Biochemical Engineering Flashcards
A competitive inhibitor of an enzyme is usually
- a highly reactive compound
- a metal ion such as Hg²⁺ or Pb²⁺
- structurally similar to the substrate.
- water insoluble
structurally similar to the substrate.
Linear inhibition is sometimes called as
- complete inhibition
- incomplete inhibtion
- partial inhibition
- mixed inhibition
complete inhibition
The types of inhibition pattern based on Michaelis Menten equation are
- competitive
- non-competitive
- uncompetitive
- all of the above
all of the above
The effect of non-competitive inhibition on a Lineweaver-Burk Plot is that
- it can move the entire curve to the right
- it can change the y-intercept
- it can change the x-intercept
- all of these
it can change the y-intercept
The rate-determining step of Michaelis Menten kinetics is
- the complex formation step
- the complex dissociation step to produce product
- the product formation step
- Both (a)and(c)
the complex dissociation step to produce product
In competitive inhibition a factor is obtained from the measurement of
- Vmax
- KM
- Y-intercept in Lineweaver-Burk Plot
- None of these
KM
Which of these proteases is not a cysteine active site protease?
- Calpain
- Cathepsin D
- Papain
- None of the above
Cathepsin D
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
- A 10 fold decrease in Km would increase velocity
- Both (a) and (b)
- A 10 fold increase in Vmax would decrease velocity 20 fold
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
- transition
- fit and fine
- Pasteur
induced fit
The active site of an enzyme remains
- at the center of globular proteins
- rigid and does not change shape
- complementary to the rest of the molecule
- none of the above
none of the above
Which category of enzymes belongs to class two in the international classification?
- Hydrolases
- Ligases
- Transferases
- Isomerase
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
- non-significant
- significant
- nothing to do with the reliability
- non significant in selected cases
significant
The relationship between Keq, Km and Vmax is known as
- Haldane equation
- Michaelis Menten equation
- Numerical solution approach
- Gibbs-Helmholtz equation
Haldane equation
The reciprocal equation for non competitive inhibition can be arranged to the equation for the
- Dixon plot
- Woolf-Augusteinsson-Hofstee plot
- Eadie-Scatchard plot
- Hanes-Woolf plot
Dixon plot
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
- Additional substrate molecules are energized to overcome the activation energy of the reaction
- The activation energy of the reaction is increased, thus decreasing the likelihood that any substrate molecules will overcome it
- The activation energy of the reaction is lowered so that a fewer substrate molecules can overcome it
The activation energy of the reaction is lowered so that a larger proportion of the substrate qualifies to overcome it
Which of the following common drugs is not a specific enzyme inhibitor?
- Iodine
- Methotrexate
- Sulfbnilamide
- Penicillin
Iodine
The enzyme inhibition can occur by
- reversible inhibitors
- irreversible inhibitors
- Both (a) and (b)
- None of these
Both (a) and (b)
In a Lineweaver-Burk Plot, competitive inhibitor shows which of the following effect?
- It moves the entire curve to right
- It moves the entire curve to left
- It changes the x-intercept
- It has no effect on the slope
It changes the x-intercept
Which of the following statements is not true?
- Enzymes are proteins that bind to specific substrates and increase the velocity of reactions involving those substrates
- Enzymes function by overcoming the activation energy barrier of a reaction
- Enzymes make thermodynamically favorable reactions to proceed; they cannot make unfavorable reactions to occur
- Enzymes only function when they are in intact cells
Enzymes only function when they are in intact cells
Non-competitive inhibitor of an enzyme catalyzed reaction
- decreases Vmax
- binds to Michaelis complex (ES)
- both (a) and (b)
- can actually increase reaction velocity in rare cases
both (a) and (b)
An enzyme and a reactant molecule maintain relationship as
- a temporary association
- an association stabilized by a covalent bond
- one in which the enzyme is changed permanently
- non complementary binding
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
- 0.42
- 0.093
- 6.693
0.115
The plot commonly used for determining the value of Vmax is
- Lineweaver Burk plot
- Langmuir plot
- Eadie Hofstee plot
- all of these
all of these
Quasi steady state is also known as
- Michaelis Menten approach
- Briggs-Haldane approach
- Pseudo steady state
- all of the above
Pseudo steady state
Which of these enzymes contains a Zinc (Zn) ion?
- Carboxypeptidase A
- Phosphorylase B kinase
- Tyrosine hydroxylase
- Phosphodiesterase
Carboxypeptidase A
A noncompetitive inhibitor of an enzyme-catalyzed reaction
- increases KM and increases Vmax
- increases KM and reduces Vmax
- reduces KM and increases Vmax
- reduces KM and reduces Vmax
increases KM and reduces Vmax
An allosteric inhibitor of an enzyme usually
- participates in feedback regulation
- denatures the enzyme
- is a hydrophobic compound
- causes the enzyme to work faster
participates in feedback regulation
Which of the following activity is possible by transferases?
- Transfer of methyl groups
- Transfer of glycosyl group
- Both (a) and (b)
- None of these
Both (a) and (b)
A classical uncompetitive inhibitor is a compound that binds
- reversibly to the enzyme substrate complex yielding an inactive ESI complex
- irreversibly to the enzyme substrate complex yielding an inactive ESI complex
- reversibly to the enzyme substrate complex yielding an active ESI complex
- irreversibly to the enzyme substrate complex yielding an active ESI complex
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
- Koshland curve
- Michaelis-Menten hyperbola
- Can not be determined
Hill plot
β-amylase is
- endoenzyme
- exoenzyme
- saccharifying enzyme
- both (b) and (c)
both (b) and (c)
Juice clarification extraction is facilitated by using
- cellulases
- amylase
- inulinase
- lactase
cellulases
Lysozyme is naturally present in
- egg white
- bacteria
- tears & milk
- all of these
all of these
Enzymes act as antimicrobials
- by depriving an organism of a necessary metabolite
- by generating a substances toxic to the organism
- by attracting a cell wall component
- all of the above
all of the above
Trichoderma β-glucanase is reported
- to stabilize mashing
- to convert taste fractions of dextrins to fermentable sugars in beer
- to convert starch to dextrin
- all of the above
to stabilize mashing
The bitter taste of the high protein materials is reduced by using
- invertase
- dectinase
- protease
- none of these
protease
Sulphydryl oxidase is used for
- discoloration
- clarification of images
- UHT milk off flavour removal
- all of these
UHT milk off flavour removal
α-amylase is an endo enzyme which requires
- Ca
- Cu
- Mn
- None of these
Ca
Liquefaction of starch to dextrin is carried out by
- α-amylase
- cellulase
- pectinase
- all of these
α-amylase
Which is true about rennet?
- It is a mixture of protease chymosin and pepsin
- It is a mixture of rennin and pepsin
- Both (a) and (b)
- none of the above
Both (a) and (b)
Milk digestibility is improved by using
- RNase
- lactase
- β-amylase
- none of these
lactase
Which of the following mainly serve to convert starch into high fructose corn syrup (HFCS)?
- α-amylase
- Gluco-isomerase
- Gluco-amylase
- all of these
all of these
Lysozyme
- catalyses hydrolysis of β-1-4 linkages between N-acetyl muranic acid and N-acetyl glucosamine in peptideoglycan
- catalyses hydrolysis of α-1-4 linkages between N-acetyl muranic acid and N-acetyl glucosamine in peptideoglycan
- catalyses hydrolysis of α-1-4 linkages between N-diacetyl muranic acid and N-diacetyl glucosamine in peptideoglycan
- all of the above
catalyses hydrolysis of β-1-4 linkages between N-acetyl muranic acid and N-acetyl glucosamine in peptideoglycan
Hersperidinase is used for
- juice clarification
- juice debittering
- off flavour reduction
- RNA reduction in fish
juice clarification
Which of the following metallic ion is there in ascorbic acid oxidase?
- Mg
- Fe
- Cu
- Mn
Cu
Which of the enzyme combination is commercially used for the removal of oxygen?
- Glucose oxidase-cellulase
- Glucose oxidase-catalase
- Glucose oxidase-lactase
- All of these
Glucose oxidase-catalase
The enzyme used to reduce bitterness of grapes commonly contains
- α-L-rhamonosidase
- β-d-glucosidase
- β- galactosidase
- both (a) and (b)
both (a) and (b)
Citrus juice debittering can be carried out using
- limoninase
- inulinase
- anthocyanase
- None of these
limoninase
Which of the following enzyme is responsible for causing vitamin B deficiency disease beriberi?
- Ascorbic acid oxidase
- Thiaminase
- Lipoxygenase
- None of these
Thiaminase
Soya off flavour removal may be achieved using
- di acetyl reductase
- β- amylase
- aldehyde oxidase
- protease
aldehyde oxidase
The reduction in off flavour of beer is practiced through
- hersperidinase
- rnase
- invertase
- diacetyl reductase
diacetyl reductase
Discoloration can be achieved by using
- sulphloydryl oxidase
- proteases
- anthocyanase
- all of these
anthocyanase
The prosthetic group present in phenolase enzyme is
- Mg
- Cu
- Ca
- Fe
Cu
Enzymes degrade, alter or synthesize a food component through
- oxidation/reduction/isomerization
- hydrolysis/synthesis
- group transfer
- all of the above
all of the above
The enzyme β-galactosidase is also known as
- lactase
- EC3.2.1.23
- both (a) and (b)
- isomerase
both (a) and (b)
Chymosin hydrolyses the bond between
- Alanine and glycine
- Phenyl alanine and methonine
- Glutamic acid and alanine
- Alanine and phenyl alanine
Phenyl alanine and methonine
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
- relative activity
- purity ratio
- all of these
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
- (ν0 + νi)/ν0
- (ν0νi)/ν0
- (ν0-νi)/νi
(ν0 - νi)/ν0
The rate equation in competitive inhibition based on Michaelis Menten equation is given by
- rmaxS/(Km (1+I/Ki)+S))
- rmaxE/(Km (1+I/Ki)+S))
- rmaxI/(Km (1+I/Ki)+S))
- rmaxS/(Km (1+I/Ki))
rmaxS/(Km (1+I/Ki)+S))
Classical noncompetitive inhibition is obtained only under
- slow equilibrium conditions
- moderate equilibrium conditions
- rapid equilibrium conditions
- non-equilibrium conditions
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
- rate of addition - rate of removal + rate of formation = 0
- rate of addition + rate of removal + rate of formation = 0
- none of the above
rate of addition - rate of removal + rate of formation = 0
For an enzyme that displays Michaelis-Menten kinetics, the reaction velocity (as a fraction of Vmax) observed at [S] = 2 KM will be
- 0.09
- 0.33
- 0.66
- 0.91
0.66
Predominantly uncompetitive inhibition may be called when
- competitive inhibition is greater than uncompetitive inhibition
- competitive inhibition is smaller than uncompetitive inhibition
- competitive inhibition is equal to uncompetitive inhibition
- none of the above
competitive inhibition is greater than uncompetitive inhibition
An enzyme has a Km of 4.7 x 10-5M. 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 10-4M substrate and 5.0 x 10-5M of a competitive inhibitor?
- 13.54μ moles liter-1min-1
- 6.68μ moles liter-1min-1
- 7.57μ moles liter-1min-1
- 17.8μ moles liter-1min-1
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)
- rmaxE/(Km (1+I/Ki)+S))
- VmaxS/(Km + S)(1+I/Ki)
- rmaxS/Km
rmaxS/(Km + S)(1+I/Ki)
Which of the following statement(s) regarding enzymes, is/are false?
