SURFACE CHEMISTRY AND CATALYSIS
ADSORPTION: TYPES OF ADSORPTION, ADSORPTION OF SOLUTE FROM SOLUTIONS, ADSORPTION ISOTHERMS, FREUNDLICH’S ADSORPTION ISOTHERM, LANGMUIR’S ADSORPTION ISOTHERM
- 1.Which of the following is not an adsorbent?
a) Carbon
b) Polymers and resins
c) Clay
d) Dry sponge
Answer: d
Explanation: A sponge will absorb or take in
water from another area and put it inside of
itself. A dry sponge can hold more water than
a wet sponge is closer to saturation and as
such cannot hold more water. Sponges with
more tiny holes can absorb more water than
the sponges with less tiny holes and thus
leads to the absorption process.
- 2.What do you mean by the term “Sorption”?
a) Attachment
b) Detachment
c) Diffusion
d) Thermal Expansion
Answer: a
Explanation: Sorption is a physical and
chemical process by which one substance
becomes attached to another. The reverse of
sorption is desorption.
3. The desorption curve is higher than the adsorption curve.
a) True b) False
Answer: a
Explanation: Theoretically, desorption curve is higher than adsorption curve in low pressure area if the material is mesoporous (2-50nm). If the material is microporous (<2nm), both curves should be matched together.
- 4.Which of the following isotherm is
applicable to physical adsorption?
a) Langmuir
b) BET
c) Freundlich
d) Kisluik
Answer: c
Explanation: The Freundlich isotherm was
the first isotherm model proposed for sorption
processes. It can be applied for non ideal
sorption on heterogeneous surfaces, as well
as, multilayer sorption. A variation in the
slope between 0 and 1 is associated with a
chemisorption process, which is more
heterogeneous as the value gets closer to 0.
Due to the lack in fundamental
thermodynamic basis, since there is no
approach to Henry’s law at vanishing
concentrations, this represents a limitation of
this isotherm model.
- 5.Which type of isotherm is given from the
figure, Choose from the following options?
a) Type 1 Adsorption isotherm
b) Type 2 Adsorption isotherm
c) Type 3 Adsorption isotherm
d) Type 4 Adsorption isotherm
Answer: a
Explanation: The above graph depicts
Monolayer adsorption. This graph can be
easily explained using Langmuir Adsorption
Isotherm. Examples of Type-I adsorption are
Adsorption of Nitrogen (N2) or Hydrogen (H)
on charcoal at temperature near to -1800C.
- 6.Calculate the adsorption of a dye on
activated carbon at 25°C, where k = 0.025, n
= 0.5 and C = 0.04.
Based on the Freundlich isotherm.
a) 0.050
b) 0.030
c) 0.040
d) 0.060
Answer: c
Explanation: Given data
n = 0.5
Kd = 0.025
C = 0.04
Substitute the values in the corresponding
equation
q = Kd C(1/n)
q = (0.025) (0.04)(1/0.5)
q = 0.040.
- 7.Which of the following statements
regarding the physical adsorption of a gas on
surface of solid is not correct?
a) On increasing temperature, adsorption
increases continuously
b) Enthalpy changes are negative
c) Adsorption is specific
d) It is reversible in nature
Answer: a
Explanation: Physisorption is exothermic in
nature. Therefore according to le chateliars
principle, it occurs readily at low temperature
and decreases with increase in temperature.
Bond between adsorbent i.e. surface and
adsorbate like gases are weak so when
temperature is increasing the bond get break
easily and adsorption of adsorbate get stop so
rate will decrease on increasing temperature. - 8.Which of the following is not characteristic
of chemisorption?
a) It is irreversible
b) It is specific
c) It is multilayer phenomenon
d) Heat of adsorption is about 400kj
Answer: c
Explanation: Chemisorption involves
formation of chemical bonds between
adsorbate and adsorbent molecules. Once the
valency is satisfied, the adsorbent molecules
can’t form bond with more adsorbate
molecules. Thus only one layer is formed. - 9.For an adsorbant-adsorbate system obeying
the Langmuir adsorption isotherm, b = 0.48
bar-1 and p = 0.16 bar-1 ,At what pressure
will 50% of the surface be covered?
a) 0.05 bar
b) 0.07 bar
c) 0.08 bar
d) 0.04 bar
Answer: b
Explanation: Given data
b = 0.48 bar-1
p = 0.16 bar-1
Substitute in the corresponding equation
10.10.Adsorption of methane follows the
Langmuir adsorption isotherm at 90K. If p =
1.896cm3g-1 bar-1 and b = 0.146bar-1.
