Biochemical Engineering

Question 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

Answer 1

c. structurally similar to the substrate.

Question 2

Linear inhibition is sometimes called as
a. complete inhibition
b. incomplete inhibition
c. partial inhibition
d. mixed inhibition

Answer 2

a. complete inhibition

Question 3

The types of inhibition pattern based on Michaelis Menten equation are
a. competitive
b. non-competitive
c. uncompetitive
d. all of the above

Answer 3

d. all of the above

Question 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

Answer 4

b. it can change the y-intercept

Question 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)

Answer 5

b. the complex dissociation step to produce product

Question 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

Answer 6

b. KM

Question 7

Which of these proteases is not a cysteine active site protease?
a. Calpain
b. Cathepsin D
c. Papain
d. None of the above

Answer 7

b. Cathepsin D

Question 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

Answer 8

a. A 10-fold increase in Vmax would increase velocity 10-fold y

Question 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

Answer 9

a. induced fit

Question 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

Answer 10

d. none of the above

Question 11

Which category of enzymes belongs to class two in the international classification?
a. Hydrolases
b. Ligases
c. Transferases
d. Isomerase

Answer 11

c. Transferases

Question 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

Answer 12

b. significant

Question 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

Answer 13

a. Haldane equation

Question 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

Answer 14

a. Dixon plot

Question 15

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

Answer 15

a. The activation energy of the reaction is lowered so that a larger proportion of the substrate qualifies to overcome it

Question 16

Which of the following common drugs is not a specific enzyme inhibitor?
a. Iodine
b. Methotrexate
c. Sulfanilamide
d. Penicillin

Answer 16

a. Iodine

Question 17

The enzyme inhibition can occur by
a. reversible inhibitors
b. irreversible inhibitors
c. Both (a) and (b)
d. None of these

Answer 17

c. Both (a) and (b)

Question 18

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

Answer 18

c. It changes the x-intercept

Question 19

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

Answer 19

d. Enzymes only function when they are in intact cells

Question 20

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

Answer 20

c. both (a) and (b)

Question 21

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

Answer 21

a. a temporary association

Question 22

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

Answer 22

a. 0.115

Question 23

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

Answer 23

d. all of these

Question 24

Quasi steady state is also known as
a. Michaelis Menten approach
b. Briggs-Haldane approach
c. Pseudo steady state
d. all of the above

Answer 24

c. Pseudo steady state

Question 25

Which of these enzymes contains a Zinc (Zn) ion? a. Carboxypeptidase A b. Phosphorylase B kinase c. Tyrosine hydroxylase d. Phosphodiesterase

Answer 25

a. Carboxypeptidase A

Question 26

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

Answer 26

b. increases KM and reduces Vmax

Question 27

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

Answer 27

a. participates in feedback regulation

Question 28

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

Answer 28

c. Both (a) and (b)

Question 29

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

Answer 29

a. reversibly to the enzyme substrate complex yielding an inactive ESI complex

Question 30

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

Answer 30

a. Hill plot

Question 31

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

Answer 31

a. specific activity

Question 32

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

Answer 32

a. (ν0 - νi)/ν0

Question 33

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))

Answer 33

a. rmaxS/(Km(1+I/Ki) +S))

Question 34

Classical noncompetitive inhibition is obtained only under a. slow equilibrium conditions b. moderate equilibrium conditions c. rapid equilibrium conditions d. non-equilibrium conditions

Answer 34

c. rapid equilibrium conditions

Question 35

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

Answer 35

b. rate of addition - rate of removal + rate of formation = 0

Question 36

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

Answer 36

c. 0.66

Question 37

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

Answer 37

a. competitive inhibition is greater than uncompetitive inhibition

Question 38

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

Answer 38

a. 13.54μ moles liter-1min-1

Question 39

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

Answer 39

a. rmaxS/ (Km + S) (1+I/Ki)

Question 40

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

Answer 40

b. Enzymes provide activation energy for reactions

Question 41

The slope of Lineweaver Burk plot for Michaelis Menten equation is a. Vmax/Km b. Km/Vmax c. 1/Km d. Km*Vmax

Answer 41

b. Km/Vmax

Question 42

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

Answer 42

d. 1/[S] → 0

Question 43

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

Answer 43

d. all of these

Question 44

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

Answer 44

d. All of these

Question 45

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

Answer 45

b. The product releasing step

Question 46

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

Answer 46

c. 0.5 * Vmax

Question 47

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

Answer 47

b. no effect on substrate binding and vice versa

Question 48

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

Answer 48

b. catalyzes a chemical reaction

Question 49

Enzymes are basically a. Proteins b. Vitamins c. Fat d. Carbohydrates

Answer 49

a. Proteins

Question 50

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

Answer 50

c. d(CES)/dt = 0

Question 51

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

Answer 51

b. decreasing energy of activation

Question 52

Which category of enzymes belongs to class 5 in the international classification? a. Hydrolases b. Isomerases c. Oxido-reductases d. Cyclase

Answer 52

b. Isomerases

Question 53

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

Answer 53

a. enzyme and substrate

Question 54

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

Answer 54

d. the rate at which the enzyme can convert substrate to product

Question 55

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)

Answer 55

a. rp = rmax Cs/(Km+Cs)

Question 56

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

Answer 56

a. 0.1 * Vmax

Question 57

β-amylase is a. endoenzyme b. exoenzyme c. saccharifying enzyme d. both (b) and (c)

Answer 57

d. both (b) and (c)

Question 58

Juice clarification extraction is facilitated by using a. Cellulases b. Amylase c. Inulinase d. Lactase

Answer 58

a. Cellulases

Question 59

Lysozyme is naturally present in a. egg white b. bacteria c. tears & milk d. all of these

Answer 59

d. all of these

Question 60

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

Answer 60

d. all of the above

Question 61

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

Answer 61

a. to stabilize mashing

Question 62

The bitter taste of the high protein materials is reduced by using a. Invertase b. Dectinase c. Protease d. none of these

