BIOCHEMICAL ENGINEERING Flashcards
A competitive inhibitor of an enzyme is usually
structurally similar to the substrate.
Linear inhibition is sometimes called as
complete inhibition
The effect of non-competitive inhibition on a Lineweaver-Burk Plot is that
it can change the y-intercept
The rate-determining step of Michaelis Menten kinetics is
the complex dissociation step to produce product
In competitive inhibition a factor is obtained from the measurement of
KM
Given an enzyme with a Km = 10m M and Vmax = 100 m mol/min. If [S] =100 m M, which of the following will be true?
A 10-fold increase in Vmax would increase velocity 10-fold y
The conformational change in an enzyme after the substrate is bound that allows the chemical reaction to proceed, can be explained by
induced fit
Which category of enzymes belongs to class two in the international classification?
Transferases
The Woolf-Augusteinsson-Hofstee plot of ν versus ν/[S] and the Eadie-Scatchard plot of ν/[S] versus ν do not involve reciprocals of ν therefore are considered to be more reliable when the error in v is
significant
The relationship between Keq, Km and Vmax is known as
Haldane equation
The reciprocal equation for non-competitive inhibition can be arranged to the equation for the
Dixon plot
Which of the following common drugs is not a specific enzyme inhibitor?
Iodine
In a Lineweaver-Burk Plot, competitive inhibitor shows which of the following effect?
It changes the x-intercept
An enzyme and a reactant molecule maintain relationship as
a temporary association
An enzyme is assayed at an initial substrate concentration of 2 x 10-5 M. In 6-minute, half of the substrate is used. The Km for the substrate is 2 x 10- 3 M. The value of k in minute is
0.115
Quasi steady state is also known as
Pseudo steady state
A noncompetitive inhibitor of an enzyme-catalyzed reaction
increases KM and reduces Vmax
An allosteric inhibitor of an enzyme usually
participates in feedback regulation
A classical uncompetitive inhibitor is a compound that binds
reversibly to the enzyme substrate complex yielding an inactive ESI complex
Which graphical method is used to determine an enzyme degree of cooperativity?
Hill plot
The ratio of the amount of a protein present in a sample, which is used as a measure of purification, is known as
specific activity
If a reaction occurs in the absence of inhibitor with rate ν0 and in the presence of inhibitor with rate νi, the degree of inhibition is defined as
(ν0 - νi)/ν0
The rate equation in competitive inhibition based on Michaelis Menten equation is given by
rmaxS/(Km(1+I/Ki) +S))
Classical noncompetitive inhibition is obtained only under
rapid equilibrium conditions
In the steady state the material balance equation for any component of a system is
rate of addition - rate of removal + rate of formation = 0
Predominantly uncompetitive inhibition may be called when
competitive inhibition is greater than uncompetitive inhibition
An enzyme has a Km of 4.7 x 10-5 M. If the Vmax of the preparation is 22m moles liter-1 min-1, what velocity would be observed in the presence of 2.0 x 10-4 M substrate and 5.0 x 10-5 M of a competitive inhibitor?
13.54μ moles liter-1min-1
The rate equation in non-competitive inhibition based on Michaelis Menten equation is given by
rmaxS/ (Km + S) (1+I/Ki)
The slope of Lineweaver Burk plot for Michaelis Menten equation is
Km/Vmax
The initial velocity, V0, of an enzyme catalyzed reaction reaches Vmax as
1/[S] → 0
Which of the following step is assumed to be the slowest step in the Michaelis Menten equation?
The product releasing step
When substrate [S] = KM (Michaelis-Menten constant), the velocity of an enzyme catalyzed reaction is about
0.5 * Vmax
A classical noncompetitive inhibitor has
no effect on substrate binding and vice versa
The active site of an enzyme differs from an antibody-antigen binding site in that the enzyme active site
catalyzes a chemical reaction
Enzymes are basically
Proteins
Which of the following refers to pseudo steady state?
d(CES)/dt = 0
Most enzymes work by
decreasing energy of activation
Which category of enzymes belongs to class 5 in the international classification?
Isomerases
Lock and key theory is based on the compatibility of
enzyme and substrate
When an enzyme is functioning at Vmax, the rate of the reaction is limited by
the rate at which the enzyme can convert substrate to product
The equation for the rate of product formation for simple enzyme reaction is given by (Where rmax, maximum reaction rate, Cs substrate concentration, Cp product concentration ES, CES enzyme-substrate concentration)
rp = rmax Cs/(Km+Cs)
Juice clarification extraction is facilitated by using
Cellulases
Trichoderma β-glucanase is reported
to stabilize mashing
The bitter taste of the high protein materials is reduced by using
Protease
Sulphydryl oxidase is used for α-amylase is an endo enzyme which requires a
UHT milk off flavor removal
α-amylase is an endo enzyme which requires a
Ca
Liquefaction of starch to dextrin is carried out by
α-amylase
Milk digestibility is improved by using
Lactase
Lysozyme
catalyses hydrolysis of β-1-4 linkages between N-acetyl muranic acid and Nacetyl glucosamine in peptideoglycan
Hersperidinase is used for
juice clarification
Which of the following metallic ion is there in ascorbic acid oxidase?
Cu
Citrus juice debittering can be carried out using
Limoninase
Which of the following enzyme is responsible for causing vitamin B deficiency disease beriberi?
Thiaminase
Soya off flavour removal may be achieved using
aldehyde oxidase
The reduction in off flavour of beer is practiced through
diacetyl reductase
Discoloration can be achieved by using
anthocyanase
The prosthetic group present in phenolase enzyme is
Cu
The enzyme β-galactosidase is also known as
isomerase
Stationary phase is described as
no further increase in the cell population after a maximum value
In the accelerated phase, cell starts to
increase and the division rate increases to reach a maximum
The Monod model predicts that the specific growth rate
will increase with the concentration of the growth limiting substrate until it reaches a maximum value
A mixed fermentation is one, which produces
both acid and alcohol
The phenomenon in which substrates are used in a sequential manner is known as
diauxie
The dilution rate, D is defined as (where F = volumetric flow rate, VR = total volume of culture in the reactor and μ specific growth rate)
F/VR
Diauxie is
the stagewise uptake of nutrients
An open system in which the growth rate is maintained by adding a nutrient (present in limiting quantities) at the same rate as that medium containing micro-organism is removed is called
Chemostat
In the death phase
nutrients available for the cells are depleted and begin to die
Which of the following is not correct for the Monod model and the Michaelis Menten Model
The Monod model was derived from an analysis of the mechanism of microbial growth
Bubble column reactor has
large height to diameter ratio
An open system in which the growth rate is maintained by the removal and addition of media at such a rate as to maintain a constant cell density is called a
Turbidostat
Wash out in steady state fermentation occurs when
dilution rate is higher than the maximum specific growth rate
Fermenter should be filled with medium upto
75-80%
Bacterial growth curve is obtained by plotting
log of number of cells versus time
When intracellular enzymes of whole cells are to be used in a bio-conversion process, it is often necessary to____________the cells.
