Biochemical Engineering - Claud Flashcards
A competitive inhibitor of an enzyme is usually
a. a highly reactive compound
b. a metal ion such as Hg2+ or Pb2+
c. structurally similar to the substrate.
d. water insoluble
c. structurally similar to the substrate.
Linear inhibition is sometimes called as
a. complete inhibition
b. incomplete inhibition
c. partial inhibition
d. mixed inhibition
a. complete inhibition
The types of inhibition pattern based on Michaelis Menten equation are
a. competitive
b. non-competitive
c. uncompetitive
d. all of the above
d. all of the above
The effect of non-competitive inhibition on a Lineweaver-Burk Plot is that
a. it can move the entire curve to the right
b. it can change the y-intercept
c. it can change the x-intercept
d. all of these
b. it can change the y-intercept
The rate-determining step of Michaelis Menten kinetics is
a. the complex formation step
b. the complex dissociation step to produce product
c. the product formation step
d. Both (a)and(c)
b. the complex dissociation step to produce product
In competitive inhibition a factor is obtained from the measurement of
a. Vmax
b. KM
c. Y-intercept in Lineweaver-Burk Plot
d. None of these
b. KM
Which of these proteases is not a cysteine active site protease?
a. Calpain
b. Cathepsin D
c. Papain
d. None of the above
b. 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. A 10-fold increase in Vmax would increase velocity 10-fold y
b. A 10-fold decrease in Km would increase velocity
c. Both (a) and (b)
d. A 10-fold increase in Vmax would decrease velocity 20-fold
a. 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
a. induced fit
b. transition
c. fit and fine
d. Pasteur
a. induced fit
The active site of an enzyme remains
a. at the center of globular proteins
b. rigid and does not change shape
c. complementary to the rest of the molecule
d. none of the above
d. none of the above
Which category of enzymes belongs to class two in the international classification?
a. Hydrolases
b. Ligases
c. Transferases
d. Isomerase
c. 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
a. non-significant
b. significant
c. nothing to do with the reliability
d. non-significant in selected cases
b. significant
The relationship between Keq, Km and Vmax is known as
a. Haldane equation
b. Michaelis Menten equation
c. Numerical solution approach
d. Gibbs-Helmholtz equation
a. Haldane equation
The reciprocal equation for non-competitive inhibition can be arranged to the equation for the
a. Dixon plot
b. Woolf-Augusteinsson-Hofstee plot
c. Eadie-Scatchard plot
d. Hanes-Woolf plot
a. Dixon plot
Which of the following statements is true for enzymatically catalyzed reaction?
a. The activation energy of the reaction is lowered so that a larger proportion of the substrate qualifies to overcome it
b. Additional substrate molecules are energized to overcome the activation energy of the reaction
c. The activation energy of the reaction is increased, thus decreasing the likelihood that any substrate molecules will overcome it
d. The activation energy of the reaction is lowered so that fewer substrate molecules can overcome it
a. 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?
a. Iodine
b. Methotrexate
c. Sulfanilamide
d. Penicillin
a. Iodine
The enzyme inhibition can occur by
a. reversible inhibitors
b. irreversible inhibitors
c. Both (a) and (b)
d. None of these
c. Both (a) and (b)
In a Lineweaver-Burk Plot, competitive inhibitor shows which of the following effect?
a. It moves the entire curve to right
b. It moves the entire curve to left
c. It changes the x-intercept
d. It has no effect on the slope
c. It changes the x-intercept
Which of the following statements is not true?
a. Enzymes are proteins that bind to specific substrates and increase the velocity of reactions involving those substrates
b. Enzymes function by overcoming the activation energy barrier of a reaction
c. Enzymes make thermodynamically favorable reactions to proceed; they cannot make unfavorable reactions to occur
d. Enzymes only function when they are in intact cells
d. Enzymes only function when they are in intact cells
Non-competitive inhibitor of an enzyme catalyzed reaction
a. decreases Vmax
b. binds to Michaelis complex (ES)
c. both (a) and (b)
d. can actually increase reaction velocity in rare cases
c. both (a) and (b)
An enzyme and a reactant molecule maintain relationship as
a. a temporary association
b. an association stabilized by a covalent bond
c. one in which the enzyme is changed permanently
d. non complementary binding
a. a temporary association
An enzyme is assayed at an initial substrate concentration of 2 x 10-5M. In 6-minute, half of the substrate is used. The Km for the substrate is 2 x 10-3M. The value of k in minute is
a. 0.115
b. 0.42
c. 0.093
d. 6.693
a. 0.115
The plot commonly used for determining the value of Vmax is
a. Lineweaver Burk plot
b. Langmuir plot
c. Eadie Hofstee plot
d. all of these
d. all of these
Quasi steady state is also known as
a. Michaelis Menten approach
b. Briggs-Haldane approach
c. Pseudo steady state
d. all of the above
c. Pseudo steady state
Which of these enzymes contains a Zinc (Zn) ion?
a. Carboxypeptidase A
b. Phosphorylase B kinase
c. Tyrosine hydroxylase
d. Phosphodiesterase
a. Carboxypeptidase A
A noncompetitive inhibitor of an enzyme-catalyzed reaction
a. increases KM and increases Vmax
b. increases KM and reduces Vmax
c. reduces KM and increases Vmax
d. reduces KM and reduces Vmax
b. increases KM and reduces Vmax
An allosteric inhibitor of an enzyme usually
a. participates in feedback regulation
b. denatures the enzyme
c. is a hydrophobic compound
d. causes the enzyme to work faster
a. participates in feedback regulation
Which of the following activity is possible by transferases?
a. Transfer of methyl groups
b. Transfer of glycosyl group
c. Both (a) and (b)
d. None of these
c. Both (a) and (b)
A classical uncompetitive inhibitor is a compound that binds
a. reversibly to the enzyme substrate complex yielding an inactive ESI complex
b. irreversibly to the enzyme substrate complex yielding an inactive ESI complex
c. reversibly to the enzyme substrate complex yielding an active ESI complex
d. irreversibly to the enzyme substrate complex yielding an active ESI complex
a. reversibly to the enzyme substrate complex yielding an inactive ESI complex
Which graphical method is used to determine an enzyme degree of cooperativity?
a. Hill plot
b. Koshland curve
c. Michaelis-Menten hyperbola
d. Can not be determined
a. Hill plot
The ratio of the amount of a protein present in a sample, which is used as a measure of purification, is known as
a. specific activity
b. relative activity
c. purity ratio
d. all of these
a. 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
a. (ν0 - νi)/ν0
b. (ν0 + νi)/ν0
c. (ν0νi)/ν0
d. (ν0-νi)/νi
a. (ν0 - νi)/ν0
The rate equation in competitive inhibition based on Michaelis Menten equation is given by
a. rmaxS/(Km(1+I/Ki) +S))
b. rmaxE/(Km(1+I/Ki) +S))
c. rmaxI/(Km(1+I/Ki) +S))
d. rmaxS/(Km(1+I/Ki))
a. rmaxS/(Km(1+I/Ki) +S))
Classical noncompetitive inhibition is obtained only under
a. slow equilibrium conditions
b. moderate equilibrium conditions
c. rapid equilibrium conditions
d. non-equilibrium conditions
c. rapid equilibrium conditions
In the steady state the material balance equation for any component of a system is
a. rate of addition + rate of removal - rate of formation = 0
b. rate of addition - rate of removal + rate of formation = 0
c. rate of addition + rate of removal + rate of formation = 0
d. none of the above
b. 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
a. 0.09
b. 0.33
c. 0.66
d. 0.91
c. 0.66
Predominantly uncompetitive inhibition may be called when
a. competitive inhibition is greater than uncompetitive inhibition
b. competitive inhibition is smaller than uncompetitive inhibition
c. competitive inhibition is equal to uncompetitive inhibition
d. none of the above
a. 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?
a. 13.54μ moles liter-1min-1
b. 6.68μ moles liter-1min-1
c. 7.57μ moles liter-1min-1
d. 17.8μ moles liter-1min-1
a. 13.54μ moles liter-1min-1
The rate equation in non-competitive inhibition based on Michaelis Menten equation is given by
a. rmaxS/ (Km + S) (1+I/Ki)
b. rmaxE/ (Km (1+I/Ki) +S))
c. VmaxS/ (Km + S) (1+I/Ki)
d. rmaxS/Km
a. rmaxS/ (Km + S) (1+I/Ki)
Which of the following statement(s) regarding enzymes, is/are false?
a. Enzymes are always proteins that function as catalysts
b. Enzymes provide activation energy for reactions
c. Enzyme activity can be regulated
d. Enzymes may be used many times for a specific reaction
b. Enzymes provide activation energy for reactions
The slope of Lineweaver Burk plot for Michaelis Menten equation is
a. Vmax/Km
b. Km/Vmax
c. 1/Km
d. Km*Vmax
b. Km/Vmax
The initial velocity, V0, of an enzyme catalyzed reaction reaches Vmax as
a. [S] = KM
b. [S] = 10 * KM
c. 1/[S] = 1/KM
d. 1/[S] → 0
d. 1/[S] → 0
The usual method(s) to solve rate equation of simple enzyme kinetics is/are
a. Michaelis Menten approach
b. Briggs-Haldane approach
c. Numerical solution approach
d. all of these
d. all of these
Michaelis Menten equation can also be written as
a. (-Cs)/r = (Cs/rmax)+(Km/rmax)
b. 1/r = (1/rmax)+(Km/(rmax.Cs))
c. r = rmax-(Km.r/Cs)
d. All of these
d. All of these
Which of the following step is assumed to be the slowest step in the Michaelis Menten equation?
a. The substrate consuming step
b. The product releasing step
c. Formation of enzyme substrate complex
d. None of these
b. The product releasing step
When substrate [S] = KM (Michaelis-Menten constant), the velocity of an enzyme catalyzed reaction is about
a. 0.1 * Vmax
b. 0.2 * Vmax
c. 0.5 * Vmax
d. 0.9 * Vmax
c. 0.5 * Vmax
A classical noncompetitive inhibitor has
a. no effect on substrate binding
b. no effect on substrate binding and vice versa
c. significant effect on substrate binding
d. significant effect on substrate binding and vice versa
b. 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
a. contains modified amino acids
b. catalyzes a chemical reaction
c. is complementary to a specific ligand
d. contains amino acids without side chains
b. catalyzes a chemical reaction
Enzymes are basically
a. Proteins
b. Vitamins
c. Fat
d. Carbohydrates
a. Proteins
Which of the following refers to pseudo steady state?
a. d(CE)/dt = 0
b. d(Cp)/dt = 0
c. d(CES)/dt = 0
d. d(Cs)/dt = d(CES)/dt
c. d(CES)/dt = 0
Most enzymes work by
a. increasing energy of activation
b. decreasing energy of activation
c. not affecting energy of activation
d. none of the above
b. decreasing energy of activation
Which category of enzymes belongs to class 5 in the international classification?
a. Hydrolases
b. Isomerases
c. Oxido-reductases
d. Cyclase
b. Isomerases
Lock and key theory is based on the compatibility of
a. enzyme and substrate
b. enzyme and product
c. enzyme and enzyme substrate complex
d. enzyme substrate complex and product
a. enzyme and substrate
When an enzyme is functioning at Vmax, the rate of the reaction is limited by
a. the number of collisions between enzyme and substrate
b. the number of substrate molecules in the reaction
c. the concentration of the substrate
d. the rate at which the enzyme can convert substrate to product
d. 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)
a. rp = rmax Cs/(Km+Cs)
b. rp= rmax CES/ (Km+ CES)
c. rp = rmax Cs/(Km+CES)
d. rp = rmax Cs/(Km+Cp)
a. rp = rmax Cs/(Km+Cs)
When [S] = 0.1 *KM, the velocity of an enzyme catalyzed reaction is about:
a. 0.1 * Vmax
b. 0.3 * Vmax
c. 0.5 * Vmax
d. 0.7 * Vmax
a. 0.1 * Vmax
β-amylase is
a. endoenzyme
b. exoenzyme
c. saccharifying enzyme
d. both (b) and (c)
d. both (b) and (c)
Juice clarification extraction is facilitated by using
a. Cellulases
b. Amylase
c. Inulinase
d. Lactase
a. Cellulases
Lysozyme is naturally present in
a. egg white
b. bacteria
c. tears & milk
d. all of these
d. all of these
Enzymes act as antimicrobials
a. by depriving an organism of a necessary metabolite
b. by generating a substances toxic to the organism
c. by attracting a cell wall component
d. all of the above
d. all of the above
Trichoderma β-glucanase is reported
a. to stabilize mashing
b. to convert taste fractions of dextrins to fermentable sugars in beer
c. to convert starch to dextrin
d. all of the above
a. to stabilize mashing
The bitter taste of the high protein materials is reduced by using
a. Invertase
b. Dectinase
c. Protease
d. none of these
c. Protease
Sulphydryl oxidase is used for
a. Discoloration
b. clarification of images
c. UHT milk off flavor removal
d. all of these
c. UHT milk off flavor removal
α-amylase is an endo enzyme which requires
a. Ca
b. Cu
c. Mn
d. None of these
a. Ca
Liquefaction of starch to dextrin is carried out by
a. α-amylase
b. cellulase
c. pectinase
d. all of these
a. α-amylase
Which is true about rennet?
a. It is a mixture of protease chymosin and pepsin
b. It is a mixture of rennin and pepsin
c. Both (a) and (b)
d. none of the above
c. Both (a) and (b)
Milk digestibility is improved by using
a. RNase
b. Lactase
c. β-amylase
d. none of these
b. Lactase
Which of the following mainly serve to convert starch into high fructose corn syrup (HFCS)?
a. α-amylase
b. Gluco-isomerase
c. Gluco-amylase
d. all of these
d. all of these
Lysozyme
a. catalyses hydrolysis of β-1-4 linkages between N-acetyl muranic acid and N-acetyl glucosamine in peptideoglycan
b. catalyses hydrolysis of α-1-4 linkages between N-acetyl muranic acid and N-acetyl glucosamine in peptideoglycan
c. catalyses hydrolysis of α-1-4 linkages between N-diacetyl muranic acid and N-diacetyl glucosamine in peptideoglycan
d. all of the above
a. catalyses hydrolysis of β-1-4 linkages between N-acetyl muranic acid and N-acetyl glucosamine in peptideoglycan
Hersperidinase is used for
a. juice clarification
b. juice debittering
c. off flavour reduction
d. RNA reduction in fish
a. juice clarification
Which of the following metallic ion is there in ascorbic acid oxidase?
