Biochemical Engineering

Question 1

A competitive inhibitor of an enzyme is usually

• a highly reactive compound
• a metal ion such as Hg²⁺ or Pb²⁺
• structurally similar to the substrate.
• water insoluble

Answer 1

structurally similar to the substrate.

Question 2

Linear inhibition is sometimes called as

• complete inhibition
• incomplete inhibtion
• partial inhibition
• mixed inhibition

Answer 2

complete inhibition

Question 3

The types of inhibition pattern based on Michaelis Menten equation are

• competitive
• non-competitive
• uncompetitive
• all of the above

Answer 3

all of the above

Question 4

The effect of non-competitive inhibition on a Lineweaver-Burk Plot is that

it can move the entire curve to the right
it can change the y-intercept
it can change the x-intercept
all of these

Answer 4

it can change the y-intercept

Question 5

The rate-determining step of Michaelis Menten kinetics is

the complex formation step
the complex dissociation step to produce product
the product formation step
Both (a)and(c)

Answer 5

the complex dissociation step to produce product

Question 6

In competitive inhibition a factor is obtained from the measurement of

Vmax
KM
Y-intercept in Lineweaver-Burk Plot
None of these

Answer 6

KM

Question 7

Which of these proteases is not a cysteine active site protease?

Calpain
Cathepsin D
Papain
None of the above

Answer 7

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 10 fold increase in Vmax would increase velocity 10 fold y
A 10 fold decrease in Km would increase velocity
Both (a) and (b)
A 10 fold increase in Vmax would decrease velocity 20 fold

Answer 8

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

induced fit
transition
fit and fine
Pasteur

Answer 9

induced fit

Question 10

The active site of an enzyme remains

at the center of globular proteins
rigid and does not change shape
complementary to the rest of the molecule
none of the above

Answer 10

none of the above

Question 11

Which category of enzymes belongs to class two in the international classification?

Hydrolases
Ligases
Transferases
Isomerase

Answer 11

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

non-significant
significant
nothing to do with the reliability
non significant in selected cases

Answer 12

significant

Question 13

The relationship between Keq, Km and Vmax is known as

Haldane equation
Michaelis Menten equation
Numerical solution approach
Gibbs-Helmholtz equation

Answer 13

Haldane equation

Question 14

The reciprocal equation for non competitive inhibition can be arranged to the equation for the

Dixon plot
Woolf-Augusteinsson-Hofstee plot
Eadie-Scatchard plot
Hanes-Woolf plot

Answer 14

Dixon plot

Question 15

Which of the following statements is true for enzymatically catalyzed reaction?

The activation energy of the reaction is lowered so that a larger proportion of the substrate qualifies to overcome it
Additional substrate molecules are energized to overcome the activation energy of the reaction
The activation energy of the reaction is increased, thus decreasing the likelihood that any substrate molecules will overcome it
The activation energy of the reaction is lowered so that a fewer substrate molecules can overcome it

Answer 15

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?

Iodine
Methotrexate
Sulfbnilamide
Penicillin

Answer 16

Iodine

Question 17

The enzyme inhibition can occur by

reversible inhibitors
irreversible inhibitors
Both (a) and (b)
None of these

Answer 17

Both (a) and (b)

Question 18

In a Lineweaver-Burk Plot, competitive inhibitor shows which of the following effect?

It moves the entire curve to right
It moves the entire curve to left
It changes the x-intercept
It has no effect on the slope

Answer 18

It changes the x-intercept

Question 19

Which of the following statements is not true?

Enzymes are proteins that bind to specific substrates and increase the velocity of reactions involving those substrates
Enzymes function by overcoming the activation energy barrier of a reaction
Enzymes make thermodynamically favorable reactions to proceed; they cannot make unfavorable reactions to occur
Enzymes only function when they are in intact cells

Answer 19

Enzymes only function when they are in intact cells

Question 20

Non-competitive inhibitor of an enzyme catalyzed reaction

decreases Vmax
binds to Michaelis complex (ES)
both (a) and (b)
can actually increase reaction velocity in rare cases

Answer 20

both (a) and (b)

Question 21

An enzyme and a reactant molecule maintain relationship as

a temporary association
an association stabilized by a covalent bond
one in which the enzyme is changed permanently
non complementary binding

Answer 21

a temporary association

Question 22

An enzyme is assayed at an initial substrate concentration of 2 x 10⁻⁵ M. In 6 minute, half of the substrate is used. The Km for the substrate is 2 x 10⁻³ M. The value of k in minute is

0.115
0.42
0.093
6.693

Answer 22

0.115

Question 23

The plot commonly used for determining the value of Vmax is

Lineweaver Burk plot
Langmuir plot
Eadie Hofstee plot
all of these

Answer 23

all of these

Question 24

Quasi steady state is also known as

Michaelis Menten approach
Briggs-Haldane approach
Pseudo steady state
all of the above

Answer 24

Pseudo steady state

Question 25

Which of these enzymes contains a Zinc (Zn) ion?

Carboxypeptidase A
Phosphorylase B kinase
Tyrosine hydroxylase
Phosphodiesterase

Answer 25

Carboxypeptidase A

Question 26

A noncompetitive inhibitor of an enzyme-catalyzed reaction

increases KM and increases Vmax
increases KM and reduces Vmax
reduces KM and increases Vmax
reduces KM and reduces Vmax

Answer 26

increases KM and reduces Vmax

Question 27

An allosteric inhibitor of an enzyme usually

participates in feedback regulation
denatures the enzyme
is a hydrophobic compound
causes the enzyme to work faster

Answer 27

participates in feedback regulation

Question 28

Which of the following activity is possible by transferases?

Transfer of methyl groups
Transfer of glycosyl group
Both (a) and (b)
None of these

Answer 28

Both (a) and (b)

Question 29

A classical uncompetitive inhibitor is a compound that binds

reversibly to the enzyme substrate complex yielding an inactive ESI complex
irreversibly to the enzyme substrate complex yielding an inactive ESI complex
reversibly to the enzyme substrate complex yielding an active ESI complex
irreversibly to the enzyme substrate complex yielding an active ESI complex

Answer 29

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?

Hill plot
Koshland curve
Michaelis-Menten hyperbola
Can not be determined

Answer 30

Hill plot

Question 31

β-amylase is

endoenzyme
exoenzyme
saccharifying enzyme
both (b) and (c)

Answer 31

both (b) and (c)

Question 32

Juice clarification extraction is facilitated by using

cellulases
amylase
inulinase
lactase

Answer 32

cellulases

Question 33

Lysozyme is naturally present in

egg white
bacteria
tears & milk
all of these

Answer 33

all of these

Question 34

Enzymes act as antimicrobials

by depriving an organism of a necessary metabolite
by generating a substances toxic to the organism
by attracting a cell wall component
all of the above

Answer 34

all of the above

Question 35

Trichoderma β-glucanase is reported

to stabilize mashing
to convert taste fractions of dextrins to fermentable sugars in beer
to convert starch to dextrin
all of the above

Answer 35

to stabilize mashing

Question 36

The bitter taste of the high protein materials is reduced by using

invertase
dectinase
protease
none of these

Answer 36

protease

Question 37

Sulphydryl oxidase is used for

discoloration
clarification of images
UHT milk off flavour removal
all of these

Answer 37

UHT milk off flavour removal

Question 38

α-amylase is an endo enzyme which requires

Ca
Cu
Mn
None of these

Answer 38

Ca

Question 39

Liquefaction of starch to dextrin is carried out by

α-amylase
cellulase
pectinase
all of these

Answer 39

α-amylase

Question 40

Which is true about rennet?

It is a mixture of protease chymosin and pepsin
It is a mixture of rennin and pepsin
Both (a) and (b)
none of the above

Answer 40

Both (a) and (b)

Question 41

Milk digestibility is improved by using

RNase
lactase
β-amylase
none of these

Answer 41

lactase

Question 42

Which of the following mainly serve to convert starch into high fructose corn syrup (HFCS)?

α-amylase
Gluco-isomerase
Gluco-amylase
all of these

Answer 42

all of these

Question 43

Lysozyme

catalyses hydrolysis of β-1-4 linkages between N-acetyl muranic acid and N-acetyl glucosamine in peptideoglycan
catalyses hydrolysis of α-1-4 linkages between N-acetyl muranic acid and N-acetyl glucosamine in peptideoglycan
catalyses hydrolysis of α-1-4 linkages between N-diacetyl muranic acid and N-diacetyl glucosamine in peptideoglycan
all of the above

Answer 43

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

Question 44

Hersperidinase is used for

juice clarification
juice debittering
off flavour reduction
RNA reduction in fish

Answer 44

juice clarification

Question 45

Which of the following metallic ion is there in ascorbic acid oxidase?

Mg
Fe
Cu
Mn

Answer 45

Cu

Question 46

Which of the enzyme combination is commercially used for the removal of oxygen?

Glucose oxidase-cellulase
Glucose oxidase-catalase
Glucose oxidase-lactase
All of these

Answer 46

Glucose oxidase-catalase

Question 47

The enzyme used to reduce bitterness of grapes commonly contains

α-L-rhamonosidase
β-d-glucosidase
β- galactosidase
both (a) and (b)

Answer 47

both (a) and (b)

Question 48

Citrus juice debittering can be carried out using

limoninase
inulinase
anthocyanase
None of these

Answer 48

limoninase

Question 49

Which of the following enzyme is responsible for causing vitamin B deficiency disease beriberi?

Ascorbic acid oxidase
Thiaminase
Lipoxygenase
None of these

Answer 49

Thiaminase

Question 50

Soya off flavour removal may be achieved using

di acetyl reductase
β- amylase
aldehyde oxidase
protease

Answer 50

aldehyde oxidase

Question 51

The reduction in off flavour of beer is practiced through

hersperidinase
rnase
invertase
diacetyl reductase

Answer 51

diacetyl reductase

Question 52

Discoloration can be achieved by using

sulphloydryl oxidase
proteases
anthocyanase
all of these

Answer 52

anthocyanase

Question 53

The prosthetic group present in phenolase enzyme is

Mg
Cu
Ca
Fe

Answer 53

Cu

Question 54

Enzymes degrade, alter or synthesize a food component through

oxidation/reduction/isomerization
hydrolysis/synthesis
group transfer
all of the above

Answer 54

all of the above

Question 55

The enzyme β-galactosidase is also known as

lactase
EC3.2.1.23
both (a) and (b)
isomerase

Answer 55

both (a) and (b)

Question 56

Chymosin hydrolyses the bond between

Alanine and glycine
Phenyl alanine and methonine
Glutamic acid and alanine
Alanine and phenyl alanine

Answer 56

Phenyl alanine and methonine

Question 57

The ratio of the amount of a protein present in a sample, which is used as a measure of purification, is known as

specific activity
relative activity
purity ratio
all of these

Answer 57

specific activity

Question 58

If a reaction occurs in the absence of inhibitor with rate ν0 and in the presence of inhibitor with rate νi, the degree of inhibition is defined as

(ν0 - νi)/ν0
(ν0 + νi)/ν0
(ν0νi)/ν0
(ν0-νi)/νi

Answer 58

(ν0 - νi)/ν0

Question 59

The rate equation in competitive inhibition based on Michaelis Menten equation is given by

rmaxS/(Km (1+I/Ki)+S))
rmaxE/(Km (1+I/Ki)+S))
rmaxI/(Km (1+I/Ki)+S))
rmaxS/(Km (1+I/Ki))

Answer 59

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

Question 60

Classical noncompetitive inhibition is obtained only under

slow equilibrium conditions
moderate equilibrium conditions
rapid equilibrium conditions
non-equilibrium conditions

Answer 60

rapid equilibrium conditions

Question 61

In the steady state the material balance equation for any component of a system is

rate of addition + rate of removal - rate of formation = 0
rate of addition - rate of removal + rate of formation = 0
rate of addition + rate of removal + rate of formation = 0
none of the above

Answer 61

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

Question 62

For an enzyme that displays Michaelis-Menten kinetics, the reaction velocity (as a fraction of Vmax) observed at [S] = 2 KM will be

0.09
0.33
0.66
0.91

Answer 62

0.66

Question 63

Predominantly uncompetitive inhibition may be called when

competitive inhibition is greater than uncompetitive inhibition
competitive inhibition is smaller than uncompetitive inhibition
competitive inhibition is equal to uncompetitive inhibition
none of the above

Answer 63

competitive inhibition is greater than uncompetitive inhibition

Question 64

An enzyme has a Km of 4.7 x 10-5M. If the Vmax of the preparation is 22m moles liter-1 min-1, what velocity would be observed in the presence of 2.0 x 10-4M substrate and 5.0 x 10-5M of a competitive inhibitor?

13.54μ moles liter-1min-1
6.68μ moles liter-1min-1
7.57μ moles liter-1min-1
17.8μ moles liter-1min-1

Answer 64

13.54μ moles liter-1min-1

Question 65

The rate equation in non-competitive inhibition based on Michaelis Menten equation is given by

rmaxS/(Km + S)(1+I/Ki)
rmaxE/(Km (1+I/Ki)+S))
VmaxS/(Km + S)(1+I/Ki)
rmaxS/Km

Answer 65

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

Question 66

Which of the following statement(s) regarding enzymes, is/are false?

Enzymes are always proteins that function as catalysts
Enzymes provide activation energy for reactions
Enzyme activity can be regulated
Enzymes may be used many times for a specific reaction

Answer 66

Enzymes provide activation energy for reactions

Question 67

The slope of Lineweaver Burk plot for Michaelis Menten equation is

Vmax/Km
Km/Vmax
1/Km
Km.Vmax

Answer 67

Km/Vmax

Question 68

The initial velocity, V0, of an enzyme catalyzed reaction reaches Vmax as

[S] = KM
[S] = 10 * KM
1/[S] = 1/KM
1/[S] → 0

Answer 68

1/[S] → 0

Question 69

The usual method(s) to solve rate equation of simple enzyme kinetics is/are

Michaelis Menten approach
Briggs-Haldane approach
Numerical solution approach
all of these

Answer 69

all of these

Question 70

Michaelis Menten equation can also be written as

(-Cs)/r = (Cs/rmax)+(Km/rmax)
1/r = (1/rmax)+(Km/(rmax.Cs))
r = rmax-(Km.r/Cs)
All of these

Answer 70

All of these

Question 71

Which of the following step is assumed to be the slowest step in the Michaelis Menten equation?