- Enzymes are always proteins that function as catalysts
- Enzymes provide activation energy for reactions
- Enzyme activity can be regulated
- Enzymes may be used many times for a specific reaction
Enzymes provide activation energy for reactions
The slope of Lineweaver Burk plot for Michaelis Menten equation is
- Vmax/Km
- Km/Vmax
- 1/Km
- Km.Vmax
Km/Vmax
The initial velocity, V0, of an enzyme catalyzed reaction reaches Vmax as
- [S] = KM
- [S] = 10 * KM
- 1/[S] = 1/KM
- 1/[S] → 0
1/[S] → 0
The usual method(s) to solve rate equation of simple enzyme kinetics is/are
- Michaelis Menten approach
- Briggs-Haldane approach
- Numerical solution approach
- all of these
all of these
Michaelis Menten equation can also be written as
- (-Cs)/r = (Cs/rmax)+(Km/rmax)
- 1/r = (1/rmax)+(Km/(rmax.Cs))
- r = rmax-(Km.r/Cs)
- All of these
All of these
Which of the following step is assumed to be the slowest step in the Michaelis Menten equation?
- The substrate consuming step
- The product releasing step
- Formation of enzyme substrate complex
- None of these
The product releasing step
When substrate [S] = KM (Michaelis-Menten constant), the velocity of an enzyme catalyzed reaction is about
- 0.1 * Vmax
- 0.2 * Vmax
- 0.5 * Vmax
- 0.9 * Vmax
0.5 * Vmax
A classical noncompetitive inhibitor has
- no effect on substrate binding
- no effect on substrate binding and vice versa
- significant effect on substrate binding
- significant effect on substrate binding and vice versa
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
- contains modified amino acids
- catalyzes a chemical reaction
- is complementary to a specific ligand
- contains amino acids without side chains
catalyzes a chemical reaction
Enzymes are basically
- proteins
- vitamins
- fat
- carbohydrates
proteins
Which of the following refers to pseudo steady state ?
- d(CE)/dt = 0
- d(Cp)/dt = 0
- d(CES)/dt = 0
- d(Cs)/dt = d(CES)/dt
d(CES)/dt = 0
Most enzymes work by
- increasing energy of activation
- decreasing energy of activation
- not affecting energy of activation
- none of the above
decreasing energy of activation
Which category of enzymes belongs to class 5 in the international classification?
- Hydrolases
- Isomerases
- Oxido-reductases
- Cyclase
Isomerases
Lock and key theory is based on the compatibility of
- enzyme and substrate
- enzyme and product
- enzyme and enzyme substrate complex
- enzyme substrate complex and product
enzyme and substrate
When an enzyme is functioning at Vmax, the rate of the reaction is limited by
- the number of collisions between enzyme and substrate
- the number of substrate molecules in the reaction
- the concentration of the substrate
- the rate at which the enzyme can convert substrate to product
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)
- rp= rmax CES/(Km+ CES)
- rp = rmax Cs/(Km+CES)
- rp = rmax Cs/(Km+Cp)
rp = rmax Cs/(Km+Cs)
When [S] = 0.1 *KM, the velocity of an enzyme catalyzed reaction is about:
- 0.1 * Vmax
- 0.3 * Vmax
- 0.5 * Vmax
- 0.7 * Vmax
0.1 * Vmax
The function of the disengagement zone in an airlift fermenter is to
- prevent CO2 rich bubbles from entering the downcomer
- reduce the velocity of the bubbles
- reduce liquid loss as aerosols
- all of the above
all of the above
Stationary phase is described as
- no further increase in the cell population after a maximum value
- deceleration of growth and division rate after the growth rate reaches a maximum
- acceleration of growth and division rate after the growth rate reaches a maximum
- deceleration of growth and division rate after the growth rate reaches a minimum
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
- decrease and the division rate increases to reach a maximum
- increase and the division rate decreases to reach a maximum
- increase and the division rate increases to reach a minimum
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
- will decrease with the concentration of the growth limiting substrate
- will increase with the concentration of the growth limiting substrate
- does not depend on growth limiting substrate
will increase with the concentration of the growth limiting substrate until it reaches a maximum value
A mixed fermentation is one, which produces
- both alcohol and carbon dioxide
- both acid and carbon dioxide
- both acid and alcohol
- several different kinds of acid
both acid and alcohol
The function of a mechanical seal is to
- prevent contaminants entering the reactor
- prevent cells from leaving the reactor
- both (a) and (b)
- prevent air to enter
both (a) and (b)
The phenomenon in which substrates are used in a sequential manner is known as
- trans-substrate genesis
- dialism
- diauxie
- multiplicity
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
- VR/F
- μ/F
- F/μ
F/VR
Diauxie is
- growth factors
- microbiological die off
- the simultaneous uptake of nutrients
- the stagewise uptake of nutrients
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-organisms is removed is called
- manostat
- chemostat
- turbidostat
- culturostat
chemostat
In the death phase
- nutrients available for the cells are depleted and begin to die
- the number of viable cells will increase
- nutrients available for cells are replenished and start to multiply
- none of the above
nutrients available for the cells are depleted and begin to die
The maximum specific growth rate of an organism depends on
- medium composition
- temperature
- pH
- All of these
All of these
Which of the following is not correct for the Monod model and the Michaelis Menten Model?
- The Michaelis Menten Model was derived from a curve fitting exercise
- The Michaelis Menten model was derived from an analysis of the mechanism of microbial growth
- The Monod model was derived from an analysis of the mechanism of microbial growth
- All of the above
The Monod model was derived from an analysis of the mechanism of microbial growth
Bubble column reactor has
- large height to diameter ratio
- small height to diameter ratio
- large diameter to height ratio
- small diameter to height ratio
large height to diameter ratio
Why a T-flask used in small-scale cell culture is incubated in a horizontal position?
- To save space
- To increase the surface area of the liquid-air interface
- Both (a) and (b)
- To increase the rate of oxygen transfer into the liquid
Both (a) and (b)
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
- manostat
- chemostat
- turbidostat
- culturostat
turbidostat
Wash out in steady state fermentation occurs when
- dilution rate is less than maximum specific growth rate
- dilution rate is higher than the maximum specific growth rate
- cell concentration reaches the maximum
- specific growth rate is maximum
dilution rate is higher than the maximum specific growth rate
Fermentor should be filled with medium upto
- 65-70%
- 70-75%
- 75-80%
- 80-85%
75-80%
Bacterial growth curve is obtained by plotting
- number of cells versus time
- number of spores versus time
- log of number of cells versus time
- log of number of cells survived versus time
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
- lyophilize
- heat-kill
- denature
permeabilize
Heat transfer rates (per unit volume) will be lowest in
- Stirred tank bioreactor with biomass recycle
- Continuous air lift bioreactor
- Continuous packed bed reactor
- Continuous fluidized bed bioreactor
Continuous packed bed reactor
The function(s) of the draft tube in an airlift bioreactor is
- to reduce bubble coalescence
- to improve circulation
- to even out shear conditions throughout the reactor
- all of the above
all of the above
The Monod Model relates
- substrate utilized with the biomass consumption
- specific growth rate to the substrate availability
- yield with the biomass utilization
- the biomass concentration with specific growth rate
specific growth rate to the substrate availability
The height to diameter ratio (H/D) for the column fermenters is
- <3
- > 3
- <1.5
- > 1.5
- > 3
The high oxygen transfer efficiencies of airlift bioreactors is due to
- the large aspect ratio of the reactor, which leads to a high gas hold-up
- the large aspect ratio of the reactor, which leads to a high oxygen solubility at the base of the reactor
- the draft tube, which reduces bubble coalescence in the reactor
- all of the above
all of the above
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
- In [biomass] against time
- biomass against time
- biomass against time for stationary phase data only
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
- disengagement zone
- air riser
- flotsam
downcomer
Population doubling time, td can be expressed as (where μ is the specific growth rate.)
- log2/μ
- ln2/μ
- μ/ln2
- μ/log2
ln2/μ
A higher Ks value of Monod’s equation means
- greater affinities to substrate
- lower affinities to substrate
- unaffected with the substrate bonding
- lower dissociation constant value
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
- increases the productivity of the fermenter
- modestly increases the productivity of the fermenter
- does not affect on the productivity
decreases the productivity of the fermenter
Which of the following is correct for the prediction of time requirement in a batch fermenter?
- Carrying out experiments
- Mathematical modelling of the fermentation process
- Both (a) and (b)
- It is impossible to predict the time required for fermentation
Both (a) and (b)
In an airlift bioreactor, the spent gases released from the liquid are called
- downcomer
- disengagement zone
- air riser
- flotsam
disengagement zone
The contents in jet loop reactor are mixed through
- compressed air
- a mechanical agitator
- external pumping
- any of these
external pumping
The specific growth rate (μ) is defined as
- the concentration of biomass in the reactor
- rate of increase of total biomass in a reactor
- the rate of individual cells division or increase in their biomass
- the rate of cell death
the rate of individual cells division or increase in their biomass
The number of baffles in a standard stirred tank bioreactor is
- 8
- 6
- 4
- 2
4
In the stationary phase
- growth is proportional to death
- growth rate is equal to death rate
- growth rate is lesser than death rate
- no co-relation exist between death rate and growth rate
growth rate is equal to death rate
Which of the following is an example of a mathematical model?
- Volume of cuboid = length x breadth x height
- The Monod Model
- The Michaelis Menten Equation
- All of the above
All of the above
Biomass concentrations during fermentation is
- diluting the samples to optical density less than 0.3
- monitored by controlling the changes in biomass concentrations
- considering that optical density is proportional to the surface area of the biomass in the sample
- all of the above
all of the above
Chemostats work on the principle of
- maintaining constant volume of culture medium
- maintaining continuous flow of nutrients
- maintaining uniform nutrients concentration
- operating at higher pressure
maintaining uniform nutrients concentration
During the exponential phase the maximum specific growth rate equals specific growth rate as
- concentration of the growth limiting substrate is much less than the monod constant
- concentration of growth limiting substrate is much greater than the monod constant
- specific growth rate increases exponentially
- concentration of the growth limiting substrate is equal to the monod constant
concentration of growth limiting substrate is much greater than the monod constant
An internal draft tube is preferrred to an external draft tube because
- it is easier to clean and sterilize a reactor
- it is cheaper to build a reactor with an internal draft tube
- Both (a) and (b)
- none of the above
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
- 1958
- 1946
- 1942
- 1950
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
- of fast cell growth causing them to fill up with DNA
- cells swell up with water
- cells swell up with RNA
cells tend to grow without dividing leading to a decrease in the surface area to volume ratio
The application of just in time (JIT) manufacturing techniques in biotechnology is important because
- raw materials used in biotechnology are biodegradable
- the products of biotechnology are biodegradable
- it is a very competitive business (d) all of the above
- all of the above
all of the above
Residence time distribution (RTD) of a reactor is independent of
- micro mixing
- volume of reactor
- height of the reactor
- width of the reactor
micro mixing
The bubble column fermenter is usually limited to
- aerobic fermentations
- anaerobic fermentations
- Both (a) and (b)
- facultative fermentation
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.
