Role of an enzyme in reactions is to/as (a) decrease activation energy (b) increase activation energy (c) inorganic catalyst (d) none of the above.

Role of an enzyme in reactions is to/as
(a) decrease activation energy
(b) increase activation energy
(c) inorganic catalyst
(d) none of the above.
by

1 Answer

Answer :

(a) decrease activation energy
by

Related questions

Which one of the following statements regarding a catalyst is not correct? A An enzyme is a catalyst that only binds certain substrates. B An enzyme is a protein that is a highly efficient catalyst for one or more chemical reactions in a living system. C Catalysts increase the rate of a reaction by altering the mechanism, thereby increasing the activation energy. D Catalysts do not alter the equilibrium constant for a chemical reaction.

Description : Which one of the following statements regarding a catalyst is not correct? A An enzyme is a catalyst that only binds certain substrates. B An enzyme is a protein that is a highly ... increasing the activation energy. D Catalysts do not alter the equilibrium constant for a chemical reaction.

Last Answer : C Catalysts increase the rate of a reaction by altering the mechanism, thereby increasing the activation energy.

Pick out the correct statement. (A) In catalytic reactions, the catalyst reacts with the reactants (B) A catalyst initiates a chemical reaction (C) A catalyst lowers the activation energy of the reacting molecules (D) A catalyst cannot be recovered chemically unchanged at the end of the chemical reaction

Description : Pick out the correct statement. (A) In catalytic reactions, the catalyst reacts with the reactants (B) A catalyst initiates a chemical reaction (C) A catalyst lowers the activation energy of ... molecules (D) A catalyst cannot be recovered chemically unchanged at the end of the chemical reaction

Last Answer : (C) A catalyst lowers the activation energy of the reacting molecules

An enzyme brings about (A) Decrease in reaction time (B) Increase in reaction time (C) Increase in activation energy (D) Reduction in activation energy

Description : An enzyme brings about (A) Decrease in reaction time (B) Increase in reaction time (C) Increase in activation energy (D) Reduction in activation energy

Last Answer : Answer : D

Main function of an enzyme is to A- increase the activation energy B- decrease the activation energy C- maintain constant activation energy D- .none of these

Description : Main function of an enzyme is to A- increase the activation energy B- decrease the activation energy C- maintain constant activation energy D- .none of these

Last Answer : decrease the activation energy

The role of a catalyst in a chemical reaction is to change the (A) Equilibrium constant (B) Activation energy (C) Final products (D) Heat of reaction

Description : The role of a catalyst in a chemical reaction is to change the (A) Equilibrium constant (B) Activation energy (C) Final products (D) Heat of reaction

Last Answer : (B) Activation energy

For a heterogeneous catalytic reaction (A) Free energy of activation is lowered in the presence of catalyst, which remains unchanged at the end of reaction (B) A relatively small amount of catalyst can cause the conversion of large amount of reactants which does not mean that catalyst concentration is important (C) The catalyst does not form an intermediate complex with the reactant (D) The surface of the catalyst does not play an important role during reaction

Description : For a heterogeneous catalytic reaction (A) Free energy of activation is lowered in the presence of catalyst, which remains unchanged at the end of reaction (B) A relatively small amount of catalyst ... with the reactant (D) The surface of the catalyst does not play an important role during reaction

Last Answer : (A) Free energy of activation is lowered in the presence of catalyst, which remains unchanged at the end of reaction

Pick out the wrong statement. (A) Catalytic activity of enzyme catalysed reactions which is affected by temperature, pH value & chemical agents, is maximum at a temperature of about 45°C(B) Most of the enzyme catalysed reactions involve at least two substrates (C) Enzymes help in increasing the activation energy of the reaction (D) Equilibrium concentrations in enzyme catalysed reactions can be calculated by using the thermodynamic properties of substrates & prod

Description : Pick out the wrong statement. (A) Catalytic activity of enzyme catalysed reactions which is affected by temperature, pH value & chemical agents, is maximum at a temperature of about 45°C ... in enzyme catalysed reactions can be calculated by using the thermodynamic properties of substrates & prod

Last Answer : (C) Enzymes help in increasing the activation energy of the reaction

Metabolism is carried out by a large class of proteins that decrease the activation energy required for chemical reactions inside a cell. Therefore they only facilitate reactions that would naturally occur at a much slower rate. What is the name of these proteins that speed up biochemical reactions?