Answer 62

c. Protease

Question 63

Sulphydryl oxidase is used for a. Discoloration b. clarification of images c. UHT milk off flavor removal d. all of these

Answer 63

c. UHT milk off flavor removal

Question 64

α-amylase is an endo enzyme which requires a. Ca b. Cu c. Mn d. None of these

Answer 64

a. Ca

Question 65

Liquefaction of starch to dextrin is carried out by a. α-amylase b. cellulase c. pectinase d. all of these

Answer 65

a. α-amylase

Question 66

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

Answer 66

c. Both (a) and (b)

Question 67

Milk digestibility is improved by using a. RNase b. Lactase c. β-amylase d. none of these

Answer 67

b. Lactase

Question 68

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

Answer 68

d. all of these

Question 69

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

Answer 69

a. catalyses hydrolysis of β-1-4 linkages between N-acetyl muranic acid and N-acetyl glucosamine in peptideoglycan

Question 70

Hersperidinase is used for a. juice clarification b. juice debittering c. off flavour reduction d. RNA reduction in fish

Answer 70

a. juice clarification

Question 71

Which of the following metallic ion is there in ascorbic acid oxidase? a. Mg b. Fe c. Cu d. Mn

Answer 71

c. Cu

Question 72

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

Answer 72

b. Glucose oxidase-catalase

Question 73

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)

Answer 73

d. both (a) and (b)

Question 74

Citrus juice debittering can be carried out using a. Limoninase b. Inulinase c. Anthocyanase d. None of these

Answer 74

a. Limoninase

Question 75

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

Answer 75

b. Thiaminase

Question 76

Soya off flavour removal may be achieved using a. di acetyl reductase b. β- amylase c. aldehyde oxidase d. protease

Answer 76

c. aldehyde oxidase

Question 77

The reduction in off flavour of beer is practiced through a. Hersperidinase b. Rnase c. Invertase d. diacetyl reductase

Answer 77

d. diacetyl reductase

Question 78

Discoloration can be achieved by using a. sulphloydryl oxidase b. proteases c. anthocyanase d. all of these

Answer 78

c. anthocyanase

Question 79

The prosthetic group present in phenolase enzyme is a. Mg b. Cu c. Ca d. Fe

Answer 79

b. Cu

Question 80

Enzymes degrade, alter or synthesize a food component through a. oxidation/reduction/isomerization b. hydrolysis/synthesis c. group transfer d. all of the above

Answer 80

d. all of the above

Question 81

The enzyme β-galactosidase is also known as a. Lactase b. EC3.2.1.23 c. both (a) and (b) d. isomerase

Answer 81

d. isomerase

Question 82

Chymosin hydrolyses the bond between a. Alanine and glycine b. Phenyl alanine and methionine c. Glutamic acid and alanine d. Alanine and phenyl alanine

Answer 82

b. Phenyl alanine and methionine

Question 83

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

Answer 83

d. all of the above

Question 84

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

Answer 84

a. no further increase in the cell population after a maximum value

Question 85

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

Answer 85

a. increase and the division rate increases to reach a maximum

Question 86

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

Answer 86

a. will increase with the concentration of the growth limiting substrate until it reaches a maximum value

Question 87

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

Answer 87

c. both acid and alcohol

Question 88

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

Answer 88

c. both (a) and (b)

Question 89

The phenomenon in which substrates are used in a sequential manner is known as a. trans-substrate genesis b. dialism c. diauxie d. multiplicity

Answer 89

c. diauxie

Question 90

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

Answer 90

a. F/VR

Question 91

Diauxie is a. growth factors b. microbiological die off c. the simultaneous uptake of nutrients d. the stagewise uptake of nutrients

Answer 91

d. the stagewise uptake of nutrients

Question 92

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

Answer 92

b. Chemostat

Question 93

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

Answer 93

a. nutrients available for the cells are depleted and begin to die

Question 94

The maximum specific growth rate of an organism depends on a. medium composition b. temperature c. pH d. All of these

Answer 94

d. All of these

Question 95

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

Answer 95

c. The Monod model was derived from an analysis of the mechanism of microbial growth

Question 96

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

Answer 96

a. large height to diameter ratio

Question 97

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

Answer 97

c. Both (a) and (b)

Question 98

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

Answer 98

c. Turbidostat

Question 99

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

Answer 99

b. dilution rate is higher than the maximum specific growth rate

Question 100

Fermenter should be filled with medium upto a. 65-70% b. 70-75% c. 75-80% d. 80-85%

Answer 100

c. 75-80%

Question 101

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

Answer 101

c. log of number of cells versus time

Question 102

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

Answer 102

a. Permeabilize

Question 103

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

Answer 103

c. Continuous packed bed reactor

Question 104

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

Answer 104

d. all of the above

Question 105

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

Answer 105

b. specific growth rate to the substrate availability

Question 106

The height to diameter ratio (H/D) for the column fermenters is a. <3 b. >3 c. <1.5 d. >1.5

Answer 106

b. >3

Question 107

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

Answer 107

d. all of the above

Question 108

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

Answer 108

a. In [biomass] against time for exponential phase data only

Question 109

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

Answer 109

a. Downcomer

Question 110

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

Answer 110

b. ln2/μ

Question 111

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

Answer 111

a. greater affinities to substrate

Question 112

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

Answer 112

a. decreases the productivity of the fermenter

Question 113

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

Answer 113

c. Both (a) and (b)

Question 114

In an airlift bioreactor, the spent gases released from the liquid are called a. Downcomer b. disengagement zone c. air riser d. flotsam

Answer 114

b. disengagement zone

Question 115

The contents in jet loop reactor are mixed through a. compressed air b. a mechanical agitator c. external pumping d. any of these