The substrate consuming step
The product releasing step
Formation of enzyme substrate complex
None of these

Answer 71

The product releasing step

Question 72

When substrate [S] = KM (Michaelis-Menten constant), the velocity of an enzyme catalyzed reaction is about

0.1 * Vmax
0.2 * Vmax
0.5 * Vmax
0.9 * Vmax

Answer 72

0.5 * Vmax

Question 73

A classical noncompetitive inhibitor has

no effect on substrate binding
no effect on substrate binding and vice versa
significant effect on substrate binding
significant effect on substrate binding and vice versa

Answer 73

no effect on substrate binding and vice versa

Question 74

The active site of an enzyme differs from an antibody-antigen binding site in that the enzyme active site

contains modified amino acids
catalyzes a chemical reaction
is complementary to a specific ligand
contains amino acids without side chains

Answer 74

catalyzes a chemical reaction

Question 75

Enzymes are basically

proteins
vitamins
fat
carbohydrates

Answer 75

proteins

Question 76

Which of the following refers to pseudo steady state ?

d(CE)/dt = 0
d(Cp)/dt = 0
d(CES)/dt = 0
d(Cs)/dt = d(CES)/dt

Answer 76

d(CES)/dt = 0

Question 77

Most enzymes work by

increasing energy of activation
decreasing energy of activation
not affecting energy of activation
none of the above

Answer 77

decreasing energy of activation

Question 78

Which category of enzymes belongs to class 5 in the international classification?

Hydrolases
Isomerases
Oxido-reductases
Cyclase

Answer 78

Isomerases

Question 79

Lock and key theory is based on the compatibility of

enzyme and substrate
enzyme and product
enzyme and enzyme substrate complex
enzyme substrate complex and product

Answer 79

enzyme and substrate

Question 80

When an enzyme is functioning at Vmax, the rate of the reaction is limited by

the number of collisions between enzyme and substrate
the number of substrate molecules in the reaction
the concentration of the substrate
the rate at which the enzyme can convert substrate to product

Answer 80

the rate at which the enzyme can convert substrate to product

Question 81

The equation for the rate of product formation for simple enzyme reaction is given by (Where rmax, maximum reaction rate, Cs substrate concentration, Cp product concentration ES, CES enzyme-substrate concentration)

rp = rmax Cs/(Km+Cs)
rp= rmax CES/(Km+ CES)
rp = rmax Cs/(Km+CES)
rp = rmax Cs/(Km+Cp)

Answer 81

rp = rmax Cs/(Km+Cs)

Question 82

When [S] = 0.1 *KM, the velocity of an enzyme catalyzed reaction is about:

0.1 * Vmax
0.3 * Vmax
0.5 * Vmax
0.7 * Vmax

Answer 82

0.1 * Vmax

Question 83

The function of the disengagement zone in an airlift fermenter is to

prevent CO2 rich bubbles from entering the downcomer
reduce the velocity of the bubbles
reduce liquid loss as aerosols
all of the above

Answer 83

all of the above

Question 84

Stationary phase is described as

no further increase in the cell population after a maximum value
deceleration of growth and division rate after the growth rate reaches a maximum
acceleration of growth and division rate after the growth rate reaches a maximum
deceleration of growth and division rate after the growth rate reaches a minimum

Answer 84

no further increase in the cell population after a maximum value

Question 85

In the accelerated phase, cell starts to

increase and the division rate increases to reach a maximum
decrease and the division rate increases to reach a maximum
increase and the division rate decreases to reach a maximum
increase and the division rate increases to reach a minimum

Answer 85

increase and the division rate increases to reach a maximum

Question 86

The monod model predicts that the specific growth rate

will increase with the concentration of the growth limiting substrate until it reaches a maximum value
will decrease with the concentration of the growth limiting substrate
will increase with the concentration of the growth limiting substrate
does not depend on growth limiting substrate

Answer 86

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

both alcohol and carbon dioxide
both acid and carbon dioxide
both acid and alcohol
several different kinds of acid

Answer 87

both acid and alcohol

Question 88

The function of a mechanical seal is to

prevent contaminants entering the reactor
prevent cells from leaving the reactor
both (a) and (b)
prevent air to enter

Answer 88

both (a) and (b)

Question 89

The phenomenon in which substrates are used in a sequential manner is known as

trans-substrate genesis
dialism
diauxie
multiplicity

Answer 89

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)

F/VR
VR/F
μ/F
F/μ

Answer 90

F/VR

Question 91

Diauxie is

growth factors
microbiological die off
the simultaneous uptake of nutrients
the stagewise uptake of nutrients

Answer 91

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-organisms is removed is called

manostat
chemostat
turbidostat
culturostat

Answer 92

chemostat

Question 93

In the death phase

nutrients available for the cells are depleted and begin to die
the number of viable cells will increase
nutrients available for cells are replenished and start to multiply
none of the above

Answer 93

nutrients available for the cells are depleted and begin to die

Question 94

The maximum specific growth rate of an organism depends on

medium composition
temperature
pH
All of these

Answer 94

All of these

Question 95

Which of the following is not correct for the Monod model and the Michaelis Menten Model?

The Michaelis Menten Model was derived from a curve fitting exercise
The Michaelis Menten model was derived from an analysis of the mechanism of microbial growth
The Monod model was derived from an analysis of the mechanism of microbial growth
All of the above

Answer 95

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

Question 96

Bubble column reactor has

large height to diameter ratio
small height to diameter ratio
large diameter to height ratio
small diameter to height ratio

Answer 96

large height to diameter ratio

Question 97

Why a T-flask used in small-scale cell culture is incubated in a horizontal position?

To save space
To increase the surface area of the liquid-air interface
Both (a) and (b)
To increase the rate of oxygen transfer into the liquid

Answer 97

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

manostat
chemostat
turbidostat
culturostat

Answer 98

turbidostat

Question 99

Wash out in steady state fermentation occurs when

dilution rate is less than maximum specific growth rate
dilution rate is higher than the maximum specific growth rate
cell concentration reaches the maximum
specific growth rate is maximum

Answer 99

dilution rate is higher than the maximum specific growth rate

Question 100

Fermentor should be filled with medium upto

65-70%
70-75%
75-80%
80-85%

Answer 100

75-80%

Question 101

Bacterial growth curve is obtained by plotting

number of cells versus time
number of spores versus time
log of number of cells versus time
log of number of cells survived versus time

Answer 101

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.

permeabilize
lyophilize
heat-kill
denature

Answer 102

permeabilize

Question 103

Heat transfer rates (per unit volume) will be lowest in

Stirred tank bioreactor with biomass recycle
Continuous air lift bioreactor
Continuous packed bed reactor
Continuous fluidized bed bioreactor

Answer 103

Continuous packed bed reactor

Question 104

The function(s) of the draft tube in an airlift bioreactor is

to reduce bubble coalescence
to improve circulation
to even out shear conditions throughout the reactor
all of the above

Answer 104

all of the above

Question 105

The Monod Model relates

substrate utilized with the biomass consumption
specific growth rate to the substrate availability
yield with the biomass utilization
the biomass concentration with specific growth rate

Answer 105

specific growth rate to the substrate availability

Question 106

The height to diameter ratio (H/D) for the column fermenters is

<3
>3
<1.5
>1.5

Answer 106

> 3

Question 107

The high oxygen transfer efficiencies of airlift bioreactors is due to

the large aspect ratio of the reactor, which leads to a high gas hold-up
the large aspect ratio of the reactor, which leads to a high oxygen solubility at the base of the reactor
the draft tube, which reduces bubble coalescence in the reactor
all of the above

Answer 107

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

In [biomass] against time for exponential phase data only
In [biomass] against time
biomass against time
biomass against time for stationary phase data only

Answer 108

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

downcomer
disengagement zone
air riser
flotsam

Answer 109

downcomer

Question 110

Population doubling time, td can be expressed as (where μ is the specific growth rate.)

log2/μ
ln2/μ
μ/ln2
μ/log2

Answer 110

ln2/μ

Question 111

A higher Ks value of Monod’s equation means

greater affinities to substrate
lower affinities to substrate
unaffected with the substrate bonding
lower dissociation constant value

Answer 111

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

decreases the productivity of the fermenter
increases the productivity of the fermenter
modestly increases the productivity of the fermenter
does not affect on the productivity

Answer 112

decreases the productivity of the fermenter

Question 113

Which of the following is correct for the prediction of time requirement in a batch fermenter?
Carrying out experiments
Mathematical modelling of the fermentation process
Both (a) and (b)
It is impossible to predict the time required for fermentation

Answer 113

Both (a) and (b)

Question 114

In an airlift bioreactor, the spent gases released from the liquid are called

downcomer
disengagement zone
air riser
flotsam

Answer 114

disengagement zone

Question 115

The contents in jet loop reactor are mixed through

compressed air
a mechanical agitator
external pumping
any of these

Answer 115

external pumping

Question 116

The specific growth rate (μ) is defined as

the concentration of biomass in the reactor
rate of increase of total biomass in a reactor
the rate of individual cells division or increase in their biomass
the rate of cell death

Answer 116

the rate of individual cells division or increase in their biomass

Question 117

The number of baffles in a standard stirred tank bioreactor is

8
6
4
2

Answer 117

4

Question 118

In the stationary phase

growth is proportional to death
growth rate is equal to death rate
growth rate is lesser than death rate
no co-relation exist between death rate and growth rate

Answer 118

growth rate is equal to death rate

Question 119

Which of the following is an example of a mathematical model?

Volume of cuboid = length x breadth x height
The Monod Model
The Michaelis Menten Equation
All of the above

Answer 119

All of the above

Question 120

Biomass concentrations during fermentation is

diluting the samples to optical density less than 0.3
monitored by controlling the changes in biomass concentrations
considering that optical density is proportional to the surface area of the biomass in the sample
all of the above

Answer 120

all of the above

Question 121

Chemostats work on the principle of

maintaining constant volume of culture medium
maintaining continuous flow of nutrients
maintaining uniform nutrients concentration
operating at higher pressure

Answer 121

maintaining uniform nutrients concentration

Question 122

During the exponential phase the maximum specific growth rate equals specific growth rate as

concentration of the growth limiting substrate is much less than the monod constant
concentration of growth limiting substrate is much greater than the monod constant
specific growth rate increases exponentially
concentration of the growth limiting substrate is equal to the monod constant

Answer 122

concentration of growth limiting substrate is much greater than the monod constant

Question 123

An internal draft tube is preferrred to an external draft tube because

it is easier to clean and sterilize a reactor
it is cheaper to build a reactor with an internal draft tube
Both (a) and (b)
none of the above

Answer 123

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

1958
1946
1942
1950

Answer 124

1942

Question 125

The optical density sometimes drops during the lag phase because

cells tend to grow without dividing leading to a decrease in the surface area to volume ratio
of fast cell growth causing them to fill up with DNA
cells swell up with water
cells swell up with RNA

Answer 125

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

raw materials used in biotechnology are biodegradable
the products of biotechnology are biodegradable
it is a very competitive business (d) all of the above
all of the above

Answer 126

all of the above

Question 127

Residence time distribution (RTD) of a reactor is independent of

micro mixing
volume of reactor
height of the reactor
width of the reactor

Answer 127

micro mixing

Question 128

The bubble column fermenter is usually limited to

aerobic fermentations
anaerobic fermentations
Both (a) and (b)
facultative fermentation

Answer 128

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.

continuous
batch
fed-batch
semi continuous

Answer 129

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

Cn= Cn0 exp[μ (t - t0)]
Cn0 = Cn exp[μ (t - t0)]
Cn/Cn0 =(1/μ)exp(t-t0)
Cn0 / Cn = (1/μ)exp(t-t0)

Answer 130

Cn= Cn0 exp[μ (t - t0)]

Question 131

The diameter of the baffles in a standard stirred tank bioreactor ranges from

1/10th - 1/12th of the tank diameter
1/3rd - 1/4th of the tank diameter
1/15th - 1/20th of the tank diameter
1/20th - 1/25th of the tank diameter

Answer 131

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

Question 132

During the log phase cell numbers increase exponentially

because cells produce enzymes
because cells do not have cell membranes
because cells are autocatalysts
because the rate of cell division increases exponentially

Answer 132

because cells are autocatalysts

Question 133

Lag phase occurs mainly due to

acclimatization with new environment and substrate
higher growth temperature
substrate disliking
variation in substrate concentration

Answer 133

acclimatization with new environment and substrate

Question 134

In a batch reactor specific growth rate

remains constant throughout the process
increases exponentially
changes during the fermentation
is highest during the stationary phase

Answer 134

changes during the fermentation

Question 135

Turbidostat is recommended when continuous fermentation needs to be carried out at

high dilution rates near the washout point
low dilution rates near the washout point
moderate dilution rates near the washout point
any intensity of dilution rates near the washout point

Answer 135

high dilution rates near the washout point

Question 136

The advantage of airlift bioreactors over stirred tank bioreactors of a similar size is

higher oxygen transfer rates
more uniform shear conditions
both (a) and (b)
less foaming

Answer 136

both (a) and (b)

Question 137

Stirred tank fermenter (STF) can be employed for

aerobic fermentation of a wide range of cells including microbial, animal and plant cells
anaerobic fermentation of a wide range of cells including microbial, animal and plant cells
Both (a) and (b)
anaerobic fermentation of plant cells only

Answer 137

Both (a) and (b)

Question 138

The specific growth rate is affected by

sabstrate concentration
product concentration
oxygen supply
all of these

Answer 138

all of these

Question 139

The main function(s) of a draft tube in an air lift fermenter is/are to

increase the solubility of oxygen
distribute shear forces throughout the reactor and minimise bubble coalescence
concentrate shear forces around the sparger
concentrate shear forces near the disengagement zone

Answer 139

distribute shear forces throughout the reactor and minimise bubble coalescence

Question 140

Which of the following is incorrect?