a. Mg
b. Fe
c. Cu
d. Mn
c. Cu
Which of the enzyme combination is commercially used for the removal of oxygen?
a. Glucose oxidase-cellulase
b. Glucose oxidase-catalase
c. Glucose oxidase-lactase
d. All of these
b. Glucose oxidase-catalase
The enzyme used to reduce bitterness of grapes commonly contains
a. α-L-rhamonosidase
b. β-d-glucosidase
c. β- galactosidase
d. both (a) and (b)
d. both (a) and (b)
Citrus juice debittering can be carried out using
a. Limoninase
b. Inulinase
c. Anthocyanase
d. None of these
a. Limoninase
Which of the following enzyme is responsible for causing vitamin B deficiency disease beriberi?
a. Ascorbic acid oxidase
b. Thiaminase
c. Lipoxygenase
d. None of these
b. Thiaminase
Soya off flavour removal may be achieved using
a. di acetyl reductase
b. β- amylase
c. aldehyde oxidase
d. protease
c. aldehyde oxidase
The reduction in off flavour of beer is practiced through
a. Hersperidinase
b. Rnase
c. Invertase
d. diacetyl reductase
d. diacetyl reductase
Discoloration can be achieved by using
a. sulphloydryl oxidase
b. proteases
c. anthocyanase
d. all of these
c. anthocyanase
The prosthetic group present in phenolase enzyme is
a. Mg
b. Cu
c. Ca
d. Fe
b. Cu
Enzymes degrade, alter or synthesize a food component through
a. oxidation/reduction/isomerization
b. hydrolysis/synthesis
c. group transfer
d. all of the above
d. all of the above
The enzyme β-galactosidase is also known as
a. Lactase
b. EC3.2.1.23
c. both (a) and (b)
d. isomerase
d. isomerase
Chymosin hydrolyses the bond between
a. Alanine and glycine
b. Phenyl alanine and methionine
c. Glutamic acid and alanine
d. Alanine and phenyl alanine
b. Phenyl alanine and methionine
The function of the disengagement zone in an airlift fermenter is to
a. prevent CO2 rich bubbles from entering the downcomer
b. reduce the velocity of the bubbles
c. reduce liquid loss as aerosols
d. all of the above
d. all of the above
Stationary phase is described as
a. no further increase in the cell population after a maximum value
b. deceleration of growth and division rate after the growth rate reaches a maximum
c. acceleration of growth and division rate after the growth rate reaches a maximum
d. deceleration of growth and division rate after the growth rate reaches a minimum
a. no further increase in the cell population after a maximum value
In the accelerated phase, cell starts to
a. increase and the division rate increases to reach a maximum
b. decrease and the division rate increases to reach a maximum
c. increase and the division rate decreases to reach a maximum
d. increase and the division rate increases to reach a minimum
a. increase and the division rate increases to reach a maximum
The Monod model predicts that the specific growth rate
a. will increase with the concentration of the growth limiting substrate until it reaches a maximum value
b. will decrease with the concentration of the growth limiting substrate
c. will increase with the concentration of the growth limiting substrate
d. does not depend on growth limiting substrate
a. will increase with the concentration of the growth limiting substrate until it reaches a maximum value
A mixed fermentation is one, which produces
a. both alcohol and carbon dioxide
b. both acid and carbon dioxide
c. both acid and alcohol
d. several different kinds of acid
c. both acid and alcohol
The function of a mechanical seal is to
a. prevent contaminants entering the reactor
b. prevent cells from leaving the reactor
c. both (a) and (b)
d. prevent air to enter
c. both (a) and (b)
The phenomenon in which substrates are used in a sequential manner is known as
a. trans-substrate genesis
b. dialism
c. diauxie
d. multiplicity
c. 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)
a. F/VR
b. VR/F
c. μ/F
d. F/μ
a. F/VR
Diauxie is
a. growth factors
b. microbiological die off
c. the simultaneous uptake of nutrients
d. the stagewise uptake of nutrients
d. the stagewise uptake of nutrients
An open system in which the growth rate is maintained by adding a nutrient (present in limiting quantities) at the same rate as that medium containing micro-organism is removed is called
a. Manostat
b. Chemostat
c. Turbidostat
d. Culturostat
b. Chemostat
In the death phase
a. nutrients available for the cells are depleted and begin to die
b. the number of viable cells will increase
c. nutrients available for cells are replenished and start to multiply
d. none of the above
a. nutrients available for the cells are depleted and begin to die
The maximum specific growth rate of an organism depends on
a. medium composition
b. temperature
c. pH
d. All of these
d. All of these
Which of the following is not correct for the Monod model and the Michaelis Menten Model
a. The Michaelis Menten Model was derived from a curve fitting exercise
b. The Michaelis Menten model was derived from an analysis of the mechanism of microbial growth
c. The Monod model was derived from an analysis of the mechanism of microbial growth
d. All of the above
c. The Monod model was derived from an analysis of the mechanism of microbial growth
Bubble column reactor has
a. large height to diameter ratio
b. small height to diameter ratio
c. large diameter to height ratio
d. small diameter to height ratio
a. large height to diameter ratio
Why a T-flask used in small-scale cell culture is incubated in a horizontal position
a. To save space
b. To increase the surface area of the liquid-air interface
c. Both (a) and (b)
d. To increase the rate of oxygen transfer into the liquid
c. 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
a. Manostat
b. Chemostat
c. Turbidostat
d. Culturostat
c. Turbidostat
Wash out in steady state fermentation occurs when
a. dilution rate is less than maximum specific growth rate
b. dilution rate is higher than the maximum specific growth rate
c. cell concentration reaches the maximum
d. specific growth rate is maximum
b. dilution rate is higher than the maximum specific growth rate
Fermenter should be filled with medium upto
a. 65-70%
b. 70-75%
c. 75-80%
d. 80-85%
c. 75-80%
Bacterial growth curve is obtained by plotting
a. number of cells versus time
b. number of spores versus time
c. log of number of cells versus time
d. log of number of cells survived versus time
c. 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.
a. Permeabilize
b. Lyophilize
c. heat-kill
d. denature
a. Permeabilize
Heat transfer rates (per unit volume) will be lowest in
a. Stirred tank bioreactor with biomass recycle
b. Continuous air lift bioreactor
c. Continuous packed bed reactor
d. Continuous fluidized bed bioreactor
c. Continuous packed bed reactor
The function(s) of the draft tube in an airlift bioreactor is
a. to reduce bubble coalescence
b. to improve circulation
c. to even out shear conditions throughout the reactor
d. all of the above
d. all of the above
The Monod Model relates
a. substrate utilized with the biomass consumption
b. specific growth rate to the substrate availability
c. yield with the biomass utilization
d. the biomass concentration with specific growth rate
b. specific growth rate to the substrate availability
The height to diameter ratio (H/D) for the column fermenters is
a. <3
b. >3
c. <1.5
d. >1.5
b. >3
The high oxygen transfer efficiencies of airlift bioreactors is due to
a. the large aspect ratio of the reactor, which leads to a high gas hold-up
b. the large aspect ratio of the reactor, which leads to a high oxygen solubility at the base of the reactor
c. the draft tube, which reduces bubble coalescence in the reactor
d. all of the above
d. all of the above
The maximum specific growth rate (μm) of an organism in batch culture is equal to slope of a plot of
a. In [biomass] against time for exponential phase data only
b. In [biomass] against time
c. biomass against time
d. biomass against time for stationary phase data only
a. 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
a. Downcomer
b. disengagement zone
c. air riser
d. flotsam
a. Downcomer
Population doubling time, td can be expressed as (where μ is the specific growth rate.)
a. log2/μ
b. ln2/μ
c. μ/ln2
d. μ/log2
b. ln2/μ
A higher Ks value of Monod’s equation means
a. greater affinities to substrate
b. lower affinities to substrate
c. unaffected with the substrate bonding
d. lower dissociation constant value
a. 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
a. decreases the productivity of the fermenter
b. increases the productivity of the fermenter
c. modestly increases the productivity of the fermenter
d. does not affect on the productivity
a. decreases the productivity of the fermenter
Which of the following is correct for the prediction of time requirement in a batch fermenter?
a. Carrying out experiments
b. Mathematical modelling of the fermentation process
c. Both (a) and (b)
d. It is impossible to predict the time required for fermentation
c. Both (a) and (b)
In an airlift bioreactor, the spent gases released from the liquid are called
a. Downcomer
b. disengagement zone
c. air riser
d. flotsam
b. disengagement zone
The contents in jet loop reactor are mixed through
a. compressed air
b. a mechanical agitator
c. external pumping
d. any of these
c. external pumping
The specific growth rate (μ) is defined as
a. the concentration of biomass in the reactor
b. rate of increase of total biomass in a reactor
c. the rate of individual cells division or increase in their biomass
d. the rate of cell death
c. the rate of individual cells division or increase in their biomass
The number of baffles in a standard stirred tank bioreactor is
a. 8
b. 6
c. 4
d. 2
c. 4
In the stationary phase
a. growth is proportional to death
b. growth rate is equal to death rate
c. growth rate is lesser than death rate
d. no co-relation exist between death rate and growth rate
b. growth rate is equal to death rate
Which of the following is an example of a mathematical model?
a. Volume of cuboid = length x breadth x height
b. The Monod Model
c. The Michaelis Menten Equation
d. All of the above
d. All of the above
Biomass concentrations during fermentation is
a. diluting the samples to optical density less than 0.3
b. monitored by controlling the changes in biomass concentrations
c. considering that optical density is proportional to the surface area of the biomass in the sample
d. all of the above
d. all of the above
Chemostats work on the principle of
a. maintaining constant volume of culture medium
b. maintaining continuous flow of nutrients
c. maintaining uniform nutrients concentration
d. operating at higher pressure
c. maintaining uniform nutrients concentration
During the exponential phase the maximum specific growth rate equals specific growth rate as
a. concentration of the growth limiting substrate is much less than the Monod constant
b. concentration of growth limiting substrate is much greater than the Monod constant
c. specific growth rate increases exponentially
d. concentration of the growth limiting substrate is equal to the Monod constant
b. concentration of growth limiting substrate is much greater than the Monod constant
An internal draft tube is preferred to an external draft tube because
a. it is easier to clean and sterilize a reactor
b. it is cheaper to build a reactor with an internal draft tube
c. Both (a) and (b)
d. none of the above
a. 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
a. 1958
b. 1946
c. 1942
d. 1950
c. 1942
The optical density sometimes drops during the lag phase because
a. cells tend to grow without dividing leading to a decrease in the surface area to volume ratio
b. of fast cell growth causing them to fill up with DNA
c. cells swell up with water
d. cells swell up with RNA
a. 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
a. raw materials used in biotechnology are biodegradable
b. the products of biotechnology are biodegradable
c. it is a very competitive business
d. all of the above
d. all of the above
Residence time distribution (RTD) of a reactor is independent of
a. micro mixing
b. volume of reactor
c. height of the reactor
d. width of the reactor
a. micro mixing
The bubble column fermenter is usually limited to
a. aerobic fermentations
b. anaerobic fermentations
c. Both (a) and (b)
d. facultative fermentation
a. 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.
a. Continuous
b. Batch
c. fed-batch
d. semi continuous
b. 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
a. Cn= Cn0 exp [μ (t - t0)]
b. Cn0 = Cn exp [μ (t - t0)]
c. Cn/Cn0 =(1/μ) exp(t-t0)
d. Cn0 / Cn = (1/μ) exp(t-t0)
a. Cn= Cn0 exp [μ (t - t0)]
The diameter of the baffles in a standard stirred tank bioreactor ranges from
a. 1/10th - 1/12th of the tank diameter
b. 1/3rd - 1/4th of the tank diameter
c. 1/15th - 1/20th of the tank diameter
d. 1/20th - 1/25th of the tank diameter
a. 1/10th - 1/12th of the tank diameter
During the log phase cell numbers increase exponentially
a. because cells produce enzymes
b. because cells do not have cell membranes
c. because cells are auto catalysts
d. because the rate of cell division increases exponentially
c. because cells are auto catalysts
Lag phase occurs mainly due to
a. acclimatization with new environment and substrate
b. higher growth temperature
c. substrate disliking
d. variation in substrate concentration
c. substrate disliking
In a batch reactor specific growth rate
a. remains constant throughout the process
b. increases exponentially
c. changes during the fermentation
d. is highest during the stationary phase
c. changes during the fermentation
Turbidostat is recommended when continuous fermentation needs to be carried out at
a. high dilution rates near the washout point
b. low dilution rates near the washout point
c. moderate dilution rates near the washout point
d. any intensity of dilution rates near the washout point
a. high dilution rates near the washout point
The advantage of airlift bioreactors over stirred tank bioreactors of a similar size is
a. higher oxygen transfer rates
b. more uniform shear conditions
c. both (a) and (b)
d. less foaming
c. both (a) and (b)
Stirred tank fermenter (STF) can be employed for
a. aerobic fermentation of a wide range of cells including microbial, animal and plant cells
b. anaerobic fermentation of a wide range of cells including microbial, animal and plant cells
c. Both (a) and (b)
d. anaerobic fermentation of plant cells only
c. Both (a) and (b)
The specific growth rate is affected by
a. substrate concentration
b. product concentration
c. oxygen supply
d. all of these
d. all of these
The main function(s) of a draft tube in an air lift fermenter is/are to
a. increase the solubility of oxygen
b. distribute shear forces throughout the reactor and minimize bubble coalescence
c. concentrate shear forces around the sparger
d. concentrate shear forces near the disengagement zone
b. distribute shear forces throughout the reactor and minimize bubble coalescence
Which of the following is incorrect?
a. The mechanical agitation and aeration are effective for suspension of cells
b. The mechanical agitation and aeration are effective for mixing the medium
c. STF can’t be used for high viscosity medium
d. The mechanical agitation and aeration are effective for oxygenation
c. STF can’t be used for high viscosity medium
The contents in bubble column and air lift reactor are mixed through
a. compressed air
b. a mechanical internal moving part
c. external pumping
d. any of these
a. compressed air
Which of the following statements would be appropriate while comparing bubble column and air lift fermenter of the same size?
