Enzyme Reaction

Q1: In the reaction, C6H12O6+ 6O2 → 6CO2 + 6H2O + energy, which component is being oxidized?

A C6H12O6

B O2

C CO2

D H2O

ANS:A - C6H12O6

No answer description is available. 

Q2: Hydrogen and oxygen release enormous amounts of energy when they react. Yet, hydrogen and oxygen can be mixed together in a balloon and nothing will happen. Why?

A Competitive inhibitors are blocking the reaction from occurring in the active site

B There must be contaminating elements in the balloon that prohibit the reaction from occurring

C The energy of activation to form the transition-state complex is too high to allow the reaction to occur without assistance

D all of the above

ANS:A - Competitive inhibitors are blocking the reaction from occurring in the active site

No answer description is available. 

Q3: The ability of a competitive inhibitor to bind to an active site in an allosterically controlled enzyme is __________ than the ability of a non-competitive inhibitor to bind to an active site in the same allosterically controlled enzyme.

A greater

B lesser

C approximately equal

D half

ANS:C - approximately equal

No answer description is available. 

Q4: If the Keq for an enzymatic reaction is greater than 1, the reaction

A will be endergonic

B can not occur without the input of energy

C both (a) and (b)

D none of these

ANS:D - none of these

No answer description is available. 

Q5: Denaturation of an enzyme refers to the

A improper arrangement of the enzyme in a metabolic pathway

B loss of the enzymes proper shape

C formation of the enzymes proper shape

D formation of a new isozyme for that enzyme

ANS:C - formation of the enzymes proper shape

No answer description is available. 

Q6: Reduction is the

A loss of proton

B gain of electron

C loss of electron

D gain of protons

ANS:B - gain of electron

No answer description is available. 

Q7: About 7.3 kcal/mole are released when

A glucose is converted to CO2 and H2O

B NAD+ is reduced to NADH

C ATP hydrolysis is coupled to sucrose synthesis

D the terminal phosphate bond of ATP is broken by hydrolysis

ANS:A - glucose is converted to CO2 and H2O

No answer description is available. 

Q8: If the free energy change (ΔG) in a reaction is a negative value, it indicates that the

A reaction releases energy

B reaction absorbs energy

C reaction is in negative direction

D reaction is in positive direction

ANS:A - reaction releases energy

No answer description is available. 

Q9: An exergonic reaction is one that

A requires energy to proceed

B releases energy for work

C gives off much heat

D looses energy

ANS:B - releases energy for work

No answer description is available. 

Q10: In the reaction, C6H12O6 + 6O2 → 6CO2 + 6H2O + energy, which component is being reduced?

A O2

B CO2

C H2O

D Energy

ANS:A - O2

No answer description is available. 

Q11: An enzyme that is always produced, regardless of the presence of substrates or the end products, is called

A a constitutive enzyme

B an isoenzyme

C a repressible enzyme

D an allosteric enzyme

ANS:A - a constitutive enzyme

No answer description is available. 

Q12: A substrate binds to its enzyme at a location called the __________ site.

A coenzyme

B substrate

C active

D polypeptide

ANS:C - active

No answer description is available. 

Q13: The fact that β-oxidation of fatty acids, occurs in the mitochondria whereas fatty acid synthesis occurs in the cytoplasmic matrix, is an example of regulation of enzymatic activity by the __________ mechanism.

A compartmentation

B induction

C competitive inhibition

D repression

ANS:D - repression

No answer description is available. 

Q14: Anthranilate synthase, the first enzyme of tryptophan biosynthesis after the branch point shows feedback inhibition and repression due to

A L-tryptophan

B D-L-tryptophan hydantoin

C L-serine

D pyruvate

ANS:A - L-tryptophan

No answer description is available. Let's discuss.

Q15: An endergonic reaction is one that

A requires energy in order to proceed

B releases energy for work

C gives off much heat

D looses energy

ANS:A - requires energy in order to proceed

No answer description is available. 

Q16: Which of the following is the best evidence for the lock and key theory of enzyme action?

A Compounds similar in structure to the substrate inhibit enzyme activity

B Enzymes are found in living organisms and speed up certain reactions

C Enzymes speed up reactions by definite amounts

D Enzymes determine the direction of a reaction

ANS:A - Compounds similar in structure to the substrate inhibit enzyme activity

No answer description is available. 

Q17: The ability of Vibrio fischeri to convert chemical energy directly into radiant energy in bioluminescence is an example of __________ at work.

A Shelford's law of tolerance

B Leibig's law of the minimum

C the first law of thermodynamics

D the third law of thermodynamics

ANS:C - the first law of thermodynamics

No answer description is available. 

Q18: Oxidation is the

A loss of proton

B gain of electron

C loss of electron

D gain of protons

ANS:C - loss of electron

No answer description is available. 

Q19: The ability of FADH to be oxidized is __________ than the ability of FAD to be oxidized.

A greater

B lesser

C approximately equal

D half

ANS:A - greater

No answer description is available. 

Q20: The affinity of an enzyme for its substrate, when the enzyme has a Km of 0.50 M will be __________ than the affinity of an enzyme for its substrate when the enzyme has a Km of 0.05 M.

A greater

B lesser

C approximately equal

D half

ANS:B - lesser

No answer description is available. 

Q21: The ability of CTP to bind to aspartate carbamoyltransferase and shut down the synthesis of more CTP is an example of

A enzyme induction

B enzyme repression

C feedback inhibition of enzyme activity

D none of these

ANS:C - feedback inhibition of enzyme activity

No answer description is available. 

Q22: To a living organism, which of the following has the greatest amount of available energy per molecule?

A ATP

B ADP

C AMP

D H2O

ANS:A - ATP

No answer description is available. 

Q23: Adenosine triphosphate is a type of

A fatty acid

B amino acid

C nucleotide

D steroid

ANS:C - nucleotide

No answer description is available.



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