Permeabilize
Heat transfer rates (per unit volume) will be lowest in
Continuous packed bed reactor
The Monod Model relates
specific growth rate to the substrate availability
The height to diameter ratio (H/D) for the column fermenters is
> 3
The maximum specific growth rate (μm) of an organism in batch culture is equal to slope of a plot of
In [biomass] against time for exponential phase data only
The region of an airlift bioreactor in which the liquid travels in a downward direction is called the
Downcomer
Population doubling time, td can be expressed as (where μ is the specific growth rate.)
ln2/μ
A higher Ks value of Monod’s equation means
Greater affinities to substrate
The increased air flow rate in bubble column fermenter can cause excessive foaming and high retention of air bubbles in the column which
Decreases the productivity of the fermenter
In an airlift bioreactor, the spent gases released from the liquid are called
Disengagement zone
The contents in jet loop reactor are mixed through
External pumping
The specific growth rate (μ) is defined as
The rate of individual cells division or increase in their biomass
The number of baffles in a standard stirred tank bioreactor is
4
In the stationary phase
Growth rate is equal to death rate
Chemostats work on the principle of
Maintaining uniform nutrients concentration
During the exponential phase the maximum specific growth rate equals specific growth rate as
Concentration of growth limiting substrate is much greater than the
An internal draft tube is preferred to an external draft tube because
It is easier to clean and sterilize a reactor
A functional relationship between the specific growth rate and essential compounds concentration was proposed by Monod in
1942
The optical density sometimes drops during the lag phase because
Cells tend to grow without dividing leading to a decrease in the surface area to volume
ratio
Residence time distribution (RTD) of a reactor is independent of
Micro mixing
The bubble column fermenter is usually limited to
Aerobic fermentations
A culture in a closed vessel to which no additional medium is added and from which no waste products are removed is called a __________culture.
Batch
If the specific growth rate, μ. is constant with time during the exponential growth period, the equation correlating bacterial number density Cn), cell number concentration with respect to time can be expressed as
Cn= Cn0 exp [μ (t - t0)]
The diameter of the baffles in a standard stirred tank bioreactor ranges from
1/10th - 1/12th of the tank diameter
During the log phase cell numbers increase exponentially
Because cells are auto catalysts
Lag phase occurs mainly due to
Substrate disliking
In a batch reactor specific growth rate
Changes during the fermentation
Turbidostat is recommended when continuous fermentation needs to be carried out at
High dilution rates near the washout point
The main function(s) of a draft tube in an air lift fermenter is/are to
Distribute shear forces throughout the reactor and minimize bubble coalescence
Which of the following is incorrect?
STF can’t be used for high viscosity medium
The contents in bubble column and air lift reactor are mixed through
Compressed air
During the lag phase
Cells synthesize new proteins and membrane components
Concentration of the growth limiting substrate means
the concentration of the substrate that controls the growth rate of the cells
Tower fermenters are used for
Continuous beer production
In wastewater treatment, which bioreactor is generally used?
Trickle bed reactor
The contents in stirred tank reactor are mixed through
A mechanical agitator
The height to diameter ratio (H/D) for the tank fermenters is
<3
The relatively large volume (10 to 40% of total fermenter volume) of the seed culture is employed to
Decrease the overall fermentation time
In an airlift bioreactor, the air sparging region is called
Air riser
At the end of the lag phase, when growth begins, the division rate increases gradually and reaches a maximum value in the exponential growth period. This transitional period is commonly called the accelerated growth phase and is often included as a part of the
Lag phase
The viscosity of liquid was classified as both dilatant and rheopectic, which means that the viscosity
increased with stirring speed and increased with mixing time
A fluid in which the viscosity decreases with increasing stirrer speed and mixing time, can be represented as
pseudoplastic, thixotropic fluid
The viscosity of water at STP is approximately
0.001 kg.m-1.s-1
Bubble free aeration systems requires
silicone tubing or gas permeable membranes to facilitate gas transfer
Non-linear relationship between shear stress and shear rate exists in
non-Newtonian fluids
If the viscosity of a fluid decreases with increasing stirrer speed, then the nature of the fluid is
Pseudoplastic
A pseudoplastic fluid is one in which the viscosity
decreases with increasing stirrer speed
A viscoelastic fluid is one in which the viscosity
changes during mixing but returns to its original state after mixing
Mixing in stirred tank reactors can
be described as either laminar, transient or turbulent
The viscosity of a fluid changes with either stirrer speed or mixing time. But when mixing ceases, the viscosity returns to its original state. This fluid is best described as
Viscoelastic
In sparged mammalian cell bioreactors, the cell damage is caused because of
shear stress arising during mixing of the cell culture fluid
The SI unit for viscosity is
kg.m-1. s-1
The viscous nature of a non-Newtonian fluid
changes with the level of power input and/or the length of time during which the fluid is mixed
A Brookfield viscometer measures viscosity by determining
the torque required to move an impeller at a set speed
The best described action of Pluronic F68 (nonionic detergent) in a cell culture medium is that, it
acts on the surface properties of the cells and the culture medium
Water is a
Newtonian fluid
A liquid is flowing at 11,400 l.h-1 along a pipeline having a diameter of 4 cm. If the liquid has a density of 1 g.ml-1 and viscosity of 0.001kg.m-1.s-1, then the liquid would be in the
turbulent phase
The viscosity of a fluid increases with the length of time that it is being mixed. This fluid would be best described as being
Rheopectic
The viscosity of a fluid increases with increasing stirrer speed. This fluid would be best described as being
Dilatant
A dilatant fluid is one in which the viscosity
increases with increasing stirrer speed
A rheopectic fluid is one in which the viscosity
increases with mixing time
A fluid in which the viscosity increases with increasing stirrer speed and mixing time can be called as
dilatant, rheopectic fluid
The medium will have the highest viscosity (considering that the cells do not secrete gums) with the presence of
filamentous fungi that grow as long poorly branched chains
A Newtonian fluid is one in which the viscosity
is constant regardless of the stirrer speed or mixing time
Which pattern of mixing is preferred in stirred tank reactors during the culture of aerobic microorganisms?
