Biochemical Engineering Flashcards
A competitive inhibitor of an enzyme is usually
- a highly reactive compound
- a metal ion such as Hg²⁺ or Pb²⁺
- structurally similar to the substrate.
- water insoluble
structurally similar to the substrate.
Linear inhibition is sometimes called as
- complete inhibition
- incomplete inhibtion
- partial inhibition
- mixed inhibition
complete inhibition
The types of inhibition pattern based on Michaelis Menten equation are
- competitive
- non-competitive
- uncompetitive
- all of the above
all of the above
The effect of non-competitive inhibition on a Lineweaver-Burk Plot is that
- it can move the entire curve to the right
- it can change the y-intercept
- it can change the x-intercept
- all of these
it can change the y-intercept
The rate-determining step of Michaelis Menten kinetics is
- the complex formation step
- the complex dissociation step to produce product
- the product formation step
- Both (a)and(c)
the complex dissociation step to produce product
In competitive inhibition a factor is obtained from the measurement of
- Vmax
- KM
- Y-intercept in Lineweaver-Burk Plot
- None of these
KM
Which of these proteases is not a cysteine active site protease?
- Calpain
- Cathepsin D
- Papain
- None of the above
Cathepsin D
Given an enzyme with a Km = 10m M and Vmax = 100 m mol/min. If [S] = 100 m M, which of the following will be true?
- A 10 fold increase in Vmax would increase velocity 10 fold y
- A 10 fold decrease in Km would increase velocity
- Both (a) and (b)
- A 10 fold increase in Vmax would decrease velocity 20 fold
A 10 fold increase in Vmax would increase velocity 10 fold y
The conformational change in an enzyme after the substrate is bound that allows the chemical reaction to proceed, can be explained by
- induced fit
- transition
- fit and fine
- Pasteur
induced fit
The active site of an enzyme remains
- at the center of globular proteins
- rigid and does not change shape
- complementary to the rest of the molecule
- none of the above
none of the above
Which category of enzymes belongs to class two in the international classification?
- Hydrolases
- Ligases
- Transferases
- Isomerase
Transferases
The Woolf-Augusteinsson-Hofstee plot of ν versus ν/[S] and the Eadie-Scatchard plot of ν/[S] versus ν do not involve reciprocals of ν therefore are considered to be more reliable when the error in v is
- non-significant
- significant
- nothing to do with the reliability
- non significant in selected cases
significant
The relationship between Keq, Km and Vmax is known as
- Haldane equation
- Michaelis Menten equation
- Numerical solution approach
- Gibbs-Helmholtz equation
Haldane equation
The reciprocal equation for non competitive inhibition can be arranged to the equation for the
- Dixon plot
- Woolf-Augusteinsson-Hofstee plot
- Eadie-Scatchard plot
- Hanes-Woolf plot
Dixon plot
Which of the following statements is true for enzymatically catalyzed reaction?
- The activation energy of the reaction is lowered so that a larger proportion of the substrate qualifies to overcome it
- Additional substrate molecules are energized to overcome the activation energy of the reaction
- The activation energy of the reaction is increased, thus decreasing the likelihood that any substrate molecules will overcome it
- The activation energy of the reaction is lowered so that a fewer substrate molecules can overcome it
The activation energy of the reaction is lowered so that a larger proportion of the substrate qualifies to overcome it
Which of the following common drugs is not a specific enzyme inhibitor?
- Iodine
- Methotrexate
- Sulfbnilamide
- Penicillin
Iodine
The enzyme inhibition can occur by
- reversible inhibitors
- irreversible inhibitors
- Both (a) and (b)
- None of these
Both (a) and (b)
In a Lineweaver-Burk Plot, competitive inhibitor shows which of the following effect?
- It moves the entire curve to right
- It moves the entire curve to left
- It changes the x-intercept
- It has no effect on the slope
It changes the x-intercept
Which of the following statements is not true?
- Enzymes are proteins that bind to specific substrates and increase the velocity of reactions involving those substrates
- Enzymes function by overcoming the activation energy barrier of a reaction
- Enzymes make thermodynamically favorable reactions to proceed; they cannot make unfavorable reactions to occur
- Enzymes only function when they are in intact cells
Enzymes only function when they are in intact cells
Non-competitive inhibitor of an enzyme catalyzed reaction
- decreases Vmax
- binds to Michaelis complex (ES)
- both (a) and (b)
- can actually increase reaction velocity in rare cases
both (a) and (b)
An enzyme and a reactant molecule maintain relationship as
- a temporary association
- an association stabilized by a covalent bond
- one in which the enzyme is changed permanently
- non complementary binding
a temporary association
An enzyme is assayed at an initial substrate concentration of 2 x 10⁻⁵ M. In 6 minute, half of the substrate is used. The Km for the substrate is 2 x 10⁻³ M. The value of k in minute is
- 0.115
- 0.42
- 0.093
- 6.693
0.115
The plot commonly used for determining the value of Vmax is
- Lineweaver Burk plot
- Langmuir plot
- Eadie Hofstee plot
- all of these
all of these
Quasi steady state is also known as
- Michaelis Menten approach
- Briggs-Haldane approach
- Pseudo steady state
- all of the above
Pseudo steady state
Which of these enzymes contains a Zinc (Zn) ion?