- continuous
- batch
- fed-batch
- semi continuous
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)]
- Cn0 = Cn exp[μ (t - t0)]
- Cn/Cn0 =(1/μ)exp(t-t0)
- Cn0 / Cn = (1/μ)exp(t-t0)
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
- 1/3rd - 1/4th of the tank diameter
- 1/15th - 1/20th of the tank diameter
- 1/20th - 1/25th of the tank diameter
1/10th - 1/12th of the tank diameter
During the log phase cell numbers increase exponentially
- because cells produce enzymes
- because cells do not have cell membranes
- because cells are autocatalysts
- because the rate of cell division increases exponentially
because cells are autocatalysts
Lag phase occurs mainly due to
- acclimatization with new environment and substrate
- higher growth temperature
- substrate disliking
- variation in substrate concentration
acclimatization with new environment and substrate
In a batch reactor specific growth rate
- remains constant throughout the process
- increases exponentially
- changes during the fermentation
- is highest during the stationary phase
changes during the fermentation
Turbidostat is recommended when continuous fermentation needs to be carried out at
- high dilution rates near the washout point
- low dilution rates near the washout point
- moderate dilution rates near the washout point
- any intensity of dilution rates near the washout point
high dilution rates near the washout point
The advantage of airlift bioreactors over stirred tank bioreactors of a similar size is
- higher oxygen transfer rates
- more uniform shear conditions
- both (a) and (b)
- less foaming
both (a) and (b)
Stirred tank fermenter (STF) can be employed for
- aerobic fermentation of a wide range of cells including microbial, animal and plant cells
- anaerobic fermentation of a wide range of cells including microbial, animal and plant cells
- Both (a) and (b)
- anaerobic fermentation of plant cells only
Both (a) and (b)
The specific growth rate is affected by
- sabstrate concentration
- product concentration
- oxygen supply
- all of these
all of these
The main function(s) of a draft tube in an air lift fermenter is/are to
- increase the solubility of oxygen
- distribute shear forces throughout the reactor and minimise bubble coalescence
- concentrate shear forces around the sparger
- concentrate shear forces near the disengagement zone
distribute shear forces throughout the reactor and minimise bubble coalescence
Which of the following is incorrect?
- The mechanical agitation and aeration are effective for suspension of cells
- The mechanical agitation and aeration are effective for mixing the medium
- STF can’t be used for high viscosity medium
- The mechanical agitation and aeration are effective for oxygenation
STF can’t be used for high viscosity medium
The contents in bubble column and air lift reactor are mixed through
- compressed air
- a mechanical internal moving part
- external pumping
- any of these
external pumping
Which of the following statements would be appropriate while comparing bubble column and air lift fermenter of the same size?
- The average bubble size is smaller in an airlift bioreactor
- Oxygen transfer rate is higher in an airlift bioreactor
- The surface area for gas exchange is higher in an airlift bioreactor
- All of the above
All of the above
During the lag phase
- cells just start growing
- cells synthesize new proteins and membrane components
- cells produce antibiotics to kill competing organisms
- cells simply grow slowly
cells synthesize new proteins and membrane components
Concentration of the growth limiting substrate means
- trace elements concentration
- the concentration of the substrate that controls the growth rate of the cells
- sugar concentration in the fermentation medium
- dissolved oxygen concentration
the concentration of the substrate that controls the growth rate of the cells
Tower fermentors are used for
- continuous penicillin production
- continuous beer production
- production of enzymes
- batch production of beer
continuous beer production
n wastewater treatment, which bioreactor is generally used?
- Plug flow reactor
- Trickle bed reactor
- Tower fermentor
- CSTR
Trickle bed reactor
The contents in stirred tank rector are mixed through
- compressed air
- a mechanical agitator
- external pumping
- any of these
a mechanical agitator
The height to diameter ratio (H/D) for the tank fermenters is
- <3
- > 3
- <1.5
- > 1.5
<3
The relatively large volume (10 to 40% of total fermenter volume) of the seed culture is employed to
- increase the overall fermentation time
- increase the overall yield of biomass
- decrease the overall fermentation time
- decrease the overall yield of product
decrease the overall fermentation time
In an airlift bioreactor, the air sparging region is called
- downcomer
- disengagement zone
- air riser
- none of these
air riser
The air riser is located on the outside of the draft tube for the large-scale airlift bioreactors because of
- higher oxygen transfer rates
- a small sparge ring
- better heat transfer efficiencies
- all of these
better heat transfer efficiencies
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
- stationary phase
- death phase
- exponential growth phase
lag phase
Which of the following(s) is/are considered the limitations of the exponential growth model?
- Only predicts that cells grow exponentially during the log phase
- It does not consider factors that causes cells growth to stop or slow
- Predicts cell growth at a linear rate
- All of the above
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
- Flotsam, jetsam, downzone
- Air comer, disentanglement zone, downsizer
- All of the above
Disengagement zone, air riser, downcomer
The viscosity of liquid was classified as both dilatant and rheopectic, which means that the viscosity
- increased with stirring speed but decreased with mixing time
- increased with stirring speed and increased with mixing time
- decreased with stirring speed but increased with mixing time
- decreased with stirring speed and decreased with mixing time
increased with stirring speed and increased with mixing time
Which of the following describes the detrimental effect of bubbles on animal cells?
- Cells trapped on the surface of bubbles can be damaged when the bubbles explode, releasing their pressure and surface energies
- Cells trapped in the moving foam can be dragged apart by the bubbles
- Both (a) and (b)
- Bubbles can explode in the liquid medium causing the release of ultraviolet radiation
Both (a) and (b)
A fluid in which the viscosity decreases with increasing stirrer speed and mixing time, can be represented as
- newtonian fluid
- pseudoplastic, thixotropic fluid
- dilatant, rheopectic fluid
- dilatant, pseudoplastic fluid
pseudoplastic, thixotropic fluid
Filamentous fungal cells are more shear sensitive than bacterial cells because of
- the presence of citin in cell walls of filamentous fungi
- larger in size than bacterial cells and therefore are more susceptible to shear forces
- fungal cells are much larger than bacterial cells
- all of the above
all of the above
The viscosity of water at STP is approximately
- 0.005 kg.m-1.s-1
- 0.001 kg.m-1.s-1
- 0.003 kg.m-2.s-1
- 0.1 g.cm-1.s-1
0.001 kg.m-1.s-1
Bubble free aeration systems requires
- silicone tubing or gas permeable membranes to facilitate gas transfer
- carbon dioxide instead of air to supply oxygen
- silicone tubing or gas permeable membranes to remove carbon dioxide by oxygen in the form of hydrogen peroxide
- filled headspace of the reactor with carbon dioxide
silicone tubing or gas permeable membranes to facilitate gas transfer
Non-linear relationship between shear stress and shear rate exists in
newtonian fluids
non-newtonian fluids
both (a) and (b)
none of these
non-newtonian fluids
If the viscosity of a fluid decreases with increasing stirrer speed, then the nature of the fluid is
newtonian
pseudoplastic
dilatant
thixotropic
pseudoplastic
A pseudoplastic fluid is one in which the viscosity
is constant regardless of the stirrer speed or mixing time
changes during mixing but returns to its original state after mixing
increases with increasing stirrer speed
decreases with increasing stirrer speed
decreases with increasing stirrer speed
A viscoelastic fluid is one in which the viscosity
is constant regardless of the stirrer speed or mixing time
changes during mixing but returns to its original state after mixing
increases with increasing stirrer speed
decreases with increasing stirrer speed
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
achieve turbulent conditions by increasing the stirrer speed
induce laminar flow conditions by the addition of baffles
all of the above
be described as either laminar, transient or turbulent
In animal cell bioreactor, bubble damage can be minimized by
the addition of a shear protectorant
using a bubble free oxygen delivery system
headspace aeration
all of the above
all of the above
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
newtonian
rheopectic
viscoelastic
thixotropic
viscoelastic
In sparged mammalian cell bioreactors, the cell damage is caused because of
shear stress arising during mixing of the cell culture fluid
shear stresses arising from the breakup of bubbles at the liquid surface
shear stresses between bubbles in foam at the liquid surface
all of the above
shear stress arising during mixing of the cell culture fluid
The SI unit for viscosity is
kg.m-1.s-1
kg.m-2.s-2
kg.m-3.s-1
kg.m-1.s-2
kg.m-1.s-1
The viscous nature of a non-Newtonian fluid
remains constant with time and power input
changes with the level of power input and/or the length of time during which the fluid is mixed
is similar to that of a perfect gas
is similar to that of water
changes with the level of power input and/or the length of time during which the fluid is mixed
Which of the following compound, if added to a solution will lead to the greatest increase in viscosity?
A globular protein
Glucose
A long chain protein such as albumin
Water
A long chain protein such as albumin
A Brookfield viscometer measures viscosity by determining
the shear stress
the shear rate
the shear stress and shear rate
the torque required to move an impeller at a set speed
the torque required to move an impeller at a set speed
Which of the following factors will affect the sensitivity of animal cells to shear conditions?
Cell size
Availability of nutrients in the medium
The presence of shear protectorants in the medium
All of the above
All of the above
The best described action of Pluronic F68 (non-ionic detergent) in a cell culture medium is that, it
acts on the surface properties of the cells and the culture medium
provides nutrients for the cells
acts as a flocculant
acts as a coagulant
acts on the surface properties of the cells and the culture medium
Water is a
newtonian fluid
pseudoplastic
dilatant
rheopectic
newtonian fluid
Which of the following affect the Kolmogorov eddy size?
Stirrer speed
Physical properties of the liquid
Size and type of impeller
All of these
All of these
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
laminar phase
transient phase
turbulent phase
any of the phase
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
newtonian
rheopectic
viscoelastic
thixotropic
rheopectic
Which of the following can act as a shear protectorant?
Serum
Silicone oil
Glucose
Glutamic acid
Serum
The viscosity of a fluid increases with increasing stirrer speed. This fluid would be best described as being
newtonian
pseudoplastic
dilatant
thixotropic
dilatant
A dilatant fluid is one in which the viscosity
is constant regardless of the stirrer speed or mixing time
changes during mixing but returns to its original state after mixing
increases with increasing stirrer speed
decreases with increasing stirrer speed
increases with increasing stirrer speed
A rheopectic fluid is one in which the viscosity
is constant regardless of the stirrer speed or mixing time
changes during mixing but returns to its original state after mixing
increases with mixing time
decreases with mixing time
increases with mixing time
A fluid in which the viscosity increases with increasing stirrer speed and mixing time can be called as
newtonian fluid
pseudoplastic, thixotropic fluid
dilatant, rheopectic fluid
dilatant pseudoplastic fluid
dilatant, rheopectic fluid
The medium will have the highest viscosity (considering that the cells do not secrete gums) with the presence of
single celled bacteria
filamentous fungi that form pellets
filamentous fungi that grow as long poorly branched chains
yeast
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
changes during mixing but returns to its original state after mixing
increases with increasing stirrer speed
decreases with increasing stirrer speed
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?
Laminar flow
Transient flow
turbulent flow
all of these
all of these
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
cells are larger than the critical eddy size at which shear will have an effect
animal cells have cell walls
animal cells have cell membranes
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
increases with stirring speed but decreases with mixing time
increases with stirring speed and increases with mixing time
decreases with stirring speed but increases with mixing time
decreases with stirring speed and decreases with mixing time
decreases with stirring speed and decreases with mixing time
Pluronic F68 is added to cell culture media as
a nutrient
a shear protectorant
to increase oxygen transfer rates
all of these
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
2500
100
12,50,000
1,000,000
12,50,000
If the viscosity of a fluid decreases with the length of time that it is being mixed, then this fluid is
newtonian
rheopectic
viscoelastic
thixotropic
thixotropic
Which of the following describes the importance of the Kolmogorov eddy size in the biotechnology?