turbulent flow
Animal cell cultures do not have much effect on shear forces because
the cell size is generally smaller than the critical eddy size at which shear will have an effect
The viscosity of the culture fluid is classified as both pseudoplastic and thixotropic which indicates that the viscosity
decreases with stirring speed and decreases with mixing time
Pluronic F68 is added to cell culture media as
a shear protectorant
A stirred tank reactor containing a fluid with a density of 2.5 g.ml-1 and viscosity of 0.002 kg m-1s-1 is mixed at 120 rpm. If the fluid is mixed with an impeller having diameter 50 cm, then the Reynolds number of the liquid in the reactor is
1250000
If the viscosity of a fluid decreases with the length of time that it is being mixed, then this fluid is
Thixotropic
A thixotropic fluid is one in which the viscosity
decreases with mixing time
Newtonian fluid is one in which the viscosity
remains constant with time and power input
Reynolds number for laminar flow over a plate should be less than
5 x 10^5
The approach which is commonly used to determine the level of damage to animal cells in a culture medium is to monitor
the level of lactate dehydrogenase activity
A Brookfield viscometer cannot determine the shear stress because
the shear stress is not defined
The Komologorov eddy size
. decreases with stirrer speed
Pluronic F68 protects mammalian cells from damage stems as it is a/an
surface active agent which stabilizes foams
Reynolds number for turbulent flow over a plate should be more than
10^6
A system which requires less solvent and produces a more concentrated extract phase, is desired with a
Large distribution coefficients
Maintenance cost varies from
4-8% of the capital cost
The optimum wet solid content for the cell suspension for a bead mill is typically somewhere between
30-60% by volume
Assuming the laminar flow across the filter, the rate of filtration (dVf/dt) can be expressed as a function of pressure drop Dp by the modified D’Arcy’s equation as (where A is the area of filtering surface, K is the D’Arcy’s filter cake permeability and Lis the thickness of the filter cake)
(1/A) dVf/dt = Δp/μ(L/K)
Filtration leaf test results indicate that the filtration rate of a protein product is 100 dry lbs/(ft2 hr). What size production filter would be required to obtain 100 dry lbs of filter cake/hr?
1.54 ft2
Selectivity can be expressed as
Ratio of the distribution coefficients in different solute
The disk centrifuge is the type of centrifuge used most often for bio separations due to its
Lesser cost
The stage wise operation of adsorption is called
Contact filtration
Which of the following is not the physical method for the cells rupturing?
Enzymatic digestion
Conventional adsorption is a
Reversible process
If the solute passes through membrane freely, the the rejection coefficient (s) is
> 1
If the membrane rejects all solute, the rejection coefficient (s) is
1
In antibiotic manufacturing processes, the fermentation time ranges from
4-5 weeks
The conventional filtration involves the separation of large particles generally
dp>10μm
Which of the operation does not come under upstream processing?
Effluent treatment
For cost analysis in a fermenter system, the depreciation cost varies from
6-10% of the capital cost
Micro filtration refers to the separation of suspended material such as bacteria by using a membrane with spore sizes of
0.02 to 10μm
Start up expenses in a fermentation industry varies from
5-10% of the capital cost
The solvent flux across the membrane can be expressed as (where A is the area, Lp is the membrane permeability, σ is the reflection point, Δp is applied pressure and Δπ is the osmotic pressure)
J = Lp(Δp - σΔπ)
For the extractions operation, the selectivity should be
> 1
The purity of a solute collected between two times t1 and t2 during chromatographic separation can be calculated as
Amount of solute eluted / amount of impurity eluted
Chromatography is based on the
Different rate of movement of the solute in the column
The correlation often employed to correlate adsorption data for protein is (where Ymax is the maximum amount of solute adsorbed per mass of adsorbent, X is the mass fraction of solute in the diluent phase in solute-free basis, KL is a constant and Y is the equilibrium value of the mass of solute adsorbed per mass of adsorbent)
Y = YmaxX/(KL+X)
A typical tubular centrifuge has a bowl of 2 to 5 inch in diameter and 9 to 30 inch in height with a maximum rotating speed of
15,000 to 50,000 rpm
Water insoluble enzymes can be prepared by using multifunctional agents that are bifunctional in nature and have
Low molecular weight
Which medium is used for the production of Penicillin using immobilized cells?
Glucose medium
The immobilized enzyme produced by micro encapsulation technique provides
An extremely large surface area
Which of the following is considered as a disadvantage to the adsorption method of immobilization?
State of immobilization is very sensitive to solution pH, ionic strength, and temperature
During the enzymatic reaction of an immobilized enzyme, the rate of substrate transfer is
Equal to that of substrate consumption
The immobilized technique involving chemical method is
Covalent bond formation dependent
For a steady state condition, the change of substrate concentration (dCS/dt) is
Zero
Damkohler number (NDa) is
The ratio of the maximum reaction rate to the maximum mass transfer rate
For glucose isomerization by immobilized enzyme, the reactor generally used is
Packed Bed
If Damkohler number, NDa»_space;1, the reaction rate is much greater than the mass transfer rate and the overall reaction is controlled by the rate of mass transfer. In this case, the enzyme reaction can be described as (where Csb and Cs are the substrate concentration in bulk of solution and at the immobilized enzyme surface respectively. ks mass transfer coefficient, and a is the surface area of an immobilized enzyme particles)
rp=ksaCsb
The most commonly employed cross-linked polymer is the
Polyacrylamide gel
The support material for immobilization of cells of Bacillus subtilis is
Agarose and carbodiimide
The intraparticle mass transfer resistance can affect the rate of enzyme reaction, if enzymes are immobilized by
Copolymerization or microencapsulation
The covalent attachment of enzyme molecules is via
Nonessential amino acids residues to water insoluble, functional supports
To measure the extent to which the reaction rate is lowered because of resistance to mass transfer, the effectiveness factor of an immobilized enzyme, η can be defined as
Actual reaction rate/rate if not slowed by diffusion
The immobilization technique involving physical method is
Non-covalent bond formation dependent
Various techniques are available for determining the effective diffusivity of solute in gel. Thin disk method uses
A diffusion cell with two compartments divided by a thin gel.