Description : Metabolism is carried out by a large class of proteins that decrease the activation energy required for chemical reactions inside a cell. Therefore they only facilitate reactions that would naturally occur at a much slower rate. What is the name of these proteins that speed up biochemical reactions?

Last Answer : Enzymes

Fibrinolytic therapy is based on activation of plasminogen, the inactive proteolytic enzyme of plasma that binds to fibrin during the formation of thrombosis. Activation of plasminogen to plasmin results in selective thrombolysis at the fibrin clot surface. Which of the following statement(s) is/are true concerning agents used in thrombolytic therapy? a. Streptokinase is a bacterial protein which is antigenic in humans, resulting in allergic reactions in up to l5% of cases b. Tissue plasminogen activator acts directly on plasmin without an intermediate drug–plasmin complex c. The half-life of urokinase, streptokinase, and TPA all exceed 30 minutes d. Streptokinase is significantly cheaper than urokinase or TPA

Description : Fibrinolytic therapy is based on activation of plasminogen, the inactive proteolytic enzyme of plasma that binds to fibrin during the formation of thrombosis. Activation of plasminogen to plasmin results ... TPA all exceed 30 minutes d. Streptokinase is significantly cheaper than urokinase or TPA

Last Answer : Answer: a, b, d Streptokinase is a bacterial protein produced by group C b-hemolytic streptococci. It is therefore antigenic in humans and can be associated with allergic reaction in ... one agent over the other. Streptokinase however, is markedly less expensive than either urokinase or TPA

Enzymes increase the rates of reactions by (A) Increasing the free energy of activation (B) Decreasing the energy of activation (C) Changing the equilibrium constant of the reaction (D) Increasing the free energy change of the reaction

Description : Enzymes increase the rates of reactions by (A) Increasing the free energy of activation (B) Decreasing the energy of activation (C) Changing the equilibrium constant of the reaction (D) Increasing the free energy change of the reaction

Last Answer : Answer : B

Methylxanthine drugs such as aminophylline cause which one of the following? (a) Vasoconstriction in many vascular beds (b) Decrease in the amount of cAMP in mast cells (c) Bronchodilation (d) Activation of the enzyme phosphodiesterase (e) Sedation

Description : Methylxanthine drugs such as aminophylline cause which one of the following? (a) Vasoconstriction in many vascular beds (b) Decrease in the amount of cAMP in mast cells (c) Bronchodilation (d) Activation of the enzyme phosphodiesterase (e) Sedation

Last Answer : Ans: C

The increase in the rate of reaction with temperature is due to (A) Increase in the number of effective collisions (B) Decrease in activation energy (C) Increase in the average kinetic energy of the reacting molecules (D) None of these

Description : The increase in the rate of reaction with temperature is due to (A) Increase in the number of effective collisions (B) Decrease in activation energy (C) Increase in the average kinetic energy of the reacting molecules (D) None of these

Last Answer : (B) Decrease in activation energy

An increase in which of the following results in a decrease in the rate of the chemical reaction? (a) temperature (b) concentration (c) collision frequency (d) energy of activation

Description : An increase in which of the following results in a decrease in the rate of the chemical reaction? (a) temperature (b) concentration (c) collision frequency (d) energy of activation

Last Answer : energy of activation

Which of the following is incorrect about heterogeneous catalysis? a. The most effective catalysts are those which have small surface area b. Seperation of catlyst is easy c. Increase in the rate of reaction is due to decrease in the activation energy d. It is based upon the phenomenon of adsorption

Description : Which of the following is incorrect about heterogeneous catalysis? a. The most effective catalysts are those which have small surface area b. Seperation of catlyst is easy c. Increase in the rate of reaction is due to decrease in the activation energy d. It is based upon the phenomenon of adsorption

Last Answer : a. The most effective catalysts are those which have small surface area

