MCQOPTIONS
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MCQOPTIONS
This section includes 19 Mcqs, each offering curated multiple-choice questions to sharpen your Biochemistry knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Which of the following is false about feedback regulation? |
| A. | It is a type of enzymatic activity regulation |
| B. | The synthesis of concerned enzyme is inhibited by interfering with the gene of that enzyme |
| C. | Concentration of enzyme is reduced by the end product |
| D. | The best example is the biosynthesis of L-isoleucine from L-threonine in bacteria |
| Answer» E. | |
| 2. |
Which of the following enzyme catalyzes a reaction that introduces reduced nitrogen ito cellular metabolism? |
| A. | Bacterial glutamine synthase |
| B. | Bacterial dinitrogenase reductase |
| C. | Bacterial dinitrogenase oxidase |
| D. | Phosphatase |
| Answer» B. Bacterial dinitrogenase reductase | |
| 3. |
Which of the following takes place due to phosphorylation of isocitrate dehydrogenase? |
| A. | Inhibits the binding of citrate at active site |
| B. | Degrades the enzyme |
| C. | Enhances the substrate-binding affinity |
| D. | No reaction |
| Answer» B. Degrades the enzyme | |
| 4. |
Which of the following is false about the following reaction? |
| A. | Phosphorylase a is less active and phosphorylase b is more active |
| B. | Glycogen phosphorylase catalyzes this reaction |
| C. | Phosphorylase b can be transformed back into phosphorylase a by phosphorylase kinase |
| D. | Phosphorylase kinase catalyzes the transfer of phosphoryl groups from ATP to Phosphorylase bView Answer |
| Answer» B. Glycogen phosphorylase catalyzes this reaction | |
| 5. |
The attachment of phosphoryl groups to specific amino acid residues is catalyzed by ___________ |
| A. | Diphteria toxin and cholera toxin |
| B. | Dinitrogenase reductase |
| C. | Protein phosphatases |
| D. | Protein kinases |
| Answer» E. | |
| 6. |
Removal of phosphoryl groups is catalyzed by ___________ |
| A. | Diphteria toxin and cholera toxin |
| B. | Dinitrogenase reductase |
| C. | Protein phosphatases |
| D. | Protein kinases |
| Answer» D. Protein kinases | |
| 7. |
The allosteric inhibitor of an enzyme ___________ |
| A. | Causes the enzyme to work faster |
| B. | Binds to the active site |
| C. | Participates in feedback regulation |
| D. | Denatures the enzyme |
| Answer» D. Denatures the enzyme | |
| 8. |
WHICH_OF_THE_FOLLOWING_ENZYME_CATALYZES_A_REACTION_THAT_INTRODUCES_REDUCED_NITROGEN_ITO_CELLULAR_METABOLISM??$ |
| A. | Bacterial glutamine synthase |
| B. | Bacterial dinitrogenase reductase |
| C. | Bacterial dinitrogenase oxidase |
| D. | Phosphatase |
| Answer» B. Bacterial dinitrogenase reductase | |
| 9. |
WHICH_OF_THE_FOLLOWING_TAKES_PLACE_DUE_TO_PHOSPHORYLATION_OF_ISOCITRATE_DEHYDROGENASE??$ |
| A. | Inhibits the binding of citrate at active site |
| B. | Degrades the enzyme |
| C. | Enhances the substrate-binding affinity |
| D. | No reaction |
| Answer» B. Degrades the enzyme | |
| 10. |
Which is the enzyme that acts as a regulatory enzyme in a four-step metabolic pathway? |
| A. | First enzyme |
| B. | Fourth enzyme |
| C. | Second enzyme |
| D. | Third enzyme |
| Answer» B. Fourth enzyme | |
| 11. |
How many types of enzymatic regulation mechanism occurs in the cells? |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | 5 |
| Answer» E. | |
| 12. |
In the case of allosteric enzymes what is the graphical representation when initial velocity is plotted against substrate concentration? |
| A. | Straight line with negative slope |
| B. | Hyperbola |
| C. | Sigmoid curve |
| D. | Parabola |
| Answer» D. Parabola | |
| 13. |
Phosphorylase a +2H2O ‚Üí phosphorylase b + 2Pi |
| A. | |
| B. | Phosphorylase a is less active and phosphorylase b is more active |
| C. | Glycogen phosphorylase catalyzes this reaction |
| Answer» B. Phosphorylase a is less active and phosphorylase b is more active | |
| 14. |
The attachment of phosphoryl groups to specific amino acid residues is catalyzed by |
| A. | Diphteria toxin and cholera toxin |
| B. | Dinitrogenase reductase |
| C. | Protein phosphatases |
| D. | Protein kinases |
| Answer» E. | |
| 15. |
Removal of phosphoryl groups is catalyzed by |
| A. | Diphteria toxin and cholera toxin |
| B. | Dinitrogenase reductase |
| C. | Protein phosphatases |
| D. | Protein kinases |
| Answer» D. Protein kinases | |
| 16. |
Which of the following enzymes catalyze the ADP-ribosylation of key cellular enzymes or proteins? |
| A. | Diphteria toxin and cholera toxin |
| B. | Dinitrogenase reductase |
| C. | Protein phosphatases |
| D. | Kinase |
| Answer» B. Dinitrogenase reductase | |
| 17. |
Which of the following enzyme is responsible for the regulation of biological nitrogen fixation? |
| A. | Dinitrogenase reductase |
| B. | Dinitrogenase oxidase |
| C. | Phosphatase |
| D. | Kinase |
| Answer» B. Dinitrogenase oxidase | |
| 18. |
Which of the following is false about allosteric feedback inhibition? |
| A. | Bacterial enzyme system is the first known example |
| B. | Conversion of L-leucine to L-isoleucine |
| C. | Threonine dehydratase is inhibited by isoleucine |
| D. | If the isoleucine concentration decreases, the rate of threonine dehydration increases |
| Answer» C. Threonine dehydratase is inhibited by isoleucine | |
| 19. |
The allosteric inhibitor of an enzyme |
| A. | Causes the enzyme to work faster |
| B. | Binds to the active site |
| C. | Participates in feedback regulation |
| D. | Denatures the enzyme |
| Answer» D. Denatures the enzyme | |