- Carboxypeptidase A
- Phosphorylase B kinase
- Tyrosine hydroxylase
- Phosphodiesterase
Carboxypeptidase A
A noncompetitive inhibitor of an enzyme-catalyzed reaction
- increases KM and increases Vmax
- increases KM and reduces Vmax
- reduces KM and increases Vmax
- reduces KM and reduces Vmax
increases KM and reduces Vmax
An allosteric inhibitor of an enzyme usually
- participates in feedback regulation
- denatures the enzyme
- is a hydrophobic compound
- causes the enzyme to work faster
participates in feedback regulation
Which of the following activity is possible by transferases?
- Transfer of methyl groups
- Transfer of glycosyl group
- Both (a) and (b)
- None of these
Both (a) and (b)
A classical uncompetitive inhibitor is a compound that binds
- reversibly to the enzyme substrate complex yielding an inactive ESI complex
- irreversibly to the enzyme substrate complex yielding an inactive ESI complex
- reversibly to the enzyme substrate complex yielding an active ESI complex
- irreversibly to the enzyme substrate complex yielding an active ESI complex
reversibly to the enzyme substrate complex yielding an inactive ESI complex
Which graphical method is used to determine an enzyme degree of cooperativity?
- Hill plot
- Koshland curve
- Michaelis-Menten hyperbola
- Can not be determined
Hill plot
β-amylase is
- endoenzyme
- exoenzyme
- saccharifying enzyme
- both (b) and (c)
both (b) and (c)
Juice clarification extraction is facilitated by using
- cellulases
- amylase
- inulinase
- lactase
cellulases
Lysozyme is naturally present in
- egg white
- bacteria
- tears & milk
- all of these
all of these
Enzymes act as antimicrobials
- by depriving an organism of a necessary metabolite
- by generating a substances toxic to the organism
- by attracting a cell wall component
- all of the above
all of the above
Trichoderma β-glucanase is reported
- to stabilize mashing
- to convert taste fractions of dextrins to fermentable sugars in beer
- to convert starch to dextrin
- all of the above
to stabilize mashing
The bitter taste of the high protein materials is reduced by using
- invertase
- dectinase
- protease
- none of these
protease
Sulphydryl oxidase is used for
- discoloration
- clarification of images
- UHT milk off flavour removal
- all of these
UHT milk off flavour removal
α-amylase is an endo enzyme which requires
- Ca
- Cu
- Mn
- None of these
Ca
Liquefaction of starch to dextrin is carried out by
- α-amylase
- cellulase
- pectinase
- all of these
α-amylase
Which is true about rennet?
- It is a mixture of protease chymosin and pepsin
- It is a mixture of rennin and pepsin
- Both (a) and (b)
- none of the above
Both (a) and (b)
Milk digestibility is improved by using
- RNase
- lactase
- β-amylase
- none of these
lactase
Which of the following mainly serve to convert starch into high fructose corn syrup (HFCS)?
- α-amylase
- Gluco-isomerase
- Gluco-amylase
- all of these
all of these
Lysozyme
- catalyses hydrolysis of β-1-4 linkages between N-acetyl muranic acid and N-acetyl glucosamine in peptideoglycan
- catalyses hydrolysis of α-1-4 linkages between N-acetyl muranic acid and N-acetyl glucosamine in peptideoglycan
- catalyses hydrolysis of α-1-4 linkages between N-diacetyl muranic acid and N-diacetyl glucosamine in peptideoglycan
- all of the above
catalyses hydrolysis of β-1-4 linkages between N-acetyl muranic acid and N-acetyl glucosamine in peptideoglycan
Hersperidinase is used for
- juice clarification
- juice debittering
- off flavour reduction
- RNA reduction in fish
juice clarification
Which of the following metallic ion is there in ascorbic acid oxidase?
- Mg
- Fe
- Cu
- Mn
Cu
Which of the enzyme combination is commercially used for the removal of oxygen?
- Glucose oxidase-cellulase
- Glucose oxidase-catalase
- Glucose oxidase-lactase
- All of these
Glucose oxidase-catalase
The enzyme used to reduce bitterness of grapes commonly contains
- α-L-rhamonosidase
- β-d-glucosidase
- β- galactosidase
- both (a) and (b)
both (a) and (b)
Citrus juice debittering can be carried out using
- limoninase
- inulinase
- anthocyanase
- None of these
limoninase
Which of the following enzyme is responsible for causing vitamin B deficiency disease beriberi?