Calculate the value of θ.
a) 0.116 bar
b) 0.514 bar
c) 0.214 bar
d) 0.216 bar
Answer: d
Explanation: Given data
p = 1.896cm3g-1 bar-1
b = 0.146 bar-1
Substitute in the corresponding equation
ADSORPTION OF GASES ON SOLIDS
- 1.In Langmuir’s model of adsorption of a gas
on a solid surface the mass of gas striking a
given area of surface is to the pressure of the gas.
a) Proportional
b) Anti proportional
c) Independent
d) None of the mentioned
Answer: a
Explanation: In Langmuir’s model of
adsorption of a gas on a solid surface the
mass of gas striking a given area of surface is
proportional to the pressure of the gas. - 2.Physical adsorption increase with
in temperature.
a) Increase
b) Decrease
c) Neither increase nor decrease
d) None of the mentioned
Answer: b
Explanation: Physical adsorption increase
with decrease in temperature. - 3.The physical process that occurs when gas
or liquid molecules are brought into contact
with a solid surface and condense on the
surface
a) Absorption
b) Adsorption
c) Both Adsorption and Absorption
d) None of the mentioned
Answer: b
Explanation: Adsorption is the physical
process that occurs when gas or liquid
molecules are brought into contact with a
solid surface and condense on the surface. - 4.Adsorbent is a solid surface on which gas
or liquid molecules condense to form a film.
The above given statement is
a) Correct
b) Incorrect
c) Partially correct
d) None of the mentioned
Answer: a
Explanation: Adsorbent is a solid surface on which gas or liquid molecules condense to form a film
- 5.Adsorption when interaction between the
solid and the condensed molecules is
relatively strong as contrasted with physical
adsorption.
a) Absorption
b) Adsorption
c) Chemisorption
d) None of the mentioned
Answer: b
Explanation: “Chemisorption is the
adsorption when interaction between the solid
and the condensed molecules is relatively
strong as contrasted with physical adsorption. - 6.The gas molecules are held on solid surface
by in physical adsorption.
a) Chemical forces
b) Gravitational forces
c) Electrostatic forces
d) Vander Waal’s forces
Answer: d
Explanation: Chemisorption is the adsorption
when interaction between the solid and the
condensed molecules is relatively strong as
contrasted with physical adsorption. - 7.The extent of adsorption of a gas on a solid
depend on
a) Nature of gas
b) Pressure of gas
c) Temperature of the system
d) All of the mentioned
Answer: d
Explanation: The extent of adsorption of a
gas on a solid depend on all three nature of
gas, pressure of gas and temperature of the
system. - 8.Which of the following gases is adsorbed
by charcoal?
a) NH3
b) H2
c) N2
d) CO2
Answer: a
Explanation: NH3 is easily liquefiable and
highly water soluble gas. - 9.Langmuir isotherm Mathematical relation
for that takes place at equilibrium.
a) Absorption
b) Adsorption
c) Both Adsorption and Absorption
d) None of the mentioned
Answer: b
Explanation: Langmuir isotherm
Mathematical relation for adsorption that
takes place at equilibrium. - 10.Adsorption process must be
a) Endoethrgic
b) Endothermic
c) Exothermic
d) None
Answer: c
Explanation: Adsorption process is an
Exothermic process.
KINETICS OF SURFACE REACTIONS
- For reaction system given below, volume is
suddenly reduced to half of its value by
increasing the pressure on it. If the reaction is
of first order with respect to O2 and second
order with respect to NO, what will be the
change in the rate of reaction?
2NO(g) + O2 (g) + 2NO2 (g)
a) diminish to one-fourth of its initial value
b) diminish to one-eight of its initial value
c) increase to eight times of its initial value
d) increase to four times of its initial value
Answer: c
Explanation:
- The rate law for a reaction between the
substances A and B is given by rate = K[A]n
[B]m. On doubling the concentration of A
and halving the concentration of B. What will
be the ratio of the new rate of the earlier rate
of the reaction?
a) ( 1/2)m+n
b) m+n
c) n-m
d) 2n-m
Answer: d
Explanation:
- Rate = If the volume of reaction vessel is
suddenly reduced to 1/4th of initial value. How
new rate will be affected?