The Kolmogorov eddy size is a measure of the smallest eddy size in a liquid
When the Kolmogorov eddy size become equivalent or smaller than the cell or particle diameter, then the cell or particle will become susceptible to shear damage
At the Kolmogorov eddy size, much of the energy of the originating eddy will be released
All of the above
All of the above
A thixotropic fluid is one in which the viscosity
is constant regardless of the stirrer speed or mixing time
changes during mixing but returns to its original state after mixing
increases with mixing time
decreases with mixing time
decreases with mixing time
Newtonian fluid is one in which the viscosity
remains constant with time and power input
increases with the level of power input
decreases with the level of power input
drastically increases with the level of power input
remains constant with time and power input
Reynolds number for laminar flow over a plate should be less than
500 mm
5 x 10⁻⁵
5 x 10⁵
5 m
5 x 10⁵
The approach which is commonly used to determine the level of damage to animal cells in a culture medium is to monitor
the concentration of lactate in the medium
the level of lactate oxidase activity in the medium
the level of lactate dehydrogenase activity
the level of lactase activity in the medium
the level of lactate dehydrogenase activity
A Brookfield viscometer cannot determine the shear stress because
the shear stress is not defined
a computer is required
the impeller type is given only by numbers
all of the above
the shear stress is not defined
Which of the following is correct?
The viscosity of liquids and gases decrease with increasing temperature
The viscosity of liquids and gases increase with increasing temperature
the viscosity of gases increases with increasing temperature, but decreases in liquids
the viscosity of gases decreases with increasing temperature, but decreases in liquids.
the viscosity of gases increases with increasing temperature, but decreases in liquids
The Komologorov eddy size
is constant at all stirrer speeds
increases with stirrer speed
decreases with stirrer speed
becomes zero when the stirrer speed is very low
decreases with stirrer speed
Pluronic F68 protects mammalian cells from damage stems as it is a/an
surface active agent which stabilizes foams
surface active agent which destabilizes foams
excellent source of vitamins
coagulant
surface active agent which stabilizes foams
Reynolds number for turbulent flow over a plate should be more than
5 x 10⁻⁵
106
5 x 10⁵
500
106
Concentration polarization can be reduced further by
pre filtering the solution
reducing the flow rate per unit membrane surface area
back washing periodically
all of the above
all of the above
A system which require less solvent and produces a more concentrated extract phase, is desired with a
large distribution coefficients
small distribution coefficients
very small distribution coefficients
constant distribution coefficients
large distribution coefficients
The efficiency of cell disruption in a bead mill depends on the
concentration of the cells
amount and size of beads
type and rotational speed of agitation
all of these
all of these
A common filter medium is the cloth filter generally made of
canvas
synthetic fabrics
metal or glass fiber
all of these
all of these
An ion exchange resin is composed of
polymeric network
ionic functional groups
counter ions
all of these
all of these
Maintenance cost varies from
0-4% of the capital cost
12-16% of the capital cost
4-8% of the capital cost
8-12% of the capital cost
4-8% of the capital cost
The optimum wet solid content for the cell suspension for a bead mill is typically somewhere between
5-15% by volume
15-30% by volume
30-60% by volume
60-90% by volume
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)
dVf/dt = (1/A)Δp/μ(L/K)
(1/A) dVf/dt = Δp/μ LK
dVf/dt = (1/A)Δp/μ LK
(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
3.08 ft²
65 ft²
65 lbs/ ft².hr
1.54 ft²
Selectivity can be expressed as
ratio of the distribution coefficients in different solute
mass fraction of the solute in the extract phase at equilibrium
mass fraction of the solute in the raffinate phase
ratio of the mass fraction of the solute in the extract phase to the raffinate phase
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
continuous operation
lesser cost
higher speed
ease in operation
lesser cost
The effectiveness of a solvent can be measured by the
distribution coefficients
selectivity
both (a) and (b)
diffusivity
both (a) and (b)
The stage wise operation of adsorption is called
contact filtration
conventional adsorption
affinity adsorption
ion exchange
contact filtration
Which of the following is not the physical method for the cells rupturing?
Milling
Homogenization
Ultrasonication
Enzymatic digestion
Enzymatic digestion
Conventional adsorption is a
reversible process
irreversible process
either reversible or irreversible
none of these
reversible process
If the solute passes through membrane freely, the the rejection coefficient (s) is
1
0
>1
<1
0
If the membrane rejects all solute, the rejection coefficient (s) is
1
0
>1
<1
1
In antibiotic manufacturing processes, the fermentation time ranges from
2-3 weeks
1-2 weeks
4-5 weeks
2-4 weeks
4-5 weeks
The conventional filtration involves the separation of large particles generally
dp>5μm
dp>10μm
dp>15μm
dp>20μm
dp>10μm
Which of the operation does not come under upstream processing?
Media preparation
Inoculum development
Effluent treatment
Storage of raw material
Effluent treatment
For cost analysis in a fermentor system, the depreciation cost varies from
5-6% of the capital cost
6-7% of the capital cost
6-10% of the capital cost
8-10% of the capital cost
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
1-10A°
20-30μm
10-200A°
0.02 to 10μm
Start up expenses in a fermentation industry varies from
0-5% of the capital cost
10-15% of the capital cost
5-10% of the capital cost
15-20% of the capital cost
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)
J/A = Lp(Δp - σΔπ)
J= Lp/σΔπ
J/A = Lp/Δp
J = Lp(Δp - σΔπ)
Which of the following is considered as a pretreatment to the biological feeds?
Heating to denature the proteins
Addition of filter aids to increase the porosity
Addition of electrolytes
All of the above
All of the above
For the extractions operation, the selectivity should be
> 1
< 1
1
zero
> 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
amount of solute eluted / amount of impurity eluted
amount of solvent eluted + amount of impurity eluted
amount of solvent eluted / amount of impurity eluted
amount of solute eluted / amount of impurity eluted
Chromatography is based on the
different rate of movement of the solute in the column
separation of one solute from other constituents by being captured on the adsorbent
different rate of movement of the solvent in the column
any of the above
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)
Y= Ymax/(KL+X)
Y= YmaxX/KL
Y = Ymax- X/ (KL+X)
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
50,000 to 100,000 rpm
100,000 to 150,000 rpm
150,000 to 200,000 rpm
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
high molecular weight
high equivalent weight
low reactivity
low molecular weight
Functional groups of the nonessential amino acid residues that are suitable for the immobilization process are
free α-, β- or γ carb oxyl groups
α or β amino groups
phenyl, hydroxyl, sulfhydryl or imidazole groups
all of the above
all of the above
Which medium is used for the production of Penicillin using immobilized cells
1% peptone medium
glucose medium
Yeast extract medium
LB broth
glucose medium
Which of the following is taken as an assumption in the distributed model?
The reaction occurs at every position and the kinetics of the reaction are of the same form as observed for free enzyme.
Mass transfer through the immobilized enzyme occurs via molecular diffusion
There is no mass transfer limitation at the outside surface of the spherical immobilized enzyme
All of the above
All of the above
The immobilized enzyme produced by micro encapsulation technique provides
an extremely large surface area
smaller surface area
high amount of solvent
relatively smaller surface area
an extremely large surface area
Which of the following is considered as a disadvantage to the adsorption method of immobilization?
It is possible to separate and purify the enzymes while being immobilized
The enzymes are not usually deactivated by adsorption
The adsorption is a reversible process
State of immobilization is very sensitive to solution pH, ionic strength and temperature
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
more than that of substrate consumption
lesser than that of substrate consumption
is nothing to do with the substrate consumption
equal to that of substrate consumption
The immobilized technique involving chemical method is
covalent bond formation dependent
non-covalent bond formation dependent
both (a) and (b)
ionic bond formation dependent
covalent bond formation dependent
For a steady state condition, the change of substrate concentration (dCs/dt) is
zero
1
>1
<1
zero
Damkohler number(NDa) is
the ratio of the maximum reaction rate to the maximum mass transfer rate
the ratio of the minimum reaction rate to the maximum mass transfer rate
the ratio of the maximum reaction rate to the minimum mass transfer rate
the ratio of the minimum reaction rate to the minimum mass transfer rate
the ratio of the maximum reaction rate to the maximum mass transfer rate
For glucose isomerization by immobilized enzyme, the reactor generally used is
CSTR
plug flow
packed bed
fluidized bed
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 = ksa(Csb-Cs)
rp = ksaCsb
rp = ksaCs
rp = ksa(Csb+Cs)
rp = ksaCsb
The most commonly employed cross-linked polymer is the
polyacrylamide gel
collagen
celluloses
cation exchange resin
polyacrylamide gel
Which of the following is not the correct answer?
Immobilized enzyme may show selectively altered chemical properties
Immobilized enzyme may show selectively altered physical properties
Immobilized enzyme may simulate the realistic natural environment where the enzyme come from the cell
None of the above
None of the above
Commonly employed water insoluble supports for the covalent attachment of enzyme include
acrylamide based polymers
polypeptides
dextran
all of these
all of these
Which of the following is not a physical method of immobilization?
Adsorption
Entrapment
Micro encapsulation
None of these
None of these
The support material for immobilization of cells of Bacillus subtilis is
ion exchange resins
gelatin
Anthracite
agarose and carbodiimide
agarose and carbodiimide
The intraparticle mass transfer resistance can affect the rate of enzyme reaction, if enzymes are immobilized by
copolymerization or microencapsulation
crosslinking using multifunctional reagents
adsorption
all of the above
copolymerization or microencapsulation
The covalent attachment of enzyme molecules is via
nonessential amino acids residues to water insoluble, functional supports
essential amino acids residues to water insoluble, functional supports
nonessential amino acids residues to water soluble, functional supports
essential amino acids residues to water soluble, functional supports
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
reaction rate/rate if not slowed by diffusion
rate if not slowed by diffusion/ reaction rate
actual reaction rate/ rate if not slowed by diffusion
rate if not slowed by diffusion/ actual reaction rate
actual reaction rate/ rate if not slowed by diffusion
Which is not the method for producing immobilized enzymes with multifunctional reagents?
Enzymes are adsorbed on the surface active support followed by intermolecular cross linking
Functional groups are introduced on the support to react co-valently with enzymes
Enzymes are cross linked intermolecularly
None of the above
None of the above
The immobilization technique involving physical method is
covalent bond formation dependent
non-covalent bond formation dependent
both (a) and (b)
ionic bond formation dependent
non-covalent bond formation dependent
Which of the following is the commonly employed adsorbents?
Calcium carbonate
Alumina
Celluloses
All of these
All of these
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
a diffusion cell with two compartments
a diffusion cell with two compartments plus by a thin gel
a diffusion cell with two compartments multiply by a thin gel
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 size
increase of diffusivity and increased with the increase of particle size
decrease of diffusivity and decreased with the increase of particle size
increase of diffusivity and decrease with the decrease of particle size
increase of diffusivity and decreased with the increase of particle size
Yield coefficient represents
total biomass or product produced
conversion efficiency of a substrate into product
conversion rate of a substrate into biomass or product
production time of biomass or product
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 a initial high concentration of glucose
an aerated batch reactor containing an initial low concentration of glucose
an aerated fed-batch reactor having a low glucose concentration
an aerated continuous reactor having a low glucose concentration
an aerated batch culture containing a 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 highest substrate concentration
Organism maintaining the lowest substrate concentration
Both (a) and (b)
Organism maintaining the moderate substrate concentration
Organism maintaining the lowest substrate concentration
The continuous cultures are not widely used in industry because
they are not suited for the production of secondary metabolites
contamination or mutation can have a disastrous effect on the operation
the government will not approve the licensing of pharmaceuticals produced in continuous cultures
all of the above
all of the above
The lowest yield of ATP /is in
fermentation
aerobic respiration
anaerobic respiration
same in (a), (b) and (c)
fermentation
Mixing in an anaerobic sludge blanket reactor is due to
rapid change in water temperatures throughout the reactor
release of gases by the microbial populations
swimming of microbes
none of the above
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-1 of peptone, then the rate of protogon synthesis would be
0 g.l⁻¹h⁻¹
0.5 g.l⁻¹h⁻¹
1 g.l⁻¹h⁻¹
2 g.l⁻¹h⁻¹
0 g.l⁻¹h⁻¹
Formation of end product by Lactococcus lactis will become non-growth associated as lactic acid accumulates because
cells will redirect ATP to anabolism
cells will redirect NAD+ to anabolism
cells will redirect ATP to facilitate the diffusion of lactic acid and H+ out of the cells
cells will redirect ATP to the active transport of lactic acid and H+ out of the cells
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”?