Answer 115

c. external pumping

Question 116

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

Answer 116

c. the rate of individual cells division or increase in their biomass

Question 117

The number of baffles in a standard stirred tank bioreactor is a. 8 b. 6 c. 4 d. 2

Answer 117

c. 4

Question 118

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

Answer 118

b. growth rate is equal to death rate

Question 119

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

Answer 119

d. All of the above

Question 120

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

Answer 120

d. all of the above

Question 121

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

Answer 121

c. maintaining uniform nutrients concentration

Question 122

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

Answer 122

b. concentration of growth limiting substrate is much greater than the Monod constant

Question 123

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

Answer 123

a. it is easier to clean and sterilize a reactor

Question 124

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

Answer 124

c. 1942

Question 125

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

Answer 125

a. cells tend to grow without dividing leading to a decrease in the surface area to volume ratio

Question 126

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

Answer 126

d. all of the above

Question 127

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

Answer 127

a. micro mixing

Question 128

The bubble column fermenter is usually limited to a. aerobic fermentations b. anaerobic fermentations c. Both (a) and (b) d. facultative fermentation

Answer 128

a. aerobic fermentations

Question 129

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

Answer 129

b. Batch

Question 130

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)

Answer 130

a. Cn= Cn0 exp [μ (t - t0)]

Question 131

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

Answer 131

a. 1/10th - 1/12th of the tank diameter

Question 132

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

Answer 132

c. because cells are auto catalysts

Question 133

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

Answer 133

c. substrate disliking

Question 134

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

Answer 134

c. changes during the fermentation

Question 135

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

Answer 135

a. high dilution rates near the washout point

Question 136

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

Answer 136

c. both (a) and (b)

Question 137

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

Answer 137

c. Both (a) and (b)

Question 138

The specific growth rate is affected by a. substrate concentration b. product concentration c. oxygen supply d. all of these

Answer 138

d. all of these

Question 139

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

Answer 139

b. distribute shear forces throughout the reactor and minimize bubble coalescence

Question 140

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

Answer 140

c. STF can't be used for high viscosity medium

Question 141

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

Answer 141

a. compressed air

Question 142

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

Answer 142

d. All of the above

Question 143

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

Answer 143

b. cells synthesize new proteins and membrane components

Question 144

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

Answer 144

b. the concentration of the substrate that controls the growth rate of the cells

Question 145

Tower fermenters are used for a. continuous penicillin production b. continuous beer production c. production of enzymes d. batch production of beer

Answer 145

b. continuous beer production

Question 146

In wastewater treatment, which bioreactor is generally used? a. Plug flow reactor b. Trickle bed reactor c. Tower fermenter d. CSTR

Answer 146

b. Trickle bed reactor

Question 147

The contents in stirred tank rector are mixed through a. compressed air b. a mechanical agitator c. external pumping d. any of these

Answer 147

b. a mechanical agitator

Question 148

The height to diameter ratio (H/D) for the tank fermenters is a. <3 b. >3 c. <1.5 d. >1.5

Answer 148

a. <3

Question 149

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

Answer 149

c. decrease the overall fermentation time

Question 150

In an airlift bioreactor, the air sparging region is called a. Downcomer b. disengagement zone c. air riser d. none of these

Answer 150

c. air riser

Question 151

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

Answer 151

c. better heat transfer efficiencies

Question 152

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

Answer 152

a. lag phase

Question 153

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

Answer 153

b. It does not consider factors that causes cells growth to stop or slow

Question 154

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

Answer 154

a. Disengagement zone, air riser, downcomer

Question 155

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

Answer 155

b. increased with stirring speed and increased with mixing time

Question 156

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

Answer 156

c. Both (a) and (b)

Question 157

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

Answer 157

b. pseudoplastic, thixotropic fluid

Question 158

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

Answer 158

d. all of the above

Question 159

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

Answer 159

b. 0.001 kg.m-1.s-1

Question 160

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

Answer 160

a. silicone tubing or gas permeable membranes to facilitate gas transfer

Question 161

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

Answer 161

b. non-Newtonian fluids

Question 162

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

Answer 162

b. Pseudoplastic

Question 163

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

Answer 163

d. decreases with increasing stirrer speed

Question 164

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

Answer 164

b. changes during mixing but returns to its original state after mixing

Question 165

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

Answer 165

a. be described as either laminar, transient or turbulent

Question 166

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

Answer 166

d. all of the above

Question 167

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

Answer 167

c. Viscoelastic

Question 168

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

Answer 168

a. shear stress arising during mixing of the cell culture fluid

Question 169

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

Answer 169

a. kg.m-1. s-1

Question 170

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

Answer 170

b. changes with the level of power input and/or the length of time during which the fluid is mixed

Question 171

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

Answer 171

c. A long chain protein such as albumin

Question 172

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

Answer 172

d. the torque required to move an impeller at a set speed

Question 173

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

Answer 173

d. All of the above

Question 174

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

Answer 174

a. acts on the surface properties of the cells and the culture medium

Question 175

Water is a a. Newtonian fluid b. Pseudoplastic c. Dilatant d. Rheopectic

Answer 175

a. Newtonian fluid

Question 176

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

Answer 176

d. All of these

Question 177

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

Answer 177

c. turbulent phase

Question 178

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

Answer 178

b. Rheopectic

Question 179

Which of the following can act as a shear protectorant? a. Serum b. Silicone oil c. Glucose d. Glutamic acid

Answer 179

a. Serum

Question 180

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

Answer 180

c. Dilatant

Question 181

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

Answer 181

c. increases with increasing stirrer speed

Question 182

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

Answer 182

c. increases with mixing time

Question 183

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

Answer 183

c. dilatant, rheopectic fluid

Question 184

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

Answer 184

c. filamentous fungi that grow as long poorly branched chains

Question 185

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

Answer 185

a. is constant regardless of the stirrer speed or mixing time

Question 186

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

Answer 186

c. turbulent flow

Question 187

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

Answer 187

a. the cell size is generally smaller than the critical eddy size at which shear will have an effect

Question 188

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

Answer 188

d. decreases with stirring speed and decreases with mixing time

Question 189

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

Answer 189

b. a shear protectorant

Question 190

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

Answer 190

c. 12,50,000

Question 191

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

Answer 191

d. Thixotropic

Question 192

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

Answer 192

d. All of the above

Question 193

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

Answer 193

d. decreases with mixing time

Question 194

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

Answer 194

a. remains constant with time and power input

Question 195

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

Answer 195

c. 5 x 105

Question 196

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

Answer 196

c. the level of lactate dehydrogenase activity

Question 197

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

Answer 197

a. the shear stress is not defined

Question 198

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.

