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Fermentation Kinetics and Biochemical Engineering, Exercises of Biochemistry

University of Cebu (UC)Biochemistry

Multiple choice questions and answers on various topics related to fermentation kinetics and biochemical engineering, including enzyme kinetics, heat transfer rates, residence time distribution, and more. It is a valuable resource for students and professionals in the field of biochemical engineering.

Typology: Exercises

2020/2021

Uploaded on 04/06/2024

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mark-lawrence-magsombol 🇵🇭

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BIOCHEMICAL ENGINEERING
MULTIPLE CHOICE QUESTIONS AND ANSWERS
ENZYMES AND KINETICS
Section 1
1. 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
2. Linear inhibition is sometimes called as
a. complete inhibition
b. incomplete inhibition
c. partial inhibition
d. mixed inhibition
3. The types of inhibition pattern based on
Michaelis Menten equation are
a. competitive
b. non-competitive
c. uncompetitive
d. all of the above
4. 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
5. 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)
6. 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
7. Which of these proteases is not a cysteine
active site protease?
a. Calpain
b. Cathepsin D
c. Papain
d. None of the above
8. 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
9. 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
10. 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
11. Which category of enzymes belongs to class
two in the international classification?
a. Hydrolases
b. Ligases
c. Transferases
d. Isomerase
12. 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
13. The relationship between Keq, Kmand Vmax is
known as
a. Haldane equation
b. Michaelis Menten equation
c. Numerical solution approach
d. Gibbs-Helmholtz equation
14. 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
Biochemical Engineering: Enzymes and Kinetics – Section 1 | 1
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MULTIPLE CHOICE QUESTIONS AND ANSWERS

ENZYMES AND KINETICS

Section 1

  1. 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
  2. Linear inhibition is sometimes called as a. complete inhibition b. incomplete inhibition c. partial inhibition d. mixed inhibition
  3. The types of inhibition pattern based on Michaelis Menten equation are a. competitive b. non-competitive c. uncompetitive d. all of the above
  4. 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
  5. 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)
  6. 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
  7. Which of these proteases is not a cysteine active site protease? a. Calpain b. Cathepsin D c. Papain d. None of the above
  8. 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
  9. 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
  10. 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
  11. Which category of enzymes belongs to class two in the international classification? a. Hydrolases b. Ligases c. Transferases d. Isomerase
  12. 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
  13. 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
  14. 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 Biochemical Engineering: Enzymes and Kinetics – Section 1 | 1

MULTIPLE CHOICE QUESTIONS AND ANSWERS

ENZYMES AND KINETICS

Section 1

  1. 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
  2. Which of the following common drugs is not a specific enzyme inhibitor? a. Iodine b. Methotrexate c. Sulfanilamide d. Penicillin
  3. The enzyme inhibition can occur by a. reversible inhibitors b. irreversible inhibitors c. Both (a) and (b) d. None of these
  4. 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
  5. 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
  6. 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
  7. 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
  8. 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. b. 0. c. 0. d. 6.
  9. 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
  10. Quasi steady state is also known as a. Michaelis Menten approach b. Briggs-Haldane approach c. Pseudo steady state d. all of the above
  11. Which of these enzymes contains a Zinc (Zn) ion? a. Carboxypeptidase A b. Phosphorylase B kinase c. Tyrosine hydroxylase d. Phosphodiesterase
  12. 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
  13. 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 Biochemical Engineering: Enzymes and Kinetics – Section 1 | 2

MULTIPLE CHOICE QUESTIONS AND ANSWERS

ENZYMES AND KINETICS

Section 2

  1. 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
  2. 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. (ν 0 - νi)/ν 0 b. (ν 0 + νi)/ν 0 c. (ν 0 νi)/ν 0 d. (ν 0 -νi)/νi
  3. 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))
  4. Classical noncompetitive inhibition is obtained only under a. slow equilibrium conditions b. moderate equilibrium conditions c. rapid equilibrium conditions d. non-equilibrium conditions
  5. 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
  6. 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. b. 0. c. 0. d. 0.
  7. 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
  8. An enzyme has a Km of 4.7 x 10-5M. If the Vmax of the preparation is 22m moles liter- 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- b. 6.68μ moles liter-1min- c. 7.57μ moles liter-1min- d. 17.8μ moles liter-1min-
  9. 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
  10. 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
  11. The slope of Lineweaver Burk plot for Michaelis Menten equation is a. Vmax/Km b. Km/Vmax c. 1/Km d. Km•Vmax
  12. 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
  13. 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 Biochemical Engineering: Enzymes and Kinetics – Section 2 | 4