Aspergillus fumigatus
Saccharomyces cerevisiae
Escherichia coli
Aspergillus niger
Escherichia coli
Immobilized cell reactors for wastewater treatment have the advantage of having/being
higher cell concentration
more stable and prevent washout
higher dilution rate before the cells washout
all of the above
all of the above
Which of the statement is true for continuous reactor at steady state?
The rates of biomass, substrate and product concentrations are zero
Biomass, substrate and product concentrations are zero
Biomass, substrate and product concentrations do not change with time
Biomass, substrate and product concentrations change with time
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
turbidostat
chemostat
level stat
pH
chemostat
For organisms growing in a chemostat, the specific growth rate
cannot be determined
can be determined from the dilution rate
equals to the maximum specific growth rate of the culture
none of the above
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
decrease with time
increase with time
be constant
change randomly with time
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?
Citric acid is toxic to the cells
Alkanes cause foaming
Fast addition of alkanes will inhibit the cells and reduce oxygen transfer rates
Fast addition of alkanes will cause the cells to grow too quickly
Fast addition of alkanes will inhibit the cells and reduce oxygen transfer rates
A continuous reactor has a dilution rate of 0.5 h-1. Its residence time would be
ln(2)/0.5
ln(2) x 0.5
0.5 h
2 h
2 h
Which of the following is used to calculate mass of substrate in the reactor?
Flow rate x substrate concentration in the reactor
Volume of reactor x substrate concentration in reactor
Flow rate x mass of reactor
Volume of reactor x Flow rate
Volume of reactor x substrate concentration in reactor
If biomass yields are constant, then the biomass productivity of a culture grown in continuous reactor will
always decrease with dilution rate
increase with dilution rate until washout
remain constant irrespective of the dilution rate
decrease with dilution rate until washout
increase with dilution rate until washout
Low dissolved oxygen concentrations leads to
low biomass yields
high biomass yields
no effect on biomass yields
none of the above
low biomass yields
In a continuous reactor, the medium contains 40 g.l-1 of maltose and the medium flow rate is 10 litres per hour and the effluent contains 20 g.l-l of lactate. What is the productivity of lactate production from this reactor?
50 g maltose.l-1
50 g lactate.l-1
200 g maltose.l-1
200 g lactate.l-1
200 g lactate.l-1
A fed-batch reactor containing 1 g.l-1 of substrate in 2 litre of medium. It is fed with 1 g.l-l of substrate at the rate of 1 litre per hour. After 10 hours, the concentration of substrate in the reactor was 0.5 g.l-1 . The mass of substrate that was used by the culture in the reactor was
2g
6g
8g
12g
6g
Toxins accumulated in a reactor can lead to low biomass yields probably due to which of the following?
NAD+ is diverted away from homeostasis to anabolism
ATP is diverted away from homeostasis to anabolism
NAD+ is diverted away from anabolism to homeostasis
ATP is diverted away from anabolism to homeostasis
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
increase
increase drastically
be zero
decrease abruptly
Fluidized bed bioreactors provide higher mass transfer rates than packed bed bioreactors because
mixing is higher in fluidized bed bioreactors
particles move with the fluid in a fluidized bed bioreactor
immobilized particles are smaller in the fluidized bed bioreactors
all of the above
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]
initial mass of substrate in the reactor - final mass of substrate in the reactor + flow rate x [substrate in the feed]
initial mass of substrate in the reactor + final mass of substrate in the reactor - flow rate x [substrate in the feed]
initial mass of substrate in the reactor + final mass of substrate in the reactor - flow rate
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 litres and is being fed at a rate of 4 litres per hour. Dilution rate for this reactor will be
2 litres
2 litres per hour
2 h⁻¹
4 litres per hourv
2 h⁻¹
Mixing per unit volume is observed to be poorest in
continuous packed bed reactor
continuous fluidized bed bioreactor
continuous airlift bioreactor
none of the above
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⁻¹ and the dilution rate is set to 0.4 h-1, then the steady state concentration of glucose in the effluent will be
0 g.l⁻¹
0.5 g.l⁻¹
1.0 g.l⁻¹
10 g.l⁻¹
0.5 g.l⁻¹
A continuous reactor at steady state contains 0.04 g.l⁻¹ of biomass and 0.02 g.l⁻¹ of phenol. The feed contained 0.1 g.l⁻¹ of phenol. The biomass yield would be
0.4 g.g⁻¹
0.5 g.g⁻¹
1.0 g.g⁻¹
5.0 g.g⁻¹
0.5 g.g⁻¹
A culture system with constant environmental conditions maintained through continual provision of nutrient and removal of wastes is called __________ culture system.
continuous
batch
fed-batch
semi continuous
continuous
The main reason for production of antibiotics in fed batch reactors is
the presence of precursors is often toxic to the cells
higher yields when cells enter the stationary phase
higher yields when cell growth slows
all of the above
all of the above
Fed batch reactors is used to produce vinegar because
it can maintain low ethanol concentrations
it can maintain low acetic acid concentrations
acetic acid bacteria tend to ferment at high ethanol concentrations
all of the above
it can maintain low ethanol concentrations
When a culture of fermenting yeast becomes metabolically uncoupled, ethanol
becomes a secondary metabolite
production becomes growth associated
production becomes non-growth associated
becomes a growth nutrient
production becomes non-growth associated
Mixing profiles closest to plug flow are observed in
continuous packed bed reactor
stirred tank reactor with biomass recycles
continuous fluidized bed bioreactor
all of these
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⁻¹When this organism is grown in a 2 litre continuous on a medium containing 10 g.l⁻¹ of glucose added at 1 l.h⁻¹, the steady state concentration of biomass in the reactor will be
0 g.l⁻¹
0.4 g.l⁻¹
0.5 g.l⁻¹
10 g.l⁻¹
0 g.l⁻¹
Unsteady state mass balance for dynamic model of continuous stirred tank reactor (CSTR) is
time rate of total amount in rector = rate of addition to reactor -rate of removal + rate of formation
total amount in rector = rate of addition to reactor - rate of removal + rate of formation
rate of total amount in rector = rate of addition to reactor - rate of removal + rate of formation
none of the above
time rate of total amount in rector = rate of addition to reactor -rate of removal + rate of formation
A fed-batch reactor initially contains 2 litre of medium. If it was fed at 1 litre per hour, then after 10 hours, the volume of the reactor will be
1 litre
2 litre
3 litre
13 litre
2 litre
A Bacillus sp. produces an antibiotic only during the stationary phase when grown in a batch culture. If grown in a 5 litre continuous culture, the steady state productivity of the antibiotic
will increase until the culture washes out
will decrease after washout
will be zero
will be infinite
will be zero
In a fluidized bed reactor, the function of the disengagement zone is to
reduce loss of particles from the reactor
reduce the velocity of the particles near the surface of the reactor
reduce foaming problems
all of the above
all of the above
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?
Batch fermenter with a high initial glucose concentration
Continuous fermenter with a low initial glucose concentration
Fed batch fermenter
All of the above
Fed batch fermenter
In a glucose-yeast extract medium, Lactococcus lactis has a maximum specific growth rate (um) of 1.23 h-1. What would be the specific growth rate of this organism at steady state in a 4 litre reactor being fed at 2 litres per hour?
0.5 h-1
1.2 h-1
2.4 h-1
4 h-1
0.5 h-1
Which of the following is not correct with regards to continuous cultures?
The major industrial scale application of continuous cultures is in waste water treatment
Mutation and contamination present a major risk to the operation of continuous cultures for the production of metabolites
The continuous cultures is very useful for the production of pharmaceuticals
Continuous cultures have an advantage that they do not need to shut down as regularly as batch culture reactor
The continuous cultures is very useful for the production of pharmaceuticals
In a plug flow reactor, the highest concentration of substrates is exposed to the cells that
are near the effluent or exit of the reactor
are in the mid way along the reactor
are located near entrance of feed
are near the wall of the reactor
are located near entrance of feed
In an activated sludge process, the biomass is recycled to
increase the efficiency of the process
reduce sludge volumes
increase the concentration of cells
all of the above
all of the above
A strain of Escherichia coli has a maximum specific growth rate of 0.8 h-1 on a glucose based medium. If this organism is being grown in a chemostat with a dilution rate of 1.2 h-1, then at steady state the concentration of E. coli in the same medium will
increase
be zero
change randomly
decrease
change randomly
A fed-batch reactor containing 2 litre of medium and 0.1 g.l-l of biomass is fed with a medium containing 1 g.l-1 of substrate at 1 litre per hour. If after 10 hours, the concentration of biomass in the reactor was 0.2 g.l-1, then the biomass produced during the 10 hour period is
1.5 g
2.2 g
3.0 g
6.0 g
2.2 g
Which of the following organisms will continue their metabolism at high substrate concentrations?
Pseudomonas aeruginosa
Saccharomyces cerevisiae
Bacillus subtilis
Escherichia coli
Pseudomonas aeruginosa
Yeast is typically produced in fed batch reactors because
yeast cells produce ethanol at low glucose concentrations
yeast cells ferment at low glucose concentrations
yeast cells respire at low glucose concentrations
all of the above
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⁻¹, while reactor 2 contained 0.1 g.l⁻¹ of glucose at the start of the process then at steady state
the concentration of glucose in reactor 1 would be greater than that in reactor 2
the concentration of glucose in reactor 1 would be equal to reactor 2
the concentration of glucose in reactor 1 would always be zero.
the concentration of glucose in reactor 1 would be less than that in reactor 2
the concentration of glucose in reactor 1 would be equal to reactor 2
In a fluidized bed reactor mixing is achieved by
gravity flow of fluid
upward movement of the incoming feed
diffusion
both (a) and (b)
both (a) and (b)
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 prevent a. niger from fermenting
fed-batch reactor can be used to minimize starch concentrations and thus reduce the viscosity of the medium
continuous reactor can be used to minimize starch concentrations and their inhibitory effects
all of the above
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
aerobic respiration
anaerobic respiration
fermentation
decomposition
fermentation
In fed batch bioreactor modelling, the rate of change in the bioreactor volume is assumed to be equal to
flow rate
initial volume
volume of solids in the reactor
none of these
flow rate
Monoclonal antibodies are typically produced in fed batch reactors because
hybridoma cells ferment at high maltose concentrations
hybridoma cells yield higher lactate at high glucose concentrations
hybridoma cells respire at high glucose concentrations
none of the above
hybridoma cells yield higher lactate at high glucose concentrations
In plug flow tubular reactor the axial velocity profile on cross-section will be
constant
varying with time
non-linear
power function of time
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
biomass yields increase as the fermentation proceeds
organic acids are secondary metabolites
high concentrations of organic acid promote the growth of the microbial population
organic acids uncouple catabolism from anabolism
The concentration of biomass in a continuous stirred tank reactor is 20 g dry weight per litre. What would be the concentration of biomass in the effluent?