Answer 198

c. the viscosity of gases increases with increasing temperature, but decreases in liquids

Question 199

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

Answer 199

c. decreases with stirrer speed

Question 200

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

Answer 200

a. surface active agent which stabilizes foams

Question 201

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

Answer 201

b. 10^6

Question 202

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

Answer 202

d. all of the above

Question 203

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

Answer 203

a. large distribution coefficients

Question 204

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

Answer 204

d. all of these

Question 205

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

Answer 205

d. all of these

Question 206

An ion exchange resin is composed of a. polymeric network b. ionic functional groups c. counter ions d. all of these

Answer 206

d. all of these

Question 207

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

Answer 207

c. 4-8% of the capital cost

Question 208

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

Answer 208

c. 30-60% by volume

Question 209

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

Answer 209

a. (1/A) dVf/dt = Δp/μ(L/K)

Question 210

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

Answer 210

a. 1.54 ft2

Question 211

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

Answer 211

a. ratio of the distribution coefficients in different solute

Question 212

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

Answer 212

b. lesser cost

Question 213

The effectiveness of a solvent can be measured by the a. distribution coefficients b. selectivity c. both (a) and (b) d. diffusivity

Answer 213

c. both (a) and (b)

Question 214

The stage wise operation of adsorption is called a. contact filtration b. conventional adsorption c. affinity adsorption d. ion exchange

Answer 214

a. contact filtration

Question 215

Which of the following is not the physical method for the cells rupturing? a. Milling b. Homogenization c. Ultrasonication d. Enzymatic digestion

Answer 215

d. Enzymatic digestion

Question 216

Conventional adsorption is a a. reversible process b. irreversible process c. either reversible or irreversible d. none of these

Answer 216

a. reversible process

Question 217

If the solute passes through membrane freely, the the rejection coefficient (s) is a. 1 b. 0 c. >1 d. <1

Answer 217

c. >1

Question 218

If the membrane rejects all solute, the rejection coefficient (s) is a. 1 b. 0 c. >1 d. <1

Answer 218

a. 1

Question 219

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

Answer 219

c. 4-5 weeks

Question 220

The conventional filtration involves the separation of large particles generally a. dp>5μm b. dp>10μm c. dp>15μm d. dp>20μm

Answer 220

b. dp>10μm

Question 221

Which of the operation does not come under upstream processing? a. Media preparation b. Inoculum development c. Effluent treatment d. Storage of raw material

Answer 221

c. Effluent treatment

Question 222

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

Answer 222

c. 6-10% of the capital cost

Question 223

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°

Answer 223

a. 0.02 to 10μm

Question 224

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

Answer 224

c. 5-10% of the capital cost

Question 225

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

Answer 225

a. J = Lp(Δp - σΔπ)

Question 226

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

Answer 226

d. All of the above

Question 227

For the extractions operation, the selectivity should be a. > 1 b. < 1 c. 1 d. Zero

Answer 227

a. > 1

Question 228

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

Answer 228

b. amount of solute eluted / amount of impurity eluted

Question 229

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

Answer 229

a. different rate of movement of the solute in the column

Question 230

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)

Answer 230

a. Y = YmaxX/(KL+X)

Question 231

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

Answer 231

a. 15,000 to 50,000 rpm

Question 232

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

Answer 232

a. Low molecular weight

Question 233

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

Answer 233

d. all of the above

Question 234

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

Answer 234

b. Glucose medium

Question 235

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

Answer 235

d. All of the above

Question 236

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

Answer 236

a. An extremely large surface area

Question 237

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.

Answer 237

d. State of immobilization is very sensitive to solution pH, ionic strength, and temperature.

Question 238

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

Answer 238

a. Equal to that of substrate consumption

Question 239

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

Answer 239

a. Covalent bond formation dependent

Question 240

For a steady state condition, the change of substrate concentration (dCS/dt) is a. Zero b. 1 c. > 1 d. < 1

Answer 240

a. Zero

Question 241

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.

Answer 241

a. The ratio of the maximum reaction rate to the maximum mass transfer rate.

Question 242

For glucose isomerization by immobilized enzyme, the reactor generally used is a. CSTR b. Plug flow c. Packed Bed d. Fluidized Bed

Answer 242

c. Packed Bed

Question 243

If Damkohler number, NDa >>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)

Answer 243

b. 𝑟𝑃=𝑘𝑆𝑎𝐶𝐶𝑠b

Question 244

The most commonly employed cross-linked polymer is the a. Polyacrylamide gel b. Collagen c. Celluloses d. Cation exchange resin

Answer 244

a. Polyacrylamide gel

Question 245

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

Answer 245

d. None of the above

Question 246

Commonly employed water insoluble supports the covalent attachment of enzyme include a. Acrylamide based polymers b. Polypeptides c. Dextran d. All of these

Answer 246

d. All of these

Question 247

Which of the following is not a physical method of immobilization? a. Adsorption b. Entrapment c. Micro encapsulation d. None of these

Answer 247

d. None of these

Question 248

The support material for immobilization of cells of Bacillus subtilis is a. Ion exchange resins b. Gelatin c. Anthracite d. Agarose and carbodiimide

Answer 248

d. Agarose and carbodiimide

Question 249

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

Answer 249

a. Copolymerization or microencapsulation

Question 250

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.