The mechanical agitation and aeration are effective for suspension of cells
The mechanical agitation and aeration are effective for mixing the medium
STF can’t be used for high viscosity medium
The mechanical agitation and aeration are effective for oxygenation

Answer 140

STF can’t be used for high viscosity medium

Question 141

The contents in bubble column and air lift reactor are mixed through

compressed air
a mechanical internal moving part
external pumping
any of these

Answer 141

external pumping

Question 142

Which of the following statements would be appropriate while comparing bubble column and air lift fermenter of the same size?

The average bubble size is smaller in an airlift bioreactor
Oxygen transfer rate is higher in an airlift bioreactor
The surface area for gas exchange is higher in an airlift bioreactor
All of the above

Answer 142

All of the above

Question 143

During the lag phase

cells just start growing
cells synthesize new proteins and membrane components
cells produce antibiotics to kill competing organisms
cells simply grow slowly

Answer 143

cells synthesize new proteins and membrane components

Question 144

Concentration of the growth limiting substrate means

trace elements concentration
the concentration of the substrate that controls the growth rate of the cells
sugar concentration in the fermentation medium
dissolved oxygen concentration

Answer 144

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

Question 145

Tower fermentors are used for

continuous penicillin production
continuous beer production
production of enzymes
batch production of beer

Answer 145

continuous beer production

Question 146

n wastewater treatment, which bioreactor is generally used?

Plug flow reactor
Trickle bed reactor
Tower fermentor
CSTR

Answer 146

Trickle bed reactor

Question 147

The contents in stirred tank rector are mixed through

compressed air
a mechanical agitator
external pumping
any of these

Answer 147

a mechanical agitator

Question 148

The height to diameter ratio (H/D) for the tank fermenters is

<3
>3
<1.5
>1.5

Answer 148

<3

Question 149

The relatively large volume (10 to 40% of total fermenter volume) of the seed culture is employed to

increase the overall fermentation time
increase the overall yield of biomass
decrease the overall fermentation time
decrease the overall yield of product

Answer 149

decrease the overall fermentation time

Question 150

In an airlift bioreactor, the air sparging region is called

downcomer
disengagement zone
air riser
none of these

Answer 150

air riser

Question 151

The air riser is located on the outside of the draft tube for the large-scale airlift bioreactors because of

higher oxygen transfer rates
a small sparge ring
better heat transfer efficiencies
all of these

Answer 151

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

lag phase
stationary phase
death phase
exponential growth phase

Answer 152

lag phase

Question 153

Which of the following(s) is/are considered the limitations of the exponential growth model?

Only predicts that cells grow exponentially during the log phase
It does not consider factors that causes cells growth to stop or slow
Predicts cell growth at a linear rate
All of the above

Answer 153

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?

Disengagement zone, air riser, downcomer
Flotsam, jetsam, downzone
Air comer, disentanglement zone, downsizer
All of the above

Answer 154

Disengagement zone, air riser, downcomer

Question 155

The viscosity of liquid was classified as both dilatant and rheopectic, which means that the viscosity

increased with stirring speed but decreased with mixing time
increased with stirring speed and increased with mixing time
decreased with stirring speed but increased with mixing time
decreased with stirring speed and decreased with mixing time

Answer 155

increased with stirring speed and increased with mixing time

Question 156

Which of the following describes the detrimental effect of bubbles on animal cells?

Cells trapped on the surface of bubbles can be damaged when the bubbles explode, releasing their pressure and surface energies
Cells trapped in the moving foam can be dragged apart by the bubbles
Both (a) and (b)
Bubbles can explode in the liquid medium causing the release of ultraviolet radiation

Answer 156

Both (a) and (b)

Question 157

A fluid in which the viscosity decreases with increasing stirrer speed and mixing time, can be represented as

newtonian fluid
pseudoplastic, thixotropic fluid
dilatant, rheopectic fluid
dilatant, pseudoplastic fluid

Answer 157

pseudoplastic, thixotropic fluid

Question 158

Filamentous fungal cells are more shear sensitive than bacterial cells because of

the presence of citin in cell walls of filamentous fungi
larger in size than bacterial cells and therefore are more susceptible to shear forces
fungal cells are much larger than bacterial cells
all of the above

Answer 158

all of the above

Question 159

The viscosity of water at STP is approximately

0.005 kg.m-1.s-1
0.001 kg.m-1.s-1
0.003 kg.m-2.s-1
0.1 g.cm-1.s-1

Answer 159

0.001 kg.m-1.s-1

Question 160

Bubble free aeration systems requires

silicone tubing or gas permeable membranes to facilitate gas transfer
carbon dioxide instead of air to supply oxygen
silicone tubing or gas permeable membranes to remove carbon dioxide by oxygen in the form of hydrogen peroxide
filled headspace of the reactor with carbon dioxide

Answer 160

silicone tubing or gas permeable membranes to facilitate gas transfer

Question 161

Non-linear relationship between shear stress and shear rate exists in

newtonian fluids
non-newtonian fluids
both (a) and (b)
none of these

Answer 161

non-newtonian fluids

Question 162

If the viscosity of a fluid decreases with increasing stirrer speed, then the nature of the fluid is

newtonian
pseudoplastic
dilatant
thixotropic

Answer 162

pseudoplastic

Question 163

A pseudoplastic fluid is one in which the viscosity

is constant regardless of the stirrer speed or mixing time
changes during mixing but returns to its original state after mixing
increases with increasing stirrer speed
decreases with increasing stirrer speed

Answer 163

decreases with increasing stirrer speed

Question 164

A viscoelastic fluid is one in which the viscosity

is constant regardless of the stirrer speed or mixing time
changes during mixing but returns to its original state after mixing
increases with increasing stirrer speed
decreases with increasing stirrer speed

Answer 164

changes during mixing but returns to its original state after mixing

Question 165

Mixing in stirred tank reactors can

be described as either laminar, transient or turbulent
achieve turbulent conditions by increasing the stirrer speed
induce laminar flow conditions by the addition of baffles
all of the above

Answer 165

be described as either laminar, transient or turbulent

Question 166

In animal cell bioreactor, bubble damage can be minimized by

the addition of a shear protectorant
using a bubble free oxygen delivery system
headspace aeration
all of the above

Answer 166

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

newtonian
rheopectic
viscoelastic
thixotropic

Answer 167

viscoelastic

Question 168

In sparged mammalian cell bioreactors, the cell damage is caused because of

shear stress arising during mixing of the cell culture fluid
shear stresses arising from the breakup of bubbles at the liquid surface
shear stresses between bubbles in foam at the liquid surface
all of the above

Answer 168

shear stress arising during mixing of the cell culture fluid

Question 169

The SI unit for viscosity is

kg.m-1.s-1
kg.m-2.s-2
kg.m-3.s-1
kg.m-1.s-2

Answer 169

kg.m-1.s-1

Question 170

The viscous nature of a non-Newtonian fluid

remains constant with time and power input
changes with the level of power input and/or the length of time during which the fluid is mixed
is similar to that of a perfect gas
is similar to that of water

Answer 170

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 globular protein
Glucose
A long chain protein such as albumin
Water

Answer 171

A long chain protein such as albumin

Question 172

A Brookfield viscometer measures viscosity by determining

the shear stress
the shear rate
the shear stress and shear rate
the torque required to move an impeller at a set speed

Answer 172

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?

Cell size
Availability of nutrients in the medium
The presence of shear protectorants in the medium
All of the above

Answer 173

All of the above

Question 174

The best described action of Pluronic F68 (non-ionic detergent) in a cell culture medium is that, it

acts on the surface properties of the cells and the culture medium
provides nutrients for the cells
acts as a flocculant
acts as a coagulant

Answer 174

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

Question 175

Water is a

newtonian fluid
pseudoplastic
dilatant
rheopectic

Answer 175

newtonian fluid

Question 176

Which of the following affect the Kolmogorov eddy size?

Stirrer speed
Physical properties of the liquid
Size and type of impeller
All of these

Answer 176

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

laminar phase
transient phase
turbulent phase
any of the phase

Answer 177

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

newtonian
rheopectic
viscoelastic
thixotropic

Answer 178

rheopectic

Question 179

Which of the following can act as a shear protectorant?

Serum
Silicone oil
Glucose
Glutamic acid

Answer 179

Serum

Question 180

The viscosity of a fluid increases with increasing stirrer speed. This fluid would be best described as being

newtonian
pseudoplastic
dilatant
thixotropic

Answer 180

dilatant

Question 181

A dilatant fluid is one in which the viscosity

is constant regardless of the stirrer speed or mixing time
changes during mixing but returns to its original state after mixing
increases with increasing stirrer speed
decreases with increasing stirrer speed

Answer 181

increases with increasing stirrer speed

Question 182

A rheopectic fluid is one in which the viscosity

is constant regardless of the stirrer speed or mixing time
changes during mixing but returns to its original state after mixing
increases with mixing time
decreases with mixing time

Answer 182

increases with mixing time

Question 183

A fluid in which the viscosity increases with increasing stirrer speed and mixing time can be called as

newtonian fluid
pseudoplastic, thixotropic fluid
dilatant, rheopectic fluid
dilatant pseudoplastic fluid

Answer 183

dilatant, rheopectic fluid

Question 184

The medium will have the highest viscosity (considering that the cells do not secrete gums) with the presence of

single celled bacteria
filamentous fungi that form pellets
filamentous fungi that grow as long poorly branched chains
yeast

Answer 184

filamentous fungi that grow as long poorly branched chains

Question 185

A Newtonian fluid is one in which the viscosity

is constant regardless of the stirrer speed or mixing time
changes during mixing but returns to its original state after mixing
increases with increasing stirrer speed
decreases with increasing stirrer speed

Answer 185

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?

Laminar flow
Transient flow
turbulent flow
all of these

Answer 186

all of these

Question 187

Animal cell cultures do not have much effect on shear forces because

the cell size is generally smaller than the critical eddy size at which shear will have an effect
cells are larger than the critical eddy size at which shear will have an effect
animal cells have cell walls
animal cells have cell membranes

Answer 187

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

increases with stirring speed but decreases with mixing time
increases with stirring speed and increases with mixing time
decreases with stirring speed but increases with mixing time
decreases with stirring speed and decreases with mixing time

Answer 188

decreases with stirring speed and decreases with mixing time

Question 189

Pluronic F68 is added to cell culture media as

a nutrient
a shear protectorant
to increase oxygen transfer rates
all of these

Answer 189

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

2500
100
12,50,000
1,000,000

Answer 190

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

newtonian
rheopectic
viscoelastic
thixotropic

Answer 191

thixotropic

Question 192

Which of the following describes the importance of the Kolmogorov eddy size in the biotechnology?

The Kolmogorov eddy size is a measure of the smallest eddy size in a liquid
When the Kolmogorov eddy size become equivalent or smaller than the cell or particle diameter, then the cell or particle will become susceptible to shear damage
At the Kolmogorov eddy size, much of the energy of the originating eddy will be released
All of the above

Answer 192

All of the above

Question 193

A thixotropic fluid is one in which the viscosity

is constant regardless of the stirrer speed or mixing time
changes during mixing but returns to its original state after mixing
increases with mixing time
decreases with mixing time

Answer 193

decreases with mixing time

Question 194

Newtonian fluid is one in which the viscosity

remains constant with time and power input
increases with the level of power input
decreases with the level of power input
drastically increases with the level of power input

Answer 194

remains constant with time and power input

Question 195

Reynolds number for laminar flow over a plate should be less than

500 mm
5 x 10⁻⁵
5 x 10⁵
5 m

Answer 195

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

the concentration of lactate in the medium
the level of lactate oxidase activity in the medium
the level of lactate dehydrogenase activity
the level of lactase activity in the medium

Answer 196

the level of lactate dehydrogenase activity

Question 197

A Brookfield viscometer cannot determine the shear stress because

the shear stress is not defined
a computer is required
the impeller type is given only by numbers
all of the above

Answer 197

the shear stress is not defined

Question 198

Which of the following is correct?

The viscosity of liquids and gases decrease with increasing temperature
The viscosity of liquids and gases increase with increasing temperature
the viscosity of gases increases with increasing temperature, but decreases in liquids
the viscosity of gases decreases with increasing temperature, but decreases in liquids.

Answer 198

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

Question 199

The Komologorov eddy size

is constant at all stirrer speeds
increases with stirrer speed
decreases with stirrer speed
becomes zero when the stirrer speed is very low

Answer 199

decreases with stirrer speed

Question 200

Pluronic F68 protects mammalian cells from damage stems as it is a/an

surface active agent which stabilizes foams
surface active agent which destabilizes foams
excellent source of vitamins
coagulant

Answer 200

surface active agent which stabilizes foams

Question 201

Reynolds number for turbulent flow over a plate should be more than

5 x 10⁻⁵
106
5 x 10⁵
500

Answer 201

106

Question 202

Concentration polarization can be reduced further by

pre filtering the solution
reducing the flow rate per unit membrane surface area
back washing periodically
all of the above

Answer 202

all of the above

Question 203

A system which require less solvent and produces a more concentrated extract phase, is desired with a

large distribution coefficients
small distribution coefficients
very small distribution coefficients
constant distribution coefficients

Answer 203

large distribution coefficients

Question 204

The efficiency of cell disruption in a bead mill depends on the

concentration of the cells
amount and size of beads
type and rotational speed of agitation
all of these

Answer 204

all of these

Question 205

A common filter medium is the cloth filter generally made of

canvas
synthetic fabrics
metal or glass fiber
all of these

Answer 205

all of these

Question 206

An ion exchange resin is composed of

polymeric network
ionic functional groups
counter ions
all of these

Answer 206

all of these

Question 207

Maintenance cost varies from

0-4% of the capital cost
12-16% of the capital cost
4-8% of the capital cost
8-12% of the capital cost

Answer 207

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

5-15% by volume
15-30% by volume
30-60% by volume
60-90% by volume

Answer 208

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)

(1/A) dVf/dt = Δp/μ(L/K)
dVf/dt = (1/A)Δp/μ(L/K)
(1/A) dVf/dt = Δp/μ LK
dVf/dt = (1/A)Δp/μ LK

Answer 209

(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?