Greater than 20 g dry weight per litre
Approximately 20 g dry weight per litre
Lesser than 20 g dry weight per litre
More than 30 g dry weight per litre
Approximately 20 g dry weight per litre
The ideal tubular-flow fermenter without radial variations is called a
plug flow fermenter
continuous stirred tank fermenter (CSTF)
column fermenter
any intensity of dilution rate near the wash out points
plug flow fermenter
Pseudo-steady state in a continuous reactor refers to a reactor in which
Pseudomonads are being cultured
concentration oscillate around a mean value
concentration increase with time
concentration decrease with time
concentration oscillate around a mean value
The toxicity of organic acids to cells
enhances as the pH falls
reduces as the pH falls
is not affected by pH
is highest at pH 7.0
enhances as the pH falls
Which of the following is best described as secondary metabolite?
Acetic acid produced from the oxidation of ethanol
Ethanol from the fermentation of glucose
Penicillin
Citric acid from the partial oxidation of glucose
Penicillin
A microorganism which is subjected to the Crabtree effect is most likely to
ferment in the presence of low concentrations of sugar and dissolved oxygen
respire in the presence of low sugar and high dissolved oxygen concentrations
ferment in the presence of high concentrations of sugar and dissolved oxygen
respire in the presence of high sugar and low dissolved oxygen concentrations
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 product formation is termed as
uncoupled
growth associated
non-growth associated
metabolically uncoupled
growth associated
Which of the following would be correct concerning the concentration of biomass (X). growth limiting substrate (S) and product (P) in a chemostat when the cells have been washed out?
X,S and P will be zero
X,S and P can not be predicted for the above condition
X and P will be zero while S is equal to the substrate concentration in feed
None of the above
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-1 in a medium with glucose as a growth limiting substrate. To prevent wash out, the dilution rate must be set to
greater than 0.8 h⁻¹
less than 0.8 h⁻¹
equal to 0.8 h⁻¹
1.6 h⁻¹
less than 0.8 h⁻¹
Saccharomyces cerevisiae when grown in high glucose concentration medium, the cells activity depends on which of the following?
High concentration of dissolved oxygen
Low concentration of dissolved oxygen
No effect of dissolved oxygen
High concentration of dissolved oxygen and sodium salts
No effect of dissolved oxygen
Continuous culture has an advantage over to a batch cultures as
continuous reactors do not need to be shut down and cleaned as regularly as a batch reactor
most downstream and upstream processes are continuous in nature and thus the operation of continuous bioreactor can be better integrated into the overall manufacturing process
cells can be maintained at a constant physiological state simply by setting the dilution rate
all of the above
all of the above
In the batch-fed mode, substrate will be added
only at the beginning of the fermentation process
periodically throughout the fermentation process
only at the end of the fermentation process
substrate is never added
only at the end of the fermentation process
When Escherichia coli grow in a well aerated medium, which of the following will occur?
Fructose di-phosphate accumulation inside the cells leading to cell respiration
Fructose di-phosphate accumulation inside the cells leading to fermentation
Fructose di-phosphate will accumulate regardless of the medium composition
Fructose di-phosphate will accumulate inside the cells leading to anaerobic respiration
Fructose di-phosphate accumulation inside the cells leading to fermentation
to start agitation and aeration section 1
Swirling and vortex formation can be prevented by
using baffles
using diffusion ring with turbines
both (a) and (b)
none of these
both (a) and (b)
Power number is expressed as
P₀ / N²Dᵢ³ρ
P₀ / N³Dᵢ⁵ρ
P₀ / N³Dᵢ³ρ
P₀ / N²Dᵢ²ρ
P₀ / N³Dᵢ⁵ρ
The power consumption in a stirring vessel can be assessed by using a
dynamometer
strain gauge attached to agitator shaft
watt meter attached to agitator motor
all of these
all of these
Surface renewal theory predicts that the mass transfer coefficient is
directly proportional to the square root of the molecular diffusivity
inversely proportional to the square root of the molecular diffusivity
directly proportional to the cube root of the molecular diffusivity
indirectly proportional to the cube root of the molecular diffusivity
directly proportional to the square root of the molecular diffusivity
The oxygen transfer rate in a bioreactor will increase if
oil is added
antifoam is added
detergent like molecules are added
increase in the reactor temperature
detergent like molecules are added
Which of the following impellers are used for wide range of viscosities?
paddles
turbines
propellers
none of these
turbines
Which of the following type(s) of stirrer can be used for microbiological processes?
Mig
Intermig
Turbine
All of these
All of these
The range of width for the baffle in the fermenter is __________ times of vessel diameter
1/10 to 1/12
1/8 to 1/10
1/5 to 1/8
none of these
1/10 to 1/12
The average concentration of oxygen in the boundary layers surrounding the bubbles (Co*) in a reactor is normally determined by
ultra-small dissolved oxygen probes
laser based photographic systems
measuring the steady state concentration of oxygen in the bulk liquid prior to inoculation of the reactor
measuring the steady state concentration of oxygen in the bulk liquid after inoculation of the reactor
measuring the steady state concentration of oxygen in the bulk liquid prior to inoculation of the reactor
Why vortexing is undesirable in the agitation of biological systems?
The collision between the cells, impeller and air bubbles will lead to cell damage
Poor mixing despite the use of high stirrer speeds
Mixing will not be in the turbulent region
All of the above
All of the above
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
gas-liquid interface
bubble boundary layer
bulk liquid
gas phase
bubble boundary layer
Penetration theory assumes that turbulent eddies travel from the bulk of the phase to the interface where they remain constant for a constant exposure time (te). The model correlating KL, mass transfer coefficient and DAB, diffusivity can be expressed as
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 Co,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 h⁻¹
32 h⁻¹
16 h⁻¹
8h⁻¹
64 h⁻¹
Which have the maximum resistance while transferring carbon dioxide from the bulk liquid to an air bubble?
Moving through the gas liquid interface
Moving through the bubble boundary layer
Moving across the cell membrane
Moving through the bulk liquid
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
impeller diameter
square root of the impeller diameter
square of the impeller diameter
cube of the impeller diameter
square of the impeller diameter
What is the ratio of depth of liquid in vessel to the diameter of tank (H:Dt)?
1 : 1
2 : 1
4 : 1
none of these
1 : 1
Radial flow impellers
provide high shear conditions for breaking up bubbles
direct flow towards the walls of the reactor
Both (a) and (b)
provide low shear conditions and are suited for use in shear sensitive procesess
Both (a) and (b)
Transient flow range of mixing speed is obtained for
Rei<10
10<Rei<10^4
Rei>10^4
None of these
10<Rei<10^4
A typical ceiling fan would be best described as a(n)
radial flow impeller
axial flow impeller
intermig impeller
Rushton turbine
axial flow impeller
What is the ratio of diameter of impeller to the diameter of tank (Da:Dt)
1 : 3
2 : 1
4 : 1
1 : 5
1 : 3
The reason of using a flat disk in a Turbine is
to create high shear conditions
to break up bubbles more efficiently than the impeller blades
to ensure that the bulk of the energy consumption occurs at the blades
all of the above
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?
two-film theory
penetration theory
surface renewal theory
Calderbank and Moo-Young theory
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?
Addition of antifoams
Increase in temperature
Increase in stirrer speed
Both (a) and (b)
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
0.793atml/mmol
0.207atml/mmol
1.26 atml/mmol
8.74 atml/mmol
0.793atml/mmol
Gas hold up, characterizing the hydrodynamics in a fermenter, mainly depends on the
superficial gas velocity
power consumption
Both (a) and (b)
gas concentration
Both (a) and (b)
Turbine impeller consists of flat impeller blades with
a vertical pitch welded directly to the shaft
a angled pitch welded directly to the shaft
a vertical pitch welded to a horizontal disk
a angled pitch welded to a horizontal disk
a vertical pitch welded to a horizontal disk
An aerated bioreactor will increase oxygen transfer rates with the addition of detergents because it
enhances bubble coalescence
causes bubbles to expand
discourages bubble coalescence
increases the surface tension of the liquid
discourages bubble coalescence
Vortexing in stirred tank reactors can be prevented by
installing baffles in the reactor
shifting the impeller to an off-centre position
Both (a) and (b)
using axial flow impellers
Both (a) and (b)
Which of the following would be best described as an axial flow impeller?
An impeller with blades pitched at 45° to the vertical
An impeller which directs liquid flow towards the base of the reactor
Both (a) and (b)
An impeller with blades pitched at 75° to the vertical
Both (a) and (b)
Henry’s law relates
the partial pressure of oxygen and the saturation concentration of oxygen in the liquid
the oxygen transfer rate and the bubble size
the oxygen transfer rate and the temperature
the oxygen transfer rate to the partial pressure of oxygen in the liquid
the partial pressure of oxygen and the saturation concentration of oxygen in the liquid
Power number is ratio of
imposed forced to intertial force
bouyant force to inertial force
gravitation force to inertial force
imposed force to gravitational force
imposed forced to intertial 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 x π x Dt^2/4
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(s) is/are non-mechanically agitated reactors?
Stirrer tank reactor
Bubble column
Air lift reactor
Both (b) and (c)
Both (b) and (c)
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
Crystals and precipitates are thoroughly broken down, so as to ensure easy separation of the solids from the mother liquor
Both (a) and (b)
Axial flow impellers provide low shear, energy efficient mixing conditions
Crystal and precipitates are not too small, so as to ensure easy separation of the solids from the mother liquor
Which of the following will have the highest surface area available for oxygen transfer?
A shake flask
A standing test tube
A non-sparged stirred tank reactor agitated at 400 rpm
A sparged stirred tank reactor agitated at 400 rpm
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
bubbles tend to break down too rapidly under high shear conditions
bubbles tend to move too quickly through the bulk liquid
the cells clog up the surface of the bubble
bubbles tend to coalesce under the impeller
Power consumption by agitation is
a function of physical properties
a function of operating conditions
a function of vessel and impeller geometry
all of the above
all of the above
Which of the following impellers will provide radial flow?
Paddles
Flat blade turbines
Disk flat blade turbines
All of the above
All of the above
When liquid is pumped through cooling coil in a stirred tank reactor to cool. Which of the following is not correct?
If the stirrer speed is increased, the rate will be faster
Baffles in the tank will increase the rate of cooling
Faster cooling rates at a slower rate of pumping
Faster cooling rates at a faster rate of pumping
Faster cooling rates at a slower rate of pumping
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
decreasing the saturation concentration of oxygen in the reactor
decreasing the gas-holdup
all of the above
increasing the partial pressure of oxygen at the base of the reactor
Which of the following is correct for the off-centre impellers?
Off-centre impellers can be used with any size reactor
Off-centre impellers should only be used with reactors with volumes less than 10 m3
The impeller should never be placed in an off-centre position
Off-centre impellers can be used when volume is greater than 10 m3
Off-centre impellers should only be used with reactors with volumes less than 10 m3
The power required by an impeller in a gas sparged system compare to the power required by impeller operating at same speed in a gas free liquid is usually
lesser
higher
same
may be lesser or higher depending upon the geometry
lesser
Which of the following stirrer requires least amount of energy for same yield?