a. The average bubble size is smaller in an airlift bioreactor
b. Oxygen transfer rate is higher in an airlift bioreactor
c. The surface area for gas exchange is higher in an airlift bioreactor
d. All of the above
d. All of the above
During the lag phase
a. cells just start growing
b. cells synthesize new proteins and membrane components
c. cells produce antibiotics to kill competing organisms
d. cells simply grow slowly
b. cells synthesize new proteins and membrane components
Concentration of the growth limiting substrate means
a. trace elements concentration
b. the concentration of the substrate that controls the growth rate of the cells
c. sugar concentration in the fermentation medium
d. dissolved oxygen concentration
b. the concentration of the substrate that controls the growth rate of the cells
Tower fermenters are used for
a. continuous penicillin production
b. continuous beer production
c. production of enzymes
d. batch production of beer
b. continuous beer production
In wastewater treatment, which bioreactor is generally used?
a. Plug flow reactor
b. Trickle bed reactor
c. Tower fermenter
d. CSTR
b. Trickle bed reactor
The contents in stirred tank rector are mixed through
a. compressed air
b. a mechanical agitator
c. external pumping
d. any of these
b. a mechanical agitator
The height to diameter ratio (H/D) for the tank fermenters is
a. <3
b. >3
c. <1.5
d. >1.5
a. <3
The relatively large volume (10 to 40% of total fermenter volume) of the seed culture is employed to
a. increase the overall fermentation time
b. increase the overall yield of biomass
c. decrease the overall fermentation time
d. decrease the overall yield of product
c. decrease the overall fermentation time
In an airlift bioreactor, the air sparging region is called
a. Downcomer
b. disengagement zone
c. air riser
d. none of these
c. air riser
The air riser is located on the outside of the draft tube for the large-scale airlift bioreactors because of
a. higher oxygen transfer rates
b. a small sparge ring
c. better heat transfer efficiencies
d. all of these
c. 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
a. lag phase
b. stationary phase
c. death phase
d. exponential growth phase
a. lag phase
Which of the following(s) is/are considered the limitations of the exponential growth model?
a. Only predicts that cells grow exponentially during the log phase
b. It does not consider factors that causes cells growth to stop or slow
c. Predicts cell growth at a linear rate
d. All of the above
b. 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?
a. Disengagement zone, air riser, downcomer
b. Flotsam, jetsam, downzone
c. Air comer, disentanglement zone, downsizer
d. All of the above
a. Disengagement zone, air riser, downcomer
The viscosity of liquid was classified as both dilatant and rheopectic, which means that the viscosity
a. increased with stirring speed but decreased with mixing time
b. increased with stirring speed and increased with mixing time
c. decreased with stirring speed but increased with mixing time
d. decreased with stirring speed and decreased with mixing time
b. increased with stirring speed and increased with mixing time
Which of the following describes the detrimental effect of bubbles on animal cells?
a. Cells trapped on the surface of bubbles can be damaged when the bubbles explode, releasing their pressure and surface energies
b. Cells trapped in the moving foam can be dragged apart by the bubbles
c. Both (a) and (b)
d. Bubbles can explode in the liquid medium causing the release of ultraviolet radiation
c. Both (a) and (b)
A fluid in which the viscosity decreases with increasing stirrer speed and mixing time, can be represented as
a. Newtonian fluid
b. pseudoplastic, thixotropic fluid
c. dilatant, rheopectic fluid
d. dilatant, pseudoplastic fluid
b. pseudoplastic, thixotropic fluid
Filamentous fungal cells are more shear sensitive than bacterial cells because of
a. the presence of citin in cell walls of filamentous fungi
b. larger in size than bacterial cells and therefore are more susceptible to shear forces
c. fungal cells are much larger than bacterial cells
d. all of the above
d. all of the above
The viscosity of water at STP is approximately
a. 0.005 kg.m-1.s-1
b. 0.001 kg.m-1.s-1
c. 0.003 kg.m-2.s-1
d. 0.1 g.cm-1.s-1
b. 0.001 kg.m-1.s-1
Bubble free aeration systems requires
a. silicone tubing or gas permeable membranes to facilitate gas transfer
b. carbon dioxide instead of air to supply oxygen
c. silicone tubing or gas permeable membranes to remove carbon dioxide by oxygen in the form of hydrogen peroxide
d. filled headspace of the reactor with carbon dioxide
a. silicone tubing or gas permeable membranes to facilitate gas transfer
Non-linear relationship between shear stress and shear rate exists in
a. Newtonian fluids
b. non-Newtonian fluids
c. both (a) and (b)
d. none of these
b. non-Newtonian fluids
If the viscosity of a fluid decreases with increasing stirrer speed, then the nature of the fluid is
a. Newtonian
b. Pseudoplastic
c. Dilatant
d. Thixotropic
b. Pseudoplastic
A pseudoplastic fluid is one in which the viscosity
a. is constant regardless of the stirrer speed or mixing time
b. changes during mixing but returns to its original state after mixing
c. increases with increasing stirrer speed
d. decreases with increasing stirrer speed
d. decreases with increasing stirrer speed
A viscoelastic fluid is one in which the viscosity
a. is constant regardless of the stirrer speed or mixing time
b. changes during mixing but returns to its original state after mixing
c. increases with increasing stirrer speed
d. decreases with increasing stirrer speed
b. changes during mixing but returns to its original state after mixing
Mixing in stirred tank reactors can
a. be described as either laminar, transient or turbulent
b. achieve turbulent conditions by increasing the stirrer speed
c. induce laminar flow conditions by the addition of baffles
d. all of the above
a. be described as either laminar, transient or turbulent
In animal cell bioreactor, bubble damage can be minimized by
a. the addition of a shear protectorant
b. using a bubble free oxygen delivery system
c. headspace aeration
d. all of the above
d. 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
a. Newtonian
b. Rheopectic
c. Viscoelastic
d. Thixotropic
c. Viscoelastic
In sparged mammalian cell bioreactors, the cell damage is caused because of
a. shear stress arising during mixing of the cell culture fluid
b. shear stresses arising from the breakup of bubbles at the liquid surface
c. shear stresses between bubbles in foam at the liquid surface
d. all of the above
a. shear stress arising during mixing of the cell culture fluid
The SI unit for viscosity is
a. kg.m-1. s-1
b. kg.m-2. s-2
c. kg.m-3. s-1
d. kg.m-1.s-2
a. kg.m-1. s-1
The viscous nature of a non-Newtonian fluid
a. remains constant with time and power input
b. changes with the level of power input and/or the length of time during which the fluid is mixed
c. is similar to that of a perfect gas
d. is similar to that of water
b. 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. A globular protein
b. Glucose
c. A long chain protein such as albumin
d. Water
c. A long chain protein such as albumin
A Brookfield viscometer measures viscosity by determining
a. the shear stress
b. the shear rate
c. the shear stress and shear rate
d. the torque required to move an impeller at a set speed
d. 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?
a. Cell size
b. Availability of nutrients in the medium
c. The presence of shear protectorants in the medium
d. All of the above
d. All of the above
The best described action of Pluronic F68 (non-ionic detergent) in a cell culture medium is that, it
a. acts on the surface properties of the cells and the culture medium
b. provides nutrients for the cells
c. acts as a flocculant
d. acts as a coagulant
a. acts on the surface properties of the cells and the culture medium
Water is a
a. Newtonian fluid
b. Pseudoplastic
c. Dilatant
d. Rheopectic
a. Newtonian fluid
Which of the following affect the Kolmogorov eddy size?
a. Stirrer speed
b. Physical properties of the liquid
c. Size and type of impeller
d. All of these
d. 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
a. laminar phase
b. transient phase
c. turbulent phase
d. any of the phase
c. 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
a. Newtonian
b. Rheopectic
c. Viscoelastic
d. Thixotropic
b. Rheopectic
Which of the following can act as a shear protectorant?
a. Serum
b. Silicone oil
c. Glucose
d. Glutamic acid
a. Serum
The viscosity of a fluid increases with increasing stirrer speed. This fluid would be best described as being
a. Newtonian
b. Pseudoplastic
c. Dilatant
d. Thixotropic
c. Dilatant
A dilatant fluid is one in which the viscosity
a. is constant regardless of the stirrer speed or mixing time
b. changes during mixing but returns to its original state after mixing
c. increases with increasing stirrer speed
d. decreases with increasing stirrer speed
c. increases with increasing stirrer speed
A rheopectic fluid is one in which the viscosity
a. is constant regardless of the stirrer speed or mixing time
b. changes during mixing but returns to its original state after mixing
c. increases with mixing time
d. decreases with mixing time
c. increases with mixing time
A fluid in which the viscosity increases with increasing stirrer speed and mixing time can be called as
a. Newtonian fluid
b. pseudoplastic, thixotropic fluid
c. dilatant, rheopectic fluid
d. dilatant pseudoplastic fluid
c. dilatant, rheopectic fluid
The medium will have the highest viscosity (considering that the cells do not secrete gums) with the presence of
a. single celled bacteria
b. filamentous fungi that form pellets
c. filamentous fungi that grow as long poorly branched chains
d. yeast
c. filamentous fungi that grow as long poorly branched chains
A Newtonian fluid is one in which the viscosity
a. is constant regardless of the stirrer speed or mixing time
b. changes during mixing but returns to its original state after mixing
c. increases with increasing stirrer speed
d. decreases with increasing stirrer speed
a. 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?
a. Laminar flow
b. Transient flow
c. turbulent flow
d. all of these
c. turbulent flow
Animal cell cultures do not have much effect on shear forces because
a. the cell size is generally smaller than the critical eddy size at which shear will have an effect
b. cells are larger than the critical eddy size at which shear will have an effect
c. animal cells have cell walls
d. animal cells have cell membranes
a. 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
a. increases with stirring speed but decreases with mixing time
b. increases with stirring speed and increases with mixing time
c. decreases with stirring speed but increases with mixing time
d. decreases with stirring speed and decreases with mixing time
d. decreases with stirring speed and decreases with mixing time
Pluronic F68 is added to cell culture media as
a. a nutrient
b. a shear protectorant
c. to increase oxygen transfer rates
d. all of these
b. 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
a. 2500
b. 100
c. 12,50,000
d. 1,000,000
c. 12,50,000
If the viscosity of a fluid decreases with the length of time that it is being mixed, then this fluid is
a. Newtonian
b. Rheopectic
c. Viscoelastic
d. Thixotropic
d. Thixotropic
Which of the following describes the importance of the Kolmogorov eddy size in the biotechnology?
a. The Kolmogorov eddy size is a measure of the smallest eddy size in a liquid
b. 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
c. At the Kolmogorov eddy size, much of the energy of the originating eddy will be released
d. All of the above
d. All of the above
A thixotropic fluid is one in which the viscosity
a. is constant regardless of the stirrer speed or mixing time
b. changes during mixing but returns to its original state after mixing
c. increases with mixing time
d. decreases with mixing time
d. decreases with mixing time
Newtonian fluid is one in which the viscosity
a. remains constant with time and power input
b. increases with the level of power input
c. decreases with the level of power input
d. drastically increases with the level of power input
a. remains constant with time and power input
Reynolds number for laminar flow over a plate should be less than
a. 500 mm
b. 5 x 10-5
c. 5 x 105
d. 5 m
c. 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
a. the concentration of lactate in the medium
b. the level of lactate oxidase activity in the medium
c. the level of lactate dehydrogenase activity
d. the level of lactase activity in the medium
c. the level of lactate dehydrogenase activity
A Brookfield viscometer cannot determine the shear stress because
a. the shear stress is not defined
b. a computer is required
c. the impeller type is given only by numbers
d. all of the above
a. the shear stress is not defined
Which of the following is correct?
a. The viscosity of liquids and gases decrease with increasing temperature
b. The viscosity of liquids and gases increase with increasing temperature
c. the viscosity of gases increases with increasing temperature, but decreases in liquids
d. the viscosity of gases decreases with increasing temperature, but decreases in liquids.
c. the viscosity of gases increases with increasing temperature, but decreases in liquids
The Komologorov eddy size
a. is constant at all stirrer speeds
b. increases with stirrer speed
c. decreases with stirrer speed
d. becomes zero when the stirrer speed is very low
c. decreases with stirrer speed
Pluronic F68 protects mammalian cells from damage stems as it is a/an
a. surface active agent which stabilizes foams
b. surface active agent which destabilizes foams
c. excellent source of vitamins
d. coagulant
a. surface active agent which stabilizes foams
Reynolds number for turbulent flow over a plate should be more than
a. 5 x 10-5
b. 10^6
c. 5 x 105
d. 500
b. 10^6
Concentration polarization can be reduced further by
a. pre filtering the solution
b. reducing the flow rate per unit membrane surface area
c. back washing periodically
d. all of the above
d. all of the above
A system which requires less solvent and produces a more concentrated extract phase, is desired with a
a. large distribution coefficients
b. small distribution coefficients
c. very small distribution coefficients
d. constant distribution coefficients
a. large distribution coefficients
The efficiency of cell disruption in a bead mill depends on the
a. concentration of the cells
b. amount and size of beads
c. type and rotational speed of agitation
d. all of these
d. all of these
A common filter medium is the cloth filter generally made of
a. Canvas
b. synthetic fabrics
c. metal or glass fiber
d. all of these
d. all of these
An ion exchange resin is composed of
a. polymeric network
b. ionic functional groups
c. counter ions
d. all of these
d. all of these
Maintenance cost varies from
a. 0-4% of the capital cost
b. 12-16% of the capital cost
c. 4-8% of the capital cost
d. 8-12% of the capital cost
c. 4-8% of the capital cost
The optimum wet solid content for the cell suspension for a bead mill is typically somewhere between
a. 5-15% by volume
b. 15-30% by volume
c. 30-60% by volume
d. 60-90% by volume
c. 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)
a. (1/A) dVf/dt = Δp/μ(L/K)
b. dVf/dt = (1/A)Δp/μ(L/K)
c. (1/A) dVf/dt = Δp/μ LK
d. dVf/dt = (1/A)Δp/μ LK
a. (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?