1.54 ft²
3.08 ft²
65 ft²
65 lbs/ ft².hr

Answer 210

1.54 ft²

Question 211

Selectivity can be expressed as

ratio of the distribution coefficients in different solute
mass fraction of the solute in the extract phase at equilibrium
mass fraction of the solute in the raffinate phase
ratio of the mass fraction of the solute in the extract phase to the raffinate phase

Answer 211

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

continuous operation
lesser cost
higher speed
ease in operation

Answer 212

lesser cost

Question 213

The effectiveness of a solvent can be measured by the

distribution coefficients
selectivity
both (a) and (b)
diffusivity

Answer 213

both (a) and (b)

Question 214

The stage wise operation of adsorption is called

contact filtration
conventional adsorption
affinity adsorption
ion exchange

Answer 214

contact filtration

Question 215

Which of the following is not the physical method for the cells rupturing?

Milling
Homogenization
Ultrasonication
Enzymatic digestion

Answer 215

Enzymatic digestion

Question 216

Conventional adsorption is a

reversible process
irreversible process
either reversible or irreversible
none of these

Answer 216

reversible process

Question 217

If the solute passes through membrane freely, the the rejection coefficient (s) is

1
0
>1
<1

Answer 217

0

Question 218

If the membrane rejects all solute, the rejection coefficient (s) is

1
0
>1
<1

Answer 218

1

Question 219

In antibiotic manufacturing processes, the fermentation time ranges from

2-3 weeks
1-2 weeks
4-5 weeks
2-4 weeks

Answer 219

4-5 weeks

Question 220

The conventional filtration involves the separation of large particles generally

dp>5μm
dp>10μm
dp>15μm
dp>20μm

Answer 220

dp>10μm

Question 221

Which of the operation does not come under upstream processing?

Media preparation
Inoculum development
Effluent treatment
Storage of raw material

Answer 221

Effluent treatment

Question 222

For cost analysis in a fermentor system, the depreciation cost varies from

5-6% of the capital cost
6-7% of the capital cost
6-10% of the capital cost
8-10% of the capital cost

Answer 222

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

0.02 to 10μm
1-10A°
20-30μm
10-200A°

Answer 223

0.02 to 10μm

Question 224

Start up expenses in a fermentation industry varies from

0-5% of the capital cost
10-15% of the capital cost
5-10% of the capital cost
15-20% of the capital cost

Answer 224

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)

J = Lp(Δp - σΔπ)
J/A = Lp(Δp - σΔπ)
J= Lp/σΔπ
J/A = Lp/Δp

Answer 225

J = Lp(Δp - σΔπ)

Question 226

Which of the following is considered as a pretreatment to the biological feeds?

Heating to denature the proteins
Addition of filter aids to increase the porosity
Addition of electrolytes
All of the above

Answer 226

All of the above

Question 227

For the extractions operation, the selectivity should be

> 1
< 1
1
zero

Answer 227

> 1

Question 228

The purity of a solute collected between two times t1 and t2 during chromatographic separation can be calculated as

amount of solute eluted - amount of impurity eluted
amount of solute eluted / amount of impurity eluted
amount of solvent eluted + amount of impurity eluted
amount of solvent eluted / amount of impurity eluted

Answer 228

amount of solute eluted / amount of impurity eluted

Question 229

Chromatography is based on the

different rate of movement of the solute in the column
separation of one solute from other constituents by being captured on the adsorbent
different rate of movement of the solvent in the column
any of the above

Answer 229

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)

Y = YmaxX/(KL+X)
Y= Ymax/(KL+X)
Y= YmaxX/KL
Y = Ymax- X/ (KL+X)

Answer 230

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

15,000 to 50,000 rpm
50,000 to 100,000 rpm
100,000 to 150,000 rpm
150,000 to 200,000 rpm

Answer 231

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

low molecular weight
high molecular weight
high equivalent weight
low reactivity

Answer 232

low molecular weight

Question 233

Functional groups of the nonessential amino acid residues that are suitable for the immobilization process are

free α-, β- or γ carb oxyl groups
α or β amino groups
phenyl, hydroxyl, sulfhydryl or imidazole groups
all of the above

Answer 233

all of the above

Question 234

Which medium is used for the production of Penicillin using immobilized cells

1% peptone medium
glucose medium
Yeast extract medium
LB broth

Answer 234

glucose medium

Question 235

Which of the following is taken as an assumption in the distributed model?

The reaction occurs at every position and the kinetics of the reaction are of the same form as observed for free enzyme.
Mass transfer through the immobilized enzyme occurs via molecular diffusion
There is no mass transfer limitation at the outside surface of the spherical immobilized enzyme
All of the above

Answer 235

All of the above

Question 236

The immobilized enzyme produced by micro encapsulation technique provides

an extremely large surface area
smaller surface area
high amount of solvent
relatively smaller surface area

Answer 236

an extremely large surface area

Question 237

Which of the following is considered as a disadvantage to the adsorption method of immobilization?

It is possible to separate and purify the enzymes while being immobilized
The enzymes are not usually deactivated by adsorption
The adsorption is a reversible process
State of immobilization is very sensitive to solution pH, ionic strength and temperature

Answer 237

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

equal to that of substrate consumption
more than that of substrate consumption
lesser than that of substrate consumption
is nothing to do with the substrate consumption

Answer 238

equal to that of substrate consumption

Question 239

The immobilized technique involving chemical method is

covalent bond formation dependent
non-covalent bond formation dependent
both (a) and (b)
ionic bond formation dependent

Answer 239

covalent bond formation dependent

Question 240

For a steady state condition, the change of substrate concentration (dCs/dt) is

zero
1
>1
<1

Answer 240

zero

Question 241

Damkohler number(NDa) is

the ratio of the maximum reaction rate to the maximum mass transfer rate
the ratio of the minimum reaction rate to the maximum mass transfer rate
the ratio of the maximum reaction rate to the minimum mass transfer rate
the ratio of the minimum reaction rate to the minimum mass transfer rate

Answer 241

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

CSTR
plug flow
packed bed
fluidized bed

Answer 242

packed bed

Question 243

If Damkohler number, NDa&raquo_space;1, the reaction rate is much greater than the mass transfer rate and the overall reaction is controlled by the rate of mass transfer. In this case, the enzyme reaction can be described as (where Csb and Cs are the substrate concentration in bulk of solution and at the immobilized enzyme surface respectively. ks mass transfer coefficient, and a is the surface area of an immobilized enzyme particles)

rp = ksa(Csb-Cs)
rp = ksaCsb
rp = ksaCs
rp = ksa(Csb+Cs)

Answer 243

rp = ksaCsb

Question 244

The most commonly employed cross-linked polymer is the

polyacrylamide gel
collagen
celluloses
cation exchange resin

Answer 244

polyacrylamide gel

Question 245

Which of the following is not the correct answer?

Immobilized enzyme may show selectively altered chemical properties
Immobilized enzyme may show selectively altered physical properties
Immobilized enzyme may simulate the realistic natural environment where the enzyme come from the cell
None of the above

Answer 245

None of the above

Question 246

Commonly employed water insoluble supports for the covalent attachment of enzyme include

acrylamide based polymers
polypeptides
dextran
all of these

Answer 246

all of these

Question 247

Which of the following is not a physical method of immobilization?

Adsorption
Entrapment
Micro encapsulation
None of these

Answer 247

None of these

Question 248

The support material for immobilization of cells of Bacillus subtilis is

ion exchange resins
gelatin
Anthracite
agarose and carbodiimide

Answer 248

agarose and carbodiimide

Question 249

The intraparticle mass transfer resistance can affect the rate of enzyme reaction, if enzymes are immobilized by

copolymerization or microencapsulation
crosslinking using multifunctional reagents
adsorption
all of the above

Answer 249

copolymerization or microencapsulation

Question 250

The covalent attachment of enzyme molecules is via

nonessential amino acids residues to water insoluble, functional supports
essential amino acids residues to water insoluble, functional supports
nonessential amino acids residues to water soluble, functional supports
essential amino acids residues to water soluble, functional supports

Answer 250

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

reaction rate/rate if not slowed by diffusion
rate if not slowed by diffusion/ reaction rate
actual reaction rate/ rate if not slowed by diffusion
rate if not slowed by diffusion/ actual reaction rate

Answer 251

actual reaction rate/ rate if not slowed by diffusion

Question 252

Which is not the method for producing immobilized enzymes with multifunctional reagents?

Enzymes are adsorbed on the surface active support followed by intermolecular cross linking
Functional groups are introduced on the support to react co-valently with enzymes
Enzymes are cross linked intermolecularly
None of the above

Answer 252

None of the above

Question 253

The immobilization technique involving physical method is

covalent bond formation dependent
non-covalent bond formation dependent
both (a) and (b)
ionic bond formation dependent

Answer 253

non-covalent bond formation dependent

Question 254

Which of the following is the commonly employed adsorbents?

Calcium carbonate
Alumina
Celluloses
All of these

Answer 254

All of these

Question 255

Various techniques are available for determining the effective diffusivity of solute in gel. Thin disk method uses

a diffusion cell with two compartments divided by a thin gel
a diffusion cell with two compartments
a diffusion cell with two compartments plus by a thin gel
a diffusion cell with two compartments multiply by a thin gel

Answer 255

a diffusion cell with two compartments divided by a thin gel

Question 256

The effectiveness factor increases with the

increase of diffusivity and decreased with the increase of particle size
increase of diffusivity and increased with the increase of particle size
decrease of diffusivity and decreased with the increase of particle size
increase of diffusivity and decrease with the decrease of particle size

Answer 256

increase of diffusivity and decreased with the increase of particle size

Question 257

Yield coefficient represents

total biomass or product produced
conversion efficiency of a substrate into product
conversion rate of a substrate into biomass or product
production time of biomass or product

Answer 257

conversion efficiency of a substrate into product

Question 258

The lowest biomass yield in a culture of Escherichia coli will be in

an aerated batch culture containing a initial high concentration of glucose
an aerated batch reactor containing an initial low concentration of glucose
an aerated fed-batch reactor having a low glucose concentration
an aerated continuous reactor having a low glucose concentration

Answer 258

an aerated batch culture containing a 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?

Organism maintaining the highest substrate concentration
Organism maintaining the lowest substrate concentration
Both (a) and (b)
Organism maintaining the moderate substrate concentration

Answer 259

Organism maintaining the lowest substrate concentration

Question 260

The continuous cultures are not widely used in industry because

they are not suited for the production of secondary metabolites
contamination or mutation can have a disastrous effect on the operation
the government will not approve the licensing of pharmaceuticals produced in continuous cultures
all of the above

Answer 260

all of the above

Question 261

The lowest yield of ATP /is in

fermentation
aerobic respiration
anaerobic respiration
same in (a), (b) and (c)

Answer 261

fermentation

Question 262

Mixing in an anaerobic sludge blanket reactor is due to

rapid change in water temperatures throughout the reactor
release of gases by the microbial populations
swimming of microbes
none of the above

Answer 262

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-1 of peptone, then the rate of protogon synthesis would be

0 g.l⁻¹h⁻¹
0.5 g.l⁻¹h⁻¹
1 g.l⁻¹h⁻¹
2 g.l⁻¹h⁻¹

Answer 263

0 g.l⁻¹h⁻¹

Question 264

Formation of end product by Lactococcus lactis will become non-growth associated as lactic acid accumulates because

cells will redirect ATP to anabolism
cells will redirect NAD+ to anabolism
cells will redirect ATP to facilitate the diffusion of lactic acid and H+ out of the cells
cells will redirect ATP to the active transport of lactic acid and H+ out of the cells

Answer 264

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”?

Aspergillus fumigatus
Saccharomyces cerevisiae
Escherichia coli
Aspergillus niger

Answer 265

Escherichia coli

Question 266

Immobilized cell reactors for wastewater treatment have the advantage of having/being

higher cell concentration
more stable and prevent washout
higher dilution rate before the cells washout
all of the above

Answer 266

all of the above

Question 267

Which of the statement is true for continuous reactor at steady state?

The rates of biomass, substrate and product concentrations are zero
Biomass, substrate and product concentrations are zero
Biomass, substrate and product concentrations do not change with time
Biomass, substrate and product concentrations change with time

Answer 267

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

turbidostat
chemostat
level stat
pH

Answer 268

chemostat

Question 269

For organisms growing in a chemostat, the specific growth rate

cannot be determined
can be determined from the dilution rate
equals to the maximum specific growth rate of the culture
none of the above

Answer 269

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

decrease with time
increase with time
be constant
change randomly with time

Answer 270

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?

Citric acid is toxic to the cells
Alkanes cause foaming
Fast addition of alkanes will inhibit the cells and reduce oxygen transfer rates
Fast addition of alkanes will cause the cells to grow too quickly

Answer 271

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-1. Its residence time would be

ln(2)/0.5
ln(2) x 0.5
0.5 h
2 h

Answer 272

2 h

Question 273

Which of the following is used to calculate mass of substrate in the reactor?

