Q.1 Which of the following is a common application of genetically engineered bacteria in the food industry?
Production of vitamin C
Bacterial fermentation for yogurt
Bioremediation of oil spills
Generation of electricity
Explanation - Genetically engineered bacteria are used to enhance yogurt production by improving acid production and flavor. Vitamin C is produced by plants, bioremediation is environmental, and electricity generation is unrelated to food production.
Correct answer is: Bacterial fermentation for yogurt
Q.2 Which enzyme is most commonly used in PCR to amplify DNA segments?
DNA polymerase
RNA polymerase
Ligase
Helicase
Explanation - DNA polymerase, particularly the heat‑stable Taq polymerase, extends primers during PCR to amplify DNA. RNA polymerase synthesizes RNA, ligase joins DNA fragments, and helicase unwinds DNA strands.
Correct answer is: DNA polymerase
Q.3 What is the primary role of the CRISPR-Cas system in bacterial biotechnology?
To produce antibiotics
To edit genomes with high precision
To degrade proteins
To synthesize carbohydrates
Explanation - CRISPR-Cas provides a programmable, precise system to insert, delete, or modify genes in microorganisms, making it a powerful tool for genetic engineering in biotechnology.
Correct answer is: To edit genomes with high precision
Q.4 Which microorganism is commonly used to produce the antibiotic penicillin?
Streptomyces griseus
Escherichia coli
Saccharomyces cerevisiae
Bacillus subtilis
Explanation - Streptomyces species, especially Streptomyces griseus, naturally produce penicillin. E. coli is a model organism, S. cerevisiae is a yeast, and B. subtilis is used for enzyme production.
Correct answer is: Streptomyces griseus
Q.5 In biopharmaceutical production, what is the purpose of using a bioreactor?
To sterilize the product
To maintain optimal growth conditions for cells
To test drug efficacy
To package the final product
Explanation - Bioreactors provide controlled environment—temperature, pH, oxygen—for microbial or mammalian cell cultures to produce therapeutic proteins.
Correct answer is: To maintain optimal growth conditions for cells
Q.6 Which metabolic pathway is exploited to produce bioethanol from corn?
Glycolysis
Pentose phosphate pathway
Cori cycle
Citric acid cycle
Explanation - Starch in corn is hydrolyzed to sugars, which undergo glycolysis in yeast to produce ethanol. The other pathways are not directly involved in fermentation.
Correct answer is: Glycolysis
Q.7 Which of the following best describes the use of lipase enzymes in detergents?
To bind detergent molecules to dirt
To break down fat stains into water‑soluble compounds
To increase detergent viscosity
To neutralize detergent acidity
Explanation - Lipases catalyze the hydrolysis of fats, turning oily stains into water‑soluble soaps, enhancing cleaning efficiency.
Correct answer is: To break down fat stains into water‑soluble compounds
Q.8 What is the main advantage of using recombinant DNA technology to produce insulin?
It eliminates the need for animal extraction
It increases the sweetness of insulin
It reduces the cost of insulin production
It prevents insulin from degrading in the body
Explanation - Recombinant DNA allows bacterial cells to produce human insulin, removing dependence on animal pancreases and reducing contamination risks.
Correct answer is: It eliminates the need for animal extraction
Q.9 In the context of biotechnology, what is a biopesticide?
A pesticide derived from synthetic chemicals
A pesticide made from biological organisms or their products
A pesticide that destroys all insects in a field
A pesticide that only works on plant diseases
Explanation - Biopesticides are derived from natural materials such as microbes, fungi, or plant extracts, offering a targeted and eco‑friendly pest control.
Correct answer is: A pesticide made from biological organisms or their products
Q.10 Which bacterial enzyme is used to generate ATP during fermentation in anaerobic conditions?
Pyruvate oxidase
Alcohol dehydrogenase
Lactate dehydrogenase
Glucose oxidase
Explanation - Lactate dehydrogenase converts pyruvate to lactate in lactic acid fermentation, regenerating NAD⁺ and enabling continued glycolysis to produce ATP.
Correct answer is: Lactate dehydrogenase
Q.11 Why is the bacterium Bacillus subtilis considered a model organism for studying sporulation?
It is a plant pathogen
It forms spores that are easily visualized
It has a very large genome
It can survive in extreme heat
Explanation - Bacillus subtilis sporulates readily and its spores are visible under a microscope, making it ideal for studying developmental biology.
Correct answer is: It forms spores that are easily visualized
Q.12 Which technique is used to separate proteins based on their isoelectric point?
SDS‑PAGE
Isoelectric focusing
Chromatography
Western blot
Explanation - Isoelectric focusing separates proteins according to the pH at which they carry no net charge (isoelectric point).
Correct answer is: Isoelectric focusing
Q.13 What is a major benefit of using yeast in biofuel production?
Yeast can photosynthesize
Yeast can ferment sugars to ethanol efficiently
Yeast produces large amounts of methane
Yeast can grow in zero‑gravity environments
Explanation - Yeast, especially Saccharomyces cerevisiae, is highly efficient at converting sugars into ethanol, making it ideal for biofuel fermentation.
Correct answer is: Yeast can ferment sugars to ethanol efficiently
Q.14 Which of the following best describes the role of proteases in the production of cheese?
They add flavor to the cheese
They break down milk proteins into peptides and amino acids
They prevent bacterial growth
They increase the fat content
Explanation - Proteases digest casein, creating flavor compounds and giving cheese its characteristic texture.
Correct answer is: They break down milk proteins into peptides and amino acids
Q.15 Which microbial process is utilized to remove heavy metals from contaminated water?
Photosynthesis
Bioremediation
Fermentation
Transduction
Explanation - Bioremediation uses microorganisms to convert toxic heavy metals into less harmful forms or to precipitate them out of solution.
Correct answer is: Bioremediation
Q.16 In a fermentation tank, why is constant agitation important?
To keep the temperature low
To ensure even distribution of nutrients and oxygen
To reduce the pH of the medium
To sterilize the solution
Explanation - Agitation mixes the culture, preventing gradients and ensuring cells receive consistent nutrients and oxygen levels.
Correct answer is: To ensure even distribution of nutrients and oxygen
Q.17 Which microorganism is used in the production of the bioplastic polyhydroxyalkanoate (PHA)?
Pseudomonas putida
Staphylococcus aureus
Bacillus thuringiensis
Escherichia coli
Explanation - Pseudomonas species accumulate PHA as intracellular granules, which can be extracted and processed into biodegradable plastics.