MULTIPLE CHOICE QUESTIONS AND ANSWERS

ENZYMES AND KINETICS

Section 2

  1. 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
  2. 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
  3. 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
  4. 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
  5. 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
  6. Enzymes are basically a. Proteins b. Vitamins c. Fat d. Carbohydrates
  7. 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
  8. 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
  9. Which category of enzymes belongs to class 5 in the international classification? a. Hydrolases b. Isomerases c. Oxido-reductases d. Cyclase
  10. 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
  11. 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
  12. 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)
  13. 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 Biochemical Engineering: Enzymes and Kinetics – Section 2 | 5

MULTIPLE CHOICE QUESTIONS AND ANSWERS

ENZYMES AND APPLICATIONS

Section 1 b. Glucose oxidase-catalase c. Glucose oxidase-lactase d. All of these

  1. 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)
  2. Citrus juice debittering can be carried out using a. Limoninase b. Inulinase c. Anthocyanase d. None of these
  3. 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
  4. Soya off flavour removal may be achieved using a. di acetyl reductase b. β- amylase c. aldehyde oxidase d. protease
  5. The reduction in off flavour of beer is practiced through a. Hersperidinase b. Rnase c. Invertase d. diacetyl reductase
  6. Discoloration can be achieved by using a. sulphloydryl oxidase b. proteases c. anthocyanase d. all of these
  7. The prosthetic group present in phenolase enzyme is a. Mg b. Cu c. Ca d. Fe
    1. Enzymes degrade, alter or synthesize a food component through a. oxidation/reduction/isomerization b. hydrolysis/synthesis c. group transfer d. all of the above
    2. The enzyme β-galactosidase is also known as a. Lactase b. EC3.2.1. c. both (a) and (b) d. isomerase
    3. Chymosin hydrolyses the bond between a. Alanine and glycine b. Phenyl alanine and methionine c. Glutamic acid and alanine d. Alanine and phenyl alanine Biochemical Engineering: Enzymes and Applications – Section 1 | 7

MULTIPLE CHOICE QUESTIONS AND ANSWERS

FERMENTATION KINETICS

Section 1

  1. 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
  2. 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
  3. 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
  4. 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
  5. 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
  6. 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 7. The phenomenon in which substrates are used in a sequential manner is known as a. trans-substrate genesis b. dialism c. diauxie d. multiplicity 8. 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 9. Diauxie is a. growth factors b. microbiological die off c. the simultaneous uptake of nutrients d. the stagewise uptake of nutrients 10. 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 11. 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 12. The maximum specific growth rate of an organism depends on a. medium composition b. temperature c. pH d. All of these 13. 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 Biochemical Engineering: Fermentation Kinetics – Section 1 | 8

MULTIPLE CHOICE QUESTIONS AND ANSWERS

FERMENTATION KINETICS

Section 1 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

  1. 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
  2. Population doubling time, td can be expressed as (where μ is the specific growth rate.) a. log2/μ b. ln2/μ c. μ/ln d. μ/log
  3. 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
  4. 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
  5. 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
  6. In an airlift bioreactor, the spent gases released from the liquid are called a. Downcomer b. disengagement zone c. air riser d. flotsam
    1. The contents in jet loop reactor are mixed through a. compressed air b. a mechanical agitator c. external pumping d. any of these
    2. 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
    3. The number of baffles in a standard stirred tank bioreactor is a. 8 b. 6 c. 4 d. 2
    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
    5. 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
    6. Biomass concentrations during fermentation is a. diluting the samples to optical density less than 0. 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
    7. 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 Biochemical Engineering: Fermentation Kinetics – Section 1 | 10

MULTIPLE CHOICE QUESTIONS AND ANSWERS

FERMENTATION KINETICS

Section 1

  1. 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 Biochemical Engineering: Fermentation Kinetics – Section 1 | 11