a. 1.54 ft2
b. 3.08 ft2
c. 65 ft2
d. 65 lbs/ ft2.hr
a. 1.54 ft2
Selectivity can be expressed as
a. ratio of the distribution coefficients in different solute
b. mass fraction of the solute in the extract phase at equilibrium
c. mass fraction of the solute in the raffinate phase
d. ratio of the mass fraction of the solute in the extract phase to the raffinate phase
a. 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
a. continuous operation
b. lesser cost
c. higher speed
d. ease in operation
b. lesser cost
The effectiveness of a solvent can be measured by the
a. distribution coefficients
b. selectivity
c. both (a) and (b)
d. diffusivity
c. both (a) and (b)
The stage wise operation of adsorption is called
a. contact filtration
b. conventional adsorption
c. affinity adsorption
d. ion exchange
a. contact filtration
Which of the following is not the physical method for the cells rupturing?
a. Milling
b. Homogenization
c. Ultrasonication
d. Enzymatic digestion
d. Enzymatic digestion
Conventional adsorption is a
a. reversible process
b. irreversible process
c. either reversible or irreversible
d. none of these
a. reversible process
If the solute passes through membrane freely, the the rejection coefficient (s) is
a. 1
b. 0
c. >1
d. <1
c. >1
If the membrane rejects all solute, the rejection coefficient (s) is
a. 1
b. 0
c. >1
d. <1
a. 1
In antibiotic manufacturing processes, the fermentation time ranges from
a. 2-3 weeks
b. 1-2 weeks
c. 4-5 weeks
d. 2-4 weeks
c. 4-5 weeks
The conventional filtration involves the separation of large particles generally
a. dp>5μm
b. dp>10μm
c. dp>15μm
d. dp>20μm
b. dp>10μm
Which of the operation does not come under upstream processing?
a. Media preparation
b. Inoculum development
c. Effluent treatment
d. Storage of raw material
c. Effluent treatment
For cost analysis in a fermenter system, the depreciation cost varies from
a. 5-6% of the capital cost
b. 6-7% of the capital cost
c. 6-10% of the capital cost
d. 8-10% of the capital cost
c. 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
a. 0.02 to 10μm
b. 1-10A°
c. 20-30μm
d. 10-200A°
a. 0.02 to 10μm
Start up expenses in a fermentation industry varies from
a. 0-5% of the capital cost
b. 10-15% of the capital cost
c. 5-10% of the capital cost
d. 15-20% of the capital cost
c. 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)
a. J = Lp(Δp - σΔπ)
b. J/A = Lp(Δp - σΔπ)
c. J= Lp/σΔπ
d. J/A = Lp/Δp
a. J = Lp(Δp - σΔπ)
Which of the following is considered as a pretreatment to the biological feeds?
a. Heating to denature the proteins
b. Addition of filter aids to increase the porosity
c. Addition of electrolytes
d. All of the above
d. All of the above
For the extractions operation, the selectivity should be
a. > 1
b. < 1
c. 1
d. Zero
a. > 1
The purity of a solute collected between two times t1 and t2 during chromatographic separation can be calculated as
a. amount of solute eluted - amount of impurity eluted
b. amount of solute eluted / amount of impurity eluted
c. amount of solvent eluted + amount of impurity eluted
d. amount of solvent eluted / amount of impurity eluted
b. amount of solute eluted / amount of impurity eluted
Chromatography is based on the
a. different rate of movement of the solute in the column
b. separation of one solute from other constituents by being captured on the adsorbent
c. different rate of movement of the solvent in the column
d. any of the above
a. 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)
a. Y = YmaxX/(KL+X)
b. Y= Ymax/(KL+X)
c. Y= YmaxX/KL
d. Y = Ymax- X/ (KL+X)
a. 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
a. 15,000 to 50,000 rpm
b. 50,000 to 100,000 rpm
c. 100,000 to 150,000 rpm
d. 150,000 to 200,000 rpm
a. 15,000 to 50,000 rpm
Water insoluble enzymes can be prepared by using multifunctional agents that are bifunctional in nature and have
a. Low molecular weight
b. High molecular weight
c. High equivalent weight
d. Low reactivity
a. Low molecular weight
Functional groups of the nonessential amino acids that are suitable for the immobilization process are
a. Free α-, β- or γ carboxyl groups
b. α or β amino groups
c. phenyl, hydroxyl, sulfhydryl, or imidazole groups
d. all of the above
d. all of the above
Which medium is used for the production of Penicillin using immobilized cells?
a. 1% peptone medium
b. Glucose medium
c. Yeast extract medium
d. LB broth
b. Glucose medium
Which of the following is taken as an assumption in the distributed model?
a. The reaction occurs at every position and the kinetics of the reaction are of the same form as observed for free enzyme.
b. Mass transfer through the immobilized enzyme occurs via molecular diffusion.
c. There is no mass transfer limitation at the outside surface of the spherical immobilized enzyme.
d. All of the above
d. All of the above
The immobilized enzyme produced by micro encapsulation technique provides
a. An extremely large surface area
b. Smaller surface area
c. High amount of solvent
d. Relatively smaller surface area
a. An extremely large surface area
Which of the following is considered as a disadvantage to the adsorption method of immobilization?
a. It is possible to separate and purify the enzymes while being immobilized.
b. The enzymes are not usually deactivated by adsorption.
c. The adsorption is a reversible process.
d. State of immobilization is very sensitive to solution pH, ionic strength, and temperature.
d. 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
a. Equal to that of substrate consumption
b. More than that of substrate consumption
c. Lesser than that of substrate consumption
d. Is nothing to do with the substrate consumption
a. Equal to that of substrate consumption
The immobilized technique involving chemical method is
a. Covalent bond formation dependent
b. Non-covalent bond formation dependent
c. Both (a) and (b)
d. Ionic bond formation dependent
a. Covalent bond formation dependent
For a steady state condition, the change of substrate concentration (dCS/dt) is
a. Zero
b. 1
c. > 1
d. < 1
a. Zero
Damkohler number (NDa) is
a. The ratio of the maximum reaction rate to the maximum mass transfer rate.
b. The ratio of the minimum reaction rate to the maximum mass transfer rate.
c. The ratio of the maximum mass transfer rate to the minimum mass transfer rate.
d. The ratio of the minimum mass transfer rate to the minimum mass transfer rate.
a. The ratio of the maximum reaction rate to the maximum mass transfer rate.
For glucose isomerization by immobilized enzyme, the reactor generally used is
a. CSTR
b. Plug flow
c. Packed Bed
d. Fluidized Bed
c. 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)
a. 𝑟𝑃=𝑘𝑆𝑎(𝐶sb−𝐶𝑠)
b. 𝑟𝑃=𝑘𝑆𝑎𝐶𝐶𝑠b
c. 𝑟𝑃=𝑘𝑠𝑎𝐶𝑠
d. 𝑟𝑃=𝑘𝑠𝑎(𝐶𝑠b+𝐶𝑠)
b. 𝑟𝑃=𝑘𝑆𝑎𝐶𝐶𝑠b
The most commonly employed cross-linked polymer is the
a. Polyacrylamide gel
b. Collagen
c. Celluloses
d. Cation exchange resin
a. Polyacrylamide gel
Which of the following is not the correct answer?
a. Immobilized enzyme may show selectively altered chemical properties.
b. Immobilized enzyme may show selectively altered physical properties.
c. Immobilized enzyme may simulate the realistic natural environment where the enzyme come from the cell.
d. None of the above
d. None of the above
Commonly employed water insoluble supports the covalent attachment of enzyme include
a. Acrylamide based polymers
b. Polypeptides
c. Dextran
d. All of these
d. All of these
Which of the following is not a physical method of immobilization?
a. Adsorption
b. Entrapment
c. Micro encapsulation
d. None of these
d. None of these
The support material for immobilization of cells of Bacillus subtilis is
a. Ion exchange resins
b. Gelatin
c. Anthracite
d. Agarose and carbodiimide
d. Agarose and carbodiimide
The intraparticle mass transfer resistance can affect the rate of enzyme reaction, if enzymes are immobilized by
a. Copolymerization or microencapsulation
b. Cross linking using multifunctional reagents
c. Adsorption
d. All of the above
a. Copolymerization or microencapsulation
The covalent attachment of enzyme molecules is via
a. Nonessential amino acids residues to water insoluble, functional supports
b. Essential amino acids residues to water insoluble, functional supports
c. Nonessential amino acids residues to water soluble, functional supports
d. Essential amino acids residues to water soluble, functional supports.
a. 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
a. Reaction rate/rate if not slowed by diffusion
b. Rate if not slowed by diffusion/reaction rate
c. Actual reaction rate/rate if not slowed by diffusion
d. Rate if not slowed by diffusion/actual reaction rate
c. Actual reaction rate/rate if not slowed by diffusion
Which is not the method for producing immobilized enzymes with multifunctional reagents?
a. Enzymes are adsorbed on the surface active support followed by intermolecular cross linking.
b. Functional groups are introduced on the support to react covalently with enzymes.
c. Enzymes are cross linked intermolecularly.
d. None of the above
d. None of the above
The immobilization technique involving physical method is
a. Covalent bond formation dependent
b. Non-covalent bond formation dependent
c. Both (a) and (b)
d. ionic bond formation dependent
b. Non-covalent bond formation dependent
which of the following is the commonly employed adsorbents?
a. Calcium carbonate
b. Alumina
c. Celluloses
d. All of these
d. All of these
Various techniques are available for determining the effective diffusivity of solute in gel. Thin disk method uses
a. A diffusion cell with two compartments divided by a thin gel.
b. A diffusion cell with two compartments.
c. A diffusion cell with two compartments plus by a thin gel.
d. A diffusion cell with two compartments multiply by a thin gel.
a. A diffusion cell with two compartments divided by a thin gel.
The effectiveness factor increases with the
a. Increase of diffusivity and decreased with the increase of particle size.
b. Increase of diffusivity and increased with the increase of particle size.
c. Decrease of diffusivity and decreased with the increased of particle size.
d. Increase of diffusivity and decreased with the decrease of particle size.
a. Increase of diffusivity and decreased with the increase of particle size.
Yield coefficient represents
a. Total biomass or product produced.
b. Conversion efficiency of a substrate into product.
c. Conversion rate of a substrate into biomass or product.
d. Production time of biomass or product
b. Conversion efficiency of a substrate into product.
The lowest biomass yield in a culture of Escherichia coli will be in
a. An aerated batch culture containing an initial high concentration of glucose.
b. An aerated batch reactor containing an initial low concentration of glucose.
c. An aerated fed-batch reactor having a low glucose concentration.
d. An aerated continuous reactor having a low glucose concentration
a. An aerated batch culture containing an initial high concentration of glucose.
When two populations compete for a single growth limiting substrate in a continuous fermenter, which organism would not be washed out?
a. Organism maintaining the highest substrate concentration.
b. Organism maintaining the lowest substrate concentration.
c. Both (a) and (b)
d. Organism maintaining the moderate substrate concentration.
b. Organism maintaining the lowest substrate concentration.
The continuous cultures are not widely used in industry because
a. They are not suited for the production of secondary metabolites.
b. Contamination or mutation can have a disastrous effect on the operation.
c. The government will not approve the licensing of pharmaceuticals produced in continuous cultures.
d. All of the above.
d. All of the above.
The lowest yield of ATP is in
a. Fermentation
b. Aerobic respiration
c. anaerobic respiration
d. same in (a), (b), and (c)
a. Fermentation
Mixing in an anaerobic sludge blanket reactor is due to
a. Rapid change in water temperatures throughout the reactor.
b. Release of gases by the microbial populations.
c. Swimming of microbes.
d. None of the above
b. Release of gases by the microbial populations.
In batch culture, protogon is produced from peptone during the stationary phase with a yield of 0.4 protogon mg per g of peptone. If it is to be produced in a chemostat at a dilution rate of 0.5 h-1 from a medium containing 10 g/L of peptone, then the rate of protogon synthesis would be
a. 0 g/L-h
b. 0.5 g/L-h
c. 1 g/L-h
d. 2 g/L-h
a. 0 g/L-h
Formation of end product by Lactococcus lactis will become non-growth associated as lactic acid accumulates because
a. Cells will redirect ATP to anabolism.
b. Cells will redirect NAD+ to anabolism.
c. Cells will redirect ATP to facilitate the diffusion of lactic acid and H+ out of the cells.
d. Cells will redirect ATP to the active transport of lactic acid and H+ out of the cells.
d. 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”?
a. Aspergillus fumigatus
b. Saccharomyces cerevisiae
c. Escherichia coli
d. Aspergillus niger
c. Escherichia coli
Immobilized cell reactors for wastewater treatment have the advantage of having/being
a. Higher cell concentration
b. More stable and prevent washout
c. Higher dilution rate before the cells washout
d. All of the above
d. All of the above
Which of the statement is true for continuous reactor at steady state?
a. The rates of biomass, substrate, and product concentrations are zero.
b. Biomass, substrate, and product concentrations are zero.
c. Biomass, substrate, and product concentrations do not change with time.
d. Biomass, substrate, and product concentrations change with time.
c. 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
a. Turbidostat
b. Chemostat
c. Level stat
d. pH
b. Chemostat
for organisms growing in a chemostat, the specific growth rate
a. Cannot be determined.
b. Can be determined from the dilution rate.
c. Equals to the maximum specific growth rate of the culture.
d. None of the above
b. 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
a. Decrease with time.
b. Increase with time.
c. Be constant.
d. Change randomly with time
c. 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?
a. Citric acid is toxic to the cells.
b. Alkanes cause foaming.
c. Fast addition of alkanes will inhibit the cells and reduce oxygen transfer rates.
d. Fast addition of alkanes will cause the cells to grow too quickly.
c. Fast addition of alkanes will inhibit the cells and reduce oxygen transfer rates.