Flow rate x substrate concentration in the reactor
Volume of reactor x substrate concentration in reactor
Flow rate x mass of reactor
Volume of reactor x Flow rate

Answer 273

Volume of reactor x substrate concentration in reactor

Question 274

If biomass yields are constant, then the biomass productivity of a culture grown in continuous reactor will

always decrease with dilution rate
increase with dilution rate until washout
remain constant irrespective of the dilution rate
decrease with dilution rate until washout

Answer 274

increase with dilution rate until washout

Question 275

Low dissolved oxygen concentrations leads to

low biomass yields
high biomass yields
no effect on biomass yields
none of the above

Answer 275

low biomass yields

Question 276

In a continuous reactor, the medium contains 40 g.l-1 of maltose and the medium flow rate is 10 litres per hour and the effluent contains 20 g.l-l of lactate. What is the productivity of lactate production from this reactor?

50 g maltose.l-1
50 g lactate.l-1
200 g maltose.l-1
200 g lactate.l-1

Answer 276

200 g lactate.l-1

Question 277

A fed-batch reactor containing 1 g.l-1 of substrate in 2 litre of medium. It is fed with 1 g.l-l of substrate at the rate of 1 litre per hour. After 10 hours, the concentration of substrate in the reactor was 0.5 g.l-1 . The mass of substrate that was used by the culture in the reactor was

2g
6g
8g
12g

Answer 277

6g

Question 278

Toxins accumulated in a reactor can lead to low biomass yields probably due to which of the following?

NAD+ is diverted away from homeostasis to anabolism
ATP is diverted away from homeostasis to anabolism
NAD+ is diverted away from anabolism to homeostasis
ATP is diverted away from anabolism to homeostasis

Answer 278

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

decrease abruptly
increase
increase drastically
be zero

Answer 279

decrease abruptly

Question 280

Fluidized bed bioreactors provide higher mass transfer rates than packed bed bioreactors because

mixing is higher in fluidized bed bioreactors
particles move with the fluid in a fluidized bed bioreactor
immobilized particles are smaller in the fluidized bed bioreactors
all of the above

Answer 280

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

initial mass of substrate in the reactor + final mass of substrate in the reactor + flow rate x [substrate in the feed]
initial mass of substrate in the reactor - final mass of substrate in the reactor + flow rate x [substrate in the feed]
initial mass of substrate in the reactor + final mass of substrate in the reactor - flow rate x [substrate in the feed]
initial mass of substrate in the reactor + final mass of substrate in the reactor - flow rate

Answer 281

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 litres and is being fed at a rate of 4 litres per hour. Dilution rate for this reactor will be

2 litres
2 litres per hour
2 h⁻¹
4 litres per hourv

Answer 282

2 h⁻¹

Question 283

Mixing per unit volume is observed to be poorest in

continuous packed bed reactor
continuous fluidized bed bioreactor
continuous airlift bioreactor
none of the above

Answer 283

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 =0.1 g.l⁻¹, if the concentration of glucose in the feed is 10 g.l⁻¹ and the dilution rate is set to 0.4 h-1, then the steady state concentration of glucose in the effluent will be

0 g.l⁻¹
0.5 g.l⁻¹
1.0 g.l⁻¹
10 g.l⁻¹

Answer 284

0.5 g.l⁻¹

Question 285

A continuous reactor at steady state contains 0.04 g.l⁻¹ of biomass and 0.02 g.l⁻¹ of phenol. The feed contained 0.1 g.l⁻¹ of phenol. The biomass yield would be

0.4 g.g⁻¹
0.5 g.g⁻¹
1.0 g.g⁻¹
5.0 g.g⁻¹

Answer 285

0.5 g.g⁻¹

Question 286

A culture system with constant environmental conditions maintained through continual provision of nutrient and removal of wastes is called __________ culture system.

continuous
batch
fed-batch
semi continuous

Answer 286

continuous

Question 287

The main reason for production of antibiotics in fed batch reactors is

the presence of precursors is often toxic to the cells
higher yields when cells enter the stationary phase
higher yields when cell growth slows
all of the above

Answer 287

all of the above

Question 288

Fed batch reactors is used to produce vinegar because

it can maintain low ethanol concentrations
it can maintain low acetic acid concentrations
acetic acid bacteria tend to ferment at high ethanol concentrations
all of the above

Answer 288

it can maintain low ethanol concentrations

Question 289

When a culture of fermenting yeast becomes metabolically uncoupled, ethanol

becomes a secondary metabolite
production becomes growth associated
production becomes non-growth associated
becomes a growth nutrient

Answer 289

production becomes non-growth associated

Question 290

Mixing profiles closest to plug flow are observed in

continuous packed bed reactor
stirred tank reactor with biomass recycles
continuous fluidized bed bioreactor
all of these

Answer 290

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⁻¹When this organism is grown in a 2 litre continuous on a medium containing 10 g.l⁻¹ of glucose added at 1 l.h⁻¹, the steady state concentration of biomass in the reactor will be

0 g.l⁻¹
0.4 g.l⁻¹
0.5 g.l⁻¹
10 g.l⁻¹

Answer 291

0 g.l⁻¹

Question 292

Unsteady state mass balance for dynamic model of continuous stirred tank reactor (CSTR) is

time rate of total amount in rector = rate of addition to reactor -rate of removal + rate of formation
total amount in rector = rate of addition to reactor - rate of removal + rate of formation
rate of total amount in rector = rate of addition to reactor - rate of removal + rate of formation
none of the above

Answer 292

time rate of total amount in rector = rate of addition to reactor -rate of removal + rate of formation

Question 293

A fed-batch reactor initially contains 2 litre of medium. If it was fed at 1 litre per hour, then after 10 hours, the volume of the reactor will be

1 litre
2 litre
3 litre
13 litre

Answer 293

2 litre

Question 294

A Bacillus sp. produces an antibiotic only during the stationary phase when grown in a batch culture. If grown in a 5 litre continuous culture, the steady state productivity of the antibiotic

will increase until the culture washes out
will decrease after washout
will be zero
will be infinite

Answer 294

will be zero

Question 295

In a fluidized bed reactor, the function of the disengagement zone is to

reduce loss of particles from the reactor
reduce the velocity of the particles near the surface of the reactor
reduce foaming problems
all of the above

Answer 295

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?

Batch fermenter with a high initial glucose concentration
Continuous fermenter with a low initial glucose concentration
Fed batch fermenter
All of the above

Answer 296

Fed batch fermenter

Question 297

In a glucose-yeast extract medium, Lactococcus lactis has a maximum specific growth rate (um) of 1.23 h-1. What would be the specific growth rate of this organism at steady state in a 4 litre reactor being fed at 2 litres per hour?

0.5 h-1
1.2 h-1
2.4 h-1
4 h-1

Answer 297

0.5 h-1

Question 298

Which of the following is not correct with regards to continuous cultures?

The major industrial scale application of continuous cultures is in waste water treatment
Mutation and contamination present a major risk to the operation of continuous cultures for the production of metabolites
The continuous cultures is very useful for the production of pharmaceuticals
Continuous cultures have an advantage that they do not need to shut down as regularly as batch culture reactor

Answer 298

The continuous cultures is 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

are near the effluent or exit of the reactor
are in the mid way along the reactor
are located near entrance of feed
are near the wall of the reactor

Answer 299

are located near entrance of feed

Question 300

In an activated sludge process, the biomass is recycled to

increase the efficiency of the process
reduce sludge volumes
increase the concentration of cells
all of the above

Answer 300

all of the above

Question 301

A strain of Escherichia coli has a maximum specific growth rate of 0.8 h-1 on a glucose based medium. If this organism is being grown in a chemostat with a dilution rate of 1.2 h-1, then at steady state the concentration of E. coli in the same medium will

increase
be zero
change randomly
decrease

Answer 301

change randomly

Question 302

A fed-batch reactor containing 2 litre of medium and 0.1 g.l-l of biomass is fed with a medium containing 1 g.l-1 of substrate at 1 litre per hour. If after 10 hours, the concentration of biomass in the reactor was 0.2 g.l-1, then the biomass produced during the 10 hour period is

1.5 g
2.2 g
3.0 g
6.0 g

Answer 302

2.2 g

Question 303

Which of the following organisms will continue their metabolism at high substrate concentrations?

Pseudomonas aeruginosa
Saccharomyces cerevisiae
Bacillus subtilis
Escherichia coli

Answer 303

Pseudomonas aeruginosa

Question 304

Yeast is typically produced in fed batch reactors because

yeast cells produce ethanol at low glucose concentrations
yeast cells ferment at low glucose concentrations
yeast cells respire at low glucose concentrations
all of the above

Answer 304

yeast 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⁻¹, while reactor 2 contained 0.1 g.l⁻¹ of glucose at the start of the process then at steady state

the concentration of glucose in reactor 1 would be greater than that in reactor 2
the concentration of glucose in reactor 1 would be equal to reactor 2
the concentration of glucose in reactor 1 would always be zero.
the concentration of glucose in reactor 1 would be less than that in reactor 2

Answer 305

the concentration of glucose in reactor 1 would be equal to reactor 2

Question 306

In a fluidized bed reactor mixing is achieved by

gravity flow of fluid
upward movement of the incoming feed
diffusion
both (a) and (b)

Answer 306

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

fed-batch reactor can be used to minimize starch concentrations and prevent a. niger from fermenting
fed-batch reactor can be used to minimize starch concentrations and thus reduce the viscosity of the medium
continuous reactor can be used to minimize starch concentrations and their inhibitory effects
all of the above

Answer 307

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

aerobic respiration
anaerobic respiration
fermentation
decomposition

Answer 308

fermentation

Question 309

In fed batch bioreactor modelling, the rate of change in the bioreactor volume is assumed to be equal to

flow rate
initial volume
volume of solids in the reactor
none of these

Answer 309

flow rate

Question 310

Monoclonal antibodies are typically produced in fed batch reactors because

hybridoma cells ferment at high maltose concentrations
hybridoma cells yield higher lactate at high glucose concentrations
hybridoma cells respire at high glucose concentrations
none of the above

Answer 310

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

constant
varying with time
non-linear
power function of time

Answer 311

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

organic acids uncouple catabolism from anabolism
biomass yields increase as the fermentation proceeds
organic acids are secondary metabolites
high concentrations of organic acid promote the growth of the microbial population

Answer 312

organic acids uncouple catabolism from anabolism

Question 313

The concentration of biomass in a continuous stirred tank reactor is 20 g dry weight per litre. What would be the concentration of biomass in the effluent?

Greater than 20 g dry weight per litre
Approximately 20 g dry weight per litre
Lesser than 20 g dry weight per litre
More than 30 g dry weight per litre

Answer 313

Approximately 20 g dry weight per litre

Question 314

The ideal tubular-flow fermenter without radial variations is called a

plug flow fermenter
continuous stirred tank fermenter (CSTF)
column fermenter
any intensity of dilution rate near the wash out points

Answer 314

plug flow fermenter

Question 315

Pseudo-steady state in a continuous reactor refers to a reactor in which

Pseudomonads are being cultured
concentration oscillate around a mean value
concentration increase with time
concentration decrease with time

Answer 315

concentration oscillate around a mean value

Question 316

The toxicity of organic acids to cells

enhances as the pH falls
reduces as the pH falls
is not affected by pH
is highest at pH 7.0

Answer 316

enhances as the pH falls

Question 317

Which of the following is best described as secondary metabolite?

Acetic acid produced from the oxidation of ethanol
Ethanol from the fermentation of glucose
Penicillin
Citric acid from the partial oxidation of glucose

Answer 317

Penicillin

Question 318

A microorganism which is subjected to the Crabtree effect is most likely to

ferment in the presence of low concentrations of sugar and dissolved oxygen
respire in the presence of low sugar and high dissolved oxygen concentrations
ferment in the presence of high concentrations of sugar and dissolved oxygen
respire in the presence of high sugar and low dissolved oxygen concentrations

Answer 318

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 product formation is termed as

uncoupled
growth associated
non-growth associated
metabolically uncoupled

Answer 319

growth associated

Question 320

Which of the following would be correct concerning the concentration of biomass (X). growth limiting substrate (S) and product (P) in a chemostat when the cells have been washed out?

X,S and P will be zero
X,S and P can not be predicted for the above condition
X and P will be zero while S is equal to the substrate concentration in feed
None of the above

Answer 320

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-1 in a medium with glucose as a growth limiting substrate. To prevent wash out, the dilution rate must be set to

greater than 0.8 h⁻¹
less than 0.8 h⁻¹
equal to 0.8 h⁻¹
1.6 h⁻¹

Answer 321

less than 0.8 h⁻¹

Question 322

Saccharomyces cerevisiae when grown in high glucose concentration medium, the cells activity depends on which of the following?

High concentration of dissolved oxygen
Low concentration of dissolved oxygen
No effect of dissolved oxygen
High concentration of dissolved oxygen and sodium salts

Answer 322

No effect of dissolved oxygen

Question 323

Continuous culture has an advantage over to a batch cultures as

continuous reactors do not need to be shut down and cleaned as regularly as a batch reactor
most downstream and upstream processes are continuous in nature and thus the operation of continuous bioreactor can be better integrated into the overall manufacturing process
cells can be maintained at a constant physiological state simply by setting the dilution rate
all of the above

Answer 323

all of the above

Question 324

In the batch-fed mode, substrate will be added

only at the beginning of the fermentation process
periodically throughout the fermentation process
only at the end of the fermentation process
substrate is never added

Answer 324

only at the end of the fermentation process

Question 325

When Escherichia coli grow in a well aerated medium, which of the following will occur?