(a)1/10
(b)1/8
(c)8
(d)16
Answer :d
Explanation:
When volume is reduced to 1/4 , concentration become four times and reaction rate become 16 times because it is 2 order reaction .
- 4.On which factor the rate constant of a
reaction does not depend upon?
a) temperature
b) activation energy
c) catalyst
d) concentration of reactants and products
Answer: d
Explanation: The rate constant of reaction
does not depend on concentration of reactant
& product (only on nature of reactant &
product). - 5.The rate of reaction, A + B Products, is
given by the equation, r = k[A][B]. If B is
taken in excess, what would be the order of
reaction?
a) 2
b) 1
c) zero
d) unpredictable
Answer: b
Explanation: A + B → Products
H = k[A][B] [if B is taken in large excess
then according to pseudo first order reaction.
B is taken as constant]. So, order = 1.
- 6.In a reaction, 2A2 + B2 → 2A2B, when the
reactant A will disappear?
a) half the rate that B will decrease
b) the same rate that B will decrease
c) double the rate that A2B will form
d) twice the rate that B will decrease
Answer: d
Explanation:
So, the reactant A will disappear when A is
twice the rate that B will decrease.
- 7.The rate of reaction that does not involve
gases, is not dependent on
a) pressure
b) temperature
c) concentration
d) catalyst
Answer: a
Explanation: The rate of reaction that does
not involve gases does not depend on
pressure.
- 8.Which is not true for a second order reduction?
a) It can have rate constant 1 x 10-2 L mol-1 s-1
b) Its half-life is inversely proportional to its
initial concentration
c) Time to complete 75% reaction is twice of
half-life
d) T50 = 1/(ka⋅A0)
Answer: c
Explanation:
but t75 = 3 * t50
So, option Time to complete 75% reaction is
twice of half-life is wrong statement for n =2.
- 9.The rate of decomposition of a substance
increases concentration of substance at same
temperature. Find out order of reaction.
a) 1
b) 2
c) 3
d) 0
Answer: b
Explanation: Rate = k [A]α
R1 = k[A]n
R2 = k [1.5 A]n = 2.25 R1
k(1.5A)n = 2.25k[A]n
(1.5)n * [A]n = 2.25*[A]n
n log (1.5) = log (2.25)
n = 2. - 10.If a reaction is nth order the half-life
period of the initial concentration
of the reactants.
a) is independent
b) varies inversely as (n-1)th power
c) varies inversely as nth power
d) varies directly as (n-1)th power
Answer: b
Explanation: For nth order;
So, varies inversely as (n –1)th power.
UNIMOLECULAR REACTIONS
- 1.Molecularity of a reaction is equal to the
total number of
a) Products formed in the elementary step
b) Reactants taking part in elementary step
c) Reactants and products in the elementary
step
d) Reactants and products in the final step
Answer: b
Explanation: Molecularity of a reaction is
equal to the total number of reactants taking
part in an elementary step. It is defined as the
number of molecules or ions that participate
in the rate determining step.
- 2.The molecularity of a multi-step reaction
does not make any sense.
a) True
b) False
Answer: a
Explanation: The molecularity of a multistep reaction does not make any sense. The
molecularity of each step is different. And
molecularity of one step can only be
determined at a time.
- 3.The elementary processes with
molecularity greater than are not
known.
a) 1
b) 2
c) 3
d) 0
Answer: c
Explanation: The elementary processes with
molecularity greater than three are not
known. There is no such reaction which has
the molecularity greater than three.
- 4.Which of the following statement is
incorrect about the molecularity of a reaction?
a) It is a theoretical concept
b) Each step of a multi-step reaction has a
unique molecularity
c) It is equal to the total number of reactants
taking part in elementary step
d) It can be zero, fractional or integer
Answer: d
Explanation: Molecularity is always a whole
number. It can be neither zero nor fractional.
All the other options are correct.
- 5.Which of the following factor does not
effect the rate of reaction?
a) Concentration of the reactant
b) Temperature
c) Pressure
d) Effect of catalyst
Answer: c
Explanation: The reaction rate does not
depend upon the pressure. It only depends
upon the concentration of the reactant,
temperature and effect of catalyst.
- 6.The effective collisions between the
reactant molecules at higher temperatures
a) Increase
b) Decrease
c) Remains same
d) First increase then decrease
Answer: a
Explanation: The effective collisions
between the reactant molecules at higher
temperatures increase. At higher temperature
randomness increases and molecules moves
with a faster velocity which results in more
collision between the reactants.