A continuous reactor has a dilution rate of 0.5/h. Its residence time would be
a. ln(2)/0.5
b. ln(2) x 0.5
c. 0.5 h
d. 2 h
d. 2 h
Which of the following is used to calculate mass of substrate in the reactor?
a. Flow rate x substrate concentration in the reactor
b. Volume of reactor x substrate concentration in reactor
c. Flow rate x mass of reactor
d. Volume of reactor x flow rate
b. Volume of reactor x substrate concentration in reactor
If biomass yields are constant, then the biomass productivity of a culture growth in continuous reactor will
a. Always decrease with dilution rate
b. Increase with dilution rate until washout
c. Remain constant irrespective of the dilution rate
d. Decrease with dilution rate until washout
b. Increase with dilution rate until washout
Low dissolved oxygen concentrations leads to
a. Low biomass yields
b. High biomass yields
c. No effect on biomass yields
d. Decrease with dilution rate until washout
a. Low biomass yields
In a continuous reactor, the medium contains 40 g/L of maltose and the medium flow rate is 10 liters per hour and the effluent contains 20 g/L of lactate. What is the productivity of lactate production from this reactor?
a. 50 g-maltose/L
b. 50 g-lactate/L
c. 200 g-maltose/L
d. 200 g-lactate/L
d. 200 g-lactate/L
A fed-batch reactor containing 1 g/L of substrate in 2 liter of medium. It is fed with 1 g/L of substrate at the rate of 1 liter per hour. After 10 hours, the concentration of substrate in the reactor was 0.5 g/L. the mass of substrate that was used by the culture in the reactor was
a. 2g
b. 6g
c. 8g
d. 12g
b. 6g
Toxins accumulated in a reactor can lead to low biomass yields probably due to which of the following?
a. NAD+ is diverted away from homeostasis to anabolism.
b. ATP is diverted away from homeostasis to anabolism.
c. NAD+ is diverted away from anabolism to homeostasis.
d. ATP is diverted away from anabolism to homeostasis.
d. 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
a. Decrease abruptly.
b. Increase.
c. Increase drastically.
d. Be zero.
a. Decrease abruptly.
Fluidized bed bioreactors provide higher mass transfer rates than packed bed bioreactors because
a. Mixing is higher in fluidized bed bioreactors.
b. Particles move with the fluid in a fluidized bed bioreactor.
c. Immobilized particles are smaller in the fluidized bed bioreactors.
d. All of the above.
b. Particles move with the fluid in a fluidized bed bioreactor.
In fed-batch fermentation, mass of substrate utilized is calculated using the relationship
a. Initial mass of substrate in the reactor + final mass of substrate in the reactor + flow rate x [substrate in the feed].
b. Initial mass of substrate in the reactor – final mass of substrate in the reactor + flow rate x [substrate in the feed]
c. Initial mass of substrate in the reactor + final mass of substrate in the reactor - flow rate x [substrate in the feed]
d. Initial mass of substrate in the reactor + final mass of substrate in the reactor - flow rate
b. Initial mass of substrate in the reactor – final mass of substrate in the reactor + flow rate x [substrate in the feed]
A chemostat has a liquid volume of 2 liters and is being fed at a rate of 4 liters per hour. Dilution rate for this reactor will be
a. 2 liters
b. 2 liters per hour
c. 2 h^-1
d. 4 liters per hour
c. 2 h^-1
Mixing per unit volume is observed to be poorest in
a. Continuous packed bed reactor
b. Continuous fluidized bed bioreactor
c. Continuous airlift bioreactor
d. None of the above
a. 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=0.1𝑔.𝑙^−1, if the concentration of glucose in the feed is 10 g/L and the dilution rate is set to 0.4/h, then the steady state concentration of glucose in the effluent will be
a. 0 g/L
b. 0.5 g/L
c. 1.0 g/L
d. 10 g/L
b. 0.5 g/L
A continuous reactor at steady state contains 0.04 g/L of biomass and 0.02 g/L of phenol. The feed contained 0.1 g/L of phenol. The biomass yield would be
a. 0.4 g/g
b. 0.5 g/g
c. 1.0 g/g
d. 5.0 g/g
b. 0.5 g/g
A culture system with constant environmental conditions maintained through continual provision of nutrient and removal of wastes is called ___ culture system.
a. Continuous
b. Batch
c. Fed-batch
d. Semi continuous
a. Continuous
The main reason for production of antibiotics in fed batch reactors is
a. The presence of precursors is often toxic to the cells.
b. Higher yields when cells enter the stationary phase.
c. Higher yields when cell growth slows.
d. All of the above.
d. All of the above.
Fed batch reactors is used to produce vinegar because
a. It can maintain low ethanol concentrations.
b. It can maintain low acetic acid concentrations.
c. Acetic acid bacteria tend to ferment at high ethanol concentrations.
d. All of the above
a. It can maintain low ethanol concentrations.
When a culture of fermenting yeast becomes metabolically uncoupled, ethanol
a. Becomes a secondary metabolite.
b. Production becomes growth associated.
c. Production becomes non-growth associated.
d. Becomes a growth nutrient
c. Production becomes non-growth associated
Mixing profiles closest to plug flow are observed in
a. Continuous packed bed reactor,
b. Stirred tank reactor with biomass recycles.
c. Continuous fluidized bed bioreactor.
d. All of these.
a. Continuous packed bed reactor,
On a glucose medium, the growth of an organism is characterized by the following Monod model and stoichiometric parameters 𝜇𝑚=0.3 ℎ^−1,𝐾𝑆=0.05 𝑔.𝑙^−1 and 𝑌xs =0.3 𝑔.𝑔^−1. When this organism is grown in a 2-liter continuous on a medium containing 10 g/L of glucose added at 1 L/h, the steady state concentration of biomass in the reactor will be
a. 0 g/L
b. 0.4 g/L
c. 0.5 g/L
d. 10 g/L
a. 0 g/L
Unsteady state mass balance for dynamic model of continuous stirred tank reactor (CSTR) is
a. Time rate of total amount in reactor = rate of addition to reactor – rate of removal + rate of formation
b. Total amount in reactor = rate of addition to reactor – rate of removal + rate of formation
c. Rate of total amount in reactor = rate of addition to reactor – rate of removal + rate of formation
d. None of the above
a. Time rate of total amount in reactor = rate of addition to reactor – rate of removal + rate of formation
A fed-batch reactor initially contains 2 liter of medium. If it was fed at 1 liter per hour, then after 10 hours, the volume of the reactor will be
a. 1 liter
b. 2 liter
c. 3 liter
d. 13 liter
b. 2 liter
A Bacillus sp. Produces an antibiotic only during the stationary phase when grown in a batch culture. If grown in a 5 liter continuous culture, the steady state productivity of the antibiotic
a. Will increase until the culture washes out.
b. Will decrease after washout.
c. Will be zero.
d. Will be infinite.
c. Will be zero.
In a fluidized bed reactor, the function of the disengagement zone is to
a. Reduce loss of particles from the reactor.
b. Reduce the velocity of the particles near the surface of the reactor.
c. Reduce foaming problems.
d. All of the above.
d. 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?
a. Batch fermenter with a high initial glucose concentration.
b. Continuous fermenter with a low initial glucose concentration.
c. Fed batch fermenter.
d. All of the above.
c. Fed batch fermenter
In a glucose-yeast extract medium, Lactococcus lactis has a maximum specific growth rate (μm) of 1.23/h. what would be the specific growth rate of this organism at steady state in a 4-liter reactor being fed at 2 liters per hour?
a. 0.5/h
b. 1.2/h
c. 2.4/h
d. 4/h
a. 0.5/h
Which of the following is not correct with regards to continuous cultures?
a. The major industrial scale application of continuous cultures is in wastewater treatment.
b. Mutation and contamination present a major risk to the operation of continuous cultures for the production of metabolites.
c. The continuous cultures are very useful for the production of pharmaceuticals.
d. Continuous cultures have an advantage that they do not need to shut down as regularly as batch culture reactor.
c. The continuous cultures are very useful for the production of pharmaceuticals.
In a plug flow reactor, the highest concentration of substrates is exposed to the cells that
a. Are near the effluent or exit of the reactor.
b. Are in the mid way along the reactor.
c. Are located near entrance of feed.
d. Are near the wall of the reactor.
c. Are located near entrance of feed.
In an activated sludge process, the biomass is recycled to
a. Increase the efficiency of the process.
b. Reduce sludge volumes.
c. Increase the concentration of cells.
d. All of the above.
d. All of the above.
A strain of Escherichia coli has a maximum specific growth rate of 0.8/h on a glucose based medium. If this organism is being grown in a chemostat with a dilution rate of 1.2/h, then at steady state the concentration of E. coli in the same medium will
a. Increase
b. Be zero
c. Change randomly
d. Decrease
b. Be zero
fed-batch reactor containing 2 liters of medium and 0.1 g/L of biomass is fed with a medium containing 1 g/L of substrate at 1 liter per hour. If after 10 hours, the concentration of biomass in the reactor was 0.2 g/L, then the biomass produced during the 10-hour period is
a. 1.5 g
b. 2.2 g
c. 3.0 g
d. 6.0 g
b. 2.2 g
Which of the following organisms will continue their metabolism at high substrate concentrations?
a. Pseudomonas aeruginosa
b. Saccharomyces cerevisiae
c. Bacillus subtilis
d. Escherichia coli
a. Pseudomonas aeruginosa
Yeast is typically produced in fed batch reactors because
a. Yeast cells produce ethanol at low glucose concentrations.
b. Yeast cells ferment at low glucose concentrations.
c. Year cells respire at low glucose concentrations.
d. All of the above.
c. Year cells respire at low glucose concentrations.
Two continuous bioreactors containing the same organisms, fed with the same feed at the same dilution rate were compared. Reactor 1 started with an initial concentration of glucose of 10 g/L, while reactor 2 contained 0.1 g/L of glucose at the start of the process then at steady state
a. The concentration of glucose in reactor 1 would be greater than that in reactor 2.
b. The concentration of glucose in reactor 1 would be equal to reactor 2.
c. The concentration of glucose in reactor 1 would always be zero.
d. The concentration of glucose in reactor 1 would be less than that in reactor 2.
b. The concentration of glucose in reactor 1 would be equal to reactor 2.
In a fluidized bed reactor mixing is achieved by
a. Gravity flow of fluid.
b. Upward movement of the incoming feed.
c. Diffusion.
d. Both (a) and (b)
d. 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
a. Fed-batch reactor can be used to minimize starch concentrations and prevent a. niger from fermenting
b. Fed-batch reactor can be used to minimize starch concentrations and thus reduce the viscosity of the medium.
c. Continuous reactor can be used to minimize starch concentrations and their inhibitory effects.
d. All of the above
b. 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
a. Aerobic respiration
b. Anaerobic respiration
c. Fermentation
d. Decomposition
c. Fermentation
In fed batch bioreactor modelling, the rate of change in the bioreactor volume is assumed to be equal to
a. Flow rate
b. Initial volume
c. Volume of solids in the reactor
d. None of these
a. Flow rate
Monoclonal antibodies are typically produced in fed batch reactors because
a. Hybridoma cells ferment at high maltose concentrations.
b. Hybridoma cells yield higher lactate at high glucose concentrations.
c. hybridoma cells respire at high glucose concentrations.
d. None of the above
b. Hybridoma cells yield higher lactate at high glucose concentrations.
In plug flow tubular reactor, the axial velocity profile on cross-section will be
a. Constant
b. Varying with time
c. Non-linear
d. Power function of time
a. 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
a. Organic acids uncouple catabolism from anabolism.
b. Biomass yields increase as the fermentation proceeds.
c. Organic acids are secondary metabolites.
d. High concentrations or organic acid promote the growth of the microbial population.
a. Organic acids uncouple catabolism from anabolism.
The concentration of biomass in a continuous stirred tank reactor is 20 g dry weight per liter. What would be the concentration of biomass in the effluent?
a. Greater than 20 g dry weight per liter.
b. Approximately 20 g dry weight per liter.
c. Lesser than 20 g dry weight per liter.
d. More than 30 g dry weight per liter.
b. Approximately 20 g dry weight per liter.
The ideal tubular-flow fermenter without radial variations is called
a. Plug flow fermenter
b. Continuous stirred tank fermenter (CSTF)
c. Column fermenter
d. Any intensity of dilution rate near the wash out points.
a. Plug flow fermenter
Pseudo-steady state in a continuous reactor refers to a reactor in which
a. Pseudomonads are being cultured
b. Concentration oscillate around a mean value
c. Concentration increase with time
d. Concentration decrease with time
b. Concentration oscillate around a mean value
The toxicity of organic acids to cells
a. Enhances as the pH falls
b. Reduces as the pH falls
c. Is not affect by pH
d. Is highest at pH 7.0
a. Enhances as the pH falls
Which of the following is best described as secondary metabolite?
a. Acetic acid produced from the oxidation of methanol.
b. Ethanol from the fermentation of glucose.
c. Penicillin
d. Citric acid from the partial oxidation of glucose.
c. Penicillin
A microorganism which is subjected to the Crabtree effect is most likely to
a. Ferment in the presence of low concentrations of sugar and dissolved oxygen.
b. Respire in the presence of low sugar and high dissolved oxygen concentrations.
c. Ferment in the presence of high concentrations of sugar and dissolved oxygen.
d. Respire in the presence of high sugar and low dissolved oxygen concentrations
c. Ferment in the presence of high concentrations of sugar and dissolved oxygen.
When the product formation is approximately equal to the rate of cell growth, the pattern of produce formation is termed as
a. Uncoupled
b. Growth associated
c. Non-growth associated
d. Metabolically associated
b. Growth associated
Which of the following would be correct concerning the concentration of biomass (X), growth limiting substrate (S), and produce (P) in a chemostat when the cells have been washed out?
a. X, S, and P will be zero.
b. X, S, and P can not be predicted for the above condition.
c. X, and P will be zero while S is equal to the substrate concentration in feed.
d. None of the above
c. X, and P will be zero while S is equal to the substrate concentration in feed.
Pseudomonas aeruginosa has a maximum specific growth rate of 0.8/h in a medium with glucose as a growth limiting substrate. To prevent washout, the dilution rate must be set to
a. Greater than 0.8/h
b. Less than 0.8/h
c. Equal to 0.8/h
d. 1.6/h
b. Less than 0.8/h
Saccharomyces cerevisiae when grown in high glucose concentration medium, the cells activity depends on which of the following?
a. High concentration of dissolved oxygen
b. Low concentration of dissolved oxygen
c. No effect of dissolved oxygen
d. High concentration of dissolved oxygen and sodium salts.
c. No effect of dissolved oxygen
Continuous culture has an advantage over to a batch cultures as
a. Continuous reactors do not need to be shut down as regularly as batch reactors.
b. 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.
c. Cells can be maintained at a constant physiological state simply by setting the dilution rate.
d. All of the above.
d. All of the above.
