure of the sensor
The chemical synthesis of the sensor material
Explanation - Biorecognition provides selectivity for the analyte of interest.
Correct answer is: The specific interaction between the target molecule and a bioreceptor
Q.86 Which parameter is most critical when designing a cell‑based electrical stimulation protocol?
Light intensity
Electric field strength and pulse duration
Temperature of the incubator
Sound frequency
Explanation - Electrical stimulation parameters directly influence cellular responses.
Correct answer is: Electric field strength and pulse duration
Q.87 In a 'dynamic culture' system, what does 'dynamic' refer to?
Constant temperature
Continuous media flow or mixing
Variable pH
Fluctuating light levels
Explanation - Dynamic culture involves fluid movement, enhancing nutrient distribution.
Correct answer is: Continuous media flow or mixing
Q.88 Which of the following is a key feature of an 'organ‑on‑a‑chip' that differentiates it from a static cell culture?
It uses only bacterial cells
It incorporates fluid flow and mechanical cues
It does not require any electrodes
It is always 2‑D
Explanation - Dynamic conditions in organ‑on‑a‑chip mimic physiological environments.
Correct answer is: It incorporates fluid flow and mechanical cues
Q.89 What is the main advantage of using 'hydrogel' as a scaffold material?
It conducts electricity
It is hydrophobic
It mimics the natural ECM and allows cell infiltration
It is magnetic
Explanation - Hydrogels provide a hydrated, biocompatible matrix for cells.
Correct answer is: It mimics the natural ECM and allows cell infiltration
Q.90 In cell culture, what is a 'co‑culture'?
Culturing cells in a vacuum
Culturing two or more cell types together
Using a culture medium with no supplements
Growing cells on a single layer of material
Explanation - Co‑culture studies interactions between different cell types.
Correct answer is: Culturing two or more cell types together
Q.91 Which parameter is not typically monitored by an online pH sensor in a cell bioreactor?
Oxygen concentration
CO₂ level
pH
Temperature
Explanation - Online pH sensors measure acidity but not CO₂ directly; CO₂ is usually inferred from pH.
Correct answer is: CO₂ level
Q.92 What is the purpose of a 'gradient generator' in microfluidic cell culture?
To create temperature gradients
To produce chemical concentration gradients across the channel
To mix colors
To sterilize the device
Explanation - Gradients allow studying dose‑response relationships in a single device.
Correct answer is: To produce chemical concentration gradients across the channel
Q.93 Which of the following best describes 'electrochemiluminescence' (ECL) in biosensing?
Light emission triggered by electrical excitation of a chemical species
Light absorption in an electric field
Electrical discharge in a vacuum
Magnetic resonance imaging
Explanation - ECL generates light upon applying an electric potential, used for highly sensitive detection.
Correct answer is: Light emission triggered by electrical excitation of a chemical species
Q.94 Which of the following is a common strategy to prevent contamination in large‑scale cell production?
Use of antibiotics only
Sterile filtration, closed systems, and environmental monitoring
Leaving the culture open to air
Using unfiltered media
Explanation - Multiple containment steps reduce contamination risk in large‑volume cultures.
Correct answer is: Sterile filtration, closed systems, and environmental monitoring
Q.95 What is the primary role of 'cell‑penetrating peptides (CPPs)' in biotechnology?
To provide structural support
To facilitate intracellular delivery of molecules
To sterilize cell cultures
To generate electricity
Explanation - CPPs help transport drugs or nucleic acids across cellular membranes.
Correct answer is: To facilitate intracellular delivery of molecules
Q.96 Which of the following is a key consideration when designing a scaffold for bone tissue engineering?
Electrical conductivity
High porosity and mechanical strength
Low surface area
Transparent optical properties
Explanation - Bone scaffolds must support load while allowing cell infiltration.
Correct answer is: High porosity and mechanical strength
Q.97 What does the 'MTT assay' measure in cell culture?
DNA content
Cell viability via mitochondrial activity
Protein concentration
pH level
Explanation - MTT is reduced by active mitochondria, producing a colored formazan product.
Correct answer is: Cell viability via mitochondrial activity
Q.98 In the context of electrical stimulation, what is a 'charge‑balanced' waveform?
One that delivers more positive charge
One that delivers more negative charge
One where total positive and negative charge are equal to prevent electrode corrosion
One that has a high frequency
Explanation - Charge‑balanced pulses avoid electrochemical damage to electrodes and cells.
Correct answer is: One where total positive and negative charge are equal to prevent electrode corrosion
Q.99 Which of the following is a key indicator of successful stem cell differentiation?
Expression of lineage‑specific markers
Increase in cell size
Decrease in media pH
Higher antibiotic tolerance
Explanation - Specific markers confirm the cells have adopted a target phenotype.
Correct answer is: Expression of lineage‑specific markers
Q.100 What does the term 'bioreactor' mean in cell culture?
A device used to heat cells
A closed vessel that allows controlled growth of large cell populations
A microscope for observing cells
A type of cell line
Explanation - Bioreactors support large‑scale production with controlled environment.