Correct answer is: Pseudomonas putida
Q.18 What is the main purpose of using a fed‑batch strategy in recombinant protein production?
To maintain a constant substrate concentration and prevent product inhibition
To speed up the growth rate
To reduce the need for oxygen
To simplify downstream purification
Explanation - Fed‑batch allows controlled addition of nutrients, preventing toxic accumulation and maximizing yield.
Correct answer is: To maintain a constant substrate concentration and prevent product inhibition
Q.19 Which enzyme is key in the synthesis of antibiotics by fungi?
DNA polymerase
Polyketide synthase
ATP synthase
Peptidoglycan synthase
Explanation - Polyketide synthases assemble complex antibiotic molecules such as erythromycin in fungal biosynthetic pathways.
Correct answer is: Polyketide synthase
Q.20 In the production of recombinant vaccines, what is the role of a plasmid vector?
To act as an adjuvant
To carry the antigen gene into host cells
To degrade unwanted proteins
To provide antibiotics for selection
Explanation - A plasmid vector transports the gene encoding the antigen into host cells, enabling protein expression for vaccine production.
Correct answer is: To carry the antigen gene into host cells
Q.21 What type of bacteria is used in the production of the food preservative nisin?
Staphylococcus aureus
Lactococcus lactis
Bacillus subtilis
Clostridium botulinum
Explanation - Lactococcus lactis naturally produces the bacteriocin nisin, which inhibits spoilage and pathogenic bacteria.
Correct answer is: Lactococcus lactis
Q.22 Which analytical technique is used to quantify nucleic acids in a sample?
Spectrophotometry
Titration
Gel electrophoresis
Chromatography
Explanation - Spectrophotometers measure absorbance at 260 nm to estimate nucleic acid concentration.
Correct answer is: Spectrophotometry
Q.23 Which process is involved in the production of the cosmetic ingredient hyaluronic acid?
Fermentation by Streptococcus zooepidermicus
Chemical synthesis from glucose
Extraction from shark cartilage
Enzymatic hydrolysis of collagen
Explanation - Bacterial fermentation is the most common industrial method for producing hyaluronic acid for cosmetics and medicine.
Correct answer is: Fermentation by Streptococcus zooepidermicus
Q.24 In bioprocess monitoring, what does a pH probe measure?
The concentration of proteins
The acidity or alkalinity of the culture medium
The temperature of the reactor
The dissolved oxygen level
Explanation - A pH probe detects the hydrogen ion concentration, informing adjustments to maintain optimal microbial growth.
Correct answer is: The acidity or alkalinity of the culture medium
Q.25 Which of these is a characteristic advantage of using microalgae for biofuel production?
They do not require CO2
They have a very low biomass yield
They can be cultivated in wastewater
They are resistant to all pathogens
Explanation - Microalgae can grow in nutrient‑rich wastewater, reducing cultivation costs and improving sustainability.
Correct answer is: They can be cultivated in wastewater
Q.26 Which metabolic by‑product of yeast fermentation is often used in the production of certain soft drinks?
Carbon dioxide
Acetic acid
Lactic acid
Butyric acid
Explanation - Yeast fermentation produces CO₂, which is used to carbonate beverages like beer and soft drinks.
Correct answer is: Carbon dioxide
Q.27 What is the role of a buffer solution in a bioreactor?
To supply nutrients
To maintain a stable pH
To increase oxygen solubility
To sterilize the culture
Explanation - Buffers resist changes in pH caused by metabolic acids or bases, ensuring optimal enzyme activity.
Correct answer is: To maintain a stable pH
Q.28 Which type of enzyme is used to remove nucleic acids from a protein purification column?
Trypsin
RNase A
Protease K
Lipase
Explanation - RNase A digests RNA contaminants, while DNase A is used for DNA removal.
Correct answer is: RNase A
Q.29 Why are biocontrol agents used in agriculture?
To increase soil pH
To replace synthetic fertilizers
To suppress plant diseases and pests naturally
To generate electric fields around crops
Explanation - Biocontrol agents, like Bacillus spp., produce antimicrobials that target plant pathogens, reducing reliance on chemicals.
Correct answer is: To suppress plant diseases and pests naturally
Q.30 Which microorganism is primarily used for the production of lactic acid in the food industry?
Streptomyces coelicolor
Lactobacillus acidophilus
Pseudomonas aeruginosa
Clostridium tetani
Explanation - Lactobacillus species ferment sugars to produce lactic acid, used in yogurt, cheese, and pickles.
Correct answer is: Lactobacillus acidophilus
Q.31 Which of the following best describes an expression vector?
A tool that carries a selectable marker gene
A plasmid that provides a promoter and gene of interest for protein expression
A chromosome fragment that increases mutation rate
An enzyme that degrades host DNA
Explanation - An expression vector contains regulatory elements to drive high-level transcription and translation of the inserted gene.
Correct answer is: A plasmid that provides a promoter and gene of interest for protein expression
Q.32 In microbial fuel cells, what role do bacteria play?
They absorb light to produce electricity
They oxidize organic matter, releasing electrons to an electrode
They act as a catalyst for chemical reactions
They generate heat
Explanation - Electrogenic bacteria transfer electrons from substrate oxidation to the anode, producing electric current.
Correct answer is: They oxidize organic matter, releasing electrons to an electrode
Q.33 Which of these is a common substrate for the production of polyhydroxybutyrate (PHB) by bacteria?
Glucose
Lactose
Sodium chloride
Oxygen
Explanation - Glucose is fermented by bacteria like Cupriavidus necator to accumulate PHB, a biodegradable plastic.
Correct answer is: Glucose
Q.34 What is a key benefit of using yeast in the production of recombinant therapeutic proteins?
Yeast produce high levels of endotoxins
Yeast perform eukaryotic post‑translational modifications
Yeast cells are large and easy to harvest
Yeast cannot be genetically engineered
Explanation - Yeast cells can add glycosylations and other modifications essential for protein function.
Correct answer is: Yeast perform eukaryotic post‑translational modifications
Q.35 In a bioprocess, what is meant by a 'fed‑batch' operation?
A continuous feeding and draining system
A batch process where the feed is added gradually over time
A process with no substrate added
A process that feeds only at the start
Explanation - Fed‑batch supplies nutrients slowly, preventing substrate inhibition and improving product titers.