Answer 250

a. Nonessential amino acids residues to water insoluble, functional supports

Question 251

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

Answer 251

c. Actual reaction rate/rate if not slowed by diffusion

Question 252

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

Answer 252

d. None of the above

Question 253

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

Answer 253

b. Non-covalent bond formation dependent

Question 254

which of the following is the commonly employed adsorbents? a. Calcium carbonate b. Alumina c. Celluloses d. All of these

Answer 254

d. All of these

Question 255

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.

Answer 255

a. A diffusion cell with two compartments divided by a thin gel.

Question 256

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.

Answer 256

a. Increase of diffusivity and decreased with the increase of particle size.

Question 257

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

Answer 257

b. Conversion efficiency of a substrate into product.

Question 258

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

Answer 258

a. An aerated batch culture containing an initial high concentration of glucose.

Question 259

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.

Answer 259

b. Organism maintaining the lowest substrate concentration.

Question 260

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.

Answer 260

d. All of the above.

Question 261

The lowest yield of ATP is in a. Fermentation b. Aerobic respiration c. anaerobic respiration d. same in (a), (b), and (c)

Answer 261

a. Fermentation

Question 262

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

Answer 262

b. Release of gases by the microbial populations.

Question 263

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

Answer 263

a. 0 g/L-h

Question 264

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.

Answer 264

d. Cells will redirect ATP to the active transport of lactic acid and H+ out of the cells.

Question 265

Which of the following would not be subjected to the “glucose effect”? a. Aspergillus fumigatus b. Saccharomyces cerevisiae c. Escherichia coli d. Aspergillus niger

Answer 265

c. Escherichia coli

Question 266

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

Answer 266

d. All of the above

Question 267

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.

Answer 267

c. Biomass, substrate, and product concentrations do not change with time.

Question 268

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

Answer 268

b. Chemostat

Question 269

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

Answer 269

b. Can be determined from the dilution rate.

Question 270

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

Answer 270

c. Be constant.

Question 271

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.

Answer 271

c. Fast addition of alkanes will inhibit the cells and reduce oxygen transfer rates.

Question 272

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

Answer 272

d. 2 h

Question 273

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

Answer 273

b. Volume of reactor x substrate concentration in reactor

Question 274

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

Answer 274

b. Increase with dilution rate until washout

Question 275

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

Answer 275

a. Low biomass yields

Question 276

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

Answer 276

d. 200 g-lactate/L

Question 277

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

Answer 277

b. 6g

Question 278

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.

Answer 278

d. ATP is diverted away from anabolism to homeostasis.

Question 279

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.

Answer 279

a. Decrease abruptly.

Question 280

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.

Answer 280

b. Particles move with the fluid in a fluidized bed bioreactor.

Question 281

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

Answer 281

b. Initial mass of substrate in the reactor – final mass of substrate in the reactor + flow rate x [substrate in the feed]

Question 282

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

Answer 282

c. 2 h^-1

Question 283

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

Answer 283

a. Continuous packed bed reactor

Question 284

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

Answer 284

b. 0.5 g/L

Question 285

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

Answer 285

b. 0.5 g/g

Question 286

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

Answer 286

a. Continuous

Question 287

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.

Answer 287

d. All of the above.

Question 288

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

Answer 288

a. It can maintain low ethanol concentrations.

Question 289

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

Answer 289

c. Production becomes non-growth associated

Question 290

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.

Answer 290

a. Continuous packed bed reactor,

Question 291

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

Answer 291

a. 0 g/L

Question 292

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

Answer 292

a. Time rate of total amount in reactor = rate of addition to reactor – rate of removal + rate of formation

Question 293

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

Answer 293

b. 2 liter

Question 294

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.

Answer 294

c. Will be zero.

Question 295

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.

Answer 295

d. All of the above.

Question 296

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.

Answer 296

c. Fed batch fermenter

Question 297

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

Answer 297

a. 0.5/h

Question 298

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.

Answer 298

c. The continuous cultures are very useful for the production of pharmaceuticals.

Question 299

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.

Answer 299

c. Are located near entrance of feed.

Question 300

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.

Answer 300

d. All of the above.

Question 301

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

Answer 301

b. Be zero

Question 302

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

Answer 302

b. 2.2 g

Question 303

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

Answer 303

a. Pseudomonas aeruginosa

Question 304

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.

Answer 304

c. Year cells respire at low glucose concentrations.

Question 305

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.

Answer 305

b. The concentration of glucose in reactor 1 would be equal to reactor 2.

Question 306

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)

Answer 306

d. Both (a) and (b)

Question 307

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

Answer 307

b. Fed-batch reactor can be used to minimize starch concentrations and thus reduce the viscosity of the medium.

Question 308

The fastest route of NADH reoxidation is a. Aerobic respiration b. Anaerobic respiration c. Fermentation d. Decomposition

Answer 308

c. Fermentation

Question 309

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

Answer 309

a. Flow rate

Question 310

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

Answer 310

b. Hybridoma cells yield higher lactate at high glucose concentrations.

Question 311

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

Answer 311

a. Constant

Question 312

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.

Answer 312

a. Organic acids uncouple catabolism from anabolism.

Question 313

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.

Answer 313

b. Approximately 20 g dry weight per liter.

Question 314

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.

Answer 314

a. Plug flow fermenter

Question 315

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

Answer 315

b. Concentration oscillate around a mean value

Question 316

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

Answer 316

a. Enhances as the pH falls

Question 317

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.

Answer 317

c. Penicillin

Question 318

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

Answer 318

c. Ferment in the presence of high concentrations of sugar and dissolved oxygen.