A catalyst is a substance which (a) Changes the equilibrium of a reaction so that the concentration of the product increases (b) Increases the rate of reaction and increases the equilibrium concentration of products (c) Hastens the attainment of equilibrium (d) Increases the activation energy

Description : A catalyst is a substance which (a) Changes the equilibrium of a reaction so that the concentration of the product increases (b) Increases the rate of reaction and increases the equilibrium concentration of products (c) Hastens the attainment of equilibrium (d) Increases the activation energy

Last Answer : Ans:(c)

Pick out the correct statement. (A) A lower temperature favours the reaction of lower activation energy (B) The dispersion number for a reactor/vessel is uL/D (C) The rate controlling step in a reaction involving many steps is the fastest step (D) Pore volume and porosity of a catalyst is measured by Brunauer￾Emmett-Teller (BET) technique

Description : Pick out the correct statement. (A) A lower temperature favours the reaction of lower activation energy (B) The dispersion number for a reactor/vessel is uL/D (C) The rate controlling step in ... step (D) Pore volume and porosity of a catalyst is measured by Brunauer￾Emmett-Teller (BET) technique

Last Answer : (A) A lower temperature favours the reaction of lower activation energy

Catalytic action in a catalytic chemical reaction follows from the ability of catalyst to change the (A) Activation energy (B) Equilibrium constant (C) Heat of reaction (D) None of these

Description : Catalytic action in a catalytic chemical reaction follows from the ability of catalyst to change the (A) Activation energy (B) Equilibrium constant (C) Heat of reaction (D) None of these

Last Answer : (A) Activation energy

A catalyst (A) Initiates a reaction (B) Lowers the activation energy of reacting molecules (C) Is capable of reacting with any one of the reactants (D) Cannot be recovered chemically unchanged at the end of a chemical reaction

Description : A catalyst (A) Initiates a reaction (B) Lowers the activation energy of reacting molecules (C) Is capable of reacting with any one of the reactants (D) Cannot be recovered chemically unchanged at the end of a chemical reaction

Last Answer : (C) Is capable of reacting with any one of the reactants

The reason why a catalyst increases the rate of reaction is that, it (A) Decreases the energy barrier for reaction (B) Increases the activation energy (C) Decreases the molecular collision diameter (D) None of these

Description : The reason why a catalyst increases the rate of reaction is that, it (A) Decreases the energy barrier for reaction (B) Increases the activation energy (C) Decreases the molecular collision diameter (D) None of these

Last Answer : (A) Decreases the energy barrier for reaction

Pick out the wrong statement. (A) Use of different catalysts in a reversible catalytic chemical reaction does not change the equilibrium composition (B) Alumina is added as a promoter to iron catalyst in ammonia synthesis reaction (C) Activation energy for a reaction is obtained from the intercept of the Arrhenius plot (D) Presence of inerts affects the equilibrium conversion of reactants in a chemical reaction

Description : Pick out the wrong statement. (A) Use of different catalysts in a reversible catalytic chemical reaction does not change the equilibrium composition (B) Alumina is added as a promoter to ... Arrhenius plot (D) Presence of inerts affects the equilibrium conversion of reactants in a chemical reaction

Last Answer : (C) Activation energy for a reaction is obtained from the intercept of the Arrhenius plot

Pick out the wrong statement. (A) Exit age description function (E) and internal age distribution function (I) are related as, E = -(dI/dθ) (B) Chemisorption studies are useful in the determination of catalyst surface area and pore size distribution (C) A higher temperature favours the reaction of higher activation energy (D) A catalyst increases the potential energy barrier over which the reactants must pass to form products

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Last Answer : (D) A catalyst increases the potential energy barrier over which the reactants must pass to form products

Pick out the correct statement. (A) A catalyst does not change AH of the reaction (B) A catalyst changes the equilibrium point (C) Law of mass action was suggested by Le-Chatelier (D) The difference between the energy of reactants and that of the products is the activation energy