- 7.Concentration of the reactants is
proportional to the number of
collisions and proportional to the
reaction rate.
a) Directly, inversely
b) Directly, directly
c) Inversely, directly
d) Inversely, inversely
Answer: b
Explanation: Concentration of the reactants
is directly proportional to the number of
collisions and also directly proportional to the
reaction rate. The more the collision, more
will be the reaction rate and hence more will
be the concentration of reactants. - 8.The reaction rate is greatly influenced by
a) Nature of bond in the reactant molecules
b) Strength of bond in the reactant molecules
c) Both nature and strength of the reactant
molecules
d) It does not depend on either nature or
strength of the reactant molecules
Answer: c
Explanation: The reaction rate is greatly
influenced by both nature and strength of the
reactant molecules. Reactants are the major
factor that affects the rate of the reaction. - 9.The reactions register an increase in rates
in the presence of radiations of specific
wavelengths.
a) True
b) False
Answer: a
Explanation: The reactions register an
increase in rates in the presence of radiations
of specific wavelengths. - 10.Select the correct option from the
following option.
a) Catalyst is used to increase the rate of
reaction by altering chemically during the
course of reaction
b) Catalyst is used to decrease the rate of
reaction by altering chemically during the
course of reaction
c) Catalyst is used to increase the rate of
reaction and remains unaltered chemically
during the course of reaction
d) Catalyst is used to decrease the rate of
reaction and remains altered chemically
during the course of reaction
Answer: c
Explanation: Catalyst is used to increase the
rate of reaction and remains unaltered
chemically during the course of the reaction.
With a catalyst, reactions occur faster and
require less activation energy. Because
catalysts are not consumed in the catalyzed
reaction, they can continue to catalyze the
reaction of further quantities of reactant.
LANGMUIR APPLICATIONS OF ADSORPTION ON POLLUTION ABATEMENT
- 1.Which of the following is not an
adsorbent?
a) Carbon
b) Polymers and resins
c) Clay
d) Dry sponge
Answer: d
Explanation: A sponge will absorb or take in
water from another area and put it inside of
itself. A dry sponge can hold more water than
a wet sponge is closer to saturation and as
such cannot hold more water. Sponges with
more tiny holes can absorb more water than
the sponges with less tiny holes and thus
leads to the absorption process. - 2.What do you mean by the term “Sorption”?
a) Attachment
b) Detachmen
c) Diffusion
d) Thermal Expansion
Answer: a
Explanation: Sorption is a physical and
chemical process by which one substance
becomes attached to another. The reverse of
sorption is desorption
3.3. The desorption curve is higher than the adsorption curve.
a) True
b) False
Answer: a
Explanation: Theoretically, desorption curve is higher than adsorption curve in low pressure area if the material is mesoporous (2-50nm). If the material is microporous (<2nm), both curves should be matched together
- 4.Which of the following isotherm is
applicable to physical adsorption?
a) Langmuir
b) BET
c) Freundlich
d) Kisluik
Answer: c
Explanation: The Freundlich isotherm was
the first isotherm model proposed for sorption
processes. It can be applied for non ideal
sorption on heterogeneous surfaces, as well
as, multilayer sorption. A variation in the
slope between 0 and 1 is associated with a
chemisorption process, which is more
heterogeneous as the value gets closer to 0.
Due to the lack in fundamental
thermodynamic basis, since there is no
approach to Henry’s law at vanishing
concentrations, this represents a limitation of
this isotherm model. - 5.Which type of isotherm is given from the
figure, Choose from the following options?
a) Type 1 Adsorption isotherm
b) Type 2 Adsorption isotherm
c) Type 3 Adsorption isotherm
d) Type 4 Adsorption isotherm
Answer: a
Explanation: The above graph depicts Monolayer adsorption. This graph can be easily explained using Langmuir Adsorption Isotherm. Examples of Type-I adsorption are Adsorption of Nitrogen (N2) or Hydrogen (H) on charcoal at temperature near to -1800C.
- 6.Calculate the adsorption of a dye on
activated carbon at 25°C, where k = 0.025, n
= 0.5 and C = 0.04.
Based on the Freundlich isotherm.
a) 0.050
b) 0.030
c) 0.040
d) 0.060
Answer: c
Explanation: Given data
n = 0.5
Kd = 0.025
C = 0.04
Substitute the values in the corresponding
equation
q = Kd C(1/n)
q = (0.025) (0.04)(1/0.5)
q = 0.040.