Question 319

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

Answer 319

b. Growth associated

Question 320

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

Answer 320

c. X, and P will be zero while S is equal to the substrate concentration in feed.

Question 321

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

Answer 321

b. Less than 0.8/h

Question 322

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.

Answer 322

c. No effect of dissolved oxygen

Question 323

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.

Answer 323

d. All of the above.

Question 324

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.

Answer 324

c. Only at the end of the fermentation process

Question 325

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

Answer 325

b. Fructose di-phosphate accumulation inside the cells leading to fermentation.

Question 326

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

Answer 326

c. Both (a) and (b)

Question 327

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 *

Answer 327

b. 𝑃o/𝑁^3𝐷𝑖^5𝜌

Question 328

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

Answer 328

d. All of these

Question 329

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.

Answer 329

a. Directly proportional to the square root of the molecular diffusivity.

Question 330

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.

Answer 330

c. Detergent-like molecules are added.

Question 331

Which of the following impellers are used for wide range of viscosities? a. Paddles b. Turbines c. Propellers d. None of these

Answer 331

b. Turbines

Question 332

Which of the following type(s) of stirrer can be used for microbiological processes? a. Mig b. Intermig c. Turbine d. All of these

Answer 332

d. All of these

Question 333

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

Answer 333

a. 1/10 to 1/12

Question 334

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.

Answer 334

c. Measuring the steady state concentration of oxygen in the bulk liquid prior to inoculation of the reactor.

Question 335

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.

Answer 335

d. All of the above.

Question 336

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

Answer 336

b. Bubble boundary layer

Question 337

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) *

Answer 337

b. 𝐾𝐿=2(DAB/π te)^0.50

Question 338

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

Answer 338

a. 64 h-1

Question 339

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

Answer 339

b. Moving through the bubble boundary layer.

Question 340

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

Answer 340

c. Square of the impeller diameter

Question 341

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

Answer 341

a. 1:1

Question 342

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

Answer 342

c. Both (a) and (b)

Question 343

Transient flow range of mixing speed is obtained for a. Rei < 10 b. 10 < Rei < 104 c. Rei > 104 d. None of these

Answer 343

b. 10 < Rei < 104

Question 344

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

Answer 344

b. Axial flow impeller

Question 345

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

Answer 345

a. 1:3

Question 346

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

Answer 346

c. To ensure that the bulk of the energy consumption occurs at the blades.

Question 347

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

Answer 347

d. Calderbank and Moo-Young theory

Question 348

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)

Answer 348

c. Increase in stirrer speed

Question 349

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

Answer 349

a. 0.793 atm-L/mmol

Question 350

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

Answer 350

c. Both (a) and (b)

Question 351

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

Answer 351

c. A vertical pitch welded to a horizontal disk.

Question 352

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.

Answer 352

c. Discourages bubble coalescence.

Question 353

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.

Answer 353

c. Both (a) and (b)

Question 354

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.

Answer 354

c. Both (a) and (b)

Question 355

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.

Answer 355

a. The partial pressure of oxygen and the saturation concentration of oxygen in the liquid.

Question 356

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.

Answer 356

a. Imposed forced to inertial force.

Question 357

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 *

Answer 357

b. 𝑉𝐿=𝐻𝐿×𝜋×𝐷𝑡^2/4

Question 358

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 *

Answer 358

a. 𝐻=(𝑍𝑓-𝑍𝑙)/𝑍𝑓

Question 359

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)

Answer 359

d. Both (b) and (c)

Question 360

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

Answer 360

a. Crystal and precipitates are not too small, so as to ensure easy separation of the solids from the mother liquor.

Question 361

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.

Answer 361

d. A sparge stirred tank reactor agitated at 400 rpm.

Question 362

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.

Answer 362

a. Bubbles tend to coalesce under the impeller.

Question 363

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

Answer 363

d. All of the above

Question 364

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

Answer 364

d. All of the above

Question 365

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.

Answer 365

c. Faster cooling rates at a slower rate of pumping.

Question 366

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.

Answer 366

a. Increasing the partial pressure of oxygen at the base of the reactor.

Question 367

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

Answer 367

b. Off-center impellers should only be used with reactors with volumes less than 10 m^3.

Question 368

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

Answer 368

a. Lesser

Question 369

Which of the following stirrer requires least amount of energy for same yield? a. Mig b. Intermig c. Turbine d. Disc

Answer 369

b. Intermig

Question 370

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

Answer 370

d. 40,000 L

Question 371

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.

Answer 371

a. The saturation concentration of oxygen is higher.

Question 372

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) *

Answer 372

a. 𝑘𝐿∝(Pm/V)^0.33

Question 373

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

Answer 373

a. Increasing KLa but lowering CO*

Question 374

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

Answer 374

d. All of the above

Question 375

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.

Answer 375

c. Both (a) and (b)

Question 376

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

Answer 376

c. A Rushton turbine

Question 377

Power number (NP) is also known as a. Froude’s number b. Bond’s number c. Newton’s number d. Rayleigh’s number

Answer 377

c. Newton’s number

Question 378

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

Answer 378

a. The air escapes without being distributed by the agitator.

Question 379

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

Answer 379

c. 5.0 m

Question 380

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.

Answer 380

d. All of the above.

Question 381

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

Answer 381

a. 1.3 m

Question 382

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

Answer 382

a. The steady state oxygen concentration in a mixed aerated reactor before inoculation.

Question 383

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.

Answer 383

a. Using specially designed axial flow impellers.

Question 384

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

Answer 384

d. All of the above

Question 385

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.

Answer 385

c. Both (a) and (b)

Question 386

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

Answer 386

b. 0.8

Question 387

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

Answer 387

d. All of these

Question 388

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

Answer 388

a. 20 and 150 rpm

Question 389

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

Answer 389

a. Oxygen material balance in an aerated batch fermenter during the growth of microorganisms.

Question 390

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.