Correct answer is: A batch process where the feed is added gradually over time
Q.36 Which microbial enzyme is responsible for breaking down cellulose into glucose?
Amylase
Cellulase
Protease
Lipase
Explanation - Cellulases hydrolyze β‑1,4‑glycosidic bonds in cellulose, producing glucose for fermentation.
Correct answer is: Cellulase
Q.37 Which of the following is a direct application of microbial lipase in the food industry?
Flavor enhancement in cheese
Increased fat content
Reduction of lactose
Neutralization of acids
Explanation - Lipases release free fatty acids from milk fat, improving flavor and texture of cheese.
Correct answer is: Flavor enhancement in cheese
Q.38 What is the primary function of a selection marker in a plasmid used for protein expression?
To increase plasmid copy number
To provide an antibiotic resistance gene for selecting transformed cells
To encode the protein of interest
To degrade host DNA
Explanation - Selection markers enable researchers to identify cells that have incorporated the plasmid by growing them on selective media.
Correct answer is: To provide an antibiotic resistance gene for selecting transformed cells
Q.39 In the biotransformation of a drug, which microorganism is often used for the stereoselective reduction of ketones?
Escherichia coli
Pseudomonas putida
Streptomyces albus
Lactobacillus plantarum
Explanation - Pseudomonas strains possess enantioselective reductases that produce chiral alcohols from ketones, valuable in pharmaceuticals.
Correct answer is: Pseudomonas putida
Q.40 Which process uses microorganisms to convert organic waste into biogas?
Fermentation
Anaerobic digestion
Aerobic respiration
Photosynthesis
Explanation - Anaerobic digesters break down waste in the absence of oxygen, producing methane‑rich biogas.
Correct answer is: Anaerobic digestion
Q.41 Which of the following is an advantage of using a monoclonal antibody production platform in biotechnology?
It is inexpensive to produce
It can be produced in any bacterial strain
It offers high specificity to a single antigen
It requires no purification steps
Explanation - Monoclonal antibodies are identical immune cells producing one antibody type, ensuring precise target binding.
Correct answer is: It offers high specificity to a single antigen
Q.42 What is the main difference between a prokaryotic and eukaryotic expression system?
Only prokaryotes can be genetically engineered
Eukaryotes can perform complex post‑translational modifications
Prokaryotes cannot replicate plasmids
Eukaryotes produce no proteins
Explanation - Eukaryotic cells add glycosylations and other modifications essential for many therapeutic proteins.
Correct answer is: Eukaryotes can perform complex post‑translational modifications
Q.43 Which enzyme is used to break down starch into glucose in the industrial production of bioethanol?
Invertase
Amyloglucosidase
Protease
Lipase
Explanation - Amyloglucosidase hydrolyzes α‑1,4‑glucosidic bonds in starch, releasing glucose for fermentation.
Correct answer is: Amyloglucosidase
Q.44 What is a 'bioreactor' in the context of bioprocessing?
A device for heating cultures
A vessel that provides controlled conditions for microbial growth
A type of bacterial cell
An enzyme that degrades plastics
Explanation - Bioreactors maintain temperature, pH, oxygen, and nutrient supply to maximize microbial productivity.
Correct answer is: A vessel that provides controlled conditions for microbial growth
Q.45 Which type of fermentation produces lactic acid as a by‑product?
Alkaline fermentation
Acidogenic fermentation
Lactic acid fermentation
Methanogenic fermentation
Explanation - Lactic acid fermentation is carried out by lactic acid bacteria, converting sugars into lactic acid.
Correct answer is: Lactic acid fermentation
Q.46 In recombinant DNA technology, what is the purpose of a promoter?
To cut DNA at a specific site
To initiate transcription of a gene
To bind antibiotics
To degrade RNA
Explanation - A promoter is a DNA sequence that RNA polymerase recognizes to start transcribing the downstream gene.
Correct answer is: To initiate transcription of a gene
Q.47 Which of these is an example of a microbial-derived enzyme used in laundry detergents?
Pepsin
Cellulase
Trypsin
Lipase
Explanation - Cellulases help remove cellulose fibers from fabrics, improving cleaning efficiency.
Correct answer is: Cellulase
Q.48 Which organism is widely used for the production of recombinant human insulin?
Escherichia coli
Saccharomyces cerevisiae
Pseudomonas aeruginosa
Bacillus subtilis
Explanation - E. coli can be engineered to produce human insulin after processing to remove signal peptides.
Correct answer is: Escherichia coli
Q.49 What is the role of an inducer in an inducible expression system?
It serves as a nutrient
It triggers gene expression upon addition
It degrades the plasmid
It neutralizes pH
Explanation - Inducers like IPTG bind to repressor proteins, freeing RNA polymerase to transcribe the target gene.
Correct answer is: It triggers gene expression upon addition
Q.50 Which bioprocessing parameter is directly related to the rate of cell growth?
Dissolved oxygen concentration
Temperature
Substrate concentration
All of the above
Explanation - Temperature, substrate availability, and oxygen levels all influence microbial growth kinetics.
Correct answer is: All of the above
Q.51 What is the purpose of using an enzyme such as DNase during protein purification?
To remove DNA contaminants
To digest proteins
To break down carbohydrates
To increase viscosity
Explanation - DNase cleaves DNA, reducing viscosity and preventing contamination of purified protein preparations.
Correct answer is: To remove DNA contaminants
Q.52 Which of the following is a common technique for analyzing protein purity?
Mass spectrometry
Western blot
Thin‑layer chromatography
All of the above
Explanation - All listed methods are used to assess the purity and identity of proteins in biotechnology.
Correct answer is: All of the above
Q.53 Which microorganism is known for producing the enzyme amylase used in baking?
Trichoderma reesei
Saccharomyces cerevisiae
Aspergillus niger
Clostridium acetobutylicum
Explanation - Aspergillus niger secretes large amounts of amylase, aiding dough fermentation by breaking starches.
Correct answer is: Aspergillus niger
Q.54 What is a primary advantage of using filamentous fungi over bacteria for enzyme production?
Fungi grow faster
Fungi can perform complex post‑translational modifications
Fungi are easier to genetically manipulate
Fungi produce fewer by‑products
Explanation - Fungi can add glycosylations and other modifications necessary for certain eukaryotic enzymes.
Correct answer is: Fungi can perform complex post‑translational modifications
Q.55 In the context of enzyme immobilization, what is a common matrix material?