Mig
Intermig
Turbine
Disc
Intermig
A reactor has a total volume of 50,000 litres. If it has a headspace volume of 10,000 litres, then volume of liquid in the reactor will be
10,000 l
20,000 l
30,000 l
40,000 l
40,000 l
Pure oxygen, if used instead of air will increase oxygen transfer rates because
the saturation concentration of oxygen is higher
the bubble size is smaller
the oxygen transfer coefficient is larger
the partial pressure of oxygen in the gas phase is lower
the saturation concentration of oxygen is higher
For aerated mixing vessels in an aqueous solution, the mass transfer coefficient (kL) co-relating power consumption (Pm) and fermenter volume (V) can be expressed as
kL ∝ (Pm/V)^0.33
kL ∝ (Pm/V)^0.66
kL ∝ (Pm/V)^0.50
kL ∝ (Pm/V)
kL ∝ (Pm/V)^0.33
Higher temperatures affect oxygen transfer rates by
increasing KLa but lowering Co
lowering KLabut increasing Co
increasing KLaand increasing Co
lowering KLa and lowering Co
increasing KLa but lowering C*o
The Intermig impeller is
an axial flow impeller which can be used for the culture of aerobic organisms
directed upwards rather than towards the base of the reactor
a fork shaped extensions to the impeller facilitate bubble break up
All of the above
All of the above
Main reason for using baffles in stirred tank reactors are
baffles permit turbulence conditions to arise at low stirrer speed
baffles will allow axial mixing to occur even with radial flow impellers
both (a) and (b)
baffles prevent turbulent conditions in stirred tank reactors
both (a) and (b)
Which of the following is not classified as an axial flow impeller?
A propeller
A marine impeller
A Rushton turbine
A hydrofoil impeller
A Rushton turbine
Power number (Np) is also known as
Froude’s number
Bond’s number
Newton’s number
Rayleigh’s number
Newton’s number
Flooding is a condition/phenomenon which occur in a bioreactor when
The air escapes without being distributed by the agitator
The fermenter medium spills out the reactor due to foaming
The volume of foam is more than the volume of broth
None of the above
The air escapes without being distributed by the agitator
A cylindrical reactor has a liquid volume of 100,000 litres. 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:
1.0 m
3.0 m
5.0 m
7.0 m
5.0 m
Detergent like substances produced by microorganisms during a fermentation will lead to
decrease the surface tension of the liquid
accumulate at the gas liquid interface
decrease the rate of bubble coalescence
all of the above
all of the above
A cylindrical reactor fitted with Rushton Turbine has a liquid volume of 100,000 litres. 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
3.3 m
5.3 m
7.3 m
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
the steady state oxygen concentration in a mixed aerated reactor after inoculation
the steady state oxygen concentration in the boundary layer using a micro-probe
volume of oxygen supplied
the steady state oxygen concentration in a mixed aerated reactor before inoculation
Impeller damage can be minimized by
using specially designed axial flow impellers
using radial flow impellers
using Intermig impellers
all of the above
using specially designed axial flow impellers
To increase the oxygen transfer rate in a shake flask culture system, which of the following (s) is/are followed?
Liquid volume in the flask is reduced
Stirrer speed is increased
Baffled flasks are used
All of the above
All of the above
What is/are the major difference(s) between disc and turbine type stirrer?
Blades in disc type are projected out beyond the edge of disc while blades are curved one in turbine type
Turbine type requires 50 % less air than disc type for the same yield and energy consumption
Both (a) and (b)
Number of blades in the stirrer
Both (a) and (b)
In the design of a paddle agitator, the ratio of paddle diameter to tank diameter is normally taken as
0.1
0.8
0.25
0.5
0.8
The oxygen absorption rate can be determined by
sodium sulfite oxidation method
dynamic gassing out technique
direct measurement
all of these
all of these
Industrial paddle agitators turn at the speed of
20 and 150 rpm
150 and 300 rpm
400 and 800 rpm
1150 rpm
20 and 150 rpm
The dynamic technique is based on the
oxygen material balance in an aerated batch fermenter during the growth of microorganisms
change of the oxygen concentration
oxidation of the sodium sulfite to sodium sulfate
oxygen material balance in a fermenter
oxygen material balance in an aerated batch fermenter during the growth of microorganisms
The addition of antifoams to an aerated bioreactor will decrease oxygen transfer rates because antifoams
increase the tendency of bubbles to coalesce
tend to accumulate in the gas liquid interface
reduce the surface tension of the liquid
All of the above answers
All of the above answers
During fermentation, the saturation concentration of oxygen was reduced from 7 ppm. to 1 ppm. Which one of the following conclusions can be drawn?
Microbial growth is oxygen limited since the oxygen concentration is lesser than the saturation concentration
Microbial growth is not oxygen limited since the oxygen concentration is lesser than the saturation concentration
Experimental error leads to the reduction
No conclusion can be drawn
No conclusion can be drawn
If the stirrer speed is too slow, bubbles will accumulate and coalescese under the impeller. This phenomenon is known as a
coalesced impeller
flooded impeller
river impeller
dry impeller
flooded impeller
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?
The growth rate is limited by the rate of mass transfer of the alkane into the fermentation medium
The growth rate is limited by the intrinsic kinetic properties of the cells and not by mass transfer
The growth rate is neither mass transfer nor kinetically limited
No conclusion on the growth rate can be withdrawn
No conclusion on the growth rate can be withdrawn
Reynolds (Rei) number for the impeller is given by (where Di, stirrer diameter; N, stirrer speed, ρ, density of fluid and μ, viscosity of fluid)
DiVρ/μ
Di²Nρ/μ
Di²Vρ/μ
DiNρ/μ
Di²Nρ/μ
The advantage of axial flow impellers over radial flow impellers is that axial flow impellers
provide better lift of solids
provide high shear conditions
provide low shear conditions
are cheaper to build
provide better lift of solids
Larger propellers turn at the speed of
20 to 150 rpm
150 to 300 rpm
400 to 800 rpm
1150 rpm
400 to 800 rpm
A microbial population in a suspension culture will only be limited by oxygen availability if the dissolved oxygen
concentration is less than the critical concentration
concentration is greater than the critical concentration
levels are greater than the saturation concentration of oxygen
levels are equal to saturation oxygen level
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
KL = DAB
KL= Zf/DAB
KL = DAB.Zf
KL = DAB/Zf
Froude number is avoided in calculation of power requirements for low viscosity liquid mixing systems when
baffled systems are used
Reynolds number is less than 300
both (a)and(b)
none of these
both (a)and(b)
A fermentation system has a KLaof 3 s-1 and a C0* of 5 ppm of O2. If the bulk liquid is completely depleted of oxygen, then the oxygen transfer rate will be equal to
zero
15 mg.l⁻¹.s⁻¹
10 mg.l⁻¹.s⁻¹
5 mg.l⁻¹.s⁻¹
15 mg.l⁻¹.s⁻¹
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
100%
75%
50%
25%
25%
A fermentation system has aKLa of 3 s⁻¹ and a C0* of 5 ppm of O2. If the bulk liquid is saturated with oxygen then the oxygen transfer rate will be equal to
zero
3 mg.l⁻¹.s⁻¹
5 mg.l⁻¹.s⁻¹
15 mg.l⁻¹.s⁻¹
zero
hich of the following would be best described as a radial flow impeller?
An impeller with blades pitched at 45° to the vertical
A Rushton turbine
Both (a) and (b)
An impeller which directs liquid flow towards the base of the reactor
A Rushton turbine
Small propellers turn at the speed of either
20 or 150 rpm
150 or 300 rpm
400 or 800 rpm
1150 rpm or 1750 rpm
1150 rpm or 1750 rpm
In aerobic microorganisms cultures radial flow impellers are used because
they provide energy efficient high turbulent mixing conditions
they provide low shear mixing conditions
they provide high shear mixing conditions
they ensure that bubble size is maximized leading to high oxygen transfer rates
they provide high shear mixing conditions
The effect of increasing the stirrer speed in an unbaffled stirred tank reactor is that
a small increase in stirrer speed will cause the liquid to enter the turbulent flow regime
as the stirrer speed increases, the liquid will continue to circulate and then become turbulent
as the stirrer speed increases, the liquid will continue to circulate. Eventually a vortex will form.
A vortex will form at low stirrer speeds. As the stirrer speed increases the liquid will start to circulate
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
10<Rei<10^4
Rei>10^4
None of these
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
Np = N2Di(Rei)^-1
Np = K(Rei)
Np = KNDi(Rei)^-2
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(Rei)^-1
Np = N2Di(Rei)^-1
Np = K
Can’t be correlated
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.h⁻¹
less than 23 kg.h⁻¹
greater than 23 kg.h⁻¹
2.3 kg.h⁻¹
23 kg.h⁻¹
Axial flow impellers
provide high shear conditions for breaking up bubbles
provide low shear conditions and are suited for use in shear sensitive procesess
provide direct flow towards the walls of the reactor
none of the above
provide low shear conditions and are suited for use in shear sensitive procesess
Bioreactors, where vortex is formed, another dimensionless number, __________ is useful.
Stanton
Rayleigh
Bond
Froude
Froude
Oxygen transfer rate is increased with an increase in the stirrer speed in aerated bioreactor because
it decrease the bubble size
it decreases the size of the boundary layer surrounding a bubble
it increases the rate of movement of oxygen molecules through the bulk liquid
all of the above
all of the above
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
the reaction was mass transfer limited at 500 rpm
the reaction did not involve any mass transfer step
the movement of molecules in the reactor at 300 rpm occurred due to diffusion alone
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 cooling water temperature
higher stirrer speed
the removal of baffles from the reactor
slower stirrer speed
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)
H = Vs/(Vs+ Vt)
H = Vs/(Vs.Vt)
H = (Vs+Vt)/Vs
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
The KLa of the medium decreases with the concentration of dissolved salts and sugars, leading to a lower oxygen transfer rate
The KLa of the medium increases with the concentration of dissolved salts and sugars, leading to a lower oxygen transfer rate
None of the above
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
Radial flow
Both (a)and(b)
None of these
Axial flow
In a tall reactor, oxygen transfer rates will be
highest at the surface of the reactor
highest at the base of the reactor
highest in the middle of the reactor
the same throughout the reactor
highest at the base of the reactor
Which of the following impeller is used in situation where strong vertical currents are desirable for suspending heavily particles?
Propeller
Paddle
Turbine
None of these
Propeller
Laminar flow range of mixing speed is obtained for
Rei<10
10<Rei<10^4
Rei>10^4
None of these
Rei<10
Which of the following number is calculated from the diameter and peripheral speed of the impeller?
Reynolds number
Froude number
Power number
None of these
Reynolds number
A higher liquid height will lead to a higher gas hold up by which the oxygen transfer rate will be
higher throughout the reactor
lower throughout the reactor
higher at the base of the reactor
lower at the base of the reactor
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
increase the residence time of the cooling water in the jacket
increase the cooling water-jacket wall boundary layer size
all of the above
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
more than the power required by an impeller in operating at same speed in a gas free system
same as the power required by an impeller in operating at same speed in a gas free system
none of the above
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
A bubble with a diameter of 5 mm
A bubble with a diameter of 15 mm
A bubble with a diameter of 50 mm
A bubble with a diameter of 1 mm
Which device is commonly used for measuring the rate of rotation (rpm) of the stirrer shaft?