Answer 390

d. All of the above answers.

Question 391

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.

Answer 391

d. No conclusion can be drawn.

Question 392

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

Answer 392

b. Flooded impeller

Question 393

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.

Answer 393

d. No conclusion on the growth rate can be withdrawn.

Question 394

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 *

Answer 394

b. 𝐷𝑖^2Np/𝜇

Question 395

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.

Answer 395

a. Provide better lift of solids.

Question 396

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

Answer 396

c. 400 to 800 rpm

Question 397

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.

Answer 397

a. Concentration is less than the critical concentration.

Question 398

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

Answer 398

a. 𝐾𝐿=𝐷𝐴B/𝑍𝑓

Question 399

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

Answer 399

c. Both (a) and (b)

Question 400

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

Answer 400

b. 15 mg L-1 s-1

Question 401

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%

Answer 401

d. 25%

Question 402

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-

Answer 402

a. Zero

Question 403

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.

Answer 403

b. A Rushton turbine

Question 404

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

Answer 404

d. 1150 rpm or 1750 rpm

Question 405

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.

Answer 405

c. They provide high shear mixing conditions.

Question 406

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.

Answer 406

c. As the stirrer speed increases, the liquid will continue to circulate. Eventually a vortex will form.

Question 407

Turbulent flow range of mixing speed is obtained for a. Rei < 10 b. 10 < Rei < 104 c. Rei > 104 d. None of these

Answer 407

c. Rei > 104

Question 408

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 *

Answer 408

a. 𝑁𝑃=𝐾(𝑅𝑒𝑖)^−1

Question 409

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. *

Answer 409

c. 𝑁𝑃=𝐾

Question 410

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

Answer 410

a. 23 kg h^-1

Question 411

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

Answer 411

b. Provide low shear conditions and are suited for use in shear sensitive processes.

Question 412

Bioreactors, where vortex is formed, another dimensionless number, ___ is useful. a. Stanton b. Rayleigh c. Bond d. Froude

Answer 412

d. Froude

Question 413

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.

Answer 413

d. All of the above.

Question 414

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.

Answer 414

a. The reaction was mass transfer limited at 300 rpm.

Question 415

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.

Answer 415

b. Higher stirrer speed.

Question 416

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

Answer 416

b. 𝐻=𝑉s/(𝑉s+𝑉𝑡)

Question 417

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.

Answer 417

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.

Question 418

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

Answer 418

a. Axial flow

Question 419

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.

Answer 419

b. Highest at the base of the reactor.

Question 420

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

Answer 420

a. Propeller

Question 421

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

Answer 421

a. Rei < 10

Question 422

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

Answer 422

a. Reynolds number

Question 423

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.

Answer 423

c. Higher at the base of the reactor.

Question 424

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.

Answer 424

a. Increase the level of turbulence of the cooling water in the jacket.

Question 425

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

Answer 425

a. Lesser than the power required by an impeller in operating at same speed in a gas free system.

Question 426

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.

Answer 426

a. A bubble with a diameter of 1 mm.

Question 427

Which device is commonly used for measuring the rate of rotation (rpm) of the stirrer shaft? a. Anemometer b. Manometer c. Tachometer d. Barometer

Answer 427

c. Tachometer

Question 428

The sterilization method depends a. Nature of additive b. Volume and feed rate c. Both (a) and (b) d. None of these

Answer 428

c. Both (a) and (b)

Question 429

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)

Answer 429

a. ln(2)/D

Question 430

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

Answer 430

a. 𝑑𝑃/𝐷c

Question 431

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

Answer 431

a. Δ=𝐴.𝑡.𝑒^-𝐸𝑅𝑇

Question 432

The del factor (Δ) increases as the final number of cells a. Decreases b. Increases c. Zero d. Constant

Answer 432

a. Decreases

Question 433

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

Answer 433

b. Δoverall =Δheating+Δholding+Δcooling

Question 434

The filter material used for air filtration system is/are a. Glass wool b. Glass fibre c. Norite d. All of the above

Answer 434

d. All of the above

Question 435

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

Answer 435

a. Dispersion model

Question 436

The collection efficiency by diffusion increases with a. Decreasing particle size. b. Decreasing air velocity. c. Both (a) and (b) d. Increasing particle size

Answer 436

c. Both (a) and (b)

Question 437

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.

Answer 437

a. Lower pressure drop and are less liable to wetting or combustion.

Question 438

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

Answer 438

d. Increasing particle size

Question 439

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

Answer 439

a. Larger heat transfer area

Question 440

The mechanism of air filtration in fibrous filter is a. Electrostatic attraction b. Impaction c. Interception d. All of the above

Answer 440

d. All of the above

Question 441

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+∝)

Answer 441

a. 𝑉=𝑉o/(1−∝)

Question 442

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

Answer 442

a. Reynolds number

Question 443

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

Answer 443

c. Bacillus stearothermophilus

Question 444

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

Answer 444

c. 𝐽𝑛 =-𝐷 𝑑𝑐𝑛 /𝑑x

Question 445

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

Answer 445

b. < 0.5 μm

Question 446

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%.

Answer 446

c. The depth required to reduce population by 90%.

Question 447

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

Answer 447

c. Increases to an optimum with increase in air velocity and decreases on further increase of air velocity.

Question 448

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

Answer 448

a. 𝜂𝑖=0.075𝑁st^1.2

Question 449

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

Answer 449

c. Both (a) and (b)

Question 450

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

Answer 450

a. 1−nimp nint ndif

Question 451

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

Answer 451

a. Less rapid than in steam

Question 452

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

Answer 452

a. 0.5

Question 453

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

Answer 453

c. 23

Question 454

Sterilization can be carried out by a. Heat b. Radiation c. Chemical agents d. All of these

Answer 454

d. All of these

Question 455

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

Answer 455

a. Stokes and Reynolds number

Question 456

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

Answer 456

a. Adiabatic conditions

Question 457

The highest temperature which appears to be feasible for batch sterilization is a. 121°C b. 100°C c. 105°C d. 130°C

Answer 457

a. 121°C

Question 458

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

Answer 458

c. Both (a) and (b)

Question 459

The mechanical means of accomplishing sterilization of fermentation media/equipment is a. Ultrasonic b. Radiation c. Chemical agents d. None of these

Answer 459

a. Ultrasonic

Question 460

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

Answer 460

b. 0.6 m

Question 461

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.