Description : Pick out the correct statement. (A) A catalyst does not change AH of the reaction (B) A catalyst changes the equilibrium point (C) Law of mass action was suggested by Le-Chatelier (D) The difference between the energy of reactants and that of the products is the activation energy

Last Answer : (A) A catalyst does not change AH of the reaction

The catalyst in a first order chemical reaction changes the (A) Equilibrium constant(B) Activation energy(C) Heat of formation of the product(D) Heat of reaction

Description : The catalyst in a first order chemical reaction changes the (A) Equilibrium constant (B) Activation energy (C) Heat of formation of the product (D) Heat of reaction

Last Answer : (B) Activation energy

A catalyst in a chemical reaction (A) Decreases the activation energy (B) Alters the reaction mechanism (C) Increases the frequency of collisions of reacting species (D) All (A), (B) and (C)

Description : A catalyst in a chemical reaction (A) Decreases the activation energy (B) Alters the reaction mechanism (C) Increases the frequency of collisions of reacting species (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

What happens when a catalyst is added to a system at equilibrium? A The reaction follows an alternative pathway of lower activation energy. B The heat of reaction decreases. C The potential energy of the reactants decreases. D The potential energy of the products decreases. E The rate of chemical reaction decreases.

Description : What happens when a catalyst is added to a system at equilibrium? A The reaction follows an alternative pathway of lower activation energy. B The heat of reaction decreases. C The potential ... decreases. D The potential energy of the products decreases. E The rate of chemical reaction decreases.

Last Answer : A The reaction follows an alternative pathway of lower activation energy.

A high concentration of PTH in blood causes (A) Increase in plasma calcium and inorganic phosphorous (B) Decrease in plasma calcium and inorganic phosphorous (C) Increase in plasma calcium and decrease in plasma inorganic phosphorous (D) Decrease in plasma calcium and increase in plasma inorganic phosphorous

Description : A high concentration of PTH in blood causes (A) Increase in plasma calcium and inorganic phosphorous (B) Decrease in plasma calcium and inorganic phosphorous (C) Increase in plasma calcium ... in plasma inorganic phosphorous (D) Decrease in plasma calcium and increase in plasma inorganic phosphorous

Last Answer : Answer : C

Chemoautotrophic bacteria obtain the energy they need from a. The Reactions Of Photosynthesis. b. Sunlight. c. Carbon Dioxide In The Atmosphere. d. Inorganic Chemicals.

Description : Chemoautotrophic bacteria obtain the energy they need from a. The Reactions Of Photosynthesis. b. Sunlight. c. Carbon Dioxide In The Atmosphere. d. Inorganic Chemicals.

Last Answer : b. Sunlight.

Organic catalysts differ from the inorganic catalyst in the sense that the former is (A) Active at cryogenic temperatures only (B) Prohibitively costly (C) Proteinous in nature (D) Active at very high temperature only

Description : Organic catalysts differ from the inorganic catalyst in the sense that the former is (A) Active at cryogenic temperatures only (B) Prohibitively costly (C) Proteinous in nature (D) Active at very high temperature only

Last Answer : (C) Proteinous in nature

Characteristics of Vitamin D and its metabolites include which one of the following? (a) Act to decrease serum levels of calcium (b) Activation of their Vitamin D receptors increases cellular CAMP (c) Calcitriol is the major derivative responsible for increasing intestinal absorption of phosphate (d) Metabolites of Vitamin D increase renal excretion of calcium (e) Vitamin D deficiency results in Pager’s disease

Description : Characteristics of Vitamin D and its metabolites include which one of the following? (a) Act to decrease serum levels of calcium (b) Activation of their Vitamin D receptors increases cellular CAMP ... Vitamin D increase renal excretion of calcium (e) Vitamin D deficiency results in Pager's disease

Last Answer : Ans: C

Enzymes increases the rate of reactions by (A) Increasing the free energy of activation (B) Decreasing the energy of activation (C) Changing the equilibrium constant of the reaction (D) Increasing the free energy change of the reaction

Description : Enzymes increases the rate of reactions by (A) Increasing the free energy of activation (B) Decreasing the energy of activation (C) Changing the equilibrium constant of the reaction (D) Increasing the free energy change of the reaction