- Ascorbic acid oxidase
- Thiaminase
- Lipoxygenase
- None of these
Thiaminase
Soya off flavour removal may be achieved using
- di acetyl reductase
- β- amylase
- aldehyde oxidase
- protease
aldehyde oxidase
The reduction in off flavour of beer is practiced through
- hersperidinase
- rnase
- invertase
- diacetyl reductase
diacetyl reductase
Discoloration can be achieved by using
- sulphloydryl oxidase
- proteases
- anthocyanase
- all of these
anthocyanase
The prosthetic group present in phenolase enzyme is
- Mg
- Cu
- Ca
- Fe
Cu
Enzymes degrade, alter or synthesize a food component through
- oxidation/reduction/isomerization
- hydrolysis/synthesis
- group transfer
- all of the above
all of the above
The enzyme β-galactosidase is also known as
- lactase
- EC3.2.1.23
- both (a) and (b)
- isomerase
both (a) and (b)
Chymosin hydrolyses the bond between
- Alanine and glycine
- Phenyl alanine and methonine
- Glutamic acid and alanine
- Alanine and phenyl alanine
Phenyl alanine and methonine
The ratio of the amount of a protein present in a sample, which is used as a measure of purification, is known as
- specific activity
- relative activity
- purity ratio
- all of these
specific activity
If a reaction occurs in the absence of inhibitor with rate ν0 and in the presence of inhibitor with rate νi, the degree of inhibition is defined as
- (ν0 - νi)/ν0
- (ν0 + νi)/ν0
- (ν0νi)/ν0
- (ν0-νi)/νi
(ν0 - νi)/ν0
The rate equation in competitive inhibition based on Michaelis Menten equation is given by
- rmaxS/(Km (1+I/Ki)+S))
- rmaxE/(Km (1+I/Ki)+S))
- rmaxI/(Km (1+I/Ki)+S))
- rmaxS/(Km (1+I/Ki))
rmaxS/(Km (1+I/Ki)+S))
Classical noncompetitive inhibition is obtained only under
- slow equilibrium conditions
- moderate equilibrium conditions
- rapid equilibrium conditions
- non-equilibrium conditions
rapid equilibrium conditions
In the steady state the material balance equation for any component of a system is
- rate of addition + rate of removal - rate of formation = 0
- rate of addition - rate of removal + rate of formation = 0
- rate of addition + rate of removal + rate of formation = 0
- none of the above
rate of addition - rate of removal + rate of formation = 0
For an enzyme that displays Michaelis-Menten kinetics, the reaction velocity (as a fraction of Vmax) observed at [S] = 2 KM will be
- 0.09
- 0.33
- 0.66
- 0.91
0.66
Predominantly uncompetitive inhibition may be called when
- competitive inhibition is greater than uncompetitive inhibition
- competitive inhibition is smaller than uncompetitive inhibition
- competitive inhibition is equal to uncompetitive inhibition
- none of the above
competitive inhibition is greater than uncompetitive inhibition
An enzyme has a Km of 4.7 x 10-5M. If the Vmax of the preparation is 22m moles liter-1 min-1, what velocity would be observed in the presence of 2.0 x 10-4M substrate and 5.0 x 10-5M of a competitive inhibitor?
- 13.54μ moles liter-1min-1
- 6.68μ moles liter-1min-1
- 7.57μ moles liter-1min-1
- 17.8μ moles liter-1min-1
13.54μ moles liter-1min-1
The rate equation in non-competitive inhibition based on Michaelis Menten equation is given by
- rmaxS/(Km + S)(1+I/Ki)
- rmaxE/(Km (1+I/Ki)+S))
- VmaxS/(Km + S)(1+I/Ki)
- rmaxS/Km
rmaxS/(Km + S)(1+I/Ki)
Which of the following statement(s) regarding enzymes, is/are false?
- Enzymes are always proteins that function as catalysts
- Enzymes provide activation energy for reactions
- Enzyme activity can be regulated
- Enzymes may be used many times for a specific reaction
Enzymes provide activation energy for reactions
The slope of Lineweaver Burk plot for Michaelis Menten equation is
- Vmax/Km
- Km/Vmax
- 1/Km
- Km.Vmax
Km/Vmax
The initial velocity, V0, of an enzyme catalyzed reaction reaches Vmax as
- [S] = KM
- [S] = 10 * KM
- 1/[S] = 1/KM
- 1/[S] → 0
1/[S] → 0
The usual method(s) to solve rate equation of simple enzyme kinetics is/are
- Michaelis Menten approach
- Briggs-Haldane approach
- Numerical solution approach
- all of these
all of these
Michaelis Menten equation can also be written as
- (-Cs)/r = (Cs/rmax)+(Km/rmax)
- 1/r = (1/rmax)+(Km/(rmax.Cs))
- r = rmax-(Km.r/Cs)
- All of these
All of these
Which of the following step is assumed to be the slowest step in the Michaelis Menten equation?
- The substrate consuming step
- The product releasing step
- Formation of enzyme substrate complex
- None of these
The product releasing step
When substrate [S] = KM (Michaelis-Menten constant), the velocity of an enzyme catalyzed reaction is about
- 0.1 * Vmax
- 0.2 * Vmax
- 0.5 * Vmax
- 0.9 * Vmax
0.5 * Vmax
A classical noncompetitive inhibitor has
- no effect on substrate binding
- no effect on substrate binding and vice versa
- significant effect on substrate binding
- significant effect on substrate binding and vice versa
no effect on substrate binding and vice versa
The active site of an enzyme differs from an antibody-antigen binding site in that the enzyme active site
- contains modified amino acids
- catalyzes a chemical reaction
- is complementary to a specific ligand
- contains amino acids without side chains
catalyzes a chemical reaction
Enzymes are basically
- proteins
- vitamins
- fat
- carbohydrates
proteins
Which of the following refers to pseudo steady state ?
- d(CE)/dt = 0
- d(Cp)/dt = 0
- d(CES)/dt = 0
- d(Cs)/dt = d(CES)/dt
d(CES)/dt = 0
Most enzymes work by
- increasing energy of activation
- decreasing energy of activation
- not affecting energy of activation
- none of the above
decreasing energy of activation
Which category of enzymes belongs to class 5 in the international classification?