- 7.Which of the following statements
regarding the physical adsorption of a gas on
surface of solid is not correct?
a) On increasing temperature, adsorption
increases continuously
b) Enthalpy changes are negative
c) Adsorption is specific
d) It is reversible in nature
Answer: a
Explanation: Physisorption is exothermic in
nature. Therefore according to le chateliars
principle, it occurs readily at low temperature
and decreases with increase in temperature.
Bond between adsorbent i.e. surface and
adsorbate like gases are weak so when
temperature is increasing the bond get break
easily and adsorption of adsorbate get stop so
rate will decrease on increasing temperature. - 8.Which of the following is not characteristic
of chemisorption?
a) It is irreversible
b) It is specific
c) It is multilayer phenomenon
d) Heat of adsorption is about 400kj
Answer: c
Explanation: Chemisorption involves
formation of chemical bonds between
adsorbate and adsorbent molecules. Once the
valency is satisfied, the adsorbent molecules
can’t form bond with more adsorbate
molecules. Thus only one layer is formed. - 9.For an adsorbant-adsorbate system obeying
the Langmuir adsorption isotherm, b = 0.48
bar-1 and p = 0.16 bar-1. At what pressure
will 50% of the surface be covered?
a) 0.05 bar
b) 0.07 bar
c) 0.08 bar
d) 0.04 bar
Answer: b
Explanation: Given data
b = 0.48 bar-1
p = 0.16 bar-1
Substitute in the corresponding equation
- Adsorption of methane follows the
Langmuir adsorption isotherm at 90K. If p =1.896cm3g-1
bar-1 and b = 0.146bar-1.
Calculate the value of θ.
a) 0.116 bar
b) 0.514 bar
c) 0.214 bar
d) 0.216 bar
Answer: d
Explanation: Given data
p = 1.896cm3g-1 bar-1
b = 0.146 bar-1
Substitute in the corresponding equation
CATALYSIS:
CATALYST – TYPES OF CATALYSIS – AUTOCATALYSIS,CATALYTIC POISONING, ACID BASE CATALYSIS – APPLICATIONS (CATALYTIC CONVERTOR)
- 1.Which of the following is not a
characteristic of a catalyst?
a) It participates in the reaction
b) It enhances the equilibrium rate
c) It activates equilibrium
d) It initialises the reaction
Answer: a
Explanation: The main purpose of using a
catalyst is only to increase the rate of
achieving the equilibrium state in case of
slow reaction. Other than that it will not
initiate or involve in the reaction. - 2.Which of the following will decrease the
rate of reaction?
a) Catalytic poison
b) Positive catalyst
c) Negative catalyst
d) Catalytic promoters
Answer: a
Explanation: Catalytic poisons are the once
which are used to slow down the reaction
inorder to avoid explosion when the
temperature or pressure increase the critical
value. Hence catalytic poisons are used such
as aluminium oxide. - 3.Which of the following is a catalytic
poison?
a) Potassium nitrate
b) Aluminium nitrate
c) Aluminium oxide
d) Chlorine
Answer: c
Explanation: Aluminium oxide is known for
its sophisticated properties and is mainly used
in the process of corrosion preventing it
absorbs moisture and has high retentivity and
hence is used as a catalytic poison. - 4.Which of the following is used as a
catalytic promoter?
a) Chlorine
b) Nitrate
c) Bromine
d) Helium
Answer: b
Explanation: The use of a promoter is to
increase the rate of equilibrium. We know
that nitrogen has promoting properties in the
case of nitrate molecules. Thus the can act as
good promoters in reaction. - Which of the following is used as a catalyst for the following reaction?
2SO2 + O2 ⟶ 2SO3
a) Chlorine
b) Nitrous oxide
c) Sulphur di oxide
d) Potassium chloride
Answer: b
Explanation: Since sulphur and nitrogen
components have the same equilibrium
valencies, we can see that one will promote
the other and vice versa. Thus nitrogen
molecule is the best for sulphur molecules. - 6.Which of the following is used as a catalyst
for the following reaction?
N2 + 3H2 ⟶ 2NH3
a) Zinc
b) Chlorine
c) Platinum
d) Water
Answer: c
Explanation: Since nitrogen and noble
metals components have the same
equilibrium valencies, we can see that one
will promote the other and vice versa. Thus
nitrogen molecule is the best for platinum
molecules. - 7.Which of the following is used as a catalyst
for the following reaction?