The effectiveness factor increases with the
Increase of diffusivity and decreased with the increase of particle
Yield coefficient represents
Conversion efficiency of a substrate into product.
The lowest biomass yield in a culture of Escherichia coli will be in
An aerated batch culture containing an initial high concentration of glucose.
When two populations compete for a single growth limiting substrate in a continuous fermenter, which organism would not be washed out?
Organism maintaining the lowest substrate concentration.
The lowest yield of ATP is in
Fermentation
Mixing in an anaerobic sludge blanket reactor is due to
Release of gases by the microbial populations.
In batch culture, protogon is produced from peptone during the stationary phase with a yield of 0.4 protogon mg per g of peptone. If it is to be produced in a chemostat at a dilution rate of 0.5 h-1 from a medium containing 10 g/L of peptone, then the rate of protogon synthesis would be
0 g/L-h
Formation of end product by Lactococcus lactis will become non-growth associated as lactic acid accumulates because
Cells will redirect ATP to the active transport of lactic acid and H+ out of the cells.
Which of the following would not be subjected to the “glucose effect”?
Escherichia coli
Which of the statement is true for continuous reactor at steady state?
Biomass, substrate, and product concentrations do not change with time
A continuous bioreactor in which only the flow rate is used to control the rate of cell or product productivity is called
Chemostat
For organisms growing in a chemostat, the specific growth rate
Can be determined from the dilution rate.
Saccharomyces cerevisiae is being grown in a chemostat converts glucose to biomass, ethanol, glycerol, and carbon dioxide. At steady state, the concentration of glucose, biomass, ethanol, and glycerol will
Be constant
In aerobic yeast fermentation for production of citric acid from alkanes using a fed-batch culture, why alkanes are slowly fed to the yeast?
Fast addition of alkanes will inhibit the cells and reduce oxygen transfer rates.
A continuous reactor has a dilution rate of 0.5/h. Its residence time would be
2 h
Which of the following is used to calculate mass of substrate in the reactor?
Volume of reactor x substrate concentration in reactor
If biomass yields are constant, then the biomass productivity of a culture growth in continuous reactor will
Increase with dilution rate until washout
In a continuous reactor, the medium contains 40 g/L of maltose and the medium flow rate is 10 liters per hour and the effluent contains 20 g/L of lactate. What is the productivity of lactate production from this reactor?
200 g-lactate/L
A fed-batch reactor containing 1 g/L of substrate in 2 liter of medium. It is fed with 1 g/L of substrate at the rate of 1 liter per hour. After 10 hours, the concentration of substrate in the reactor was 0.5 g/L. the mass of substrate that was used by the culture in the reactor was
6g
Toxins accumulated in a reactor can lead to low biomass yields probably due to which of the following?
ATP is diverted away from anabolism to homeostasis.
The cellular productivity in a continuous stirred tank fermenter (CSTF) increases with an increase in the dilution rate and reaches a maximum value. If the dilution rate is increased beyond the maximum point, the productivity will
Decrease abruptly
Fluidized bed bioreactors provide higher mass transfer rates than packed bed bioreactors because
Particles move with the fluid in a fluidized bed bioreactor
In fed-batch fermentation, mass of substrate utilized is calculated using the relationship
Initial mass of substrate in the reactor – final mass of substrate in the reactor + flow rate x [substrate in the feed]
A chemostat has a liquid volume of 2 liters and is being fed at a rate of 4 liters per hour. Dilution rate for this reactor will be
2 h-1
Mixing per unit volume is observed to be poorest in
Continuous packed bed reactor
The growth of an organism on glucose is described by the following Monod model parameters: 𝜇𝑚 = 0.5 ℎ−1 and 𝐾𝑆 = 0.1 𝑔. 𝑙−1, if the concentration of glucose in the feed is 10 g/L and the dilution rate is set to 0.4/h, then the steady state concentration of glucose in the effluent will be
0.5 g/L
A continuous reactor at steady state contains 0.04 g/L of biomass and 0.02 g/L of phenol. The feed contained 0.1 g/L of phenol. The biomass yield would be
0.5 g/g
A culture system with constant environmental conditions maintained through continual provision of nutrient and removal of wastes is called ___ culture system
Continuous
Fed batch reactors is used to produce vinegar because
It can maintain low ethanol concentrations.
When a culture of fermenting yeast becomes metabolically uncoupled, ethanol
Production becomes non-growth associated
Mixing profiles closest to plug flow are observed in
Continuous packed bed reactor
On a glucose medium, the growth of an organism is characterized by the following Monod model and stoichiometric parameters 𝜇𝑚 = 0.3 ℎ−1, 𝐾𝑆 = 0.05 𝑔. 𝑙 −1 and 𝑌𝑋s = 0.3 𝑔. 𝑔−1. When this organism is grown in a 2- liter continuous on a medium containing 10 g/L of glucose added at 1 L/h, the steady state concentration of biomass in the reactor will be
0 g/L
Unsteady state mass balance for dynamic model of continuous stirred tank reactor (CSTR) is
Time rate of total amount in reactor = rate of addition to reactor – rate of removal + rate of formation
A fed-batch reactor initially contains 2 liter of medium. If it was fed at 1 liter per hour, then after 10 hours, the volume of the reactor will be
2 liter
A Bacillus sp. Produces an antibiotic only during the stationary phase when grown in a batch culture. If grown in a 5 liter continuous culture, the steady state productivity of the antibiotic
Will be zero
Saccharomyces cerevisiae produces high biomass yields at low glucose concentrations and high dissolved oxygen concentrations. Which of the following should be followed for maximizing its biomass productivity?