Fructose di-phosphate accumulation inside the cells leading to cell respiration
Fructose di-phosphate accumulation inside the cells leading to fermentation
Fructose di-phosphate will accumulate regardless of the medium composition
Fructose di-phosphate will accumulate inside the cells leading to anaerobic respiration

Answer 325

Fructose di-phosphate accumulation inside the cells leading to fermentation

Question 326

to start agitation and aeration section 1

Question 327

Swirling and vortex formation can be prevented by

using baffles
using diffusion ring with turbines
both (a) and (b)
none of these

Answer 327

both (a) and (b)

Question 328

Power number is expressed as

P₀ / N²Dᵢ³ρ
P₀ / N³Dᵢ⁵ρ
P₀ / N³Dᵢ³ρ
P₀ / N²Dᵢ²ρ

Answer 328

P₀ / N³Dᵢ⁵ρ

Question 329

The power consumption in a stirring vessel can be assessed by using a

dynamometer
strain gauge attached to agitator shaft
watt meter attached to agitator motor
all of these

Answer 329

all of these

Question 330

Surface renewal theory predicts that the mass transfer coefficient is

directly proportional to the square root of the molecular diffusivity
inversely proportional to the square root of the molecular diffusivity
directly proportional to the cube root of the molecular diffusivity
indirectly proportional to the cube root of the molecular diffusivity

Answer 330

directly proportional to the square root of the molecular diffusivity

Question 331

The oxygen transfer rate in a bioreactor will increase if

oil is added
antifoam is added
detergent like molecules are added
increase in the reactor temperature

Answer 331

detergent like molecules are added

Question 332

Which of the following impellers are used for wide range of viscosities?

paddles
turbines
propellers
none of these

Answer 332

turbines

Question 333

Which of the following type(s) of stirrer can be used for microbiological processes?

Mig
Intermig
Turbine
All of these

Answer 333

All of these

Question 334

The range of width for the baffle in the fermenter is __________ times of vessel diameter

1/10 to 1/12
1/8 to 1/10
1/5 to 1/8
none of these

Answer 334

1/10 to 1/12

Question 335

The average concentration of oxygen in the boundary layers surrounding the bubbles (Co*) in a reactor is normally determined by

ultra-small dissolved oxygen probes
laser based photographic systems
measuring the steady state concentration of oxygen in the bulk liquid prior to inoculation of the reactor
measuring the steady state concentration of oxygen in the bulk liquid after inoculation of the reactor

Answer 335

measuring the steady state concentration of oxygen in the bulk liquid prior to inoculation of the reactor

Question 336

Why vortexing is undesirable in the agitation of biological systems?

The collision between the cells, impeller and air bubbles will lead to cell damage
Poor mixing despite the use of high stirrer speeds
Mixing will not be in the turbulent region
All of the above

Answer 336

All of the above

Question 337

The rate limiting step in the movement of oxygen from the gas phase in a bubble to the cell is the movement of oxygen molecules through

gas-liquid interface
bubble boundary layer
bulk liquid
gas phase

Answer 337

bubble boundary layer

Question 338

Penetration theory assumes that turbulent eddies travel from the bulk of the phase to the interface where they remain constant for a constant exposure time (te). The model correlating KL, mass transfer coefficient and DAB, diffusivity can be expressed as

Answer 338

Question 339

The oxygen uptake requirements of a microbial population is characterized by the following parameters: μm = 0.2 h⁻¹, K0 = 0.2 mg O2.l⁻¹, Y0 = 0.5 mg dry weight/mg O2 and Co,crit=0.8 mg.l-1 The required concentration of cells is 1000 mg.l⁻¹ and the saturation oxygen concentration of the medium is 5.8 mg.l⁻¹. The required KLa must be greater than

64 h⁻¹
32 h⁻¹
16 h⁻¹
8h⁻¹

Answer 339

64 h⁻¹

Question 340

Which have the maximum resistance while transferring carbon dioxide from the bulk liquid to an air bubble?

Moving through the gas liquid interface
Moving through the bubble boundary layer
Moving across the cell membrane
Moving through the bulk liquid

Answer 340

Moving through the bubble boundary layer

Question 341

If liquid density and viscosity remains constant, then the Reynolds number in a stirred tank reactor will vary with the

impeller diameter
square root of the impeller diameter
square of the impeller diameter
cube of the impeller diameter

Answer 341

square of the impeller diameter

Question 342

What is the ratio of depth of liquid in vessel to the diameter of tank (H:Dt)?

1 : 1
2 : 1
4 : 1
none of these

Answer 342

1 : 1

Question 343

Radial flow impellers

provide high shear conditions for breaking up bubbles
direct flow towards the walls of the reactor
Both (a) and (b)
provide low shear conditions and are suited for use in shear sensitive procesess

Answer 343

Both (a) and (b)

Question 344

Transient flow range of mixing speed is obtained for

Rei<10
10<Rei<10^4
Rei>10^4
None of these

Answer 344

10<Rei<10^4

Question 345

A typical ceiling fan would be best described as a(n)

radial flow impeller
axial flow impeller
intermig impeller
Rushton turbine

Answer 345

axial flow impeller

Question 346

What is the ratio of diameter of impeller to the diameter of tank (Da:Dt)

1 : 3
2 : 1
4 : 1
1 : 5

Answer 346

1 : 3

Question 347

The reason of using a flat disk in a Turbine is

to create high shear conditions
to break up bubbles more efficiently than the impeller blades
to ensure that the bulk of the energy consumption occurs at the blades
all of the above

Answer 347

to ensure that the bulk of the energy consumption occurs at the blades

Question 348

Which of the following is not considered among the three best-known theories of interphase mass transfer?

two-film theory
penetration theory
surface renewal theory
Calderbank and Moo-Young theory

Answer 348

Calderbank and Moo-Young theory

Question 349

Which of the following is most likely to cause an increase in the rate of oxygen transfer into a particular aerated fermentation system?

Addition of antifoams
Increase in temperature
Increase in stirrer speed
Both (a) and (b)

Answer 349

Increase in stirrer speed

Question 350

At 25°C, the saturation concentration of oxygen in water is 1.26 mmol/l and the partial pressure of oxygen is 1 atm. The Henry’s law constant will be

0.793atml/mmol
0.207atml/mmol
1.26 atml/mmol
8.74 atml/mmol

Answer 350

0.793atml/mmol

Question 351

Gas hold up, characterizing the hydrodynamics in a fermenter, mainly depends on the

superficial gas velocity
power consumption
Both (a) and (b)
gas concentration

Answer 351

Both (a) and (b)

Question 352

Turbine impeller consists of flat impeller blades with

a vertical pitch welded directly to the shaft
a angled pitch welded directly to the shaft
a vertical pitch welded to a horizontal disk
a angled pitch welded to a horizontal disk

Answer 352

a vertical pitch welded to a horizontal disk

Question 353

An aerated bioreactor will increase oxygen transfer rates with the addition of detergents because it

enhances bubble coalescence
causes bubbles to expand
discourages bubble coalescence
increases the surface tension of the liquid

Answer 353

discourages bubble coalescence

Question 354

Vortexing in stirred tank reactors can be prevented by

installing baffles in the reactor
shifting the impeller to an off-centre position
Both (a) and (b)
using axial flow impellers

Answer 354

Both (a) and (b)

Question 355

Which of the following would be best described as an axial flow impeller?

An impeller with blades pitched at 45° to the vertical
An impeller which directs liquid flow towards the base of the reactor
Both (a) and (b)
An impeller with blades pitched at 75° to the vertical

Answer 355

Both (a) and (b)

Question 356

Henry’s law relates

the partial pressure of oxygen and the saturation concentration of oxygen in the liquid
the oxygen transfer rate and the bubble size
the oxygen transfer rate and the temperature
the oxygen transfer rate to the partial pressure of oxygen in the liquid

Answer 356

the partial pressure of oxygen and the saturation concentration of oxygen in the liquid

Question 357

Power number is ratio of

imposed forced to intertial force
bouyant force to inertial force
gravitation force to inertial force
imposed force to gravitational force

Answer 357

imposed forced to intertial force

Question 358

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

Answer 358

VL=HL x π x Dt^2/4

Question 359

The average fractional gas hold up (H) can be given as (where Zf and Zl are the level of aerated and clear liquid respectively)

Answer 359

H = (Zf-Zl)/Zf

Question 360

Which of the following(s) is/are non-mechanically agitated reactors?

Stirrer tank reactor
Bubble column
Air lift reactor
Both (b) and (c)

Answer 360

Both (b) and (c)

Question 361

Which of the following best explains the reasons for using axial flow impellers in crystallization and precipitation reactions?

Crystal and precipitates are not too small, so as to ensure easy separation of the solids from the mother liquor
Crystals and precipitates are thoroughly broken down, so as to ensure easy separation of the solids from the mother liquor
Both (a) and (b)
Axial flow impellers provide low shear, energy efficient mixing conditions

Answer 361

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

Question 362

Which of the following will have the highest surface area available for oxygen transfer?

A shake flask
A standing test tube
A non-sparged stirred tank reactor agitated at 400 rpm
A sparged stirred tank reactor agitated at 400 rpm

Answer 362

A sparged stirred tank reactor agitated at 400 rpm

Question 363

A flooded impeller will lead to poor oxygen transfer rates because

bubbles tend to coalesce under the impeller
bubbles tend to break down too rapidly under high shear conditions
bubbles tend to move too quickly through the bulk liquid
the cells clog up the surface of the bubble

Answer 363

bubbles tend to coalesce under the impeller

Question 364

Power consumption by agitation is

a function of physical properties
a function of operating conditions
a function of vessel and impeller geometry
all of the above

Answer 364

all of the above

Question 365

Which of the following impellers will provide radial flow?

Paddles
Flat blade turbines
Disk flat blade turbines
All of the above

Answer 365

All of the above

Question 366

When liquid is pumped through cooling coil in a stirred tank reactor to cool. Which of the following is not correct?

If the stirrer speed is increased, the rate will be faster
Baffles in the tank will increase the rate of cooling
Faster cooling rates at a slower rate of pumping
Faster cooling rates at a faster rate of pumping

Answer 366

Faster cooling rates at a slower rate of pumping

Question 367

When the height of an aerated bioreactor is increased, it will increase the oxygen transfer rate by

increasing the partial pressure of oxygen at the base of the reactor
decreasing the saturation concentration of oxygen in the reactor
decreasing the gas-holdup
all of the above

Answer 367

increasing the partial pressure of oxygen at the base of the reactor

Question 368

Which of the following is correct for the off-centre impellers?

Off-centre impellers can be used with any size reactor
Off-centre impellers should only be used with reactors with volumes less than 10 m3
The impeller should never be placed in an off-centre position
Off-centre impellers can be used when volume is greater than 10 m3

Answer 368

Off-centre impellers should only be used with reactors with volumes less than 10 m3

Question 369

The power required by an impeller in a gas sparged system compare to the power required by impeller operating at same speed in a gas free liquid is usually

lesser
higher
same
may be lesser or higher depending upon the geometry

Answer 369

lesser

Question 370

Which of the following stirrer requires least amount of energy for same yield?

Mig
Intermig
Turbine
Disc

Answer 370

Intermig

Question 371

A reactor has a total volume of 50,000 litres. If it has a headspace volume of 10,000 litres, then volume of liquid in the reactor will be

10,000 l
20,000 l
30,000 l
40,000 l

Answer 371

40,000 l

Question 372

Pure oxygen, if used instead of air will increase oxygen transfer rates because

the saturation concentration of oxygen is higher
the bubble size is smaller
the oxygen transfer coefficient is larger
the partial pressure of oxygen in the gas phase is lower

Answer 372

the saturation concentration of oxygen is higher

Question 373

For aerated mixing vessels in an aqueous solution, the mass transfer coefficient (kL) co-relating power consumption (Pm) and fermenter volume (V) can be expressed as

kL ∝ (Pm/V)^0.33
kL ∝ (Pm/V)^0.66
kL ∝ (Pm/V)^0.50
kL ∝ (Pm/V)

Answer 373

kL ∝ (Pm/V)^0.33

Question 374

Higher temperatures affect oxygen transfer rates by

increasing KLa but lowering Co
lowering KLabut increasing Co
increasing KLaand increasing Co
lowering KLa and lowering Co

Answer 374

increasing KLa but lowering C*o

Question 375

The Intermig impeller is

an axial flow impeller which can be used for the culture of aerobic organisms
directed upwards rather than towards the base of the reactor
a fork shaped extensions to the impeller facilitate bubble break up
All of the above

Answer 375

All of the above

Question 376

Main reason for using baffles in stirred tank reactors are

baffles permit turbulence conditions to arise at low stirrer speed
baffles will allow axial mixing to occur even with radial flow impellers
both (a) and (b)
baffles prevent turbulent conditions in stirred tank reactors

Answer 376

both (a) and (b)

Question 377

Which of the following is not classified as an axial flow impeller?

A propeller
A marine impeller
A Rushton turbine
A hydrofoil impeller

Answer 377

A Rushton turbine

Question 378

Power number (Np) is also known as

Froude’s number
Bond’s number
Newton’s number
Rayleigh’s number

Answer 378

Newton’s number

Question 379

Flooding is a condition/phenomenon which occur in a bioreactor when

The air escapes without being distributed by the agitator
The fermenter medium spills out the reactor due to foaming
The volume of foam is more than the volume of broth
None of the above

Answer 379

The air escapes without being distributed by the agitator

Question 380

A cylindrical reactor has a liquid volume of 100,000 litres. It has an aspect ratio the ratio of the channel height to width of 1:1. The height of the liquid in the reactor will be approximately:

1.0 m
3.0 m
5.0 m
7.0 m

Answer 380

5.0 m

Question 381

Detergent like substances produced by microorganisms during a fermentation will lead to

decrease the surface tension of the liquid
accumulate at the gas liquid interface
decrease the rate of bubble coalescence
all of the above

Answer 381

all of the above

Question 382

A cylindrical reactor fitted with Rushton Turbine has a liquid volume of 100,000 litres. It has an aspect ratio (the ratio of the channel height to the width) of 2:1. The diameter of the impeller should be approximately:

1.3 m
3.3 m
5.3 m
7.3 m

Answer 382

1.3 m

Question 383

In the bubble boundary layer, oxygen concentration can be determined by measuring

the steady state oxygen concentration in a mixed aerated reactor before inoculation
the steady state oxygen concentration in a mixed aerated reactor after inoculation
the steady state oxygen concentration in the boundary layer using a micro-probe
volume of oxygen supplied

Answer 383

the steady state oxygen concentration in a mixed aerated reactor before inoculation

Question 384

Impeller damage can be minimized by

using specially designed axial flow impellers
using radial flow impellers
using Intermig impellers
all of the above

Answer 384

using specially designed axial flow impellers

Question 385

To increase the oxygen transfer rate in a shake flask culture system, which of the following (s) is/are followed?