- Hydrolases
- Isomerases
- Oxido-reductases
- Cyclase
Isomerases
Lock and key theory is based on the compatibility of
- enzyme and substrate
- enzyme and product
- enzyme and enzyme substrate complex
- enzyme substrate complex and product
enzyme and substrate
When an enzyme is functioning at Vmax, the rate of the reaction is limited by
- the number of collisions between enzyme and substrate
- the number of substrate molecules in the reaction
- the concentration of the substrate
- the rate at which the enzyme can convert substrate to product
the rate at which the enzyme can convert substrate to product
The equation for the rate of product formation for simple enzyme reaction is given by (Where rmax, maximum reaction rate, Cs substrate concentration, Cp product concentration ES, CES enzyme-substrate concentration)
- rp = rmax Cs/(Km+Cs)
- rp= rmax CES/(Km+ CES)
- rp = rmax Cs/(Km+CES)
- rp = rmax Cs/(Km+Cp)
rp = rmax Cs/(Km+Cs)
When [S] = 0.1 *KM, the velocity of an enzyme catalyzed reaction is about:
- 0.1 * Vmax
- 0.3 * Vmax
- 0.5 * Vmax
- 0.7 * Vmax
0.1 * Vmax
The function of the disengagement zone in an airlift fermenter is to
- prevent CO2 rich bubbles from entering the downcomer
- reduce the velocity of the bubbles
- reduce liquid loss as aerosols
- all of the above
all of the above
Stationary phase is described as
- no further increase in the cell population after a maximum value
- deceleration of growth and division rate after the growth rate reaches a maximum
- acceleration of growth and division rate after the growth rate reaches a maximum
- deceleration of growth and division rate after the growth rate reaches a minimum
no further increase in the cell population after a maximum value
In the accelerated phase, cell starts to
- increase and the division rate increases to reach a maximum
- decrease and the division rate increases to reach a maximum
- increase and the division rate decreases to reach a maximum
- increase and the division rate increases to reach a minimum
increase and the division rate increases to reach a maximum
The monod model predicts that the specific growth rate
- will increase with the concentration of the growth limiting substrate until it reaches a maximum value
- will decrease with the concentration of the growth limiting substrate
- will increase with the concentration of the growth limiting substrate
- does not depend on growth limiting substrate
will increase with the concentration of the growth limiting substrate until it reaches a maximum value
A mixed fermentation is one, which produces
- both alcohol and carbon dioxide
- both acid and carbon dioxide
- both acid and alcohol
- several different kinds of acid
both acid and alcohol
The function of a mechanical seal is to
- prevent contaminants entering the reactor
- prevent cells from leaving the reactor
- both (a) and (b)
- prevent air to enter
both (a) and (b)
The phenomenon in which substrates are used in a sequential manner is known as
- trans-substrate genesis
- dialism
- diauxie
- multiplicity
diauxie
The dilution rate, D is defined as(where F = volumetric flow rate, VR = total volume of culture in the reactor and μ specific growth rate)
- F/VR
- VR/F
- μ/F
- F/μ
F/VR
Diauxie is
- growth factors
- microbiological die off
- the simultaneous uptake of nutrients
- the stagewise uptake of nutrients
the stagewise uptake of nutrients
An open system in which the growth rate is maintained by adding a nutrient (present in limiting quantities) at the same rate as that medium containing micro-organisms is removed is called
- manostat
- chemostat
- turbidostat
- culturostat
chemostat
In the death phase
- nutrients available for the cells are depleted and begin to die
- the number of viable cells will increase
- nutrients available for cells are replenished and start to multiply
- none of the above
nutrients available for the cells are depleted and begin to die
The maximum specific growth rate of an organism depends on
- medium composition
- temperature
- pH
- All of these
All of these
Which of the following is not correct for the Monod model and the Michaelis Menten Model?
- The Michaelis Menten Model was derived from a curve fitting exercise
- The Michaelis Menten model was derived from an analysis of the mechanism of microbial growth
- The Monod model was derived from an analysis of the mechanism of microbial growth
- All of the above
The Monod model was derived from an analysis of the mechanism of microbial growth
Bubble column reactor has
- large height to diameter ratio
- small height to diameter ratio
- large diameter to height ratio
- small diameter to height ratio
large height to diameter ratio
Why a T-flask used in small-scale cell culture is incubated in a horizontal position?
- To save space
- To increase the surface area of the liquid-air interface
- Both (a) and (b)
- To increase the rate of oxygen transfer into the liquid
Both (a) and (b)
An open system in which the growth rate is maintained by the removal and addition of media at such a rate as to maintain a constant cell density is called a
- manostat
- chemostat
- turbidostat
- culturostat
turbidostat
Wash out in steady state fermentation occurs when
- dilution rate is less than maximum specific growth rate
- dilution rate is higher than the maximum specific growth rate
- cell concentration reaches the maximum
- specific growth rate is maximum
dilution rate is higher than the maximum specific growth rate
Fermentor should be filled with medium upto
- 65-70%
- 70-75%
- 75-80%
- 80-85%
75-80%
Bacterial growth curve is obtained by plotting
- number of cells versus time
- number of spores versus time
- log of number of cells versus time
- log of number of cells survived versus time
log of number of cells versus time
When intracellular enzymes of whole cells are to be used in a bio-conversion process, it is often necessary to____________the cells.