Fed batch fermenter
In a glucose-yeast extract medium, Lactococcus lactis has a maximum specific growth rate (μm) of 1.23/h. what would be the specific growth rate of this organism at steady state in a 4-liter reactor being fed at 2 liters per hour?
0.5/h
Which of the following is not correct with regards to continuous cultures?
The continuous cultures are very useful for the production of pharmaceuticals
In a plug flow reactor, the highest concentration of substrates is exposed to the cells that
Are located near entrance of feed.
A strain of Escherichia coli has a maximum specific growth rate of 0.8/h on a glucose based medium. If this organism is being grown in a chemostat with a dilution rate of 1.2/h, then at steady state the concentration of E. coli in the same medium will
Be zero
A fed-batch reactor containing 2 liters of medium and 0.1 g/L of biomass is fed with a medium containing 1 g/L of substrate at 1 liter per hour. If after 10 hours, the concentration of biomass in the reactor was 0.2 g/L, then the biomass produced during the 10-hour period is
2.2 g
Which of the following organisms will continue their metabolism at high substrate concentrations?
Pseudomonas aeruginosa
Yeast is typically produced in fed batch reactors because
Yeast cells respire at low glucose concentrations.
Two continuous bioreactors containing the same organisms, fed with the same feed at the same dilution rate were compared. Reactor 1 started with an initial concentration of glucose of 10 g/L, while reactor 2 contained 0.1 g/L of glucose at the start of the process then at steady state
The concentration of glucose in reactor 1 would be equal to reactor 2
The production of an amylase from starch by Aspergillus niger is often performed in a fed batch fermenter. This is due to the reason that
Fed-batch reactor can be used to minimize starch concentrations and thus reduce the viscosity of the medium.
The fastest route of NADH reoxidation is
Fermentation
In fed batch bioreactor modelling, the rate of change in the bioreactor volume is assumed to be equal to
Flow rate
Monoclonal antibodies are typically produced in fed batch reactors because
Hybridoma cells yield higher lactate at high glucose concentrations
In plug flow tubular reactor, the axial velocity profile on cross-section will be
Constant
Production of organic acids in batch culture is generally growth associated phase followed by non-growth associated production. The probable reason for this is that
Organic acids uncouple catabolism from anabolism.
The concentration of biomass in a continuous stirred tank reactor is 20 g dry weight per liter. What would be the concentration of biomass in the effluent?
Approximately 20 g dry weight per liter.
The ideal tubular-flow fermenter without radial variations is called
Plug flow fermenter
Pseudo-steady state in a continuous reactor refers to a reactor in which
Concentration oscillate around a mean value
The toxicity of organic acids to cells
Enhances as the pH falls
Which of the following is best described as secondary metabolite?
Penicillin
A microorganism which is subjected to the Crabtree effect is most likely to
Ferment in the presence of high concentrations of sugar and dissolved oxygen.
When the product formation is approximately equal to the rate of cell growth, the pattern of produce formation is termed as
Growth associated
Which of the following would be correct concerning the concentration of biomass (X), growth limiting substrate (S), and produce (P) in a chemostat when the cells have been washed out?
X, and P will be zero while S is equal to the substrate concentration in feed.
Pseudomonas aeruginosa has a maximum specific growth rate of 0.8/h in a medium with glucose as a growth limiting substrate. To prevent washout, the dilution rate must be set to
Less than 0.8/h
Saccharomyces cerevisiae when grown in high glucose concentration medium, the cells activity depends on which of the following?
No effect of dissolved oxygen
In a batch-fed mode, substrate will be added
Only at the end of the fermentation process.
When Escherichia coli grown in a well aerated medium, which of the following will occur?
Fructose di-phosphate accumulation inside the cells leading to fermentation.
Surface renewal theory predicts that the mass transfer coefficient is
Directly proportional to the square root of the molecular diffusivity
The oxygen transfer rate in a bioreactor will increase if
Detergent-like molecules are added.
Which of the following impellers are used for wide range of viscosities?
Turbines
Surface renewal theory predicts that the mass transfer coefficient is ___ times of vessel diameter.
1/10 to 1/12
The average concentration of oxygen in the boundary layers surrounding the bubbles (C0 * ) in a reactor is normally determined by
Measuring the steady state concentration of oxygen in the bulk liquid prior to inoculation of the reactor.
The rate limiting step in the movement of oxygen from the gas phase in a bubble to the cell is the movement of oxygen molecules through
Bubble boundary layer
The oxygen uptake requirements of a microbial population is characterized by the following parameters: μm = 0.2 h-1, K0 = 0.2 mg O2 L-1, Y0 = 0.5 mg dry weight/mg O2 and C0,crit = 0.8 mg L-1. The required concentration of cells is 1000 mg L-1 and the saturation oxygen concentration of the medium is 5.8 mg L-1. The required KLa must be greater than
64 per hour
Which have the maximum resistance while transferring carbon dioxide from the bulk liquid to an air bubble?
Moving through the bubble boundary layer.
If liquid density and viscosity remains constant, then the Reynolds number in a stirred tank reactor will vary with the
Square of the impeller diameter
What is the ratio of depth of liquid in vessel to the diameter of tank (H:Dt)?
1:1
Transient flow range of mixing speed is obtained for
10 < Rei < 10000
A typical ceiling fan would be best described as a(n)
Axial flow impeller
What is the ratio of diameter of impeller to the diameter of tank (Da:Dt)?
1:3
The reason of using a flat disk in a Turbine is
To ensure that the bulk of the energy consumption occurs at the blades.
Which of the following is not considered among the three best-known theories of interphase mass transfer?
Calderbank and Moo-Young theory
Which of the following is most likely to cause an increase in the rate of oxygen transfer into a particular aerated fermentation system?
Increase in stirrer speed
At 25°C, the saturation concentration of oxygen in water is 1.26 mmol/L and the partial pressure of oxygen is 1 atm. The Henry’s law constant will be
0.793 atm-L/mmol
Turbine impeller consists of flat impeller blades with
A vertical pitch welded to a horizontal disk.
An aerated bioreactor will increase oxygen transfer rates with the addition of detergents because it
Discourages bubble coalescence.
Henry’s law relates
The partial pressure of oxygen and the saturation concentration of oxygen in the liquid.