Correct answer is: A closed vessel that allows controlled growth of large cell populations
Q.101 Which parameter is crucial for ensuring proper nutrient supply in a perfusion bioreactor?
Temperature gradient
Flow rate
Ambient noise
Light intensity
Explanation - The flow rate determines how quickly fresh medium reaches cells.
Correct answer is: Flow rate
Q.102 What is a 'spheroid' in cell culture?
A single flat layer of cells
A 3‑D aggregated cluster of cells
A type of microscope slide
A chemical reagent
Explanation - Spheroids mimic the 3‑D environment of tissues more closely than monolayers.
Correct answer is: A 3‑D aggregated cluster of cells
Q.103 In electrical impedance spectroscopy, which component of the impedance model represents cell membrane capacitance?
R
C
L
Z
Explanation - Capacitance (C) reflects the dielectric properties of the cell membrane.
Correct answer is: C
Q.104 What does 'MTT' stand for in the MTT assay?
Methyl Thiazole Tetrazolium
Metal Thiol Transferase
Molecular Tethered Thymine
Methionine Transferase
Explanation - MTT is a yellow dye reduced to purple formazan by metabolically active cells.
Correct answer is: Methyl Thiazole Tetrazolium
Q.105 Which of the following is a typical cell line used in electrical stimulation studies?
HEK293
NIH/3T3
HeLa
All of the above
Explanation - These lines are often used due to their ease of transfection and response to stimuli.
Correct answer is: All of the above
Q.106 In a 2‑D culture, what is the effect of increasing substrate stiffness?
Cells spread more and differentiate into osteogenic lineages
Cells become rounder
Medium pH drops
Cells die instantly
Explanation - Higher stiffness can promote bone‑like differentiation due to mechanotransduction.
Correct answer is: Cells spread more and differentiate into osteogenic lineages
Q.107 What is the purpose of adding 'feeder cells' in embryonic stem cell culture?
To provide a nutrient‑rich environment
To provide growth factors and extracellular matrix to maintain pluripotency
To produce antibiotics
To generate electrical signals
Explanation - Feeder layers secrete factors that support stem cell self‑renewal.
Correct answer is: To provide growth factors and extracellular matrix to maintain pluripotency
Q.108 Which parameter is critical when using a 'patch‑clamp' technique?
Temperature of the bath
Seal resistance between pipette and membrane
Ambient humidity
Light intensity
Explanation - A high‑resistance seal (giga‑ohm) ensures accurate current recording.
Correct answer is: Seal resistance between pipette and membrane
Q.109 In a 'dual‑electrode' biosensor, what is the typical arrangement of the electrodes?
Two electrodes placed at the same point
One working electrode and one reference electrode
Two electrodes in a parallel configuration with a reference electrode
All electrodes in series
Explanation - This configuration allows accurate potential measurement and current flow.
Correct answer is: Two electrodes in a parallel configuration with a reference electrode
Q.110 What does 'OD600' refer to in cell culture?
Optical density at 600 nm, used to estimate bacterial density
Optical density of the medium at 600 nm
Oxygen depletion at 600 molecules
Organic dye 600
Explanation - OD600 is a quick measure of bacterial growth based on light scattering.
Correct answer is: Optical density at 600 nm, used to estimate bacterial density
Q.111 Which type of microfluidic channel geometry is best suited for generating a stable gradient?
Straight channel
T‑junction
Y‑junction
Cyclic channel
Explanation - Y‑junctions allow mixing of two streams to create a concentration gradient.
Correct answer is: Y‑junction
Q.112 What is the key advantage of using 'microelectrode arrays' (MEAs) in cardiac tissue engineering?
They provide mechanical support
They allow non‑invasive measurement of electrical activity
They generate light for imaging
They increase oxygen supply
Explanation - MEAs record action potentials from cultured cardiac cells without contacting them.
Correct answer is: They allow non‑invasive measurement of electrical activity
Q.113 Which of the following is NOT a commonly used growth factor for mesenchymal stem cell (MSC) expansion?
TGF‑β
FGF‑2
EGF
Interferon‑γ
Explanation - Interferon‑γ is mainly used for immune modulation, not MSC growth.
Correct answer is: Interferon‑γ
Q.114 What is 'photonics' in the context of cell biology?
The study of light interaction with cells and tissues
The production of photons for illumination
The synthesis of photons
The measurement of magnetic fields
Explanation - Photonics includes optical imaging, phototherapy, and light‑controlled actuators.
Correct answer is: The study of light interaction with cells and tissues
Q.115 Which parameter is measured by a 'pH electrode' in a cell culture bioreactor?
pH of the medium
Electrical conductivity
Temperature
Light intensity
Explanation - pH electrodes provide continuous monitoring of acidity or alkalinity.
Correct answer is: pH of the medium
Q.116 In a 'cell‑based assay', why is it important to keep the temperature at 37 °C?
It prevents the medium from freezing
It matches the physiological temperature of mammalian cells
It increases electrical resistance
It reduces light scattering
Explanation - Human cells grow optimally at body temperature (37 °C).
Correct answer is: It matches the physiological temperature of mammalian cells