- permeabilize
- lyophilize
- heat-kill
- denature
permeabilize
Heat transfer rates (per unit volume) will be lowest in
- Stirred tank bioreactor with biomass recycle
- Continuous air lift bioreactor
- Continuous packed bed reactor
- Continuous fluidized bed bioreactor
Continuous packed bed reactor
The function(s) of the draft tube in an airlift bioreactor is
- to reduce bubble coalescence
- to improve circulation
- to even out shear conditions throughout the reactor
- all of the above
all of the above
The Monod Model relates
- substrate utilized with the biomass consumption
- specific growth rate to the substrate availability
- yield with the biomass utilization
- the biomass concentration with specific growth rate
specific growth rate to the substrate availability
The height to diameter ratio (H/D) for the column fermenters is
- <3
- > 3
- <1.5
- > 1.5
- > 3
The high oxygen transfer efficiencies of airlift bioreactors is due to
- the large aspect ratio of the reactor, which leads to a high gas hold-up
- the large aspect ratio of the reactor, which leads to a high oxygen solubility at the base of the reactor
- the draft tube, which reduces bubble coalescence in the reactor
- all of the above
all of the above
The maximum specific growth rate (μm) of an organism in batch culture is equal to slope of a plot of
- In [biomass] against time for exponential phase data only
- In [biomass] against time
- biomass against time
- biomass against time for stationary phase data only
In [biomass] against time for exponential phase data only
The region of an airlift bioreactor in which the liquid travels in a downward direction is called the
- downcomer
- disengagement zone
- air riser
- flotsam
downcomer
Population doubling time, td can be expressed as (where μ is the specific growth rate.)
- log2/μ
- ln2/μ
- μ/ln2
- μ/log2
ln2/μ
A higher Ks value of Monod’s equation means
- greater affinities to substrate
- lower affinities to substrate
- unaffected with the substrate bonding
- lower dissociation constant value
greater affinities to substrate
The increased air flow rate in bubble column fermenter can cause excessive foaming and high retention of air bubbles in the column which
- decreases the productivity of the fermenter
- increases the productivity of the fermenter
- modestly increases the productivity of the fermenter
- does not affect on the productivity
decreases the productivity of the fermenter
Which of the following is correct for the prediction of time requirement in a batch fermenter?
- Carrying out experiments
- Mathematical modelling of the fermentation process
- Both (a) and (b)
- It is impossible to predict the time required for fermentation
Both (a) and (b)
In an airlift bioreactor, the spent gases released from the liquid are called
- downcomer
- disengagement zone
- air riser
- flotsam
disengagement zone
The contents in jet loop reactor are mixed through
- compressed air
- a mechanical agitator
- external pumping
- any of these
external pumping
The specific growth rate (μ) is defined as
- the concentration of biomass in the reactor
- rate of increase of total biomass in a reactor
- the rate of individual cells division or increase in their biomass
- the rate of cell death
the rate of individual cells division or increase in their biomass
The number of baffles in a standard stirred tank bioreactor is
- 8
- 6
- 4
- 2
4
In the stationary phase
- growth is proportional to death
- growth rate is equal to death rate
- growth rate is lesser than death rate
- no co-relation exist between death rate and growth rate
growth rate is equal to death rate
Which of the following is an example of a mathematical model?
- Volume of cuboid = length x breadth x height
- The Monod Model
- The Michaelis Menten Equation
- All of the above
All of the above
Biomass concentrations during fermentation is
- diluting the samples to optical density less than 0.3
- monitored by controlling the changes in biomass concentrations
- considering that optical density is proportional to the surface area of the biomass in the sample
- all of the above
all of the above
Chemostats work on the principle of
- maintaining constant volume of culture medium
- maintaining continuous flow of nutrients
- maintaining uniform nutrients concentration
- operating at higher pressure
maintaining uniform nutrients concentration
During the exponential phase the maximum specific growth rate equals specific growth rate as
- concentration of the growth limiting substrate is much less than the monod constant
- concentration of growth limiting substrate is much greater than the monod constant
- specific growth rate increases exponentially
- concentration of the growth limiting substrate is equal to the monod constant
concentration of growth limiting substrate is much greater than the monod constant
An internal draft tube is preferrred to an external draft tube because
- it is easier to clean and sterilize a reactor
- it is cheaper to build a reactor with an internal draft tube
- Both (a) and (b)
- none of the above
it is easier to clean and sterilize a reactor
A functional relationship between the specific growth rate and essential compounds concentration was proposed by Monod in
- 1958
- 1946
- 1942
- 1950
1942
The optical density sometimes drops during the lag phase because
- cells tend to grow without dividing leading to a decrease in the surface area to volume ratio
- of fast cell growth causing them to fill up with DNA
- cells swell up with water
- cells swell up with RNA
cells tend to grow without dividing leading to a decrease in the surface area to volume ratio
The application of just in time (JIT) manufacturing techniques in biotechnology is important because
- raw materials used in biotechnology are biodegradable
- the products of biotechnology are biodegradable
- it is a very competitive business (d) all of the above
- all of the above
all of the above
Residence time distribution (RTD) of a reactor is independent of
- micro mixing
- volume of reactor
- height of the reactor
- width of the reactor
micro mixing
The bubble column fermenter is usually limited to
- aerobic fermentations
- anaerobic fermentations
- Both (a) and (b)
- facultative fermentation
aerobic fermentations
A culture in a closed vessel to which no additional medium is added and from which no waste products are removed is called a __________ culture.