Power number is ratio of
Imposed forced to inertial force.
The volume of liquid (VL) in a cylindrical reactor can be calculated from the liquid height (HL) and tank diameter (Dt) using the following equation.
𝑽𝑳 = 𝑯𝑳 × 𝝅 × 𝑫𝒕𝟐 /4
The average fractional gas hold up (H) can be given as (where Zf and Zl are the level of aerated and clear liquid respectively)
𝑯 = (𝒁𝒇 − 𝒁𝒍)/𝒁f
Which of the following best explains the reasons for using axial flow impellers in crystallization and precipitation reactions?
Crystal and precipitates are not too small, so as to ensure easy separation of the solids from the mother liquor.
When the height of an aerated bioreactor is increased it will increase the oxygen transfer rate by
Increasing the partial pressure of oxygen at the base of the reactor
Which of the following is correct for the offcenter impellers?
Off-center impellers should only be used with reactors with volumes less than 10 m3 .
The power required by an impeller in a gas sparged system compared to the power required by the impeller operating at same speed in a gas free liquid is usually
Lesser
Which of the following stirrer requires least amount of energy for same yield?
Intermig
A reactor has a total volume of 50,000 liters. If it has a headspace volume of 10,000 liters, then volume of liquid in the reactor will be
40,000 L
Pure oxygen, if used instead of air will increase oxygen transfer rates because
The saturation concentration of oxygen is higher.
For aerated mixing vessels in an aqueous solution, the mass transfer coefficient (kL) corelating power consumption (Pm_ and fermenter volume (V) can be expressed as
kL∝ (Pm/V)0.33
Higher temperatures affect oxygen transfer rates by
Increasing KLa but lowering CO
Which of the following is not classified as an axial flow impeller?
A Rushton turbine
Power number (NP) is also known as
Newton’s number
Flooding is a condition/phenomenon which occur in a bioreactor when
The air escapes without being distributed by the agitator.
A cylindrical reactor has a liquid volume of 100,000 liters. It has an aspect ratio, the ratio of the channel height to width of 1:1. The height of the liquid in the reactor will be approximately:
5.0 m
A cylindrical reactor fitted with Rushton Turbine has a liquid volume of 100,000 liters. It has an aspect ratio (the ratio of the channel height to the width) of 2:1. The diameter of the impeller should be approximately:
1.3 m
In the bubble boundary layer, oxygen concentration can be determined by measuring
The steady state oxygen concentration in a mixed aerated reactor before inoculation.
Impeller damage can be minimized by
Using specially designed axial flow impellers.
In the design of a paddle agitator, the ratio of paddle diameter to tank diameter is normally taken as
0.8
Industrial paddle agitators turn at the speed of
20 and 150 rpm
The dynamic technique is based on the
Oxygen material balance in an aerated batch fermenter during the growth of microorganisms.
If the stirrer speed is too slow, bubbles will accumulate and coalesces under the impeller. This phenomenon is known as a
Flooded impeller
Reynolds (Rei) number for the impeller is given by (where Di), stirrer diameter; N, stirrer speed; ⍴, density of fluid; and μ, viscosity of fluid).
Di2Nρ/μ
The advantage of axial flow impellers over radial flow impellers is that axial flow impellers
Provide better lift of solids.
Larger propellers turn at the speed of
400 to 800 rpm
A microbial population in a suspension culture will only be limited byoxygen availability if the dissolved oxygen
Concentration is less than the critical concentration.
Which of the following model holds correct for the two-film theory? (where KL is the mass transfer coefficient, DAB diffusivity and Zf film thickness)
KL=DAB/Zf
A fermentation system has a KLa of 3 s-1 and a CO* of 5 ppm of O2. If the bulk liquid is completely depleted of oxygen, then the oxygen transfer rate will be equal to
15 mg/L-s
During aeration, a cylindrical reactor had a height of 10 m. Without aeration, the height was 7.5 m. Under these aeration and mixing conditions, the gas hold up in the reactor is
0.25
A fermentation system has a KLa of 3 s-1 and a CO* of 5 ppm of O2. If the bulk liquid is saturated with oxygen, then the oxygen transfer rate will be equal to
0
Which of the following would be best described as radial flow impeller?
A Rushton turbine
Small propellers turn at the speed of either
1150 rpm or 1750 rpm
In aerobic microorganisms cultures radial flow impellers are used because
They provide high shear mixing conditions.
The effect of increasing the stirrer speed in an unbaffled stirred tank reactor is that
As the stirrer speed increases, the liquid will continue to circulate. Eventually a vortex will form.
Turbulent flow range of mixing speed is obtained for
Rei > 10^4
For laminar flow, Reynolds number is correlated with power number as (where K, a constant which depends on the container geometry and shape of stirrer; Rei is Reynolds number for agitator; Di, stirrer diameter; and N, stirrer speed).
Np=K(Rei)-1
For turbulent flow, Reynolds number is correlated with power number as (where K, a constant which depends on the container geometry and shape of stirrer; Rei is Reynolds number for agitator; Di, stirrer diameter; and N, stirrer speed).
Np = K
In a bioreactor, if at a particular time the oxygen transfer rate is 23 kg h-1, then the oxygen uptake will be
23 kg/hr
Axial flow impellers
Provide low shear conditions and are suited for use in shear sensitive processes.
Bioreactors, where vortex is formed, another dimensionless number, ____ is useful.
Froude
If the stirring speed increased from 300 to 500 rpm leads to an increase in the reaction rate by two folds. Then it may be concluded that
The reaction was mass transfer limited at 300 rpm.
An increase in the heat transfer in the stirred tank reactor will be observed at
higher stirrer speed
In a two-phase system where the continuous phase remains in place, the gas hold up can be expressed as (where VS and Vt are the superficial gas velocity and bubble rise velocity).
𝑯 = 𝑽𝑺/(𝑽𝑺 + 𝑽𝒕)
What is the effect of the concentration of dissolved salts and sugars on the oxygen transfer rate?
The saturation concentration of oxygen in the medium decreases with the concentration of dissolved salts and sugars, leading to a lower oxygen transfer rate.
Which of the following impellers generate a flow parallel to the axis of shaft?
Axial flow
In a tall reactor, oxygen transfer rates will be
Highest at the base of the reactor.