Silica gel
Polyethylene glycol
Polyvinyl alcohol
All of the above
Explanation - Enzymes can be immobilized on silica, PEG, or PVAc to enhance stability and reusability.
Correct answer is: All of the above
Q.56 Which of the following best describes the use of microbial lipases in biodiesel production?
They convert triglycerides into fatty acids
They catalyze the transesterification of triglycerides into methyl esters
They synthesize glucose from lipids
They produce ethanol from fats
Explanation - Lipases mediate the conversion of oils into biodiesel (methyl esters) without harsh chemicals.
Correct answer is: They catalyze the transesterification of triglycerides into methyl esters
Q.57 Which bacterial enzyme is commonly used to break down gluten in food processing?
Trypsin
Protease
Amylase
Lipase
Explanation - Proteases cleave gluten proteins, reducing their allergenic properties.
Correct answer is: Protease
Q.58 In the production of recombinant proteins, what is a 'constitutive promoter'?
A promoter that is always active
A promoter that is induced by light
A promoter that is active only during stationary phase
A promoter that is suppressed by antibiotics
Explanation - Constitutive promoters drive continuous expression of the gene, regardless of environmental signals.
Correct answer is: A promoter that is always active
Q.59 What is the main purpose of a fermentation starter culture?
To add flavor to the product
To ensure consistent inoculum density and microbial composition
To increase the pH of the medium
To provide vitamins
Explanation - Starter cultures standardize the fermentation process by providing a known microbial population.
Correct answer is: To ensure consistent inoculum density and microbial composition
Q.60 Which of the following microorganisms is used for the production of the antibiotic tetracycline?
Streptomyces aureus
Streptomyces rimosus
Bacillus cereus
Escherichia coli
Explanation - Streptomyces rimosus naturally produces tetracycline, an important broad‑spectrum antibiotic.
Correct answer is: Streptomyces rimosus
Q.61 Which method is commonly employed to separate proteins based on their charge?
Gel electrophoresis
Affinity chromatography
Anion exchange chromatography
Size exclusion chromatography
Explanation - Anion exchange binds negatively charged proteins, allowing separation by charge differences.
Correct answer is: Anion exchange chromatography
Q.62 What is a key advantage of using genetically engineered yeast for vaccine production?
Yeast produce fewer impurities
Yeast can produce large amounts of vaccine antigens quickly
Yeast are resistant to all viruses
Yeast do not require any media
Explanation - Yeast can scale rapidly and produce high yields of antigens used in subunit vaccines.
Correct answer is: Yeast can produce large amounts of vaccine antigens quickly
Q.63 Which of these is NOT a common industrial use of microbial lipase?
Synthesis of biodiesel
Detergent formulation
Production of antibiotics
Food flavor enhancement
Explanation - Lipases are mainly used in biodiesel, detergents, and flavoring; antibiotics are usually synthesized by other pathways.
Correct answer is: Production of antibiotics
Q.64 In a bioreactor, why is the dissolved oxygen level critical for aerobic fermentation?
It prevents bacterial contamination
It determines the rate of aerobic metabolism and product formation
It maintains temperature
It regulates pH
Explanation - Dissolved oxygen is essential for aerobic organisms; low levels limit growth and metabolite synthesis.
Correct answer is: It determines the rate of aerobic metabolism and product formation
Q.65 Which of the following best describes an industrial enzyme's 'specific activity'?
Units per milligram of total protein
Km value of the enzyme
Optimal temperature for activity
Number of active sites
Explanation - Specific activity measures how active an enzyme is per unit protein, indicating purity and performance.
Correct answer is: Units per milligram of total protein
Q.66 Which microorganism is exploited for producing the enzyme cellulase used in the paper industry?
Clostridium thermocellum
Saccharomyces cerevisiae
Streptomyces coelicolor
Escherichia coli
Explanation - Clostridium thermocellum produces large amounts of cellulases under anaerobic conditions suitable for pulp processing.
Correct answer is: Clostridium thermocellum
Q.67 In the context of bioprocessing, what does the term 'cell density' refer to?
The amount of cells per unit volume
The size of individual cells
The mass of the culture broth
The pH of the medium
Explanation - Cell density indicates how many cells are present per milliliter, affecting metabolic rates.
Correct answer is: The amount of cells per unit volume
Q.68 Which of the following is a major challenge in using microorganisms for drug delivery?
Ensuring high temperatures
Controlling the release kinetics of the drug
Providing enough oxygen
Keeping the culture sterile
Explanation - Designing microorganisms to release drugs at desired rates while avoiding host immune responses is challenging.
Correct answer is: Controlling the release kinetics of the drug
Q.69 Which technique is used to monitor the growth of microorganisms in a bioreactor?
Spectrophotometry at 600 nm
Mass spectrometry
Fluorescence microscopy
Gel electrophoresis
Explanation - Optical density at 600 nm (OD600) correlates with cell concentration in liquid cultures.
Correct answer is: Spectrophotometry at 600 nm
Q.70 What is a 'bioreactor' primarily used for in pharmaceutical production?
To synthesize small molecules chemically
To cultivate cells or microbes for producing biologics
To isolate DNA fragments
To analyze protein structures
Explanation - Bioreactors enable scalable production of therapeutic proteins, vaccines, and other biologics.
Correct answer is: To cultivate cells or microbes for producing biologics
Q.71 Which of the following is an example of a microbial metabolite used as a pharmaceutical?
Insulin
Erythromycin
Cholesterol
Glucose
Explanation - Erythromycin, produced by Streptomyces venezuelae, is a macrolide antibiotic used clinically.
Correct answer is: Erythromycin
Q.72 Why is pH control essential during fermentation processes?
It prevents temperature fluctuations
It ensures optimal enzyme activity and microbial growth
It regulates oxygen levels
It reduces viscosity of the culture
Explanation - Enzymes and cells have specific pH ranges; deviations can inhibit metabolic activity.
Correct answer is: It ensures optimal enzyme activity and microbial growth
Q.73 Which enzyme is used in the manufacturing of high‑fructose corn syrup?
Invertase
Amylase
Cellulase
Protease
Explanation - Invertase converts sucrose into glucose and fructose, producing high‑fructose corn syrup.
Correct answer is: Invertase
Q.74 In protein engineering, what is a 'site‑directed mutagenesis' technique used for?
To delete entire genes
To introduce specific amino‑acid substitutions
To amplify DNA fragments
To label proteins with fluorescent tags
Explanation - Site‑directed mutagenesis modifies a single codon to study functional changes in the protein.