- continuous
- batch
- fed-batch
- semi continuous
batch
If the specific growth rate, μ. is constant with time during the exponential growth period, the equation correlating bacterial number density Cn), cell number concentration with respect to time can be expressed as
- Cn= Cn0 exp[μ (t - t0)]
- Cn0 = Cn exp[μ (t - t0)]
- Cn/Cn0 =(1/μ)exp(t-t0)
- Cn0 / Cn = (1/μ)exp(t-t0)
Cn= Cn0 exp[μ (t - t0)]
The diameter of the baffles in a standard stirred tank bioreactor ranges from
- 1/10th - 1/12th of the tank diameter
- 1/3rd - 1/4th of the tank diameter
- 1/15th - 1/20th of the tank diameter
- 1/20th - 1/25th of the tank diameter
1/10th - 1/12th of the tank diameter
During the log phase cell numbers increase exponentially
- because cells produce enzymes
- because cells do not have cell membranes
- because cells are autocatalysts
- because the rate of cell division increases exponentially
because cells are autocatalysts
Lag phase occurs mainly due to
- acclimatization with new environment and substrate
- higher growth temperature
- substrate disliking
- variation in substrate concentration
acclimatization with new environment and substrate
In a batch reactor specific growth rate
- remains constant throughout the process
- increases exponentially
- changes during the fermentation
- is highest during the stationary phase
changes during the fermentation
Turbidostat is recommended when continuous fermentation needs to be carried out at
- high dilution rates near the washout point
- low dilution rates near the washout point
- moderate dilution rates near the washout point
- any intensity of dilution rates near the washout point
high dilution rates near the washout point
The advantage of airlift bioreactors over stirred tank bioreactors of a similar size is
- higher oxygen transfer rates
- more uniform shear conditions
- both (a) and (b)
- less foaming
both (a) and (b)
Stirred tank fermenter (STF) can be employed for
- aerobic fermentation of a wide range of cells including microbial, animal and plant cells
- anaerobic fermentation of a wide range of cells including microbial, animal and plant cells
- Both (a) and (b)
- anaerobic fermentation of plant cells only
Both (a) and (b)
The specific growth rate is affected by
- sabstrate concentration
- product concentration
- oxygen supply
- all of these
all of these
The main function(s) of a draft tube in an air lift fermenter is/are to
- increase the solubility of oxygen
- distribute shear forces throughout the reactor and minimise bubble coalescence
- concentrate shear forces around the sparger
- concentrate shear forces near the disengagement zone
distribute shear forces throughout the reactor and minimise bubble coalescence
Which of the following is incorrect?
- The mechanical agitation and aeration are effective for suspension of cells
- The mechanical agitation and aeration are effective for mixing the medium
- STF can’t be used for high viscosity medium
- The mechanical agitation and aeration are effective for oxygenation
STF can’t be used for high viscosity medium
The contents in bubble column and air lift reactor are mixed through
- compressed air
- a mechanical internal moving part
- external pumping
- any of these
external pumping
Which of the following statements would be appropriate while comparing bubble column and air lift fermenter of the same size?
- The average bubble size is smaller in an airlift bioreactor
- Oxygen transfer rate is higher in an airlift bioreactor
- The surface area for gas exchange is higher in an airlift bioreactor
- All of the above
All of the above
During the lag phase
- cells just start growing
- cells synthesize new proteins and membrane components
- cells produce antibiotics to kill competing organisms
- cells simply grow slowly
cells synthesize new proteins and membrane components
Concentration of the growth limiting substrate means
- trace elements concentration
- the concentration of the substrate that controls the growth rate of the cells
- sugar concentration in the fermentation medium
- dissolved oxygen concentration
the concentration of the substrate that controls the growth rate of the cells
Tower fermentors are used for
- continuous penicillin production
- continuous beer production
- production of enzymes
- batch production of beer
continuous beer production
n wastewater treatment, which bioreactor is generally used?
- Plug flow reactor
- Trickle bed reactor
- Tower fermentor
- CSTR
Trickle bed reactor
The contents in stirred tank rector are mixed through
- compressed air
- a mechanical agitator
- external pumping
- any of these
a mechanical agitator
The height to diameter ratio (H/D) for the tank fermenters is
- <3
- > 3
- <1.5
- > 1.5
<3
The relatively large volume (10 to 40% of total fermenter volume) of the seed culture is employed to
- increase the overall fermentation time
- increase the overall yield of biomass
- decrease the overall fermentation time
- decrease the overall yield of product
decrease the overall fermentation time
In an airlift bioreactor, the air sparging region is called
- downcomer
- disengagement zone
- air riser
- none of these
air riser
The air riser is located on the outside of the draft tube for the large-scale airlift bioreactors because of
- higher oxygen transfer rates
- a small sparge ring
- better heat transfer efficiencies
- all of these
better heat transfer efficiencies
At the end of the lag phase, when growth begins, the division rate increases gradually and reaches a maximum value in the exponential growth period. This transitional period is commonly called the accelerated growth phase and is often included as a part of the
- lag phase
- stationary phase
- death phase
- exponential growth phase
lag phase
Which of the following(s) is/are considered the limitations of the exponential growth model?
- Only predicts that cells grow exponentially during the log phase
- It does not consider factors that causes cells growth to stop or slow
- Predicts cell growth at a linear rate
- All of the above
It does not consider factors that causes cells growth to stop or slow
To describe components of an airlift bioreactor which of the follow-ings are generally included?