Which of the following impeller is used in situations where strong vertical currents are desirable for heavily suspending particles?
Propeller
Laminar flow range of mixing speed is obtained for
Rei < 10
Which of the following number is calculated from the diameter and peripheral speed of the impeller?
Reynolds Number
A higher liquid height will lead to a higher gas hold up by which the oxygen transfer rate will be
Higher at the base of the reactor.
The main function of the dimples provided in the cooling jacket is to
Increase the level of turbulence of the cooling water in the jacket.
The power required by an agitator operating in a gas-sparged system is
Lesser than the power required by an impeller in operating at same speed in a gas free system.
Which of the following will have the largest interfacial area per unit volume?
A bubble with a diameter of 1 mm
Which device is commonly used for measuring the rate of rotation (rpm) of the stirrer shaft?
Tachometer
The specific death rate of an organism can be expressed as
ln (2)/D
The interception efficiency can be expressed as (where dP is the particle diameter and DC cylindrical collection diameter).
dp/Dc
The relationship between the del factor, temperature and time is given as
Δ= A.t.e^-(E/RT)
The del factor (Δ) increases as the final number of cells
decreases
The overall del factor (Δ) may be represented as
Δoverall = Δheating + Δholding + Δcooling
The deviation from ideal plug flow due to axial mixing can be described by the
Dispersion model
Glass fibers are favorable as a filter medium because they give a
Lower pressure drop and are less liable to wetting or combustion.
The collection efficiency by interception increases with the
Increasing particle size
For indirect heating, the plate and frame heat exchange is generally more effective than the shell and tube heat transfer due to its
Larger heat transfer area
If the packing density (α) is defined as the volume of the fiber unit volume of filter bed, the velocity with the filter void space is equal to (where V1 is velocity in fluid void space and V0 is undisturbed fluid velocity).
V = Vo/(1-∝)
For the turbulent flow, the dispersion coefficient is correlated as a function of
Reynolds number
In sterilization process, spore of which of the following organism is considered as control?
Bacillus stearothermophilus
Analogus to the molecular diffusion, the xdirectional flux or microorganisms suspended in a medium due to the axial mixing can be represented as (where Jn is flux component ‘n’, cn is concentration of ‘n’)
Jn = -D dcn/dx
The typical size of particles collected by diffusion mechanism is
< 0.5 μm
The X90 value for a filtration system is
The depth required to reduce population by 90%.
The value of K
Increases to an optimum with increase in air velocity and decreases on further increase of air velocity.
Model proposed by the Friedlander, correlating the air filtration efficiency by impaction can be expressed as (where NSt is the Stokes number).
ηimp= 0.075NSt1.2
The efficiency of fibrous filter by combined mechanism is given by (where ηimp, ηint, ηdif are the efficiencies by impaction, interception, and diffusion, respectively).
1 - ηimpηintηdif
The heat conduction in dry air is
Less rapid than in steam
For laminar flow of Newtonian fluid through a smooth round pipe, the ratio of average fluid velocity to the maximum velocity is
0.5
The reduction of number of cells from 10^10 to one will result into the del factor (Δ) of
23
The collection efficiency by the inertial impaction mechanism is the function of
Stokes and Reynolds number
The heated medium passes through a holding section, which is usually maintained in
Adiabatic conditions
The highest temperature which appears to be feasible for batch sterilization is
121°C
The mechanical means of accomplishing sterilization of fermentation media/equipment is
Ultrasonic
The radius of the filter with a depth of 14 cm required for a volumetric airflow rate of 10 m3 /min is approximately
0.6 m
The moist heat is more effective than the dry heat because the intrinsic heat resistance of vegetative cells is greatly
Increased in a dry state.
The destruction of microorganisms by steam may be described as
First order chemical reaction.
Typical aeration rates for aerobic fermentation are
0.5 – 1.0 vvm
The maximum desirable limit Bureau of Indian Standards (BIS) of lead in the drinking water is
0.05 mg/L
Zeolite softening process removes
Both temporary and permanent hardness of water
Conventional tertiary treatment is
Chemical coagulation and flocculation
The maximum desirable limit (BIS) of total hardness (as CaCO3) in drinking water is
300 ppm
The chemical oxygen demand (COD) measures the
Amount of oxygen that would be removed from the water in order to oxidize pollution.
Hardness of water does not
Make it unfit for drinking.
Permanent hard water may be softened by passing it through
Sodium hexametaphosphate
Zeolite used in zeolite softening process for the treatment of hard water gets exhausted after certain time of usage but can be regenerated by flushing it with
10% sodium chloride solution
Temporary hardness of water is caused by the presence of
Bicarbonates of calcium and magnesium
Secondary treatment uses ___ to consume wastes.
Microorganisms
Application of quaternary ammonium compounds as sanitizing agents tends to
Increase the percentage of gram(-)ve rods on utensils.
Permanent hardness of water is caused by the presence of
Chlorides and sulfates of calcium and magnesium
According to BIS, the maximum permissible limit of dissolved solids in drinking water is
2000 mg/L
Acid used mostly for removal of milk stone
Nitric acid
Which of the following chemical is sometime added in the process of coagulation and flocculation?
Aluminum sulphate
Which of the following physical method is used as germicidal in modern time for the treatment of drinking water?
UV radiation
Sanitizer used specifically for vitreous enamel are
Weak alkali with sodium silicate
Inhibitors are used along with sanitizer to
To prevent corrosion
Sanitizers used for rubber made equipment are
Strong alkalis
Biological oxidation processes usually referred as biological treatment, are the most common form of
Secondary treatment
The maximum permissible limit (BIS) of turbidity in drinking water is
10 NTU
Sedimentation is a physical process used in wastewater treatment to
Remove particles that are more dense than water.
The ultimate source of water is
Rain and snow
Permanent hardness of water may be removed by the addition o
Soda ash
Both temporary and permanent hardness of water can be removed on boiling water with
Sodium carbonate
Temporary hardness of water may be removed by adding
Calcium hydroxide
The maximum desirable limit (BIS) of mercury in the drinking water is
0.001 mg/L
From the following sanitizers which one comes under category of surface active agents?