H2O2 ⟶ 2H2O + O2
a) Chlorine
b) Bromine
c) Platinum
d) Noble solutions
Answer: c
Explanation: Since oxygen and noble metals
components have same equilibrium valencies,
we can see that one will promote the other
and vice versa. Thus oxygen molecule is the
best for platinum molecules.
- 8.Which of the following is used as a
catalytic poison for the same reaction:
SO2 + O2 ⟶ 2SO3
a) Platinum
b) Bromine
c) Magnesium
d) Silver
Answer: a
Explanation: Though nitrogen is used as a
promoter, we can see that platinum reduces
its activity and hence decreases the rate of
reaction of equilibrium in the above reaction. - 9.Where is the intermediate theory used?
a) Heterogeneous components
b) Homogeneous components
c) Miscible components
d) Immiscible components
Answer: a
Explanation: Intermediate theory is the
process in which an intermediate product is
formed and hence it is suitable for
homogeneous components and not for
heterogeneous components. - 10.Calculate the amount of intermediate
components formed from the given data.
S=12
T=10
C=12
a) 1
b) 0
c) 2
d) 10
Answer: d
Explanation: we know that the amount of
intermediate components formed is given by
the formula s*c/12. So here we have 12*10/12=10.
CATALYTIC PROMOTERS
- 1.Some vectors carry a mutant form of
promoter known as lacUV5 promoter. It
carries in the promoter region and
the efficiency.
a) point mutations, decreases
b) point mutations, increases
c) frameshift mutations, increases
d) frameshift mutations, increases
Answer: b
Explanation: In some vectors, lacUV5
promoter is present. It is a mutant form and
carries point mutations which increase the
efficiency. - 2.Lambda PL promoter is used in which
vectors?
a) Cloning vectors
b) Expression vectors
c) Both cloning and expression vectors
d) Bacteriophage Mu
Answer: b
Explanation: Lambda PL promoters are the
promoters for the left region in bacteriophage
lambda. It is widely used in expression
vectors. - 3.The promoter can be controlled by a
repressor which is temperature sensitive.
a) True
b) False
Answer: a
Explanation: The promoter is activated at a
temperature higher than 30 degrees because at
this temperature repressor is inactivated. - 4.Choose the correct statement for rifampcin.
a) It inactivates both E. coli polymerase and
T7 polymerase
b) It activates both E. coli polymerase and T7
polymerase
c) It inhibits T7 polymerase but doesn’t
inhibits E. coli polymerase
d) It inhibits E. coli polymerase but doesn’t
inhibits T7 polymerase
Answer: d
Explanation: Rifampcin is added in order to
reduce the transcription of other genes. It
inhibits the E. coli RNA polymerase but
doesn’t inhibit the T7 polymerase.
- 5.The operon encodes proteins
involved in arabinose metabolism.
a) araBCD
b) araABD
c) araBAD
d) araDBA
Answer: c
Explanation: The araBAD operon encodes
proteins involved in arabinose metabolism. It
is controlled by AraC transcriptional
regulator. - 6.tac promoter is an example of which type of promoter?
a) hybrid promoter
b) fusion promoter
c) lacZ promoter
d) araBAD promoter
Answer: a
Explanation: Hybrid promoters are those
promoters which are produced by two
promoters from different sources. Tac
promoter is a hybrid promoter produced from
trp promoter and lacUV5 promoter. - 7.The tac promoter is made by region of trp promoter and region of the lacUV5 promoter.
a) 10, 35
b) 35, 10
c) 10, 10
d) 35, 35
Answer: b
Explanation: It is a hybrid promoter made by
35 regions of trp promoter and 10 regions of
the lacUV5 promoter. - 8.The tac promoter includes the lac operator
and is regulated by a repressor.
a) True
b) False
Answer: a
Explanation: The tac promoter includes the
lac operator and is regulated by the repressor.