Last Answer : Answer : B

Enzymes accelerate the rate of reactions by (A) Increasing the equilibrium constant of reactions (B) Increasing the energy of activation (C) Decreasing the energy of activation (D) Decreasing the free energy change of the reaction

Description : Enzymes accelerate the rate of reactions by (A) Increasing the equilibrium constant of reactions (B) Increasing the energy of activation (C) Decreasing the energy of activation (D) Decreasing the free energy change of the reaction

Last Answer : Answer : C

The reactions of high molecularity are rare, because (A) Of very large activation energy of many bodies (B) Of low probability of many body collisions (C) Many body collisions are not favoured energetically (D) Of requirement of very large concentration for such reactions

Description : The reactions of high molecularity are rare, because (A) Of very large activation energy of many bodies (B) Of low probability of many body collisions (C) Many body collisions are not favoured energetically (D) Of requirement of very large concentration for such reactions

Last Answer : (B) Of low probability of many body collisions

Pick out the wrong statement. (A) In a multistep reaction, the slowest step is the rate determining step (B) In general, the rate of a reaction becomes triple for every 10°C rise in temperature (C) Slow chemical reactions have generally high values of activation energy (D) Molecularity of a reaction cannot be zero but the order of a reaction can be zero

Description : Pick out the wrong statement. (A) In a multistep reaction, the slowest step is the rate determining step (B) In general, the rate of a reaction becomes triple for every 10°C rise in temperature (C ... energy (D) Molecularity of a reaction cannot be zero but the order of a reaction can be zero

Last Answer : (B) In general, the rate of a reaction becomes triple for every 10°C rise in temperature

Pick out the correct statement. (A) Reactions with high activation energies are very temperature sensitive (B) Chemical equilibrium is a static state (C) A photochemical reaction is catalysed by light (D) A chemical reaction occurs when the energy of the reacting molecule is less than the activation energy of the reaction

Description : Pick out the correct statement. (A) Reactions with high activation energies are very temperature sensitive (B) Chemical equilibrium is a static state (C) A photochemical reaction is catalysed by ... occurs when the energy of the reacting molecule is less than the activation energy of the reaction

Last Answer : (A) Reactions with high activation energies are very temperature sensitive (B) Chemical equilibrium is a static state

Pick out the wrong statement: (A) Chemical reactions with high activation energy are very temperature sensitive (B) A flat velocity profile exists in a plug flow reactor (C) The residence time for all the elements of fluid in case of a P.F.R. need not be same (D) Half life of a reaction increases with increased initial concentration for reaction orders more than one

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Last Answer : (C) The residence time for all the elements of fluid in case of a P.F.R. need not be same

Reactions with high activation energy are (A) Very temperature sensitive (B) Temperature insensitive (C) Always irreversible (D) Always reversible

Description : Reactions with high activation energy are (A) Very temperature sensitive (B) Temperature insensitive (C) Always irreversible (D) Always reversible

Last Answer : (A) Very temperature sensitive

The minimum energy required to allow a chemical reaction to proceed is termed as the 'threshold energy '. Chemical reactions with low activation energy are: (A) Always irreversible (B) Insensitive to temperature changes (C) Mostly irreversible (D) Highly temperature sensitive

Description : The minimum energy required to allow a chemical reaction to proceed is termed as the 'threshold energy '. Chemical reactions with low activation energy are: (A) Always irreversible (B) Insensitive to temperature changes (C) Mostly irreversible (D) Highly temperature sensitive

Last Answer : (B) Insensitive to temperature changes

The reactions with low activation energy are (A) Always spontaneous (B) Slow (C) Fast (D) Non-spontaneous

Description : The reactions with low activation energy are (A) Always spontaneous (B) Slow (C) Fast (D) Non-spontaneous

Last Answer : (C) Fast

Pick out the wrong statement. (A) Visible radiation provides the necessary activation energy in photochemical reactions (B) The order and molecularity of a complex reaction may not be the same (C) For a second order reaction, the slope of the graph/plot between rate and (concentration) is equal to the rate constant (k) (D) Molecularity of the reaction is always a whole number greater than zero

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Last Answer : (B) The order and molecularity of a complex reaction may not be the same

Proteins that cause reactions to proceed more rapidly and lower the energy of activation are called.