Liquid volume in the flask is reduced
Stirrer speed is increased
Baffled flasks are used
All of the above

Answer 385

All of the above

Question 386

What is/are the major difference(s) between disc and turbine type stirrer?

Blades in disc type are projected out beyond the edge of disc while blades are curved one in turbine type
Turbine type requires 50 % less air than disc type for the same yield and energy consumption
Both (a) and (b)
Number of blades in the stirrer

Answer 386

Both (a) and (b)

Question 387

In the design of a paddle agitator, the ratio of paddle diameter to tank diameter is normally taken as

0.1
0.8
0.25
0.5

Answer 387

0.8

Question 388

The oxygen absorption rate can be determined by

sodium sulfite oxidation method
dynamic gassing out technique
direct measurement
all of these

Answer 388

all of these

Question 389

Industrial paddle agitators turn at the speed of

20 and 150 rpm
150 and 300 rpm
400 and 800 rpm
1150 rpm

Answer 389

20 and 150 rpm

Question 390

The dynamic technique is based on the

oxygen material balance in an aerated batch fermenter during the growth of microorganisms
change of the oxygen concentration
oxidation of the sodium sulfite to sodium sulfate
oxygen material balance in a fermenter

Answer 390

oxygen material balance in an aerated batch fermenter during the growth of microorganisms

Question 391

The addition of antifoams to an aerated bioreactor will decrease oxygen transfer rates because antifoams

increase the tendency of bubbles to coalesce
tend to accumulate in the gas liquid interface
reduce the surface tension of the liquid
All of the above answers

Answer 391

All of the above answers

Question 392

During fermentation, the saturation concentration of oxygen was reduced from 7 ppm. to 1 ppm. Which one of the following conclusions can be drawn?

Microbial growth is oxygen limited since the oxygen concentration is lesser than the saturation concentration
Microbial growth is not oxygen limited since the oxygen concentration is lesser than the saturation concentration
Experimental error leads to the reduction
No conclusion can be drawn

Answer 392

No conclusion can be drawn

Question 393

If the stirrer speed is too slow, bubbles will accumulate and coalescese under the impeller. This phenomenon is known as a

coalesced impeller
flooded impeller
river impeller
dry impeller

Answer 393

flooded impeller

Question 394

The maximum solubility of the alkane in the medium is 5 ppm. If the actual dissolved concentration of the alkane in the medium is 1 ppm. what conclusion may be drawn?

The growth rate is limited by the rate of mass transfer of the alkane into the fermentation medium
The growth rate is limited by the intrinsic kinetic properties of the cells and not by mass transfer
The growth rate is neither mass transfer nor kinetically limited
No conclusion on the growth rate can be withdrawn

Answer 394

No conclusion on the growth rate can be withdrawn

Question 395

Reynolds (Rei) number for the impeller is given by (where Di, stirrer diameter; N, stirrer speed, ρ, density of fluid and μ, viscosity of fluid)

DiVρ/μ
Di²Nρ/μ
Di²Vρ/μ
DiNρ/μ

Answer 395

Di²Nρ/μ

Question 396

The advantage of axial flow impellers over radial flow impellers is that axial flow impellers

provide better lift of solids
provide high shear conditions
provide low shear conditions
are cheaper to build

Answer 396

provide better lift of solids

Question 397

Larger propellers turn at the speed of

20 to 150 rpm
150 to 300 rpm
400 to 800 rpm
1150 rpm

Answer 397

400 to 800 rpm

Question 398

A microbial population in a suspension culture will only be limited by oxygen availability if the dissolved oxygen

concentration is less than the critical concentration
concentration is greater than the critical concentration
levels are greater than the saturation concentration of oxygen
levels are equal to saturation oxygen level

Answer 398

concentration is less than the critical concentration

Question 399

Which of the following model holds correct for the two-film theory? (where KL is the mass transfer coefficient, DAB diffusivity and Zf film thickness)

KL = DAB/Zf
KL = DAB
KL= Zf/DAB
KL = DAB.Zf

Answer 399

KL = DAB/Zf

Question 400

Froude number is avoided in calculation of power requirements for low viscosity liquid mixing systems when

baffled systems are used
Reynolds number is less than 300
both (a)and(b)
none of these

Answer 400

both (a)and(b)

Question 401

A fermentation system has a KLaof 3 s-1 and a C0* of 5 ppm of O2. If the bulk liquid is completely depleted of oxygen, then the oxygen transfer rate will be equal to

zero
15 mg.l⁻¹.s⁻¹
10 mg.l⁻¹.s⁻¹
5 mg.l⁻¹.s⁻¹

Answer 401

15 mg.l⁻¹.s⁻¹

Question 402

During aeration, a cylindrical reactor had a height of 10 m. Without aeration, the height was 7.5 m. Under these aeration and mixing conditions, the gas hold up in the reactor is

100%
75%
50%
25%

Answer 402

25%

Question 403

A fermentation system has aKLa of 3 s⁻¹ and a C0* of 5 ppm of O2. If the bulk liquid is saturated with oxygen then the oxygen transfer rate will be equal to

zero
3 mg.l⁻¹.s⁻¹
5 mg.l⁻¹.s⁻¹
15 mg.l⁻¹.s⁻¹

Answer 403

zero

Question 404

hich of the following would be best described as a radial flow impeller?

An impeller with blades pitched at 45° to the vertical
A Rushton turbine
Both (a) and (b)
An impeller which directs liquid flow towards the base of the reactor

Answer 404

A Rushton turbine

Question 405

Small propellers turn at the speed of either

20 or 150 rpm
150 or 300 rpm
400 or 800 rpm
1150 rpm or 1750 rpm

Answer 405

1150 rpm or 1750 rpm

Question 406

In aerobic microorganisms cultures radial flow impellers are used because

they provide energy efficient high turbulent mixing conditions
they provide low shear mixing conditions
they provide high shear mixing conditions
they ensure that bubble size is maximized leading to high oxygen transfer rates

Answer 406

they provide high shear mixing conditions

Question 407

The effect of increasing the stirrer speed in an unbaffled stirred tank reactor is that

a small increase in stirrer speed will cause the liquid to enter the turbulent flow regime
as the stirrer speed increases, the liquid will continue to circulate and then become turbulent
as the stirrer speed increases, the liquid will continue to circulate. Eventually a vortex will form.
A vortex will form at low stirrer speeds. As the stirrer speed increases the liquid will start to circulate

Answer 407

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

Question 408

Turbulent flow range of mixing speed is obtained for

Rei<10
10<Rei<10^4
Rei>10^4
None of these

Answer 408

Rei>10^4

Question 409

For laminar flow, Reynolds number is correlated with power number as (where K, a constant which depends on the container geometry and shape of stirrer; Rei is Reynolds number for agitator; Di, stirrer diameter and N, stirrer speed)

Np = K(Rei)^-1
Np = N2Di(Rei)^-1
Np = K(Rei)
Np = KNDi(Rei)^-2

Answer 409

Np = K(Rei)^-1

Question 410

For turbulent flow, Reynolds number is correlated with power number as (where K, a constant which depends on the container geometry and shape of stirrer; Rei, is Reynolds number for agitator; Di, stirrer diameter and N, stirrer speed)

Np = K(Rei)^-1
Np = N2Di(Rei)^-1
Np = K
Can’t be correlated

Answer 410

Np = K

Question 411

In a bioreactor, if at a particular time the oxygen transfer rate is 23 kg.h-1, then the oxygen uptake will be

23 kg.h⁻¹
less than 23 kg.h⁻¹
greater than 23 kg.h⁻¹
2.3 kg.h⁻¹

Answer 411

23 kg.h⁻¹

Question 412

Axial flow impellers

provide high shear conditions for breaking up bubbles
provide low shear conditions and are suited for use in shear sensitive procesess
provide direct flow towards the walls of the reactor
none of the above

Answer 412

provide low shear conditions and are suited for use in shear sensitive procesess

Question 413

Bioreactors, where vortex is formed, another dimensionless number, __________ is useful.

Stanton
Rayleigh
Bond
Froude

Answer 413

Froude

Question 414

Oxygen transfer rate is increased with an increase in the stirrer speed in aerated bioreactor because

it decrease the bubble size
it decreases the size of the boundary layer surrounding a bubble
it increases the rate of movement of oxygen molecules through the bulk liquid
all of the above

Answer 414

all of the above

Question 415

If the stirring speed increased from 300 to 500 rpm leads to an increase in the reaction rate by two folds. Then it may be concluded that

the reaction was mass transfer limited at 300 rpm
the reaction was mass transfer limited at 500 rpm
the reaction did not involve any mass transfer step
the movement of molecules in the reactor at 300 rpm occurred due to diffusion alone

Answer 415

the reaction was mass transfer limited at 300 rpm

Question 416

An increase in the heat transfer in the stirred tank reactor will be observed at

higher cooling water temperature
higher stirrer speed
the removal of baffles from the reactor
slower stirrer speed

Answer 416

higher stirrer speed

Question 417

In a two-phase system where the continuous phase remains in place, the gas hold up can be expressed as (where Vs and Vt are the superficial gas velocity and bubble rise velocity)

H = Vs/(Vs-Vt)
H = Vs/(Vs+ Vt)
H = Vs/(Vs.Vt)
H = (Vs+Vt)/Vs

Answer 417

H = Vs/(Vs+ Vt)

Question 418

What is the effect of the concentration of dissolved salts and sugars on the oxygen transfer rate?

The saturation concentration of oxygen in the medium decreases with the concentration of dissolved salts and sugars, leading to a lower oxygen transfer rate
The KLa of the medium decreases with the concentration of dissolved salts and sugars, leading to a lower oxygen transfer rate
The KLa of the medium increases with the concentration of dissolved salts and sugars, leading to a lower oxygen transfer rate
None of the above

Answer 418

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 419

Which of the following impellers generate a flow parallel to the axis of shaft?

Axial flow
Radial flow
Both (a)and(b)
None of these

Answer 419

Axial flow

Question 420

In a tall reactor, oxygen transfer rates will be

highest at the surface of the reactor
highest at the base of the reactor
highest in the middle of the reactor
the same throughout the reactor

Answer 420

highest at the base of the reactor

Question 421

Which of the following impeller is used in situation where strong vertical currents are desirable for suspending heavily particles?

Propeller
Paddle
Turbine
None of these

Answer 421

Propeller

Question 422

Laminar flow range of mixing speed is obtained for

Rei<10
10<Rei<10^4
Rei>10^4
None of these

Answer 422

Rei<10

Question 423

Which of the following number is calculated from the diameter and peripheral speed of the impeller?

Reynolds number
Froude number
Power number
None of these

Answer 423

Reynolds number

Question 424

A higher liquid height will lead to a higher gas hold up by which the oxygen transfer rate will be

higher throughout the reactor
lower throughout the reactor
higher at the base of the reactor
lower at the base of the reactor

Answer 424

higher at the base of the reactor

Question 425

The main function of the dimples provided in the cooling jacket is to

increase the level of turbulence of the cooling water in the jacket
increase the residence time of the cooling water in the jacket
increase the cooling water-jacket wall boundary layer size
all of the above

Answer 425

increase the level of turbulence of the cooling water in the jacket

Question 426

The power required by an agitator operating in a gas-sparged system is

lesser than the power required by an impeller in operating at same speed in a gas free system
more than the power required by an impeller in operating at same speed in a gas free system
same as the power required by an impeller in operating at same speed in a gas free system
none of the above

Answer 426

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

Question 427

Which of the following will have the largest interfacial area per unit volume?

A bubble with a diameter of 1 mm
A bubble with a diameter of 5 mm
A bubble with a diameter of 15 mm
A bubble with a diameter of 50 mm

Answer 427

A bubble with a diameter of 1 mm

Question 428

Which device is commonly used for measuring the rate of rotation (rpm) of the stirrer shaft?

Anemometer
Manometer
Tachometer
Barometer

Answer 428

Tachometer

Question 429

The sterilization method depends

nature of additive
volume and feed rate
both (a) and (b)
none of these

Answer 429

both (a) and (b)

Question 430

The specific death rate of an organism can be expressed as

ln 2/D
D/ln2
D.ln2
2.0.3/ln2

Answer 430

ln 2/D

Question 431

The interception efficiency can be expressed as (where dp is the particle diameter and Dc cylindrical collection diameter)

dp/Dc
dp x Dc
dp/Dc x 100
dpDc/100

Answer 431

dp/Dc

Question 432

The relationship between the del factor, temperature and time is given as

Δ = A.t. e^(-E/RT)
Δ = 1/(A.t. e^(-E/RT))
Δ = A.t. e^(E/RT)
Δ = A.t.T

Answer 432

Δ = A.t. e^(-E/RT)

Question 433

The del factor (Δ) increases as the final number of cells

decreases
increases
zero
constant

Answer 433

decreases

Question 434

The overall del factor (Δ) may be represented as

Δoverall = Δheating + Δholding- Δcooling
Δoverall = Δheating + Δholding+ Δcooling
Δoverall = Δheating - Δholding+ Δcooling
Δoverall = Δheating - Δholding- Δcooling

Answer 434

Δoverall = Δheating + Δholding+ Δcooling

Question 435

The filter material used for air filtration system is/are

glass wool
glass fibre
norite
all of the above

Answer 435

all of the above

Question 436

The deviation from ideal plug flow due to axial mixing can be described by the

dispersion model
Langmuir model
Friedlander model
Pasceri model

Answer 436

dispersion model

Question 437

The collection efficiency by diffusion increases with

decreasing particle size
decreasing air velocity
both (a) and (b)
increasing particle size

Answer 437

both (a) and (b)

Question 438

Glass fibers are favorable as a filter medium because they give a

lower pressure drop and are less liable to wetting or combustion
more pressure drop and are less liable to wetting or combustion
lower pressure drop and are more liable to wetting or combustion
more pressure drop and are more liable to wetting or combustion

Answer 438

lower pressure drop and are less liable to wetting or combustion

Question 439

The collection efficiency by interception increases with the

increasing particle diameter
increasing air flow velocity
both (a) and (b)
increasing particle size

Answer 439

increasing particle size

Question 440

For indirect heating, the plate and frame heat exchanger is generally more effective than the shell and tube heat transfer due to its

larger heat transfer area
smaller heat transfer area
lesser cost
more number of plates

Answer 440

larger heat transfer area

Question 441

The mechanism of air filtration in fibrous filter is

electrostatic attraction
impaction
interception
all of these

Answer 441

all of these

Question 442

If the packing density (α) is defined as the volume of the fiber unit volume of filter bed, the velocity within the filter void space is equal to (where Vis velocity in fluid void space and V0 is undisturbed fluid velocity)

V = V0/(1-α)
V-V0 = 1 - α
V = V0(1 - α)
V = V0/(1 + α)

Answer 442

V = V0/(1-α)

Question 443

For the turbulent flow, the dispersion coefficient is correlated as a function of

Reynolds number
Sherwood number
Schmidt number
Grashof number

Answer 443

Reynolds number

Question 444

In sterilization process, spore of which of the following organism is considered as control?