Answer 461

a. Increased in a dry state.

Question 462

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

Answer 462

a. First order chemical reaction.

Question 463

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

Answer 463

b. 0.5 – 1.0 vvm

Question 464

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

Answer 464

a. 0.05 mg/L

Question 465

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.

Answer 465

c. Both temporary and permanent hardness of water.

Question 466

Conventional tertiary treatment is a. Chemical coagulation and flocculation b. Filtration c. Sedimentation d. None of these

Answer 466

a. Chemical coagulation and flocculation

Question 467

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

Answer 467

b. 300 ppm

Question 468

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

Answer 468

b. Amount of oxygen that would be removed from the water in order to oxidize pollution.

Question 469

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

Answer 469

c. Make it unfit for drinking.

Question 470

Permanent hard water may be softened by passing it through a. Sodium silicate b. Sodium bicarbonate c. Sodium hexametaphosphate d. Sodium phosphate

Answer 470

c. Sodium hexametaphosphate

Question 471

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

Answer 471

d. 10% sodium chloride solution

Question 472

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

Answer 472

c. Bicarbonates of calcium and magnesium

Question 473

Secondary treatment uses ___ to consume wastes. a. Microorganisms b. Chemicals c. Filtration d. None of these

Answer 473

a. Microorganisms

Question 474

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

Answer 474

c. Increase the percentage of gram(-)ve rods on utensils.

Question 475

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

Answer 475

c. Chlorides and sulfates of calcium and magnesium

Question 476

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

Answer 476

c. 2000 mg/L

Question 477

Acid used mostly for removal of milk stone a. Phosphoric acid b. Nitric acid c. Gluconic acid d. Tartaric acid

Answer 477

b. Nitric acid

Question 478

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

Answer 478

a. Aluminum sulphate

Question 479

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

Answer 479

c. UV radiation

Question 480

Sanitizer used specifically for vitreous enamel are a. Strong alkalis b. Strong acids c. Weak alkali with sodium silicate d. None of these

Answer 480

c. Weak alkali with sodium silicate

Question 481

The common methods used for disinfection in wastewater treatment plants are a. Chlorination b. UV light c. Both (a) and (b) d. Phenolic solvent

Answer 481

c. Both (a) and (b)

Question 482

Inhibitors are used along with sanitizer to a. Improve their action. b. To prevent corrosion. c. Both (a) and (b) d. None of these

Answer 482

b. To prevent corrosion.

Question 483

Sanitizers used for rubber made equipment are a. Strong acids b. Strong alkalis c. Combination of both d. None of these

Answer 483

b. Strong alkalis

Question 484

Which of the following substances are commonly used in a filter? a. Charcoal b. Sand c. Both (a) and (b) d. Aluminum chloride

Answer 484

c. Both (a) and (b)

Question 485

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

Answer 485

b. Secondary treatment

Question 486

The maximum permissible limit (BIS) of turbidity in drinking water is a. 5 NTU b. 10 NTU c. 15 NTU d. 20 NTU

Answer 486

b. 10 NTU

Question 487

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

Answer 487

b. Remove particles that are more dense than water.

Question 488

The ultimate source of water is a. Rivers and lakes b. Dew and forest c. Rain and snow d. Underground and surface

Answer 488

c. Rain and snow

Question 489

Permanent hardness of water may be removed by the addition of a. Lime b. Soda ash c. Potassium permagnate d. Sodium bicarbonate

Answer 489

b. Soda ash

Question 490

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

Answer 490

b. Sodium carbonate

Question 491

Lagoons may be characterized as a. Anaerobic b. Facultative c. Aerated d. All of these

Answer 491

d. All of these

Question 492

Temporary hardness of water may be removed by adding a. Calcium hydroxide b. Calcium carbonate c. Calcium chloride d. Sodium bicarbonate

Answer 492

a. Calcium hydroxide

Question 493

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

Answer 493

d. 0.001 mg/L

Question 494

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

Answer 494

b. Teepol

Question 495

The purest form of naturally occurring water is a. Rain water b. River water c. Pond water d. Well water

Answer 495

a. Rain water

Question 496

Calgon is used for removal of a. Sodium carbonate b. Permanent hardness of water c. Potassium carbonate d. None of these

Answer 496

b. Permanent hardness of water

Question 497

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

Answer 497

a. 5 proteolytic and/or lipolytic organisms per mL

Question 498

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

Answer 498

c. Influent water entering the reactor.

Question 499

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.

Answer 499

a. Fluid bed biological oxidation system.

Question 500

BOD stands for a. Biochemical oxygen demand b. British oxygen demand c. British oxygen depletion d. Biological oxygen depletion

Answer 500

a. Biochemical oxygen demand

Question 501

When temporary hard water is boiled, one of the substances formed is a. Calcium bicarbonate b. Calcium sulfate c. Hydrogen chloride d. Carbon dioxide

Answer 501

d. Carbon dioxide

Question 502

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

Answer 502

b. Insoluble zeolites

Question 503

The methods used for biological treatment are a. Lagoon b. Activated sludge process c. Oxidation ditches d. All of these

Answer 503

d. All of these

Question 504

Both temporary and permanent hardness of water can be removed by a. Boiling b. Distillation c. Filtration d. Decantation

Answer 504

b. Distillation

Question 505

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

Answer 505

d. Human feces