In a batch-fed mode, substrate will be added
a. Only at the beginning of the fermentation process.
b. Periodically throughout the fermentation process.
c. Only at the end of the fermentation process.
d. Substrate is never added.
c. Only at the end of the fermentation process
When Escherichia coli grown in a well aerated medium, which of the following will occur?
a. Fructose di-phosphate accumulation inside the cells leading to cell respiration.
b. Fructose di-phosphate accumulation inside the cells leading to fermentation.
c. Fructose di-phosphate will accumulate regardless of the medium composition.
d. Fructose di-phosphate will accumulate inside the cells leading to anaerobic respiration
b. Fructose di-phosphate accumulation inside the cells leading to fermentation.
Swirling and vortex formation can be prevented by
a. Using baffles
b. Using diffusion ring with turbines
c. Both (a) and (b)
d. None of these
c. Both (a) and (b)
Power number is expressed as
a. 𝑃o/𝑁^2𝐷𝑖^3𝜌
b. 𝑃o/𝑁^3𝐷𝑖^5𝜌
c. 𝑃o/𝑁^3𝐷𝑖^3𝜌
d. 𝑃o/𝑁^2𝐷𝑖^2𝜌
*equation
b. 𝑃o/𝑁^3𝐷𝑖^5𝜌
The power consumption in a stirring vessel can be assessed by using a
a. Dynamometer
b. Strain gauge attached to agitator shaft
c. Watt meter attached to agitator motor
d. All of these
d. All of these
Surface renewal theory predicts that the mass transfer coefficient is
a. Directly proportional to the square root of the molecular diffusivity.
b. Inversely proportional to the square root of the molecular diffusivity.
c. Directly proportional to the cube root of the molecular diffusivity.
d. Indirectly proportional to the cube root of the molecular diffusivity.
a. Directly proportional to the square root of the molecular diffusivity.
The oxygen transfer rate in a bioreactor will increase if
a. Oil is added.
b. Antifoam is added.
c. Detergent-like molecules are added.
d. Increase in the reactor temperature.
c. Detergent-like molecules are added.
Which of the following impellers are used for wide range of viscosities?
a. Paddles
b. Turbines
c. Propellers
d. None of these
b. Turbines
Which of the following type(s) of stirrer can be used for microbiological processes?
a. Mig
b. Intermig
c. Turbine
d. All of these
d. All of these
The range of width for the baffle in the fermenter is ___ times of vessel diameter.
a. 1/10 to 1/12
b. 1/8 to 1/10
c. 1/5 to 1/8
d. None of these
a. 1/10 to 1/12
The average concentration of oxygen in the boundary layers surrounding the bubbles (C0*) in a reactor is normally determined by
a. Ultra-small dissolved oxygen probes.
b. Laser based photographic systems.
c. Measuring the steady state concentration of oxygen in the bulk liquid prior to inoculation of the reactor.
d. Measuring the steady state concentration of oxygen in the bulk liquid after inoculation of the reactor.
c. 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?
a. The collision between the cells, impeller, and air bubbles will lead to cell damage.
b. Poor mixing despite the use of high stirrer speeds.
c. Mixing will not be in the turbulent region.
d. All of the above.
d. 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
a. Gas-liquid interface
b. Bubble boundary layer
c. Bulk liquid
d. Gas phase
b. 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 correlation KL, mass transfer coefficient and DAB, diffusivity can be expressed as
a. 𝐾𝐿=2(DAB/π te)^0.25
b. 𝐾𝐿=2(DAB/π te)^0.50
c. 𝐾𝐿=2(DAB/π te)^0.75
d. 𝐾𝐿=2(DAB/π te)
*equation
b. 𝐾𝐿=2(DAB/π te)^0.50
The oxygen uptake requirements of a microbial population is characterized by the following parameters: μm = 0.2 h-1, K0 = 0.2 mg O2 L-1, Y0 = 0.5 mg dry weight/mg O2 and C0,crit = 0.8 mg L-1. The required concentration of cells is 1000 mg L-1 and the saturation oxygen concentration of the medium is 5.8 mg L-1. The required KLa must be greater than
a. 64 h-1
b. 32 h-1
c. 16 h-1
d. 8 h-1
a. 64 h-1
Which have the maximum resistance while transferring carbon dioxide from the bulk liquid to an air bubble?
a. Moving through the gas liquid interface.
b. Moving through the bubble boundary layer.
c. Moving across the cell membrane.
d. Moving through the bulk liquid
b. 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
a. Impeller diameter
b. Square root of the impeller diameter
c. Square of the impeller diameter
d. Cube of the impeller diameter
c. Square of the impeller diameter
What is the ratio of depth of liquid in vessel to the diameter of tank (H:Dt)?
a. 1:1
b. 2:1
c. 4:1
d. None of these
a. 1:1
Radial flow impellers
a. Provide high shear conditions for breaking up bubbles.
b. Direct flow towards the walls of the reactor.
c. Both (a) and (b)
d. Provide low shear conditions and are suited for use in shear sensitive processes
c. Both (a) and (b)
Transient flow range of mixing speed is obtained for
a. Rei < 10
b. 10 < Rei < 104
c. Rei > 104
d. None of these
b. 10 < Rei < 104
A typical ceiling fan would be best described as a(n)
a. Radial flow impeller
b. Axial flow impeller
c. Intermig impeller
d. Rushton turbine
b. Axial flow impeller
What is the ratio of diameter of impeller to the diameter of tank (Da:Dt)?
a. 1:3
b. 2:1
c. 4:1
d. 1:5
a. 1:3
The reason of using a flat disk in a Turbine is
a. To create high shear conditions
b. To break up bubbles more efficiently than the impeller blades
c. To ensure that the bulk of the energy consumption occurs at the blades.
d. All of the above
c. 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?
a. Two-film theory
b. Penetration theory
c. Surface renewal theory
d. Calderbank and Moo-Young theory
d. 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?
a. Addition of antifoams
b. Increase in temperature
c. Increase in stirrer speed
d. Both (a) and (b)
c. 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
a. 0.793 atm-L/mmol
b. 0.207 atm-L/mmol
c. 1.26 atm-L/mmol
d. 8.74 atm-L/mmol
a. 0.793 atm-L/mmol
Gas hold up, characterizing the hydrodynamics in a fermenter, mainly depends on the
a. Superficial gas velocity
b. Power consumption
c. Both (a) and (b)
d. Gas concentration
c. Both (a) and (b)
Turbine impeller consists of flat impeller blades with
a. A vertical pitch welded directly to the shaft.
b. An angled pitch welded directly to the shaft.
c. A vertical pitch welded to a horizontal disk.
d. An angled pitch welded to a horizontal disk
c. A vertical pitch welded to a horizontal disk.
An aerated bioreactor will increase oxygen transfer rates with the addition of detergents because it
a. Enhances bubble coalescence.
b. Causes bubbles to expand.
c. Discourages bubble coalescence.
d. Increases the surface tension of the liquid.
c. Discourages bubble coalescence.
Vortexing in stirred tank reactors can be prevented by
a. Installing baffles in the reactor.
b. Shifting the impeller to an off-center position.
c. Both (a) and (b)
d. Using axial flow impellers.
c. Both (a) and (b)
Which of the following would be best described as an axial flow impeller?
a. An impeller with blades pitched at 45° to the vertical.
b. An impeller which directs liquid flow towards the base of the reactor.
c. Both (a) and (b)
d. An impeller which blades pitched at 75° to the vertical.
c. Both (a) and (b)
Henry’s law relates
a. The partial pressure of oxygen and the saturation concentration of oxygen in the liquid.
b. The oxygen transfer rate and the bubble size.
c. The oxygen transfer rate and the temperature.
d. The oxygen transfer rate to the partial pressure of oxygen in the liquid.
a. The partial pressure of oxygen and the saturation concentration of oxygen in the liquid.
Power number is ratio of
a. Imposed forced to inertial force.
b. Buoyant force to inertial force.
c. Gravitation force to inertial force.
d. Imposed force to gravitation force.
a. Imposed forced to inertial force.
The volume of liquid (VL) in a cylindrical reactor can be calculated from the liquid height (HL) and tank diameter (Dt) using the following equation.
a. 𝑉𝐿=4/3×𝜋×𝐻𝐿×𝐷𝑡^3/8
b. 𝑉𝐿=𝐻𝐿×𝜋×𝐷𝑡^2/4
c. 𝑉𝐿=𝐻𝐿×𝜋×𝐷𝑡^2
d. 𝑉𝐿=4×𝜋×𝐷𝑡^2
*equation
b. 𝑉𝐿=𝐻𝐿×𝜋×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)
a. 𝐻=(𝑍𝑓-𝑍𝑙)/𝑍𝑓
b. 𝐻=𝑍𝑓/𝑍𝑙
c. 𝐻=𝑍𝑓/𝑍𝑓𝑍𝑙
d. 𝐻=(𝑍𝑓+𝑍𝑙)/𝑍𝑓
*equation
a. 𝐻=(𝑍𝑓-𝑍𝑙)/𝑍𝑓
Which of the following(s) is/are non-mechanically agitated reactors?
a. Stirrer tank reactor
b. Bubble column
c. Air lift reactor
d. Both (b) and (c)
d. Both (b) and (c)
Which of the following best explains the reasons for using axial flow impellers in crystallization and precipitation reactions?
a. Crystal and precipitates are not too small, so as to ensure easy separation of the solids from the mother liquor.
b. Crystals and precipitates are thoroughly broken down, so as to ensure easy separation of the solids from the mother liquor.
c. Both (a) and (b)
d. Axial flow impellers provide low shear, energy efficient mixing conditions
a. 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. A shake flask.
b. A standing test tube.
c. A non-sparged stirred tank reactor agitated at 400 rpm.
d. A sparge stirred tank reactor agitated at 400 rpm.
d. A sparge stirred tank reactor agitated at 400 rpm.
A flooded impeller will lead to poor oxygen transfer rates because
a. Bubbles tend to coalesce under the impeller.
b. Bubbles tend to break down too rapidly under high shear conditions.
c. Bubbles tend to move too quickly through the bulk liquid.
d. The cells clog up the surface of the bubble.
a. Bubbles tend to coalesce under the impeller.
Power consumption by agitation is
a. A function of physical properties.
b. A function of operating conditions.
c. A function of vessel and impeller geometry.
d. All of the above
d. All of the above
Which of the following impellers will provide radial flow?
a. Paddles
b. Flat blade turbines
c. Disk flat blade turbines
d. All of the above
d. 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?
a. If the stirrer speed is increased, the rate will be faster.
b. Baffles in the tank will increase the rate of cooling.
c. Faster cooling rates at a slower rate of pumping.
d. Faster cooling rates at a faster rate of pumping.
c. 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
a. Increasing the partial pressure of oxygen at the base of the reactor.
b. Decreasing the saturation concentration of oxygen in the reactor.
c. Decreasing the gas hold up
d. All of the above.
a. Increasing the partial pressure of oxygen at the base of the reactor.
Which of the following is correct for the off-center impellers?
a. Off-center impellers can be used with any size reactor.
b. Off-center impellers should only be used with reactors with volumes less than 10 m^3.
c. The impeller should never be placed in an off-center position.
d. Off-center impellers can be used when volume is greater than 10 m^3
b. Off-center impellers should only be used with reactors with volumes less than 10 m^3.
The power required by an impeller in a gas sparged system compared to the power required by the impeller operating at same speed in a gas free liquid is usually
a. Lesser
b. Higher
c. Same
d. May be lesser or higher depending upon the geometry
a. Lesser
Which of the following stirrer requires least amount of energy for same yield?
a. Mig
b. Intermig
c. Turbine
d. Disc
b. Intermig
A reactor has a total volume of 50,000 liters. If it has a headspace volume of 10,000 liters, then volume of liquid in the reactor will be
a. 10,000 L
b. 20,000 L
c. 30,000 L
d. 40,000 L
d. 40,000 L
Pure oxygen, if used instead of air will increase oxygen transfer rates because
a. The saturation concentration of oxygen is higher.
b. The bubble size is smaller.
c. The oxygen transfer coefficient is larger.
d. The partial pressure of oxygen in the gas phase is lower.
a. The saturation concentration of oxygen is higher.
For aerated mixing vessels in an aqueous solution, the mass transfer coefficient (kL) corelating power consumption (Pm_ and fermenter volume (V) can be expressed as
a. 𝑘𝐿∝(Pm/V)^0.33
b. 𝑘𝐿∝(Pm/V)^0.66
c. 𝑘𝐿∝(Pm/V)^0.50
d. 𝑘𝐿∝(Pm/V)
*equation
a. 𝑘𝐿∝(Pm/V)^0.33
Higher temperatures affect oxygen transfer rates by
a. Increasing KLa but lowering CO*
b. Lowering KLa but increasing CO*
c. Increasing KLa and increasing CO
d. Lowering KLa and lowering CO
a. Increasing KLa but lowering CO*
The Intermig impeller is
a. An axial flow impeller which can be used for the culture of aerobic organisms.
b. Directed upwards rather than towards the base of the reactor.
c. A fork shaped extensions to the impeller facilitate bubble break up.
d. All of the above
d. All of the above
Main reason for using baffles in stirred tank reactors are
a. Baffles permit turbulence conditions to arise at low stirrer speed.
b. Baffles will allow axial mixing to occur even with radial flow impellers.
c. Both (a) and (b)
d. Baffles prevent turbulent conditions in stirred tank reactors.
c. Both (a) and (b)
Which of the following is not classified as an axial flow impeller?
a. A propeller
b. A marine impeller
c. A Rushton turbine
d. A hydrofoil impeller
c. A Rushton turbine
Power number (NP) is also known as
a. Froude’s number
b. Bond’s number
c. Newton’s number
d. Rayleigh’s number
c. Newton’s number
Flooding is a condition/phenomenon which occur in a bioreactor when
a. The air escapes without being distributed by the agitator.
b. The fermenter medium spills out the reactor due to foaming.
c. The volume of foam is more than the volume of broth.
d. None of these
a. The air escapes without being distributed by the agitator.