Correct answer is: To introduce specific amino‑acid substitutions
Q.75 Which of the following microorganisms is commonly used to produce the enzyme cellulase for biofuel production?
Trichoderma reesei
Saccharomyces cerevisiae
Escherichia coli
Bacillus subtilis
Explanation - Trichoderma reesei secretes high levels of cellulases, crucial for breaking down cellulosic biomass.
Correct answer is: Trichoderma reesei
Q.76 Which of the following best describes a 'biological sensor' in biotechnology?
A device that measures pH in a culture
A system that uses biological components to detect analytes
An instrument that sequences DNA
A microscope used for cell imaging
Explanation - Biological sensors combine biomolecules like enzymes or antibodies with transducers for detection.
Correct answer is: A system that uses biological components to detect analytes
Q.77 Which of the following is a common method to purify recombinant proteins from bacterial lysates?
Affinity chromatography using His-tag
Thin‑layer chromatography
Gel electrophoresis
Spectrophotometry
Explanation - His-tagged proteins bind to nickel or cobalt resins, enabling selective purification.
Correct answer is: Affinity chromatography using His-tag
Q.78 What is the primary function of a 'biocatalyst' in industrial processes?
To act as a solvent
To accelerate chemical reactions under mild conditions
To provide energy for reactions
To serve as a nutrient source
Explanation - Biocatalysts like enzymes catalyze reactions with high specificity at lower temperatures and pressures.
Correct answer is: To accelerate chemical reactions under mild conditions
Q.79 Which of the following is a typical use of yeast in the production of fermented beverages?
As a probiotic supplement
For the fermentation of sugars into alcohol
To produce antibiotics
To generate methane
Explanation - Yeast metabolizes sugars to produce ethanol and CO₂, essential for beer and wine.
Correct answer is: For the fermentation of sugars into alcohol
Q.80 In biotechnology, what is the main purpose of using 'directed evolution'?
To create new species of microorganisms
To evolve enzymes with desired properties through iterative rounds of mutation and selection
To sequence the genome of an organism
To clone plasmids
Explanation - Directed evolution mimics natural selection to engineer enzymes with improved activity, stability, or specificity.
Correct answer is: To evolve enzymes with desired properties through iterative rounds of mutation and selection
Q.81 Which of the following is a key advantage of using microalgae over bacteria for protein production?
Microalgae can perform complex glycosylation patterns
Microalgae grow faster than bacteria
Microalgae do not require light
Microalgae produce fewer impurities
Explanation - Microalgae are eukaryotic and can perform post‑translational modifications similar to mammalian systems.
Correct answer is: Microalgae can perform complex glycosylation patterns
Q.82 What is the main role of the enzyme catalase in aerobic microorganisms?
Break down hydrogen peroxide into water and oxygen
Produce ATP via glycolysis
Synthesize cell wall components
Transport electrons in the respiratory chain
Explanation - Catalase protects cells from oxidative damage by decomposing reactive oxygen species.
Correct answer is: Break down hydrogen peroxide into water and oxygen
Q.83 Which of the following is a key parameter measured during a fed‑batch fermentation?
Substrate feeding rate
Volume of the culture
Color of the broth
Number of cell divisions per day
Explanation - The feeding rate is controlled to maintain optimal substrate levels and avoid inhibition.
Correct answer is: Substrate feeding rate
Q.84 What is the purpose of a 'chaperone' protein in recombinant protein production?
To degrade misfolded proteins
To assist in proper protein folding and assembly
To act as a DNA polymerase
To inhibit translation
Explanation - Chaperones like GroEL/ES help nascent polypeptides fold correctly, improving yield and activity.
Correct answer is: To assist in proper protein folding and assembly
Q.85 Which of the following is NOT a typical by‑product of lactic acid fermentation?
Lactic acid
Ethanol
CO₂
Water
Explanation - Lactic acid bacteria produce lactic acid and CO₂, not ethanol, which is produced by yeast fermentation.
Correct answer is: Ethanol
Q.86 What is a common use of the enzyme β‑galactosidase in biotechnology?
To produce lactose from glucose
To cleave lactose into glucose and galactose
To synthesize cellulose
To catalyze the formation of ATP
Explanation - β‑galactosidase hydrolyzes lactose, useful in dairy processing and lactose‑free products.
Correct answer is: To cleave lactose into glucose and galactose
Q.87 Which of the following best describes the 'phosphoenolpyruvate (PEP) carboxylase' enzyme?
An enzyme that converts glucose into fructose
An enzyme that fixes CO₂ into oxaloacetate in photosynthetic bacteria
An enzyme that degrades proteins
An enzyme involved in DNA replication
Explanation - PEP carboxylase catalyzes the addition of CO₂ to PEP, forming oxaloacetate, a key step in anaplerotic reactions.
Correct answer is: An enzyme that fixes CO₂ into oxaloacetate in photosynthetic bacteria
Q.88 What is the primary reason for using a 'selection marker' in a plasmid during recombinant DNA work?
To increase plasmid size
To allow growth of only transformed cells on selective media
To speed up DNA replication
To provide nutrients to host cells
Explanation - Selection markers confer antibiotic resistance, enabling researchers to isolate transformed cells.
Correct answer is: To allow growth of only transformed cells on selective media
Q.89 Which enzyme is critical for the synthesis of the polymer chitin used in bioplastics?
Chitinase
Chitin synthase
Cellulase
Protease
Explanation - Chitin synthase polymerizes N‑acetylglucosamine monomers to produce chitin.
Correct answer is: Chitin synthase
Q.90 Which of the following microorganisms is a major producer of the industrial enzyme α‑amylase?
Bacillus subtilis
Saccharomyces cerevisiae
Escherichia coli
Pseudomonas fluorescens
Explanation - Bacillus subtilis secretes large amounts of α‑amylase for starch breakdown.
Correct answer is: Bacillus subtilis
Q.91 In the production of recombinant antibodies, which host organism is commonly used?
Escherichia coli
Saccharomyces cerevisiae
Chinese hamster ovary (CHO) cells
Bacillus subtilis
Explanation - CHO cells provide mammalian post‑translational modifications necessary for therapeutic antibodies.
Correct answer is: Chinese hamster ovary (CHO) cells
Q.92 Which of the following is a common industrial application of the enzyme xylanase?