Anemometer
Manometer
Tachometer
Barometer
Tachometer
The sterilization method depends
nature of additive
volume and feed rate
both (a) and (b)
none of these
both (a) and (b)
The specific death rate of an organism can be expressed as
ln 2/D
D/ln2
D.ln2
2.0.3/ln2
ln 2/D
The interception efficiency can be expressed as (where dp is the particle diameter and Dc cylindrical collection diameter)
dp/Dc
dp x Dc
dp/Dc x 100
dpDc/100
dp/Dc
The relationship between the del factor, temperature and time is given as
Δ = A.t. e^(-E/RT)
Δ = 1/(A.t. e^(-E/RT))
Δ = A.t. e^(E/RT)
Δ = A.t.T
Δ = A.t. e^(-E/RT)
The del factor (Δ) increases as the final number of cells
decreases
increases
zero
constant
decreases
The overall del factor (Δ) may be represented as
Δoverall = Δheating + Δholding- Δcooling
Δoverall = Δheating + Δholding+ Δcooling
Δoverall = Δheating - Δholding+ Δcooling
Δoverall = Δheating - Δholding- Δcooling
Δoverall = Δheating + Δholding+ Δcooling
The filter material used for air filtration system is/are
glass wool
glass fibre
norite
all of the above
all of the above
The deviation from ideal plug flow due to axial mixing can be described by the
dispersion model
Langmuir model
Friedlander model
Pasceri model
dispersion model
The collection efficiency by diffusion increases with
decreasing particle size
decreasing air velocity
both (a) and (b)
increasing particle size
both (a) and (b)
Glass fibers are favorable as a filter medium because they give a
lower pressure drop and are less liable to wetting or combustion
more pressure drop and are less liable to wetting or combustion
lower pressure drop and are more liable to wetting or combustion
more pressure drop and are more liable to wetting or combustion
lower pressure drop and are less liable to wetting or combustion
The collection efficiency by interception increases with the
increasing particle diameter
increasing air flow velocity
both (a) and (b)
increasing particle size
increasing particle size
For indirect heating, the plate and frame heat exchanger is generally more effective than the shell and tube heat transfer due to its
larger heat transfer area
smaller heat transfer area
lesser cost
more number of plates
larger heat transfer area
The mechanism of air filtration in fibrous filter is
electrostatic attraction
impaction
interception
all of these
all of these
If the packing density (α) is defined as the volume of the fiber unit volume of filter bed, the velocity within the filter void space is equal to (where Vis velocity in fluid void space and V0 is undisturbed fluid velocity)
V = V0/(1-α)
V-V0 = 1 - α
V = V0(1 - α)
V = V0/(1 + α)
V = V0/(1-α)
For the turbulent flow, the dispersion coefficient is correlated as a function of
Reynolds number
Sherwood number
Schmidt number
Grashof number
Reynolds number
In sterilization process, spore of which of the following organism is considered as control?
Bacillus subtilis
Clostridium botulinum
Bacillus stearothermophilus
Aspergillus niger
Bacillus stearothermophilus
Analogus to the molecular diffusion, the x-directional flux of 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 = -dcn/dx
Jn = dcn/dx
Jn = -D dcn/dx
Jn = D dcn/dx
Jn = -D dcn/dx
The typical size of particles collected by diffusion mechanism is
<0.25μm
<0.5μm
<0.75μm
<1μm
<0.5μm
The X90 value for a filtration system is
the time required to reduce microbial population by 90%
the time required to traverse survivor curve by one log cycle.
the depth required to reduce population by 90%
the depth of the filter required to reduce population by 99%
the depth required to reduce population by 90%
The value of K
increases with increase in air velocity
decreases with increase in air velocity
increases to an optimum with increase in air velocity and decreases on further increase of air velocity
none of these
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 = 0.075NSt^1.2
ηimp = 0.75NSt^1.2
ηimp = 0.25NSt^1.2
ηimp = 0.025NSt^1.2
ηimp = 0.075NSt^1.2
The collection efficiency by impaction increases with
increasing particle diameter
increasing air flow velocity
both (a) and (b)
increasing particle size
both (a) and (b)
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
1 - (1 - ηimp)(1 - ηint)( 1 - ηdif)
1 - ( ηimpηint/ηdif)
None of the above
1 - ηimpηintηdif
The heat conduction in dry air is
less rapid than in steam
more rapid than in steam
similar to steam
none of these
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
0.75
0.87
0.37
0.5
The reduction of number of cells from 1010 to one will result into the del factor (Δ) of
1
10
23
10^3
23
Sterilization can be carried out by
heat
radiation
chemical agents
all of these
all of these
The collection efficiency by the inertial impaction mechanism is the function of
Stokes and Reynolds number
Stokes and Schmidt number
Grashoff and Reynolds number
Stokes and Grashof number
Stokes and Reynolds number
The heated medium passes through a holding section, which is usually maintained in
adiabatic conditions
isothermal conditions
isotropic conditions
isobaric conditions
adiabatic conditions
The highest temperature which appears to be feasible for batch sterilization is
121°C
100°C
105°C
130°C
121°C
The K used in the equation for X₁₀=2.303/K depends upon
nature of the filter material
linear velocity of the air passing through filter
both (a) and (b)
thickness of the filter₁₀
both (a) and (b)
The mechanical means of accomplishing sterilization of fermentation media/equipment is
ultrasonic
radiation
chemical agents
none of these
ultrasonic
The radius of the filter with a depth of 14 cm required for a volumetric airflow rate of 10 m3/min is approximately
1.6 m
0.6 m
3
6 m
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
decreased in a dry state
increased in a wet state
decreased in a wet state
increased in a dry state
The destruction of microorganisms by steam may be described as
first order chemical reaction
zero order chemical reaction
second order chemical reaction
none of these
first order chemical reaction
Typical aeration rates for aerobic fermentation are
0 - 0.5 vvm
0.5 - 1.0 vvm
1.0 - 1.5 vvm
1.5 - 2.0 vvm
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
0.09 mg/l
0.1 mg/l
1.0 mg/l
0.05 mg/l
Zeolite softening process removes
only temporary hardness of water
only permanent hardness of water
both temporary and permanent hardness of water
the dissolved gases in permanent hard water
both temporary and permanent hardness of water
Conventional tertiary treatment is
chemical coagulation and flocculation
filtration
sedimentation
none of these
chemical coagulation and flocculation
The maximum desirable limit (BIS) of total hardness (as CaCo3) in drinking water is
600 ppm
300 ppm
500 ppm
1000 ppm
300 ppm
The chemical oxygen demand (COD)measures the
amount of oxygen required for growth of microorganisms in water
amount of oxygen that would be removed from the water in order to oxidize pollution
amount of oxygen required to oxidize the calcium present in waste water
none of the above
amount of oxygen that would be removed from the water in order to oxidize pollution
Hardness of water does not
have any bad effect in boiler
make cooking of foods difficult
make it unfit for drinking
cause difficulty in the washing of clothes with soaps
make it unfit for drinking
Permanent hard water may be softened by passing it through
sodium silicate
sodium bicarbonate
sodium hexametaphosphate
sodium phosphate
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% calcium chloride solution
10% magnesium sulfate solution
10% magnesium chloride solution
10% sodium chloride solution
10% sodium chloride solution
Temporary hardness of water is caused by the presence of
chlorides of calcium and magnesium
sulfates of calcium and magnesium
bicarbonates of calcium and magnesium
carbonates of sodium and potassium
bicarbonates of calcium and magnesium
Secondary treatment uses __________ to consume wastes.
micro-organisms
chemicals
filtration
none of these
micro-organisms
Application of quaternary ammonium compounds as sanitizing agents tends to
favor gram positive bacteria
decrease gram positive bacteria
increase the percentage of gram(-)ve rods on utensils
none of the above
increase the percentage of gram(-)ve rods on utensils
Permanent hardness of water is caused by the presence of
bicarbonates of calcium and magnesium
carbonates of sodium and potassium
chlorides and sulfates of calcium and magnesium
phosphates of sodium and potassium
chlorides and sulfates of calcium and magnesium
According to BIS the maximum permissible limit of dissolved solids in drinking water is
1000 mg/l
500 mg/l
2000 mg/l
1500 mg/l
2000 mg/l
Acid used mostly for removal of milk stone is
phosphoric acid
nitric acid
gluconic acid
tartaric acid
nitric acid
Which of the following chemical is sometime added in the process of coagulation and flocculation?
Aluminum sulphate
Aluminum oxide
Calcium chloride
None of these
Aluminum sulphate
Which of the following physical method is used as germicidal in modern time for the treatment of drinking water?
Chlorination
Treating with potassium permagnate
UV radiation
Treating with bleaching powder
UV radiation
Sanitizer used specifically for vitreous enamel are
strong alkalis
strong acids
weak alkali with sodium silicate
none of these
weak alkali with sodium silicate
The common methods used for disinfection in waste water treatment plants are
chlorination
UV light
both (a) and (b)
Phenolic solvent
both (a) and (b)
Inhibitors are used along with sanitizer to
improve their action
to prevent corrosion
both (a) and (b)
none of these
to prevent corrosion
Sanitizers used for rubber made equipments are
strong acids
strong alkalis
combination of both
none of these
strong alkalis
Which of the following substances are commonly used in a filter?
Charcoal
Sand
Both (a) and (b)
Aluminum chloride
Both (a) and (b)
Biological oxidation processes usually referred as biological treatment, are the most common form of
primary treatment
secondary treatment
tertiary treatment
all of these
secondary treatment
The maximum permissible limit (BIS) of turbidity in drinking water is
5 NTU
10 NTU
15 NTU
20 NTU
10 NTU
Sedimentation is a physical process used in wastewater treatment to
remove particles that are less dense than water
remove particles that are more dense than water
remove the pertinacious material from the water
none of the above
remove particles that are more dense than water
The ultimate source of water is
rivers and lakes
dew and forest
rain and snow
underground and surface
rain and snow
Permanent hardness of water may be removed by the addition of
lime
soda ash
potassium permagnate
sodium bicarbonate
soda ash
Both temporary and permanent hardness of water can be removed on boiling water with
calcium hydroxide
sodium carbonate
calcium oxide
calcium carbonate
sodium carbonate
Lagoons may be characterized as
anaerobic
facultative
aerated
all of these
all of these
Temporary hardness of water may be removed by adding
calcium hydroxide
calcium carbonate
calcium chloride
sodium bicarbonate
calcium hydroxide
The maximum desirable limit (BIS of mercury in the drinking water is
0.05 mg/l
0.9 mg/l
0.1 mg/l
0.001 mg/l
0.001 mg/l
From the following sanitizers which one comes under category of surface active agents?
Tetra phosphate
Teepol
Meta phosphate
None of these
Teepol
The purest form of naturally occurring water is
rain water
river water
pond water
well water
rain water
Calgon is used for removal of
sodium carbonate
permanent hardness of water
potassium carbonate
none of these
permanent hardness of water
The water being used in dairy industry should contain not more than
5 proteolytic and/or lipolytic organisms per ml
10 proteolytic and/or lipolytic organisms per ml
15 proteolytic and/or lipolytic organisms per ml
20 proteolytic and/or lipolytic organisms/ml
5 proteolytic and/or lipolytic organisms per ml
The activated sludge process consists of returning a portion of the clarifier
effluent water entering the reactor
influent water coming out of the reactor
influent water entering the reactor
effluent water coming out of the reactor
influent water entering the reactor
The activated sludge process is sometime referred as
fluid bed biological oxidation system
fixed bed biological oxidation system
turning bed biological oxidation system
none of the above
fluid bed biological oxidation system
BOD stands for
biochemical oxygen demand
british oxygen demand
british oxygen depletion
biological oxygen depletion
biochemical oxygen demand
When temporary hard water is boiled, one of the substances formed is
calcium bicarbonate
calcium sulfate
hydrogen chloride
carbon dioxide
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 carbonates
insoluble zeolites
insoluble chlorides
insoluble sulfates
insoluble zeolites
The methods used for biological treatment are
lagoon
activated sludge process
oxidation ditches
all of these
all of these
Both temporary and permanent hardness of water can be removed by
boiling
distillation
filtration
decantation
distillation
Coliform bacteria in water is an indication of the presence of
radioactive wastes
excess fertilizer
decaying animals and plants
human feces
human feces