- Disengagement zone, air riser, downcomer
- Flotsam, jetsam, downzone
- Air comer, disentanglement zone, downsizer
- All of the above
Disengagement zone, air riser, downcomer
The viscosity of liquid was classified as both dilatant and rheopectic, which means that the viscosity
- increased with stirring speed but decreased with mixing time
- increased with stirring speed and increased with mixing time
- decreased with stirring speed but increased with mixing time
- decreased with stirring speed and decreased with mixing time
increased with stirring speed and increased with mixing time
Which of the following describes the detrimental effect of bubbles on animal cells?
- Cells trapped on the surface of bubbles can be damaged when the bubbles explode, releasing their pressure and surface energies
- Cells trapped in the moving foam can be dragged apart by the bubbles
- Both (a) and (b)
- Bubbles can explode in the liquid medium causing the release of ultraviolet radiation
Both (a) and (b)
A fluid in which the viscosity decreases with increasing stirrer speed and mixing time, can be represented as
- newtonian fluid
- pseudoplastic, thixotropic fluid
- dilatant, rheopectic fluid
- dilatant, pseudoplastic fluid
pseudoplastic, thixotropic fluid
Filamentous fungal cells are more shear sensitive than bacterial cells because of
- the presence of citin in cell walls of filamentous fungi
- larger in size than bacterial cells and therefore are more susceptible to shear forces
- fungal cells are much larger than bacterial cells
- all of the above
all of the above
The viscosity of water at STP is approximately
- 0.005 kg.m-1.s-1
- 0.001 kg.m-1.s-1
- 0.003 kg.m-2.s-1
- 0.1 g.cm-1.s-1
0.001 kg.m-1.s-1
Bubble free aeration systems requires
- silicone tubing or gas permeable membranes to facilitate gas transfer
- carbon dioxide instead of air to supply oxygen
- silicone tubing or gas permeable membranes to remove carbon dioxide by oxygen in the form of hydrogen peroxide
- filled headspace of the reactor with carbon dioxide
silicone tubing or gas permeable membranes to facilitate gas transfer
Non-linear relationship between shear stress and shear rate exists in
newtonian fluids
non-newtonian fluids
both (a) and (b)
none of these
non-newtonian fluids
If the viscosity of a fluid decreases with increasing stirrer speed, then the nature of the fluid is
newtonian
pseudoplastic
dilatant
thixotropic
pseudoplastic
A pseudoplastic fluid is one in which the viscosity
is constant regardless of the stirrer speed or mixing time
changes during mixing but returns to its original state after mixing
increases with increasing stirrer speed
decreases with increasing stirrer speed
decreases with increasing stirrer speed
A viscoelastic fluid is one in which the viscosity
is constant regardless of the stirrer speed or mixing time
changes during mixing but returns to its original state after mixing
increases with increasing stirrer speed
decreases with increasing stirrer speed
changes during mixing but returns to its original state after mixing
Mixing in stirred tank reactors can
be described as either laminar, transient or turbulent
achieve turbulent conditions by increasing the stirrer speed
induce laminar flow conditions by the addition of baffles
all of the above
be described as either laminar, transient or turbulent
In animal cell bioreactor, bubble damage can be minimized by
the addition of a shear protectorant
using a bubble free oxygen delivery system
headspace aeration
all of the above
all of the above
The viscosity of a fluid changes with either stirrer speed or mixing time. But when mixing ceases, the viscosity returns to its original state. This fluid is best described as
newtonian
rheopectic
viscoelastic
thixotropic
viscoelastic
In sparged mammalian cell bioreactors, the cell damage is caused because of
shear stress arising during mixing of the cell culture fluid
shear stresses arising from the breakup of bubbles at the liquid surface
shear stresses between bubbles in foam at the liquid surface
all of the above
shear stress arising during mixing of the cell culture fluid
The SI unit for viscosity is
kg.m-1.s-1
kg.m-2.s-2
kg.m-3.s-1
kg.m-1.s-2
kg.m-1.s-1
The viscous nature of a non-Newtonian fluid
remains constant with time and power input
changes with the level of power input and/or the length of time during which the fluid is mixed
is similar to that of a perfect gas
is similar to that of water
changes with the level of power input and/or the length of time during which the fluid is mixed
Which of the following compound, if added to a solution will lead to the greatest increase in viscosity?
A globular protein
Glucose
A long chain protein such as albumin
Water
A long chain protein such as albumin
A Brookfield viscometer measures viscosity by determining
the shear stress
the shear rate
the shear stress and shear rate
the torque required to move an impeller at a set speed
the torque required to move an impeller at a set speed
Which of the following factors will affect the sensitivity of animal cells to shear conditions?
Cell size
Availability of nutrients in the medium
The presence of shear protectorants in the medium
All of the above
All of the above
The best described action of Pluronic F68 (non-ionic detergent) in a cell culture medium is that, it
acts on the surface properties of the cells and the culture medium
provides nutrients for the cells
acts as a flocculant
acts as a coagulant
acts on the surface properties of the cells and the culture medium
Water is a
newtonian fluid
pseudoplastic
dilatant
rheopectic
newtonian fluid
Which of the following affect the Kolmogorov eddy size?
Stirrer speed
Physical properties of the liquid
Size and type of impeller
All of these
All of these
A liquid is flowing at 11,400 l.h-1 along a pipeline having a diameter of 4 cm. If the liquid has a density of 1 g.ml-1 and viscosity of 0.001kg.m-1.s-1, then the liquid would be in the
laminar phase
transient phase
turbulent phase
any of the phase
turbulent phase
The viscosity of a fluid increases with the length of time that it is being mixed. This fluid would be best described as being
newtonian
rheopectic
viscoelastic
thixotropic
rheopectic
Which of the following can act as a shear protectorant?