Description : Proteins that cause reactions to proceed more rapidly and lower the energy of activation are called.

Last Answer : ANSWER: ENZYMES

Which one of the following statements about cytochrome P450 is wrong? (a) It is a coloured cell. (b) It is an enzyme involved in oxidation reactions. (c) It has an important role in metabolism. (d) It contains iron

Description : Which one of the following statements about cytochrome P450 is wrong? (a) It is a coloured cell. (b) It is an enzyme involved in oxidation reactions. (c) It has an important role in metabolism. (d) It contains iron

Last Answer : (a) It is a coloured cell.

Catalyst is a substance, which __________ chemical reaction. (A) Increases the speed of a (B) Decreases the speed of a (C) Can either increase or decrease the speed of a (D) Alters the value of equilibrium constant in a reversible

Description : Catalyst is a substance, which __________ chemical reaction. (A) Increases the speed of a (B) Decreases the speed of a (C) Can either increase or decrease the speed of a (D) Alters the value of equilibrium constant in a reversible

Last Answer : (C) Can either increase or decrease the speed of a

The equilibrium constant of chemical reaction __________ in the presence of catalyst. (A) Increases (B) Decreases (C) Remain unaffected (D) Can either increase or decrease (depends on the type of catalyst)

Description : The equilibrium constant of chemical reaction __________ in the presence of catalyst. (A) Increases (B) Decreases (C) Remain unaffected (D) Can either increase or decrease (depends on the type of catalyst)

Last Answer : (C) Remain unaffected

An enzyme promotes a chemical reaction by (A) Lowering the energy of activation (B) Causing the release of heat which acts as a primer (C) Increasing molecular motion (D) Changing the free energy difference between substrate and product

Description : An enzyme promotes a chemical reaction by (A) Lowering the energy of activation (B) Causing the release of heat which acts as a primer (C) Increasing molecular motion (D) Changing the free energy difference between substrate and product

Last Answer : Answer : A

Enzymes (a protein) are catalysts found in organisms. Its efficiency of catalysing a reaction is due to its capacity to lower the activation energy of the reaction. The enzyme ptyalin used for food digestion is present in (A) Blood (B) Saliva (C) Intestine (D) Gland

Description : Enzymes (a protein) are catalysts found in organisms. Its efficiency of catalysing a reaction is due to its capacity to lower the activation energy of the reaction. The enzyme ptyalin used for food digestion is present in (A) Blood (B) Saliva (C) Intestine (D) Gland

Last Answer : (B) Saliva

State the role of activated complex in a reaction and state the relation with energy of activation.

Description : State the role of activated complex in a reaction and state the relation with energy of activation.

Last Answer : Ans.: When the colliding reactant molecules possess the kinetic energy equal to energy of activation then the configuration of atoms of the species at this state is different from the reactants as well as ... barrier means the activated complex is difficult to form and it is a slow reaction.  

Fight-or-flight reactions cause activation of (a) the parathyroid glands, leading to increased metabolic rate (b) the kidney, leading to suppression of renin- angiotensin-aldosterone pathway (c) the adrenal medulla, leading to increased secretion of epinephrine and norepinephrine (d) the pancreas leading to a reduction in the blood sugar levels.

Description : Fight-or-flight reactions cause activation of (a) the parathyroid glands, leading to increased metabolic rate (b) the kidney, leading to suppression of renin- angiotensin-aldosterone pathway (c) ... epinephrine and norepinephrine (d) the pancreas leading to a reduction in the blood sugar levels.

Last Answer : (c) the adrenal medulla, leading to increased secretion of epinephrine and norepinephrine

An inorganic ion required for the activity of an enzyme is known as (A) Activator (B) Cofactor (C) Coenzyme (D) None of these

Description : An inorganic ion required for the activity of an enzyme is known as (A) Activator (B) Cofactor (C) Coenzyme (D) None of these

Last Answer : Answer : B