Biodegradation of plastic bags
Pulp bleaching in the paper industry
Synthesis of antibiotics
Production of insulin
Explanation - Xylanase degrades hemicellulose, reducing the need for harsh chemicals in pulp bleaching.
Correct answer is: Pulp bleaching in the paper industry
Q.93 What is the main advantage of using a 'prokaryotic expression system' over a eukaryotic one for producing simple proteins?
Higher yields and faster growth
Ability to perform complex glycosylation
Lower cost of culture media
Both A and C
Explanation - Prokaryotes grow rapidly and can produce high yields with lower media costs; they lack complex post‑translational modifications.
Correct answer is: Both A and C
Q.94 Which of the following best describes a 'biosensor' used in detecting glucose in blood?
An electronic device that measures temperature
An enzyme‑based sensor that produces an electrical signal upon glucose binding
A mechanical sensor that counts cells
A chemical reaction that changes color of the entire blood sample
Explanation - Glucose oxidase in a biosensor reacts with glucose to produce an electrical signal proportional to glucose concentration.
Correct answer is: An enzyme‑based sensor that produces an electrical signal upon glucose binding
Q.95 Which microbial enzyme is primarily responsible for the breakdown of starch in bread dough?
Amylase
Protease
Lipase
Cellulase
Explanation - Amylase breaks down starch into sugars, feeding yeast and contributing to dough rise.
Correct answer is: Amylase
Q.96 In a bioreactor, what is the function of a 'pH-stat' controller?
To keep the temperature constant
To automatically adjust the pH by adding acid or base
To monitor cell density
To sterilize the culture
Explanation - A pH‑stat detects pH changes and adds acid/base to maintain setpoint, crucial for optimal enzyme activity.
Correct answer is: To automatically adjust the pH by adding acid or base
Q.97 Which of the following is NOT a typical step in the purification of recombinant proteins from E. coli lysate?
Cell lysis
Heat treatment to denature contaminants
Affinity chromatography
DNA sequencing
Explanation - DNA sequencing is unrelated to protein purification; steps include lysis, heat treatment, and chromatography.
Correct answer is: DNA sequencing
Q.98 What is a major benefit of using yeast for the production of ethanol from cellulosic biomass?
Yeast can directly ferment cellulose
Yeast can co‑ferment glucose and xylose efficiently
Yeast are tolerant to high ethanol concentrations
Yeast can synthesize glucose from CO₂
Explanation - Saccharomyces cerevisiae can tolerate higher ethanol levels, improving overall yield from fermentation.
Correct answer is: Yeast are tolerant to high ethanol concentrations
Q.99 Which of the following is an application of microbial lipase in the textile industry?
Bioremediation of dyes
Softening of fabrics by hydrolyzing waxes
Production of bleach
Detoxification of heavy metals
Explanation - Lipases remove natural waxes, resulting in softer fabrics during processing.
Correct answer is: Softening of fabrics by hydrolyzing waxes
Q.100 In the production of recombinant proteins, what does the term 'vector copy number' refer to?
The number of plasmid copies per cell
The number of proteins produced
The number of host cells in the culture
The number of amino acids in the protein
Explanation - Higher vector copy numbers often increase expression but can burden the host.
Correct answer is: The number of plasmid copies per cell
Q.101 Which microbial species is known for producing the antibiotic vancomycin?
Streptomyces virginiae
Streptomyces griseus
Streptomyces coelicolor
Streptomyces hygroscopicus
Explanation - Streptomyces virginiae is the natural producer of vancomycin, used to treat Gram‑positive infections.
Correct answer is: Streptomyces virginiae
Q.102 Which of the following is a key challenge in scaling up a microbial fermentation process?
Ensuring consistent pH control
Maintaining sterility across large volumes
Preventing evaporation of solvents
Controlling the color of the medium
Explanation - Large reactors increase the risk of contamination, requiring stringent sterilization protocols.
Correct answer is: Maintaining sterility across large volumes
Q.103 What does the acronym 'GMO' stand for in biotechnology?
Genetically Modified Organism
General Molecular Output
Global Microbial Operation
Glycolytic Metabolic Output
Explanation - GMO refers to an organism whose genome has been altered through genetic engineering techniques.
Correct answer is: Genetically Modified Organism
Q.104 Which of the following is a common method to quantify protein concentration in a sample?
Bradford assay
Titration
Spectrophotometry at 280 nm
Both A and C
Explanation - Bradford assay and UV absorbance at 280 nm are standard protein quantification methods.
Correct answer is: Both A and C
Q.105 Which enzyme is used to break down cellulose in the production of biofuels?
Cellulase
Lipase
Protease
Amylase
Explanation - Cellulase hydrolyzes cellulose into glucose units for subsequent fermentation into biofuel.
Correct answer is: Cellulase
Q.106 What is a key feature of a 'constitutive promoter' in a plasmid?
It requires an inducer for activation
It is always active regardless of environmental conditions
It is only active during stationary phase
It is silent unless a repressor is present
Explanation - Constitutive promoters drive continuous gene expression without induction.
Correct answer is: It is always active regardless of environmental conditions
Q.107 Which of the following is used to measure dissolved oxygen in a bioreactor?
pH meter
Oxygen electrode
Thermometer
Conductivity probe
Explanation - An oxygen electrode measures the concentration of dissolved oxygen in the culture medium.
Correct answer is: Oxygen electrode
Q.108 Which of the following microorganisms is a major source of the enzyme pepsin?
Streptomyces sp.
Bacillus sp.
Pepsin is not produced by microorganisms
Saccharomyces cerevisiae
Explanation - Pepsin is a mammalian gastric enzyme; microorganisms do not produce it.
Correct answer is: Pepsin is not produced by microorganisms
Q.109 What is the main purpose of a 'feed tank' in a fed‑batch bioreactor?
To store the culture broth
To contain the nutrient solution added gradually to the reactor
To sterilize the medium
To cool the culture
Explanation - The feed tank holds the substrate feed that is pumped into the reactor at controlled rates.
Correct answer is: To contain the nutrient solution added gradually to the reactor
Q.110 Which of the following is a common downstream processing step for purifying recombinant proteins?
Filtration
Chromatography
Heat shock
All of the above
Explanation - Chromatographic techniques (e.g., ion exchange, size exclusion) are key for protein purification.
Correct answer is: Chromatography
Q.111 What is the main function of the enzyme lactase in dairy processing?
To ferment lactose into lactic acid
To hydrolyze lactose into glucose and galactose
To produce whey protein
To sterilize milk
Explanation - Lactase breaks down lactose, enabling lactose‑free products and aiding digestion.