The repressor is to be supplied by the host. - 9.Expression of T7 promoter- lac operator
hybrid requires
a) T7 RNA polymerase
b) An inducer such as IPTG
c) Both T7 RNA polymerase and inducer
such as IPTG
d) T7 DNA polymerase
Answer: c
Explanation: Expression of T7 promoter- lac
operator hybrid requires both T7 RNA
polymerase and inducer such as IPTG. If
inducer is absent levels of expression are very
low. - 10.When lacUV5 control system is used,
addition of IPTG the expression of
a) activates, T7 RNA polymerase
b) inactivates, T7 RNA polymerase
c) activates, T7 DNA polymerase
d) inactivates, T7 DNA polymerase
Answer: a
Explanation: When a lacUV5 control system
is used, the addition of IPTG activates the
expression of T7 RNA polymerase. Thus
transcription of sequences under the control
of T7 promoter is controlled.
NZYME CATALYSIS
- 1.A is a biocatalyst that
increases the rate of the reaction without
being changed.
a) Aluminum oxide
b) Silicon dioxide
c) Enzyme
d) Hydrogen peroxide
Answer: c
Explanation: Among these options, an
enzyme is an only option which is a
biocatalyst that catalyzes the chemical
reaction without being changed while all
other options are of the catalyst which
increases or decrease the rate of reaction
based on their concentration. - 2.Enzyme increases the rate of reaction by
lowering the activation energy.
a) True
b) False
Answer: a
Explanation: Activation energy is the
difference in free energy between the
reactants and transition state. To complete a
reaction, enzyme lowers the activation energy
and crosses the transition state. - 3.What is the nature of an enzyme?
a) Vitamin
b) Lipid
c) Carbohydrate
d) Protein
Answer: d
Explanation: All enzymes are protein except
Catalytic RNA molecule. The native protein
conformation of an enzyme defines its
catalytic activity. Once the enzyme is
denatured, its catalytic activity is also lost. - 4.What is an apoenzyme?
a) It is a protein portion of an enzyme
b) It is a non-protein group
c) It is a complete, biologically active
conjugated enzyme
d) It is a prosthetic group
Answer: a
Explanation: Removal of cofactor from a
conjugated enzymes forms apoenzyme which
is a protein component. A cofactor is a nonprotein group while a complete conjugated
enzyme is known as a holoenzyme. - 5.Name the coenzyme of riboflavin (B2)?
a) NAD or NADP
b) FAD and FMN
c) Coenzyme A
d) Thiamine pyrophosphate
Answer: b
Explanation: Riboflavin is a part of vitamin
B complex, its coenzyme form is a FAD
(Flavin adenine dinucleotide) which involves
a redox reaction. NAD is a coenzyme form of
nicotinic acid, and thiamine pyrophosphate is
a coenzyme of thiamine. - 6.Which of this vitamin is associated with
the coenzyme Biocytin?
a) Nicotinic acid
b) Thiamine
c) Biotin
d) Pyridoxine
Answer: c
Explanation: Biocytin is a coenzyme of
biotin which involves in carboxylation
reaction while thiamine takes part in
decarboxylation reaction. - 7.Name the enzyme secreted by pancreas?
a) Pepsin
b) Chymotrypsin
c) Trypsin
d) Alcohol dehydrogenase
Answer: c
Explanation: Trypsin is a proteolytic
enzyme, secreted by the pancreas. It is one of
the three digestive proteinases along with
pepsin and chymotrypsin which breaks down
dietary protein molecules into simpler forms.
- 8.Name the enzyme which catalyzes the
oxidation-reduction reaction?
a) Transaminase
b) Glutamine synthetase
c) Phosphofructokinase
d) Oxidoreductase
Answer: d
Explanation: Oxidoreductase is a class of
enzyme which catalyze the oxidationreduction reaction. Some of the
oxidoreductase enzymes are oxidases,
dehydrogenases, peroxidases etc. - 9.What is the function of phosphorylase?
a) Transfer inorganic phosphate
b) Transfer a carboxylate group
c) Use H2O2 as the electron acceptor
d) Transfer amino group
Answer: a
Explanation: Phosphorylase is a transferase
enzyme which involves a transfer of
inorganic phosphate to a substrate while
transcarboxylase transfer a carboxylate group
and transaminase transfer amino group from
amino acid to the keto acid. - 10.the CORRECT function of enzyme,
Peptidase?
a) Cleave phosphodiester bond
b) Cleave amino bonds
c) Remove phosphate from a substrate
d) Removal of H2O
Answer: b
Explanation: Hydrolases are the enzymes
which cleave the bond by adding water.
