MCQOPTIONS
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MCQOPTIONS
This section includes 25 Mcqs, each offering curated multiple-choice questions to sharpen your Physics knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
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 |
| Answer» B. D-L-tryptophan hydantoin | |
| 2. |
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 |
| Answer» D. none of these | |
| 3. |
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 |
| Answer» B. Enzymes are found in living organisms and speed up certain reactions | |
| 4. |
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 |
| Answer» B. ADP | |
| 5. |
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 |
| Answer» B. lesser | |
| 6. |
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 |
| Answer» C. approximately equal | |
| 7. |
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 |
| Answer» B. lesser | |
| 8. |
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 |
| Answer» E. | |
| 9. |
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 |
| Answer» D. the third law of thermodynamics | |
| 10. |
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 |
| Answer» B. There must be contaminating elements in the balloon that prohibit the reaction from occurring | |
| 11. |
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 |
| Answer» C. formation of the enzymes proper shape | |
| 12. |
A substrate binds to its enzyme at a location called the __________ site. |
| A. | coenzyme |
| B. | substrate |
| C. | active |
| D. | polypeptide |
| Answer» D. polypeptide | |
| 13. |
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 |
| Answer» B. NAD+ is reduced to NADH | |
| 14. |
In the reaction, C6H12O6+ 6O2 → 6CO2 + 6H2O + energy, which component is being oxidized? |
| A. | C6H12O6 |
| B. | O2 |
| C. | CO2 |
| D. | H2O |
| Answer» B. O2 | |
| 15. |
Adenosine triphosphate is a type of |
| A. | fatty acid |
| B. | amino acid |
| C. | nucleotide |
| D. | steroid |
| Answer» D. steroid | |
| 16. |
In the reaction, C6H12O6 + 6O2 → 6CO2 + 6H2O + energy, which component is being reduced? |
| A. | O2 |
| B. | CO2 |
| C. | H2O |
| D. | Energy |
| Answer» B. CO2 | |
| 17. |
Reduction is the |
| A. | loss of proton |
| B. | gain of electron |
| C. | loss of electron |
| D. | gain of protons |
| Answer» C. loss of electron | |
| 18. |
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 |
| Answer» B. reaction absorbs energy | |
| 19. |
Oxidation is the |
| A. | loss of proton |
| B. | gain of electron |
| C. | loss of electron |
| D. | gain of protons |
| Answer» D. gain of protons | |
| 20. |
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 |
| Answer» E. | |
| 21. |
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 |
| Answer» B. releases energy for work | |
| 22. |
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 |
| Answer» B. an isoenzyme | |
| 23. |
An exergonic reaction is one that |
| A. | requires energy to proceed |
| B. | releases energy for work |
| C. | gives off much heat |
| D. | looses energy |
| Answer» C. gives off much heat | |
| 24. |
Counter-immunoelectrophoresis is used for the detection of |
| A. | Meningococcal antigen |
| B. | Hepatitis B surface antigen |
| C. | Alpha-fetoprotein |
| D. | All of these |
| Answer» E. | |
| 25. |
Amount of various immunoglobulin classes can be measured by |
| A. | double diffusion in one dimension |
| B. | single diffusion in two dimensions |
| C. | single diffusion in one dimension |
| D. | double diffusion in two dimensions |
| Answer» C. single diffusion in one dimension | |