Teepol
The purest form of naturally occurring water is
Rain water
Calgon is used for removal of
Permanent hardness of water
The water being used in dairy industry should contain not more than
5 proteolytic and/or lipolytic organisms per mL
The activated sludge process consists of returning a portion of the clarifier
Influent water entering the reactor.
The activated sludge process is sometime referred as
Fluid bed biological oxidation system
BOD stands for
Biochemical oxygen demand
When temporary hard water is boiled, one of the substances formed is
Carbon dioxide
Zeolite softening process removes both temporary and permanent hardness of water. In this process, the calcium and magnesium present in water are precipitated as
Insoluble zeolites
Both temporary and permanent hardness of water can be removed by
Distillation
Coliform bacteria in water is an indication of the presence of
Human feces
Which of these proteases is not a cysteine active site protease
Cathepsin D
The types of inhibition pattern based on Michaelis Menten equation are
all
The active site of an enzyme remains
none of the above
Which of the following statements is true for enzymatically catalyzed reaction?
The activation energy of the reaction is lowered so that a larger proportion of the substrate qualifies to overcome it
Which of the following statements is not true?
Enzymes only function when they are in intact cells
The plot commonly used for determining the value of Vmax is
all
Which of these enzymes contains a Zinc (Zn) ion?
Carboxypeptidase A
For an enzyme that displays Michaelis-Menten kinetics, the reaction velocity (as a fraction of Vmax) observed at [S] = 2 KMwill be
0.66
Which of the following statement(s) regarding enzymes, is/are false
Enzymes provide activation energy for reactions
The usual method(s) to solve rate equation of simple enzyme kinetics is/are
all
Michaelis Menten equation can also be written
all
When [S] = 0.1 *KM, the velocity of an enzyme catalyzed reaction is about:
0.1 * Vmax
Lysozyme is naturally present in
all
Enzymes act as antimicrobials
all
Which of the following mainly serve to convert starch into high fructose corn syrup (HFCS)?
all
Which of the enzyme combination is commercially used for the removal of oxygen?
Glucose oxidase-catalase
Enzymes degrade, alter or synthesize a food component through
all
Chymosin hydrolyses the bond between
Phenyl alanine and methionine
The function of the disengagement zone in an airlift fermenter is to
all
The maximum specific growth rate of an organism depends on
all
The function(s) of the draft tube in an airlift bioreactor is
all
The high oxygen transfer efficiencies of airlift bioreactors is due to
all
Which of the following is an example of a mathematical model?
all
Biomass concentrations during fermentation is
all
The application of just in time (JIT) manufacturing techniques in biotechnology is important because
all
The specific growth rate is affected by
all
Which of the following statements would be appropriate while comparing bubble column and air lift fermenter of the same size?
all
Which of the following(s) is/are considered the limitations of the exponential growth model?
It does not consider factors that causes cells growth to stop or slow
To describe components of an airlift bioreactor which of the follow-ings are generally included?
Disengagement zone, air riser, downcomer
Filamentous fungal cells are more shear sensitive than bacterial cells because of
all
In animal cell bioreactor, bubble damage can be minimized by
all
Which of the following compound, if added to a solution will lead to the greatest increase in viscosity?
A long chain protein such as albumin
Which of the following factors will affect the sensitivity of animal cells to shear conditions?
all
Which of the following affect the Kolmogorov eddy size?
all
Which of the following describes the importance of the Kolmogorov eddy size in the biotechnology?
all
Which of the following is correct?
the viscosity of gases increases with increasing temperature, but decreases in liquids
Concentration polarization can be reduced further by
all
The efficiency of cell disruption in a bead mill depends on the
all
A common filter medium is the cloth filter generally made of
all
An ion exchange resin is composed of
all
Which of the following is considered as a pretreatment to the biological feeds?
all
Functional groups of the nonessential amino acids that are suitable for the immobilization process are
all
Which of the following is taken as an assumption in the distributed model?
all
Commonly employed water insoluble supports the covalent attachment of enzyme include
all
Which of the following is not the correct answer?
None of the above
Which of the following is not a physical method of immobilization?
None of the above
Which is not the method for producing immobilized enzymes with multifunctional reagents?
None of the above
which of the following is the commonly employed adsorbents?
all
The continuous cultures are not widely used in industry because
all
Immobilized cell reactors for wastewater treatment have the advantage of having/being
all
Low dissolved oxygen concentrations leads to
Low biomass yields
The main reason for production of antibiotics in fed batch reactors is
all
.In a fluidized bed reactor, the function of the disengagement zone is to
all
. In an activated sludge process, the biomass is recycled to
all
Continuous culture has an advantage over to a batch cultures as
all
The power consumption in a stirring vessel can be assessed by using a
all
Which of the following type(s) of stirrer can be used for microbiological processes?
all
Why vortexing is undesirable in the agitation of biological systems?
all
Which of the following will have the highest surface area available for oxygen transfer?
A sparged stirred tank reactor agitated at 400 rpm
A flooded impeller will lead to poor oxygen transfer rates because
Bubbles tend to coalesce under the impeller.
Power consumption by agitation is
all
Which of the following impellers will provide radial flow?
all
When liquid is pumped through cooling coil in a stirred tank reactor to cool. Which of the following is not correct?
Faster cooling rates at a slower rate of pumping
The Intermig impeller is
all
. Detergent like substances produced by microorganisms during a fermentation will lead to
all
To increase the oxygen transfer rate in a shake flask culture system, which of the following (s) is/are followed?
all
The oxygen absorption rate can be determined by
all
The addition of antifoams to an aerated bioreactor will decrease oxygen transfer rates because antifoams
all
During fermentation, the saturation concentration of oxygen was reduced from 7 ppm to 1 ppm. Which one of the following conclusions can be drawn?
No conclusion can be drawn.
. The maximum solubility of the alkane in the medium is 5 ppm. If the actual dissolved concentration of the alkane in the medium is 1 ppm. What conclusion may be drawn?
No conclusion on the growth rate can be withdrawn.
Oxygen transfer rate is increased with an increase in the stirrer speed in aerated bioreactor because
all
The filter material used for air filtration system is/are
all
The mechanism of air filtration in fibrous filter is
all
.Sterilization can be carried out by
all
Lagoons may be characterized as
all
The methods used for biological treatment are
all