Serum
Silicone oil
Glucose
Glutamic acid
Serum
The viscosity of a fluid increases with increasing stirrer speed. This fluid would be best described as being
newtonian
pseudoplastic
dilatant
thixotropic
dilatant
A dilatant fluid is one in which the viscosity
is constant regardless of the stirrer speed or mixing time
changes during mixing but returns to its original state after mixing
increases with increasing stirrer speed
decreases with increasing stirrer speed
increases with increasing stirrer speed
A rheopectic fluid is one in which the viscosity
is constant regardless of the stirrer speed or mixing time
changes during mixing but returns to its original state after mixing
increases with mixing time
decreases with mixing time
increases with mixing time
A fluid in which the viscosity increases with increasing stirrer speed and mixing time can be called as
newtonian fluid
pseudoplastic, thixotropic fluid
dilatant, rheopectic fluid
dilatant pseudoplastic fluid
dilatant, rheopectic fluid
The medium will have the highest viscosity (considering that the cells do not secrete gums) with the presence of
single celled bacteria
filamentous fungi that form pellets
filamentous fungi that grow as long poorly branched chains
yeast
filamentous fungi that grow as long poorly branched chains
A Newtonian fluid is one in which the viscosity
is constant regardless of the stirrer speed or mixing time
changes during mixing but returns to its original state after mixing
increases with increasing stirrer speed
decreases with increasing stirrer speed
is constant regardless of the stirrer speed or mixing time
Which pattern of mixing is preferred in stirred tank reactors during the culture of aerobic microorganisms?
Laminar flow
Transient flow
turbulent flow
all of these
all of these
Animal cell cultures do not have much effect on shear forces because
the cell size is generally smaller than the critical eddy size at which shear will have an effect
cells are larger than the critical eddy size at which shear will have an effect
animal cells have cell walls
animal cells have cell membranes
the cell size is generally smaller than the critical eddy size at which shear will have an effect
The viscosity of the culture fluid is classified as both pseudoplastic and thixotropic which indicates that the viscosity
increases with stirring speed but decreases with mixing time
increases with stirring speed and increases with mixing time
decreases with stirring speed but increases with mixing time
decreases with stirring speed and decreases with mixing time
decreases with stirring speed and decreases with mixing time
Pluronic F68 is added to cell culture media as
a nutrient
a shear protectorant
to increase oxygen transfer rates
all of these
a shear protectorant
A stirred tank reactor containing a fluid with a density of 2.5 g.ml-1 and viscosity of 0.002 kg m-1s-1 is mixed at 120 rpm. If the fluid is mixed with an impeller having diameter 50 cm, then the Reynolds number of the liquid in the reactor is
2500
100
12,50,000
1,000,000
12,50,000
If the viscosity of a fluid decreases with the length of time that it is being mixed, then this fluid is
newtonian
rheopectic
viscoelastic
thixotropic
thixotropic
Which of the following describes the importance of the Kolmogorov eddy size in the biotechnology?
The Kolmogorov eddy size is a measure of the smallest eddy size in a liquid
When the Kolmogorov eddy size become equivalent or smaller than the cell or particle diameter, then the cell or particle will become susceptible to shear damage
At the Kolmogorov eddy size, much of the energy of the originating eddy will be released
All of the above
All of the above
A thixotropic fluid is one in which the viscosity
is constant regardless of the stirrer speed or mixing time
changes during mixing but returns to its original state after mixing
increases with mixing time
decreases with mixing time
decreases with mixing time
Newtonian fluid is one in which the viscosity
remains constant with time and power input
increases with the level of power input
decreases with the level of power input
drastically increases with the level of power input
remains constant with time and power input
Reynolds number for laminar flow over a plate should be less than
500 mm
5 x 10⁻⁵
5 x 10⁵
5 m
5 x 10⁵
The approach which is commonly used to determine the level of damage to animal cells in a culture medium is to monitor
the concentration of lactate in the medium
the level of lactate oxidase activity in the medium
the level of lactate dehydrogenase activity
the level of lactase activity in the medium
the level of lactate dehydrogenase activity
A Brookfield viscometer cannot determine the shear stress because
the shear stress is not defined
a computer is required
the impeller type is given only by numbers
all of the above
the shear stress is not defined
Which of the following is correct?
The viscosity of liquids and gases decrease with increasing temperature
The viscosity of liquids and gases increase with increasing temperature
the viscosity of gases increases with increasing temperature, but decreases in liquids
the viscosity of gases decreases with increasing temperature, but decreases in liquids.
the viscosity of gases increases with increasing temperature, but decreases in liquids
The Komologorov eddy size
is constant at all stirrer speeds
increases with stirrer speed
decreases with stirrer speed
becomes zero when the stirrer speed is very low
decreases with stirrer speed
Pluronic F68 protects mammalian cells from damage stems as it is a/an
surface active agent which stabilizes foams
surface active agent which destabilizes foams
excellent source of vitamins
coagulant
surface active agent which stabilizes foams
Reynolds number for turbulent flow over a plate should be more than
5 x 10⁻⁵
106
5 x 10⁵
500
106
Concentration polarization can be reduced further by
pre filtering the solution
reducing the flow rate per unit membrane surface area
back washing periodically
all of the above
all of the above