Peptidases belong to hydrolase class and it is
used to cleave amide bonds of proteins. - 11.Which of the following reaction is
catalyzed by Lyase?
a) Breaking of bonds
b) Formation of bonds
c) Intramolecular rearrangement of bonds
d) Transfer of group from one molecule to
another
Answer: a
Explanation: Lyase is the class of enzymes
which does not involve hydrolysis or
oxidation to break the bond. It catalyzes the
breaking of C-C, C-O, C-N, C-S bonds by the
process of elimination and results in the
formation of a double bond
MICHAELIS -MENTEN EQUATION.
- 1.Which of the following is true about
Michaelis-Menten kinetics?
a) Km, the Michaelis constant, is defined as
that concentration of substrate at which
enzyme is working at maximum velocity
b) It describes single substrate enzymes
c) Km, the Michaelis constant is defined as
the dissociation constant of the enzymesubstrate complex
d) It assumes covalent binding occurs
between enzyme and substrate
Answer: b
Explanation: Km is defined as the
concentration of substrate at which enzyme is
working at half of maximum velocity. It is
also a measure of the affinity that the enzyme
has for its substrate. Michaelis-Menten
kinetics assumes non-covalent binding
between enzyme and substrate. - 2.When the velocity of enzyme activity is
plotted against substrate concentration, which
of the following is obtained?
a) Hyperbolic curve
b) Parabola
c) Straight line with positive slope
d) Straight line with negative slope
Answer: a
Explanation: At low substrate concentration,
the rate of a reaction is determined by the rate
of formation of an enzyme-substrate complex.
- 3.Which of the following is the correct Line
weaver-Burk equation?
Answer: a
Explanation:
Line weaver-Burk equation:
- 4.Which of the following statements is true
about competitive inhibitors?
a) It is a common type of irreversible
inhibition
b) In the presence of a competitive inhibitor,
the Michaelis-Menten equation becomes
c) The apparent Km decreases in the presence of inhibitor by a factor α
d) The maximum velocity for the reaction
decreases in the presence of a competitive
inhibitor
Answer: b
Explanation: Competitive inhibition is a
common type of reversible inhibition.
The apparent Km increases in the presence of
inhibitor by a factor α.
The maximum velocity for the reaction
remains same in the presence of a competitive
inhibitor.
- 5.Which of the following statements is true
about uncompetitive inhibitors?
a) They bind covalently at a site distinct from
the substrate active site
b) In the presence of a uncompetitive
inhibitor, the Michaelis-Menten equation
becomes
c) They increase the measured Vmax
d) Apparent Km also increases
Answer: b
Explanation: They bind non-covalently at a site distinct from the substrate active site
They decrease the measured Vmax and also apparent Km.
6.The rate determining step of Michaelis Menten kinetics is
a) The complex dissociation step to produce products.
b) The complex formation step
c) The product formation step
d) None of the mentioned
Answer: a
Explanation: The breakdown of ES complex
is the rate determining step of Michaelis
Menten kinetics.
- 7.The molecule which acts directly on an
enzyme to lower its catalytic rate is
a) Repressor
b) Inhibitor
c) Modulator
d) Regulator
Answer: b
Explanation: An inhibitor is a substance that
interferes with the substrate-active site
binding and slows down the catalytic rate.
- 8.Which of the following is an example for
irreversible inhibitor?
a) Disulfiram
b) Oseltamivir
c) Protease inhibitors
d) DIPF
Answer: d
Explanation: Disulfiram, Oseltamivir and
protease inhibitors are reversible inhibitors.
- 9.Which of the following is an example of
reversible inhibitor?
a) DIPF
b) Penicillin
c) Iodoacetamide
d) Protease inhibitors
Answer: d
Explanation: DIPF, Penicillin and
Iodoacetamide are irreversible inhibitors.
- 10.Where does inhibitor binds on enzyme in
mixed inhibition?
a) At active site
b) Allosteric site
c) Does not bind on enzyme
d) Binds on substrate
Answer: b
Explanation: The inhibitor binds at a place
different from active site allosterically. - 11.The catalytic efficiency of two distinct
enzymes can be compared based on which of
the following factor?
a) Km
b) Product formation
c) Size of the enzymes
d) pH of optimum value
Answer: a
Explanation: Km is the substrate
concentration. Increased substrate
concentration increases the rate of reaction. - 12.What is the general mechanism of an
enzyme?
a) It acts by reducing the activation energy
b) It acts by increasing the activation energy
c) It acts by decreasing the pH
d) It acts by increasing the pH
Answer: a
Explanation: For the reaction to occur at a
faster rate, activation energy should be less.