MULTIPLE CHOICE QUESTIONS AND ANSWERS

FERMENTATION KINETICS

Section 2

  1. 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
  2. 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
  3. The specific growth rate is affected by a. substrate concentration b. product concentration c. oxygen supply d. all of these
  4. 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
  5. 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
  6. 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
    1. 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
    2. 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
    3. 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
    4. Tower fermenters are used for a. continuous penicillin production b. continuous beer production c. production of enzymes d. batch production of beer
    5. In wastewater treatment, which bioreactor is generally used? a. Plug flow reactor b. Trickle bed reactor c. Tower fermenter d. CSTR
    6. The contents in stirred tank rector are mixed through a. compressed air b. a mechanical agitator c. external pumping d. any of these
    7. The height to diameter ratio (H/D) for the tank fermenters is a. < b. > c. <1. d. >1. Biochemical Engineering: Fermentation Kinetics – Section 2 | 13

MULTIPLE CHOICE QUESTIONS AND ANSWERS

FERMENTATION KINETICS

Section 2

  1. 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
  2. In an airlift bioreactor, the air sparging region is called a. Downcomer b. disengagement zone c. air riser d. none of these
  3. 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
  4. 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
  5. 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
  6. 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 Biochemical Engineering: Fermentation Kinetics – Section 2 | 14

MULTIPLE CHOICE QUESTIONS AND ANSWERS

FLUID FLOW

Section 1 d. all of the above

  1. 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
  2. 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
  3. The SI unit for viscosity is a. kg.m-1. s- b. kg.m-2. s- c. kg.m-3. s- d. kg.m-1.s-
  4. 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
  5. 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
  6. 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
  7. 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
  8. The best described action of Pluronic F (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
  9. Water is a a. Newtonian fluid b. Pseudoplastic c. Dilatant d. Rheopectic
  10. 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
  11. 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
  12. 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
  13. Which of the following can act as a shear protectorant? a. Serum b. Silicone oil c. Glucose d. Glutamic acid Biochemical Engineering: Fluid Flow – Section 1 | 16

MULTIPLE CHOICE QUESTIONS AND ANSWERS

FLUID FLOW

Section 1

  1. 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
  2. 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
  3. 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
  4. 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
  5. 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
  6. 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
  7. 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
  8. 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
  9. 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
  10. 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
  11. 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, d. 1,000,
  12. 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
  13. Which of the following describes the importance of the Kolmogorov eddy size in the biotechnology? Biochemical Engineering: Fluid Flow – Section 1 | 17

MULTIPLE CHOICE QUESTIONS AND ANSWERS

DOWNSTREAM PROCESSING

Section 1

  1. 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
  2. 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
  3. 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
  4. 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
  5. An ion exchange resin is composed of a. polymeric network b. ionic functional groups c. counter ions d. all of these
  6. 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
  7. 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
  8. 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
  9. Filtration leaf test results indicate that the filtration rate of a protein product is 100 dry lbs/(ft^2 hr). What size production filter would be required to obtain 100 dry lbs of filter cake/hr? a. 1.54 ft^2 b. 3.08 ft^2 c. 65 ft^2 d. 65 lbs/ ft^2 .hr
  10. 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
  11. 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
  12. The effectiveness of a solvent can be measured by the a. distribution coefficients b. selectivity c. both (a) and (b) d. diffusivity
  13. The stage wise operation of adsorption is called a. contact filtration b. conventional adsorption c. affinity adsorption d. ion exchange
  14. Which of the following is not the physical method for the cells rupturing? a. Milling b. Homogenization c. Ultrasonication Biochemical Engineering: Downstream Processing – Section 1 | 19

MULTIPLE CHOICE QUESTIONS AND ANSWERS

DOWNSTREAM PROCESSING

Section 1 d. Enzymatic digestion

  1. Conventional adsorption is a a. reversible process b. irreversible process c. either reversible or irreversible d. none of these
  2. If the solute passes through membrane freely, the the rejection coefficient (s) is a. 1 b. 0 c. > d. <
  3. If the membrane rejects all solute, the rejection coefficient (s) is a. 1 b. 0 c. > d. <
  4. 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
  5. The conventional filtration involves the separation of large particles generally a. dp>5μm b. dp>10μm c. dp>15μm d. dp>20μm
  6. Which of the operation does not come under upstream processing? a. Media preparation b. Inoculum development c. Effluent treatment d. Storage of raw material
  7. 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
  8. 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°
  9. 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
  10. 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
  11. 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
  12. For the extractions operation, the selectivity should be a. > 1 b. < 1 c. 1 d. Zero
  13. 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
  14. 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 Biochemical Engineering: Downstream Processing – Section 1 | 20