Bacillus subtilis
Clostridium botulinum
Bacillus stearothermophilus
Aspergillus niger

Answer 444

Bacillus stearothermophilus

Question 445

Analogus to the molecular diffusion, the x-directional flux of microorganisms suspended in a medium due to the axial mixing can be represented as (where Jn is flux component ‘n’, cn is concentration of’n’)

Jn = -dcn/dx
Jn = dcn/dx
Jn = -D dcn/dx
Jn = D dcn/dx

Answer 445

Jn = -D dcn/dx

Question 446

The typical size of particles collected by diffusion mechanism is

<0.25μm
<0.5μm
<0.75μm
<1μm

Answer 446

<0.5μm

Question 447

The X90 value for a filtration system is

the time required to reduce microbial population by 90%
the time required to traverse survivor curve by one log cycle.
the depth required to reduce population by 90%
the depth of the filter required to reduce population by 99%

Answer 447

the depth required to reduce population by 90%

Question 448

The value of K

increases with increase in air velocity
decreases with increase in air velocity
increases to an optimum with increase in air velocity and decreases on further increase of air velocity
none of these

Answer 448

increases to an optimum with increase in air velocity and decreases on further increase of air velocity

Question 449

Model proposed by the Friedlander, correlating the air filtration efficiency by impaction can be expressed as (where NSt is the Stokes number)

ηimp = 0.075NSt^1.2
ηimp = 0.75NSt^1.2
ηimp = 0.25NSt^1.2
ηimp = 0.025NSt^1.2

Answer 449

ηimp = 0.075NSt^1.2

Question 450

The collection efficiency by impaction increases with

increasing particle diameter
increasing air flow velocity
both (a) and (b)
increasing particle size

Answer 450

both (a) and (b)

Question 451

The efficiency of fibrous filter by combined mechanism is given by(where ηimp,ηint,ηdif are the efficiencies by impaction, interception and diffusion respectively)

1 - ηimpηintηdif
1 - (1 - ηimp)(1 - ηint)( 1 - ηdif)
1 - ( ηimpηint/ηdif)
None of the above

Answer 451

1 - ηimpηintηdif

Question 452

The heat conduction in dry air is

less rapid than in steam
more rapid than in steam
similar to steam
none of these

Answer 452

less rapid than in steam

Question 453

For laminar flow of Newtonian fluid through a smooth round pipe, the ratio of average fluid velocity to the maximum velocity is

0.5
0.75
0.87
0.37

Answer 453

0.5

Question 454

The reduction of number of cells from 1010 to one will result into the del factor (Δ) of

1
10
23
10^3

Answer 454

23

Question 455

Sterilization can be carried out by

heat
radiation
chemical agents
all of these

Answer 455

all of these

Question 456

The collection efficiency by the inertial impaction mechanism is the function of

Stokes and Reynolds number
Stokes and Schmidt number
Grashoff and Reynolds number
Stokes and Grashof number

Answer 456

Stokes and Reynolds number

Question 457

The heated medium passes through a holding section, which is usually maintained in

adiabatic conditions
isothermal conditions
isotropic conditions
isobaric conditions

Answer 457

adiabatic conditions

Question 458

The highest temperature which appears to be feasible for batch sterilization is

121°C
100°C
105°C
130°C

Answer 458

121°C

Question 459

The K used in the equation for X₁₀=2.303/K depends upon

nature of the filter material
linear velocity of the air passing through filter
both (a) and (b)
thickness of the filter₁₀

Answer 459

both (a) and (b)

Question 460

The mechanical means of accomplishing sterilization of fermentation media/equipment is

ultrasonic
radiation
chemical agents
none of these

Answer 460

ultrasonic

Question 461

The radius of the filter with a depth of 14 cm required for a volumetric airflow rate of 10 m3/min is approximately

1.6 m
0.6 m
3
6 m

Answer 461

0.6 m

Question 462

The moist heat is more effective than the dry heat because the intrinsic heat resistance of vegetative cells is greatly

increased in a dry state
decreased in a dry state
increased in a wet state
decreased in a wet state

Answer 462

increased in a dry state

Question 463

The destruction of microorganisms by steam may be described as

first order chemical reaction
zero order chemical reaction
second order chemical reaction
none of these

Answer 463

first order chemical reaction

Question 464

Typical aeration rates for aerobic fermentation are

0 - 0.5 vvm
0.5 - 1.0 vvm
1.0 - 1.5 vvm
1.5 - 2.0 vvm

Answer 464

0.5 - 1.0 vvm

Question 465

The maximum desirable limit Bureau of Indian Standards (BIS) of lead in the drinking water is

0.05 mg/l
0.09 mg/l
0.1 mg/l
1.0 mg/l

Answer 465

0.05 mg/l

Question 466

Zeolite softening process removes

only temporary hardness of water
only permanent hardness of water
both temporary and permanent hardness of water
the dissolved gases in permanent hard water

Answer 466

both temporary and permanent hardness of water

Question 467

Conventional tertiary treatment is

chemical coagulation and flocculation
filtration
sedimentation
none of these

Answer 467

chemical coagulation and flocculation

Question 468

The maximum desirable limit (BIS) of total hardness (as CaCo3) in drinking water is

600 ppm
300 ppm
500 ppm
1000 ppm

Answer 468

300 ppm

Question 469

The chemical oxygen demand (COD)measures the

amount of oxygen required for growth of microorganisms in water
amount of oxygen that would be removed from the water in order to oxidize pollution
amount of oxygen required to oxidize the calcium present in waste water
none of the above

Answer 469

amount of oxygen that would be removed from the water in order to oxidize pollution

Question 470

Hardness of water does not

have any bad effect in boiler
make cooking of foods difficult
make it unfit for drinking
cause difficulty in the washing of clothes with soaps

Answer 470

make it unfit for drinking

Question 471

Permanent hard water may be softened by passing it through

sodium silicate
sodium bicarbonate
sodium hexametaphosphate
sodium phosphate

Answer 471

sodium hexametaphosphate

Question 472

Zeolite used in zeolite softening process for the treatment of hard water gets exhausted after certain time of usage but can be regenerated by flushing it with

10% calcium chloride solution
10% magnesium sulfate solution
10% magnesium chloride solution
10% sodium chloride solution

Answer 472

10% sodium chloride solution

Question 473

Temporary hardness of water is caused by the presence of

chlorides of calcium and magnesium
sulfates of calcium and magnesium
bicarbonates of calcium and magnesium
carbonates of sodium and potassium

Answer 473

bicarbonates of calcium and magnesium

Question 474

Secondary treatment uses __________ to consume wastes.

micro-organisms
chemicals
filtration
none of these

Answer 474

micro-organisms

Question 475

Application of quaternary ammonium compounds as sanitizing agents tends to

favor gram positive bacteria
decrease gram positive bacteria
increase the percentage of gram(-)ve rods on utensils
none of the above

Answer 475

increase the percentage of gram(-)ve rods on utensils

Question 476

Permanent hardness of water is caused by the presence of

bicarbonates of calcium and magnesium
carbonates of sodium and potassium
chlorides and sulfates of calcium and magnesium
phosphates of sodium and potassium

Answer 476

chlorides and sulfates of calcium and magnesium

Question 477

According to BIS the maximum permissible limit of dissolved solids in drinking water is

1000 mg/l
500 mg/l
2000 mg/l
1500 mg/l

Answer 477

2000 mg/l

Question 478

Acid used mostly for removal of milk stone is

phosphoric acid
nitric acid
gluconic acid
tartaric acid

Answer 478

nitric acid

Question 479

Which of the following chemical is sometime added in the process of coagulation and flocculation?

Aluminum sulphate
Aluminum oxide
Calcium chloride
None of these

Answer 479

Aluminum sulphate

Question 480

Which of the following physical method is used as germicidal in modern time for the treatment of drinking water?

Chlorination
Treating with potassium permagnate
UV radiation
Treating with bleaching powder

Answer 480

UV radiation

Question 481

Sanitizer used specifically for vitreous enamel are

strong alkalis
strong acids
weak alkali with sodium silicate
none of these

Answer 481

weak alkali with sodium silicate

Question 482

The common methods used for disinfection in waste water treatment plants are

chlorination
UV light
both (a) and (b)
Phenolic solvent

Answer 482

both (a) and (b)

Question 483

Inhibitors are used along with sanitizer to

improve their action
to prevent corrosion
both (a) and (b)
none of these

Answer 483

to prevent corrosion

Question 484

Sanitizers used for rubber made equipments are

strong acids
strong alkalis
combination of both
none of these

Answer 484

strong alkalis

Question 485

Which of the following substances are commonly used in a filter?

Charcoal
Sand
Both (a) and (b)
Aluminum chloride

Answer 485

Both (a) and (b)

Question 486

Biological oxidation processes usually referred as biological treatment, are the most common form of

primary treatment
secondary treatment
tertiary treatment
all of these

Answer 486

secondary treatment

Question 487

The maximum permissible limit (BIS) of turbidity in drinking water is

5 NTU
10 NTU
15 NTU
20 NTU

Answer 487

10 NTU

Question 488

Sedimentation is a physical process used in wastewater treatment to

remove particles that are less dense than water
remove particles that are more dense than water
remove the pertinacious material from the water
none of the above

Answer 488

remove particles that are more dense than water

Question 489

The ultimate source of water is

rivers and lakes
dew and forest
rain and snow
underground and surface

Answer 489

rain and snow

Question 490

Permanent hardness of water may be removed by the addition of

lime
soda ash
potassium permagnate
sodium bicarbonate

Answer 490

soda ash

Question 491

Both temporary and permanent hardness of water can be removed on boiling water with

calcium hydroxide
sodium carbonate
calcium oxide
calcium carbonate

Answer 491

sodium carbonate

Question 492

Lagoons may be characterized as

anaerobic
facultative
aerated
all of these

Answer 492

all of these

Question 493

Temporary hardness of water may be removed by adding

calcium hydroxide
calcium carbonate
calcium chloride
sodium bicarbonate

Answer 493

calcium hydroxide

Question 494

The maximum desirable limit (BIS of mercury in the drinking water is

0.05 mg/l
0.9 mg/l
0.1 mg/l
0.001 mg/l

Answer 494

0.001 mg/l

Question 495

From the following sanitizers which one comes under category of surface active agents?

Tetra phosphate
Teepol
Meta phosphate
None of these

Answer 495

Teepol

Question 496

The purest form of naturally occurring water is

rain water
river water
pond water
well water

Answer 496

rain water

Question 497

Calgon is used for removal of

sodium carbonate
permanent hardness of water
potassium carbonate
none of these

Answer 497

permanent hardness of water

Question 498

The water being used in dairy industry should contain not more than

5 proteolytic and/or lipolytic organisms per ml
10 proteolytic and/or lipolytic organisms per ml
15 proteolytic and/or lipolytic organisms per ml
20 proteolytic and/or lipolytic organisms/ml

Answer 498

5 proteolytic and/or lipolytic organisms per ml

Question 499

The activated sludge process consists of returning a portion of the clarifier

effluent water entering the reactor
influent water coming out of the reactor
influent water entering the reactor
effluent water coming out of the reactor

Answer 499

influent water entering the reactor

Question 500

The activated sludge process is sometime referred as

fluid bed biological oxidation system
fixed bed biological oxidation system
turning bed biological oxidation system
none of the above

Answer 500

fluid bed biological oxidation system

Question 501

BOD stands for

biochemical oxygen demand
british oxygen demand
british oxygen depletion
biological oxygen depletion

Answer 501

biochemical oxygen demand

Question 502

When temporary hard water is boiled, one of the substances formed is

calcium bicarbonate
calcium sulfate
hydrogen chloride
carbon dioxide

Answer 502

carbon dioxide

Question 503

Zeolite softening process removes both temporary and permanent hardness of water. In this process the calcium and magnesium present in water are precipitated as

insoluble carbonates
insoluble zeolites
insoluble chlorides
insoluble sulfates

Answer 503

insoluble zeolites

Question 504

The methods used for biological treatment are

lagoon
activated sludge process
oxidation ditches
all of these

Answer 504

all of these

Question 505

Both temporary and permanent hardness of water can be removed by

boiling
distillation
filtration
decantation

Answer 505

distillation

Question 506

Coliform bacteria in water is an indication of the presence of

radioactive wastes
excess fertilizer
decaying animals and plants
human feces

Answer 506

human feces