Correct answer is: To hydrolyze lactose into glucose and galactose
Q.112 Which microorganism is used for the industrial production of the antibiotic chloramphenicol?
Streptomyces venezuelae
Bacillus subtilis
Escherichia coli
Pseudomonas aeruginosa
Explanation - Streptomyces venezuelae naturally synthesizes chloramphenicol, an important broad‑spectrum antibiotic.
Correct answer is: Streptomyces venezuelae
Q.113 Which of the following is NOT typically used as a selective marker in bacterial plasmids?
Kanamycin resistance
Ampicillin resistance
Thymidine auxotrophy
Bacitracin resistance
Explanation - Bacitracin resistance is not a common selection marker; kanamycin, ampicillin, and thymidine auxotrophy are widely used.
Correct answer is: Bacitracin resistance
Q.114 Which of the following enzymes is involved in the synthesis of cellulose?
Cellulase
Cellulose synthase
Amylase
Protease
Explanation - Cellulose synthase polymerizes glucose to form cellulose, the primary structural component of plant cell walls.
Correct answer is: Cellulose synthase
Q.115 Which of the following best describes the use of 'microbial consortia' in bioremediation?
Using a single species for degradation
Using multiple species to degrade complex pollutants
Using plants to absorb pollutants
Using only fungi for pollutant breakdown
Explanation - Consortia combine complementary metabolic capabilities for efficient bioremediation.
Correct answer is: Using multiple species to degrade complex pollutants
Q.116 What is the primary function of a 'clarifier' in a bioprocessing workflow?
To filter out small molecules
To separate cells from the culture broth
To adjust the pH of the solution
To measure the protein concentration
Explanation - Clarifiers (e.g., centrifuges or filters) remove cells or debris before downstream purification.
Correct answer is: To separate cells from the culture broth
Q.117 Which of the following is a major benefit of using yeast as a host for recombinant protein production?
Yeast can grow on minimal media
Yeast provide eukaryotic post‑translational modifications
Yeast produce no endotoxins
Both B and C
Explanation - Yeast are eukaryotes, enabling glycosylation and lack of endotoxins, important for therapeutic proteins.
Correct answer is: Both B and C
Q.118 Which of the following is an example of a microbial enzyme used in the textile industry for biopolishing?
Lipase
Protease
Laccase
Amylase
Explanation - Proteases degrade surface proteins on fibers, giving a smoother appearance (biopolishing).
Correct answer is: Protease
Q.119 Which of the following microorganisms produces the enzyme chitinase?
Aspergillus niger
Bacillus subtilis
Trichoderma reesei
Pseudomonas putida
Explanation - Trichoderma reesei secretes chitinase, which degrades chitin in fungal cell walls.
Correct answer is: Trichoderma reesei
Q.120 What is the purpose of adding a 'shunt' pathway in metabolic engineering?
To increase the rate of glycolysis
To divert flux toward a desired product
To provide an alternative route for DNA replication
To reduce oxygen consumption
Explanation - A metabolic shunt redirects intermediates to enhance yield of the target metabolite.
Correct answer is: To divert flux toward a desired product
Q.121 Which of the following is a key difference between aerobic and anaerobic fermentation?
Aerobic fermentation produces ethanol; anaerobic produces lactic acid
Anaerobic fermentation requires oxygen
Aerobic fermentation produces lactic acid; anaerobic produces ethanol
Aerobic fermentation only uses yeast
Explanation - Lactic acid fermentation (e.g., by lactobacilli) is anaerobic, while yeast fermentation (ethanol) can be anaerobic but also occurs aerobically under specific conditions.
Correct answer is: Aerobic fermentation produces lactic acid; anaerobic produces ethanol
Q.122 What is a common method to remove endotoxins from recombinant protein preparations?
Centrifugation
Anion exchange chromatography
Heat treatment
Protein precipitation
Explanation - Anion exchange resins bind endotoxins, allowing their removal from protein solutions.
Correct answer is: Anion exchange chromatography
Q.123 Which of the following enzymes is responsible for the hydrolysis of disaccharides into monosaccharides?
Invertase
Amylase
Lipase
Protease
Explanation - Invertase cleaves sucrose into glucose and fructose.
Correct answer is: Invertase
Q.124 Which of the following is a typical parameter to monitor during scale‑up of a fermentation process?
Optical density of the medium
Temperature stability
Oxygen transfer rate
Color change of the broth
Explanation - Oxygen transfer rate determines the ability of the culture to maintain aerobic growth at larger volumes.
Correct answer is: Oxygen transfer rate
Q.125 What does the term 'biocatalyst' refer to in industrial biotechnology?
A chemical that speeds up reactions
A living organism or enzyme that catalyzes a reaction
A machine that controls temperature
A device that measures pH
Explanation - Biocatalysts can be enzymes or whole cells used to convert substrates into products under mild conditions.
Correct answer is: A living organism or enzyme that catalyzes a reaction
Q.126 Which of the following is an example of a microbial product used in cosmetics?
Chitin
Collagen
Glycolipid surfactants
Hydrolyzed protein
Explanation - Microbial glycolipid surfactants (e.g., rhamnolipids) are used for their mild cleaning properties in cosmetics.
Correct answer is: Glycolipid surfactants
Q.127 Which enzyme is used to degrade the cell wall of fungi to produce chitinase?
Chitin synthase
Chitinase
β‑glucanase
Laccase
Explanation - Chitinase breaks down chitin in fungal cell walls, facilitating bioprocessing.
Correct answer is: Chitinase
Q.128 What is the purpose of the 'feed-forward controller' in a bioreactor?
To anticipate changes and adjust feed rates proactively
To respond only to measured variables
To maintain constant temperature
To control pH automatically
Explanation - Feed‑forward control uses predictive models to adjust feed rates before disturbances affect the system.
Correct answer is: To anticipate changes and adjust feed rates proactively
Q.129 Which of the following is an industrial use of the enzyme laccase?
Pulp bleaching
Biofuel production
Production of antibiotics
Synthesis of insulin
Explanation - Laccase oxidizes lignin, aiding in pulp bleaching and reducing harsh chemicals.
Correct answer is: Pulp bleaching
Q.130 Which of the following statements about CRISPR‑Cas9 is TRUE?