A cylindrical reactor has a liquid volume of 100,000 liters. It has an aspect ratio, the ratio of the channel height to width of 1:1. The height of the liquid in the reactor will be approximately:
a. 1.0 m
b. 3.0 m
c. 5.0 m
d. 7.0 m
c. 5.0 m
Detergent like substances produced by microorganisms during a fermentation will lead to
a. Decrease the surface tension of the liquid.
b. Accumulate at the gas liquid interface.
c. Decrease the rate of bubble coalescence.
d. All of the above.
d. All of the above.
A cylindrical reactor fitted with Rushton Turbine has a liquid volume of 100,000 liters. It has an aspect ratio (the ratio of the channel height to the width) of 2:1. The diameter of the impeller should be approximately:
a. 1.3 m
b. 3.3 m
c. 5.3 m
d. 7.3 m
a. 1.3 m
In the bubble boundary layer, oxygen concentration can be determined by measuring
a. The steady state oxygen concentration in a mixed aerated reactor before inoculation.
b. The steady state oxygen concentration in a mixed aerated reactor after inoculation.
c. The steady state oxygen concentration in the boundary layer using a micro-probe.
d. Volume of oxygen supplied
a. The steady state oxygen concentration in a mixed aerated reactor before inoculation.
Impeller damage can be minimized by
a. Using specially designed axial flow impellers.
b. Using radial flow impellers.
c. Using Intermig impellers.
d. All of the above.
a. 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?
a. Liquid volume in the flask is reduced.
b. Stirrer speed is increased.
c. Baffled flasks are used.
d. All of the above
d. All of the above
What is/are the major difference(s) between disc and turbine type stirrer?
a. Blades in disc type are projected out beyond the edge of disc while blades are curved one in turbine type.
b. Turbine type requires 50% less air than disc type of the same yield and energy consumption.
c. Both (a) and (b)
d. Number of blades in the stirrer.
c. Both (a) and (b)
In the design of a paddle agitator, the ratio of paddle diameter to tank diameter is normally taken as
a. 0.1
b. 0.8
c. 0.25
d. 0.5
b. 0.8
The oxygen absorption rate can be determined by
a. Sodium sulfite oxidation method
b. Dynamic gassing out technique
c. Direct measurement
d. All of these
d. All of these
Industrial paddle agitators turn at the speed of
a. 20 and 150 rpm
b. 150 and 300 rpm
c. 400 and 800 rpm
d. 1150 rpm
a. 20 and 150 rpm
The dynamic technique is based on the
a. Oxygen material balance in an aerated batch fermenter during the growth of microorganisms.
b. Change of the oxygen concentration.
c. Oxidation of the sodium sulfite to sodium sulfate.
d. Oxygen material balance in a fermenter
a. 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
a. Increase the tendency of bubbles to coalesce.
b. Tend to accumulate in the gas liquid interface.
c. Reduce the surface tension of the liquid.
d. All of the above answers.
d. 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?
a. Microbial growth is oxygen limited since the oxygen concentration is lesser than the saturation concentration.
b. Microbial growth is not oxygen limited since the oxygen concentration is lesser than the saturation concentration.
c. Experimental error leads to the reduction.
d. No conclusion can be drawn.
d. No conclusion can be drawn.
If the stirrer speed is too slow, bubbles will accumulate and coalesces under the impeller. This phenomenon is known as a
a. Coalesced impeller
b. Flooded impeller
c. River impeller
d. Dry impeller
b. 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?
a. The growth rate is limited by the rate of mass transfer of the alkane into the fermentation medium.
b. The growth rate is limited by the intrinsic kinetic properties of the cells and not by mass transfer.
c. The growth rate is neither mass transfer nor kinetically limited.
d. No conclusion on the growth rate can be withdrawn.
d. 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; ⍴, density of fluid; and μ, viscosity of fluid).
a. 𝐷𝑖𝑉p/𝜇
b. 𝐷𝑖^2Np/𝜇
c. 𝐷𝑖^2𝑉p/𝜇
d. 𝐷𝑖Np/𝜇
*equation
b. 𝐷𝑖^2Np/𝜇
The advantage of axial flow impellers over radial flow impellers is that axial flow impellers
a. Provide better lift of solids.
b. Provide high shear conditions.
c. Provide low shear conditions
d. Are cheaper to build.
a. Provide better lift of solids.
Larger propellers turn at the speed of
a. 20 to 150 rpm
b. 150 to 300 rpm
c. 400 to 800 rpm
d. 1150 rpm
c. 400 to 800 rpm
A microbial population in a suspension culture will only be limited by oxygen availability if the dissolved oxygen
a. Concentration is less than the critical concentration.
b. Concentration is greater than the critical concentration.
c. Levels are greater than the saturation concentration of oxygen.
d. Levels are equal to saturation oxygen level.
a. 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)
a. 𝐾𝐿=𝐷𝐴B/𝑍𝑓
b. 𝐾𝐿=𝐷𝐴B
c. 𝐾𝐿=𝑍𝑓/𝐷𝐴B
d. 𝐾𝐿=𝐷𝐴B𝑍𝑓
a. 𝐾𝐿=𝐷𝐴B/𝑍𝑓
Froude number is avoided in calculation of power requirements for low viscosity liquid mixing systems when
a. Baffled systems are used.
b. Reynolds number is less than 300.
c. Both (a) and (b)
d. None of these
c. Both (a) and (b)
A fermentation system has a KLa of 3 s-1 and a CO* of 5 ppm of O2. If the bulk liquid is completely depleted of oxygen, then the oxygen transfer rate will be equal to
a. Zero
b. 15 mg L-1 s-1
c. 10 mg L-1 s-1
d. 5 mg L-1 s-1
b. 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
a. 100%
b. 75%
c. 50%
d. 25%
d. 25%
A fermentation system has a KLa of 3 s-1 and a CO* of 5 ppm of O2. If the bulk liquid is saturated with oxygen, then the oxygen transfer rate will be equal to
a. Zero
b. 3 mg L-1 s-1
c. 5 mg L-1 s-1
d. 15 mg L-1 s-
a. Zero
Which of the following would be best described as radial flow impeller?
a. An impeller with blades pitched at 45° to the vertical.
b. A Rushton turbine
c. Both (a) and (b)
d. An impeller which directs liquid flow towards the base of the reactor.
b. A Rushton turbine
Small propellers turn at the speed of either
a. 20 or 150 rpm
b. 150 or 300 rpm
c. 400 or 800 rpm
d. 1150 rpm or 1750 rpm
d. 1150 rpm or 1750 rpm
In aerobic microorganisms cultures radial flow impellers are used because
a. They provide energy efficient high turbulent mixing conditions.
b. They provide low shear mixing conditions.
c. They provide high shear mixing conditions.
d. They ensure that bubble size is maximized leading to high oxygen transfer rates.
c. They provide high shear mixing conditions.
The effect of increasing the stirrer speed in an unbaffled stirred tank reactor is that
a. A small increase in stirrer speed will cause the liquid to enter the turbulent flow regime.
b. As the stirrer speed increases, the liquid will continue to circulate and then become turbulent.
c. As the stirrer speed increases, the liquid will continue to circulate. Eventually a vortex will form.
d. A vortex will form at low stirrer speeds. As the stirrer speed increases the liquid will start to circulate.
c. 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
a. Rei < 10
b. 10 < Rei < 104
c. Rei > 104
d. None of these
c. Rei > 104
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).
a. 𝑁𝑃=𝐾(𝑅𝑒𝑖)^−1
b. 𝑁𝑃=𝑁^2𝐷𝑖(𝑅𝑒𝑖)^−1
c. 𝑁𝑃=𝐾(𝑅𝑒𝑖)
d. 𝑁𝑃=𝐾N𝐷𝑖(𝑅𝑒𝑖)^−2
*equation
a. 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).
a. 𝑁𝑃=𝐾(𝑅𝑒𝑖)^−1
b. 𝑁𝑃=𝑁^2𝐷𝑖(𝑅𝑒𝑖)^−1
c. 𝑁𝑃=𝐾
d. Can’t be correlated.
*equation
c. 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
a. 23 kg h^-1
b. Less than 23 kg h^-1
c. Greater than 23 kg h^-1
d. 2.3 kg h^-1
a. 23 kg h^-1
Axial flow impellers
a. Provide high shear conditions for breaking up bubbles.
b. Provide low shear conditions and are suited for use in shear sensitive processes.
c. Provide direct flow towards the walls of the reactor.
d. None of the above
b. Provide low shear conditions and are suited for use in shear sensitive processes.
Bioreactors, where vortex is formed, another dimensionless number, ___ is useful.
a. Stanton
b. Rayleigh
c. Bond
d. Froude
d. Froude
Oxygen transfer rate is increased with an increase in the stirrer speed in aerated bioreactor because
a. It decreases the bubble size.
b. It decreases the size of the boundary layer surrounding a bubble.
c. It increases the rate of movement of oxygen molecules through the bulk liquid.
d. All of the above.
d. 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
a. The reaction was mass transfer limited at 300 rpm.
b. The reaction was mass transfer limited at 500 rpm.
c. The reaction did not involve any mass transfer step.
d. The movement of molecules in the reactor at 300 rpm occurred due to diffusion alone.
a. The reaction was mass transfer limited at 300 rpm.
An increase in the heat transfer in the stirred tank reactor will be observed at
a. Higher cooling water temperature.
b. Higher stirrer speed.
c. The removal of baffles from the reactor.
d. Slower stirrer speed.
b. 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).
a. 𝐻=𝑉s/(𝑉s−𝑉𝑡)
b. 𝐻=𝑉s/(𝑉s+𝑉𝑡)
c. 𝐻=𝑉s/(𝑉s𝑉𝑡)
d. 𝐻=(𝑉s+𝑉𝑡)/𝑉s
b. 𝐻=𝑉s/(𝑉s+𝑉𝑡)
What is the effect of the concentration of dissolved salts and sugars on the oxygen transfer rate?
a. The saturation concentration of oxygen in the medium decreases with the concentration of dissolved salts and sugars, leading to a lower oxygen transfer rate.
b. The KLa of the medium decreases with the concentration of dissolved salts and sugars, leading to a lower oxygen transfer rate.
c. The KLa of the medium increases with the concentration of dissolved salts and sugars, leading to a lower oxygen transfer rate.
d. None of the above.
a. 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?
a. Axial flow
b. Radial flow
c. Both (a) and (b)
d. None of these
a. Axial flow
In a tall reactor, oxygen transfer rates will be
a. Highest at the surface of the reactor.
b. Highest at the base of the reactor.
c. Highest in the middle of the reactor.
d. The same throughout the reactor.
b. Highest at the base of the reactor.
Which of the following impeller is used in situations where strong vertical currents are desirable for heavily suspending particles?
a. Propeller
b. Paddle
c. Turbine
d. None of these
a. Propeller
Laminar flow range of mixing speed is obtained for
a. Rei < 10
b. 10 < Rei < 10^4
c. Rei > 10^4
d. None of these
a. Rei < 10
Which of the following number is calculated from the diameter and peripheral speed of the impeller?
a. Reynolds number
b. Froude number
c. Power number
d. None of these
a. Reynolds number
A higher liquid height will lead to a higher gas hold up by which the oxygen transfer rate will be
a. Higher throughout the reactor.
b. Lower throughout the reactor.
c. Higher at the base of the reactor.
d. Lower at the base of the reactor.
c. Higher at the base of the reactor.
The main function of the dimples provided in the cooling jacket is to
a. Increase the level of turbulence of the cooling water in the jacket.
b. Increase the residence time of the cooling water in the jacket.
c. Increase the cooling water-jacket wall boundary layer size.
d. All of the above.
a. 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
a. Lesser than the power required by an impeller in operating at same speed in a gas free system.
b. More than the power required by an impeller in operating at same speed in a gas free system.
c. Same as the power required by an impeller in operating at same speed in a gas free system.
d. None of the above
a. 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. A bubble with a diameter of 1 mm.
b. A bubble with a diameter of 5 mm.
c. A bubble with a diameter of 15 mm.
d. A bubble with a diameter of 50 mm.
a. A bubble with a diameter of 1 mm.
Which device is commonly used for measuring the rate of rotation (rpm) of the stirrer shaft?
a. Anemometer
b. Manometer
c. Tachometer
d. Barometer
c. Tachometer
The sterilization method depends
a. Nature of additive
b. Volume and feed rate
c. Both (a) and (b)
d. None of these
c. Both (a) and (b)
The specific death rate of an organism can be expressed as
a. ln(2)/D
b. D/ln(2)
c. Dln(2)
d. 2.0.3/ln(2)
a. ln(2)/D
The interception efficiency can be expressed as (where dP is the particle diameter and Dc cylindrical collection diameter).
a. 𝑑𝑃/𝐷c
b. 𝑑𝑃×𝐷c
c. 𝑑𝑃/𝐷c×100
d. 𝑑𝑃𝐷c/100
a. 𝑑𝑃/𝐷c
The relationship between the del factor, temperature and time is given as
a. Δ=𝐴.𝑡.𝑒^-𝐸𝑅𝑇
b. Δ=1/(𝐴.𝑡.𝑒^-(𝐸𝑅𝑇))
c. Δ=𝐴.𝑡.𝑒^𝐸𝑅𝑇
d. Δ=𝐴.𝑡.𝑇
a. Δ=𝐴.𝑡.𝑒^-𝐸𝑅𝑇
The del factor (Δ) increases as the final number of cells
a. Decreases
b. Increases
c. Zero
d. Constant
a. Decreases
The overall del factor (Δ) may be represented as
a. Δoverall =Δheating+Δholding−Δcooling
b. Δoverall =Δheating+Δholding+Δcooling
c. Δoverall =Δheating−Δholding+Δcooling
d. Δoverall =Δheating−Δholding−Δcooling
b. Δoverall =Δheating+Δholding+Δcooling
The filter material used for air filtration system is/are
a. Glass wool
b. Glass fibre
c. Norite
d. All of the above
d. All of the above
The deviation from ideal plug flow due to axial mixing can be described by the
a. Dispersion model
b. Langmuir model
c. Friedlander model
d. Pasceri model
a. Dispersion model
The collection efficiency by diffusion increases with
a. Decreasing particle size.
b. Decreasing air velocity.
c. Both (a) and (b)
d. Increasing particle size
c. Both (a) and (b)
Glass fibers are favorable as a filter medium because they give a
a. Lower pressure drop and are less liable to wetting or combustion.
b. More pressure drop and are less liable to wetting or combustion.
c. Lower pressure drop and are more liable to wetting or combustion.
d. More pressure drop and are more liable to wetting or combustion.
a. Lower pressure drop and are less liable to wetting or combustion.