It can only target bacterial genomes
It requires a PAM sequence to function
It cannot be used in mammalian cells
It is a type of antibiotic
Explanation - CRISPR‑Cas9 requires a protospacer adjacent motif (PAM) for target recognition and cleavage.
Correct answer is: It requires a PAM sequence to function
Q.131 Which of the following is a typical downstream processing step for biopharmaceuticals?
Cell lysis
Fermentation
Purification by chromatography
Fermentation broth sterilization
Explanation - Chromatography is a key downstream step to isolate the therapeutic protein from the culture broth.
Correct answer is: Purification by chromatography
Q.132 What is the main role of a 'pH‑stat' in a bioreactor?
To automatically add acid or base to maintain a set pH
To measure temperature
To monitor cell density
To sterilize the medium
Explanation - The pH‑stat adds acid/base to keep pH constant, essential for enzyme and cell function.
Correct answer is: To automatically add acid or base to maintain a set pH
Q.133 Which of the following microorganisms is a natural producer of the antibiotic vancomycin?
Streptomyces virginiae
Bacillus subtilis
Pseudomonas aeruginosa
Escherichia coli
Explanation - Vancomycin is produced by Streptomyces virginiae, used to treat Gram‑positive infections.
Correct answer is: Streptomyces virginiae
Q.134 Which of the following enzymes is used to break down cellulose for biofuel production?
Cellulase
Lipase
Protease
Amylase
Explanation - Cellulase hydrolyzes cellulose into glucose monomers, which are then fermented to biofuels.
Correct answer is: Cellulase
Q.135 What is a key advantage of using a plasmid vector with an inducible promoter?
It allows constant high-level expression
It prevents leaky expression and reduces metabolic burden until induction
It ensures plasmid copy number is always high
It makes the plasmid unstable in host cells
Explanation - Inducible promoters allow controlled expression, minimizing toxicity to host cells.
Correct answer is: It prevents leaky expression and reduces metabolic burden until induction
Q.136 Which of the following is a commonly used method for DNA sequencing?
Sanger sequencing
PCR amplification
Gel electrophoresis
Cloning into plasmids
Explanation - Sanger sequencing uses chain‑terminating nucleotides to determine DNA sequences.
Correct answer is: Sanger sequencing
Q.137 In the production of recombinant vaccines, why is a 'cell‑free' system advantageous?
It eliminates the need for living cells, speeding up production
It reduces the risk of contamination
It increases the size of the protein produced
Both A and B
Explanation - Cell‑free systems bypass cell growth, allowing rapid protein synthesis and reducing contamination risk.
Correct answer is: Both A and B
Q.138 Which of the following is a typical parameter to control in an aerobic fermentation?
Oxygen concentration
pH
Temperature
All of the above
Explanation - Maintaining optimal oxygen, pH, and temperature is crucial for maximizing yield.
Correct answer is: All of the above
Q.139 Which of the following best describes a 'bioreactor' in biotechnology?
A device that generates electricity from bacteria
A vessel that provides controlled growth conditions for cells or microbes
An instrument for measuring cell density
A machine for sterilizing culture media
Explanation - Bioreactors create optimal environments (temperature, pH, oxygen) for cell or microbial culture.
Correct answer is: A vessel that provides controlled growth conditions for cells or microbes
Q.140 Which of the following enzymes is used in the dairy industry to reduce the viscosity of whey protein?
Pepsin
Trypsin
Protease
Lipase
Explanation - Proteases cleave whey proteins, lowering viscosity and improving texture.
Correct answer is: Protease
Q.141 Which of the following microorganisms produces the enzyme xylanase for use in the pulp industry?
Aspergillus niger
Trichoderma reesei
Streptomyces coelicolor
Bacillus subtilis
Explanation - Aspergillus niger secretes xylanase, aiding in hemicellulose removal during pulp processing.
Correct answer is: Aspergillus niger
Q.142 What is the primary function of the enzyme glutamine synthetase in microbial metabolism?
To synthesize ATP from ADP
To convert glutamate and ammonia to glutamine
To break down proteins
To catalyze the fermentation of sugars
Explanation - Glutamine synthetase catalyzes the formation of glutamine from glutamate and ammonia.
Correct answer is: To convert glutamate and ammonia to glutamine
Q.143 Which of the following is a common application of microbial lipases in the detergent industry?
Saponification of fats
Hydrolysis of triglycerides in greasy stains
Formation of surfactants
All of the above
Explanation - Lipases break down oils in stains, allowing them to be washed away by detergents.
Correct answer is: Hydrolysis of triglycerides in greasy stains
Q.144 Which of the following enzymes is used to break down cellulose in the production of biofuels?
Cellulase
Protease
Lipase
Amylase
Explanation - Cellulase hydrolyzes cellulose into glucose units for fermentation.
Correct answer is: Cellulase
Q.145 Which of the following best describes the use of a 'feed tank' in a bioreactor?
To store the culture broth
To contain the nutrient solution added gradually to the reactor
To sterilize the medium
To cool the culture
Explanation - The feed tank holds the substrate feed that is pumped into the reactor at controlled rates.
Correct answer is: To contain the nutrient solution added gradually to the reactor
Q.146 Which of the following is an example of a microbial product used in cosmetics?
Chitin
Collagen
Glycolipid surfactants
Hydrolyzed protein
Explanation - Microbial glycolipid surfactants (e.g., rhamnolipids) are used for their mild cleaning properties in cosmetics.
Correct answer is: Glycolipid surfactants
Q.147 Which of the following is a major advantage of using microbial lipases in the production of biodiesel?
They can operate under harsh chemical conditions
They catalyze the transesterification of triglycerides into methyl esters
They increase the viscosity of the final product
They produce more by‑products than chemical catalysts
Explanation - Lipases enable biodiesel synthesis under milder, greener conditions than traditional chemical catalysts.
Correct answer is: They catalyze the transesterification of triglycerides into methyl esters
Q.148 Which of the following enzymes is responsible for the breakdown of polysaccharides in the food industry?
Cellulase
Lipase
Protease
Amylase
Explanation - Cellulase breaks down cellulose, improving texture and digestibility in food products.
Correct answer is: Cellulase
Q.149 What is the primary purpose of a 'clarifier' in a bioprocessing workflow?
To filter out small molecules
To separate cells from the culture broth
To adjust the pH of the solution
To measure the protein concentration
Explanation - Clarifiers (e.g., centrifuges or filters) remove cells or debris before downstream purification.
Correct answer is: To separate cells from the culture broth