The collection efficiency by interception increases with the
a. Increasing particle diameter
b. Increasing air flow velocity
c. Both (a) and (b)
d. Increasing particle size
d. Increasing particle size
For indirect heating, the plate and frame heat exchange is generally more effective than the shell and tube heat transfer due to its
a. Larger heat transfer area
b. Smaller heat transfer area
c. Lesser cost
d. More number of plates
a. Larger heat transfer area
The mechanism of air filtration in fibrous filter is
a. Electrostatic attraction
b. Impaction
c. Interception
d. All of the above
d. All of the above
If the packing density (α) is defined as the volume of the fiber unit volume of filter bed, the velocity with the filter void space is equal to (where V1 is velocity in fluid void space and Vo is undisturbed fluid velocity).
a. 𝑉=𝑉o/(1−∝)
b. 𝑉−𝑉o=1−∝
c. 𝑉=𝑉o(1−∝)
d. 𝑉=𝑉o/(1+∝)
a. 𝑉=𝑉o/(1−∝)
For the turbulent flow, the dispersion coefficient is correlated as a function of
a. Reynolds number
b. Sherwood number
c. Schmidt number
d. Grashof number
a. Reynolds number
In sterilization process, spore of which of the following organism is considered as control?
a. Bacillus subtilis
b. Clostridium botulinum
c. Bacillus stearothermophilus
d. Aspergillus niger
c. Bacillus stearothermophilus
Analogus to the molecular diffusion, the x-directional flux or microorganisms suspended in a medium due to the axial mixing can be represented as (where Jn is flux component ‘n’, cn is concentration of ‘n’)
a. 𝐽𝑛 =−𝑑𝑐𝑛 /𝑑x
b. 𝐽𝑛 =𝑑𝑐𝑛 /𝑑x
c. 𝐽𝑛 =-𝐷 𝑑𝑐𝑛 /𝑑x
d. 𝐽𝑛 =𝐷 𝑑𝑐𝑛 /𝑑x
c. 𝐽𝑛 =-𝐷 𝑑𝑐𝑛 /𝑑x
The typical size of particles collected by diffusion mechanism is
a. < 0.25 μm
b. < 0.5 μm
c. < 0.75 μm
d. < 1 μm
b. < 0.5 μm
The X90 value for a filtration system is
a. The time required to reduce microbial population by 90%.
b. The time required to traverse survivor curve by one log cycle.
c. The depth required to reduce population by 90%.
d. The depth of the filter required to reduce population by 99%.
c. The depth required to reduce population by 90%.
The value of K
a. Increases with increase in air velocity.
b. Decreases with increase in air velocity.
c. Increases to an optimum with increase in air velocity and decreases on further increase of air velocity.
d. None of these
c. 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).
a. 𝜂𝑖=0.075𝑁st^1.2
b. 𝜂𝑖=0.75𝑁st^1.2
c. 𝜂𝑖=0.25𝑁st^1.2
d. 𝜂𝑖=0.025𝑁st^1.2
a. 𝜂𝑖=0.075𝑁st^1.2
The collection efficiency by impaction increases with
a. Increasing particle diameter
b. Increasing air flow velocity
c. Both (a) and (b)
d. Increasing particle size
c. 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).
a. 1−nimp nint ndif
b. 1−(1-nimp)(1-nint)(1-ndif)
c. 1−(nimp nint/ndif)
d. None of the above
a. 1−nimp nint ndif
The heat conduction in dry air is
a. Less rapid than in steam
b. More rapid than in steam
c. Similar to steam
d. None of these
a. 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
a. 0.5
b. 0.75
c. 0.87
d. 0.37
a. 0.5
The reduction of number of cells from 1010 to one will result into the del factor (Δ) of
a. 1
b. 10
c. 23
d. 10^3
c. 23
Sterilization can be carried out by
a. Heat
b. Radiation
c. Chemical agents
d. All of these
d. All of these
The collection efficiency by the inertial impaction mechanism is the function of
a. Stokes and Reynolds number
b. Stokes and Schmidt number
c. Grashoff and Reynolds number
d. Stokes and Grashoff number
a. Stokes and Reynolds number
The heated medium passes through a holding section, which is usually maintained in
a. Adiabatic conditions
b. Isothermal conditions
c. Isotropic conditions
d. Isobaric conditions
a. Adiabatic conditions
The highest temperature which appears to be feasible for batch sterilization is
a. 121°C
b. 100°C
c. 105°C
d. 130°C
a. 121°C
The K used in the equation for X10 = 2.303/K depends upon
a. Nature of the filter material
b. Linear velocity of the air passing through filter
c. Both (a) and (b)
d. Thickness of the filter
c. Both (a) and (b)
The mechanical means of accomplishing sterilization of fermentation media/equipment is
a. Ultrasonic
b. Radiation
c. Chemical agents
d. None of these
a. Ultrasonic
The radius of the filter with a depth of 14 cm required for a volumetric airflow rate of 10 m3/min is approximately
a. 1.6 m
b. 0.6 m
c. 3 m
d. 6 m
b. 0.6 m
The moist heat is more effective than the dry heat because the intrinsic heat resistance of vegetative cells is greatly
a. Increased in a dry state.
b. Decreased in a dry state.
c. Increased in a wet state.
d. Decreased in a wet state.
a. Increased in a dry state.
The destruction of microorganisms by steam may be described as
a. First order chemical reaction.
b. Zero order chemical reaction.
c. Second order chemical reaction.
d. None of these
a. First order chemical reaction.
Typical aeration rates for aerobic fermentation are
a. 0 – 0.5 vvm
b. 0.5 – 1.0 vvm
c. 1.0 – 1.5 vvm
d. 1.5 – 2.0 vvm
b. 0.5 – 1.0 vvm
The maximum desirable limit Bureau of Indian Standards (BIS) of lead in the drinking water is
a. 0.05 mg/L
b. 0.09 mg/L
c. 0.1 mg/L
d. 1.0 mg/L
a. 0.05 mg/L
Zeolite softening process removes
a. Only temporary hardness of water.
b. Only permanent hardness of water.
c. Both temporary and permanent hardness of water.
d. The dissolved gases in permanent hard water.
c. Both temporary and permanent hardness of water.
Conventional tertiary treatment is
a. Chemical coagulation and flocculation
b. Filtration
c. Sedimentation
d. None of these
a. Chemical coagulation and flocculation
The maximum desirable limit (BIS) of total hardness (as CaCO3) in drinking water is
a. 600 ppm
b. 300 ppm
c. 500 ppm
d. 1000 ppm
b. 300 ppm
The chemical oxygen demand (COD) measures the
a. Amount of oxygen required for growth of microorganisms in water.
b. Amount of oxygen that would be removed from the water in order to oxidize pollution.
c. Amount of oxygen required to oxidize the calcium present in wastewater.
d. None of the above
b. Amount of oxygen that would be removed from the water in order to oxidize pollution.
Hardness of water does not
a. Have any bad effect in boiler.
b. Make cooking of foods difficult.
c. Make it unfit for drinking.
d. Cause diffusivity in the washing of clothes with soaps
c. Make it unfit for drinking.
Permanent hard water may be softened by passing it through
a. Sodium silicate
b. Sodium bicarbonate
c. Sodium hexametaphosphate
d. Sodium phosphate
c. 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
a. 10% calcium chloride solution
b. 10% magnesium sulfate solution
c. 10% magnesium chloride solution
d. 10% sodium chloride solution
d. 10% sodium chloride solution
Temporary hardness of water is caused by the presence of
a. Chlorides of calcium and magnesium
b. Sulfates of calcium and magnesium
c. Bicarbonates of calcium and magnesium
d. Carbonates of sodium and potassium
c. Bicarbonates of calcium and magnesium
Secondary treatment uses ___ to consume wastes.
a. Microorganisms
b. Chemicals
c. Filtration
d. None of these
a. Microorganisms
Application of quaternary ammonium compounds as sanitizing agents tends to
a. Favor gram positive bacteria
b. Decrease gram positive bacteria
c. Increase the percentage of gram(-)ve rods on utensils.
d. None of the above
c. Increase the percentage of gram(-)ve rods on utensils.
Permanent hardness of water is caused by the presence of
a. Bicarbonates of calcium and magnesium
b. Carbonates of sodium and potassium
c. Chlorides and sulfates of calcium and magnesium
d. Phosphates of sodium and potassium
c. Chlorides and sulfates of calcium and magnesium
According to BIS, the maximum permissible limit of dissolved solids in drinking water is
a. 1000 mg/L
b. 500 mg/L
c. 2000 mg/L
d. 1500 mg/L
c. 2000 mg/L
Acid used mostly for removal of milk stone
a. Phosphoric acid
b. Nitric acid
c. Gluconic acid
d. Tartaric acid
b. Nitric acid
Which of the following chemical is sometime added in the process of coagulation and flocculation?
a. Aluminum sulphate
b. Aluminum oxide
c. Calcium chloride
d. None of these
a. Aluminum sulphate
Which of the following physical method is used as germicidal in modern time for the treatment of drinking water?
a. Chlorination
b. Treating with potassium permagnate
c. UV radiation
d. Treating with bleaching powder
c. UV radiation
Sanitizer used specifically for vitreous enamel are
a. Strong alkalis
b. Strong acids
c. Weak alkali with sodium silicate
d. None of these
c. Weak alkali with sodium silicate
The common methods used for disinfection in wastewater treatment plants are
a. Chlorination
b. UV light
c. Both (a) and (b)
d. Phenolic solvent
c. Both (a) and (b)
Inhibitors are used along with sanitizer to
a. Improve their action.
b. To prevent corrosion.
c. Both (a) and (b)
d. None of these
b. To prevent corrosion.
Sanitizers used for rubber made equipment are
a. Strong acids
b. Strong alkalis
c. Combination of both
d. None of these
b. Strong alkalis
Which of the following substances are commonly used in a filter?
a. Charcoal
b. Sand
c. Both (a) and (b)
d. Aluminum chloride
c. Both (a) and (b)
Biological oxidation processes usually referred as biological treatment, are the most common form of
a. Primary treatment
b. Secondary treatment
c. Tertiary treatment
d. All of these
b. Secondary treatment
The maximum permissible limit (BIS) of turbidity in drinking water is
a. 5 NTU
b. 10 NTU
c. 15 NTU
d. 20 NTU
b. 10 NTU
Sedimentation is a physical process used in wastewater treatment to
a. Remove particles that are less dense than water.
b. Remove particles that are more dense than water.
c. Remove the pertinacious material from the water.
d. None of the above
b. Remove particles that are more dense than water.
The ultimate source of water is
a. Rivers and lakes
b. Dew and forest
c. Rain and snow
d. Underground and surface
c. Rain and snow
Permanent hardness of water may be removed by the addition of
a. Lime
b. Soda ash
c. Potassium permagnate
d. Sodium bicarbonate
b. Soda ash
Both temporary and permanent hardness of water can be removed on boiling water with
a. Calcium hydroxide
b. Sodium carbonate
c. Calcium oxide
d. Calcium carbonate
b. Sodium carbonate
Lagoons may be characterized as
a. Anaerobic
b. Facultative
c. Aerated
d. All of these
d. All of these
Temporary hardness of water may be removed by adding
a. Calcium hydroxide
b. Calcium carbonate
c. Calcium chloride
d. Sodium bicarbonate
a. Calcium hydroxide
The maximum desirable limit (BIS) of mercury in the drinking water is
a. 0.05 mg/L
b. 0.9 mg/L
c. 0.1 mg/L
d. 0.001 mg/L
d. 0.001 mg/L
From the following sanitizers which one comes under category of surface active agents?
a. Tetra phosphate
b. Teepol
c. Meta phosphate
d. None of these
b. Teepol
The purest form of naturally occurring water is
a. Rain water
b. River water
c. Pond water
d. Well water
a. Rain water
Calgon is used for removal of
a. Sodium carbonate
b. Permanent hardness of water
c. Potassium carbonate
d. None of these
b. Permanent hardness of water
The water being used in dairy industry should contain not more than
a. 5 proteolytic and/or lipolytic organisms per mL
b. 10 proteolytic and/or lipolytic organisms per mL
c. 15 proteolytic and/or lipolytic organisms per mL
d. 20 proteolytic and/or lipolytic organisms per mL
a. 5 proteolytic and/or lipolytic organisms per mL
The activated sludge process consists of returning a portion of the clarifier
a. Effluent water entering the reactor.
b. Influent water coming out of the reactor.
c. Influent water entering the reactor.
d. Effluent water coming out of the reactor
c. Influent water entering the reactor.
The activated sludge process is sometime referred as
a. Fluid bed biological oxidation system.
b. Fixed bed biological oxidation system.
c. Turning bed biological oxidation system.
d. None of these.
a. Fluid bed biological oxidation system.
BOD stands for
a. Biochemical oxygen demand
b. British oxygen demand
c. British oxygen depletion
d. Biological oxygen depletion
a. Biochemical oxygen demand
When temporary hard water is boiled, one of the substances formed is
a. Calcium bicarbonate
b. Calcium sulfate
c. Hydrogen chloride
d. Carbon dioxide
d. 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
a. Insoluble carbonates
b. Insoluble zeolites
c. Insoluble chlorides
d. Insoluble sulfates
b. Insoluble zeolites
The methods used for biological treatment are
a. Lagoon
b. Activated sludge process
c. Oxidation ditches
d. All of these
d. All of these
Both temporary and permanent hardness of water can be removed by
a. Boiling
b. Distillation
c. Filtration
d. Decantation
b. Distillation
Coliform bacteria in water is an indication of the presence of
a. Radioactive wastes
b. Excess fertilizer
c. Decaying animals and plants
d. Human feces
d. Human feces
