MCQOPTIONS
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MCQOPTIONS
This section includes 31 Mcqs, each offering curated multiple-choice questions to sharpen your Biochemistry knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Glycolysis converts ___________ |
| A. | Glucose into pyruvate |
| B. | Glucose into phosphoenolpyruvate |
| C. | Fructose into pyruvate |
| D. | Fructose into phosphoenolpyruvate |
| Answer» B. Glucose into phosphoenolpyruvate | |
| 2. |
The product formed in the first substrate level phosphorylation in glycolysis is ___________ |
| A. | Pyruvate |
| B. | 3-phosphoglycerate |
| C. | 1, 3-bisphosphoglycerate |
| D. | 2-phosphoglycerate |
| Answer» C. 1, 3-bisphosphoglycerate | |
| 3. |
High concentration of glucose 6-phosphate is inhibitory to ___________ |
| A. | Hexokinase |
| B. | Pyruvate kinase |
| C. | Glucokinase |
| D. | Phosphofructokinase-1 |
| Answer» B. Pyruvate kinase | |
| 4. |
Which substrate is used in the last step of glycolysis? |
| A. | Glyceraldehyde 3-phosphate |
| B. | Pyruvate |
| C. | Phosphoenolpyruvate |
| D. | 1, 3-bisphosphoglycerate |
| Answer» D. 1, 3-bisphosphoglycerate | |
| 5. |
What is the first step in the payoff phase of glycolysis? |
| A. | Reduction of 1, 3-bisphosphoglycerate to glyceraldehyde 3-phosphate |
| B. | Oxidation of glyceraldehyde 3-phosphate to 1, 3-bisphosphoglycerate |
| C. | Reversible conversion of dihydroxyacetone phosphate to glyceraldehyde 3-phosphate |
| D. | Irreversible conversion of dihydroxyacetone phosphate to glyceraldehyde 3-phosphate |
| Answer» C. Reversible conversion of dihydroxyacetone phosphate to glyceraldehyde 3-phosphate | |
| 6. |
Dihydroxyacetone phosphate is rapidly and reversibly converted to ___________ |
| A. | Glyceraldehyde 3-phosphate |
| B. | 1, 3-bis-phosphoglycerate |
| C. | Fructose 1, 6-bisphosphate |
| D. | Fructose 6-phosphate |
| Answer» B. 1, 3-bis-phosphoglycerate | |
| 7. |
Cleavage of Fructose 1, 6-biophosphate yields ___________ |
| A. | Two aldoses |
| B. | Two ketoses |
| C. | An aldose and a ketose |
| D. | Only a ketose |
| Answer» D. Only a ketose | |
| 8. |
Whenever the cell s ATP supply is depleted, which of the following enzyme s activity is increased? |
| A. | Hexokinase |
| B. | Pyruvate kinase |
| C. | Glucokinase |
| D. | Phosphofructokinase-1 |
| Answer» E. | |
| 9. |
What is the general term used for the anaerobic degradation of glucose to obtain energy? |
| A. | Anabolism |
| B. | Oxidation |
| C. | Fermentation |
| D. | Metabolism |
| Answer» D. Metabolism | |
| 10. |
Which of the following could act as an uncoupler of electron transport and ATP synthesis? |
| A. | The Fo base-piece of ATP synthase (without the Fl subunit) |
| B. | Dinitrophenol |
| C. | neither (a) nor (b) |
| D. | Both (a) and (b) |
| Answer» E. | |
| 11. |
Which of the following is not a mechanism for altering the flux of metabolites through the rate-determining step of a pathway? |
| A. | Allosteric control of the enzyme activity |
| B. | Diffusional coupling between adjacent active sites |
| C. | Genetic control of the enzyme concentration |
| D. | Covalent modification of the enzyme |
| Answer» C. Genetic control of the enzyme concentration | |
| 12. |
Phosphofructokinase, the major flux-controlling enzyme of glycolysis is allosterically inhibited and activated respectively by |
| A. | ATP and PEP |
| B. | AMP and Pi |
| C. | ATP and ADP |
| D. | Citrate and ATP |
| Answer» D. Citrate and ATP | |
| 13. |
Which of the following regulates glycolysis steps? |
| A. | Phosphofructokinase |
| B. | Hexose kinase |
| C. | Pyruvate kinase |
| D. | All of these |
| Answer» E. | |
| 14. |
For every one molecule of sugar glucose which is oxidized __________ molecule of pyruvic acid are produced. |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» C. 3 | |
| 15. |
In the glycogen synthase reaction, the precursor to glycogen is |
| A. | glucose-6-P |
| B. | UTP-glucose |
| C. | UDP-glucose |
| D. | glucose-1-P |
| Answer» D. glucose-1-P | |
| 16. |
In glycolysis, ATP is formed by the transfer of a high-energy phosphate from 1,3-bisphosphoglycerate to ADR No such high-energy phosphate donor has ever been isolated in mitochondria because |
| A. | the techniques for isolating the phosphate donor are not refined enough |
| B. | no such phosphate donor exists |
| C. | the high-energy phosphate donor is very short-lived and difficult to isolate |
| D. | None of the above |
| Answer» C. the high-energy phosphate donor is very short-lived and difficult to isolate | |
| 17. |
The glycolytic pathway (glucose 2 pyruvate) is found |
| A. | in all living organisms |
| B. | primarily in animals excluding particles |
| C. | only in eukaryotes |
| D. | only in yeast |
| Answer» B. primarily in animals excluding particles | |
| 18. |
Glycogen has |
| A. | -1,4 linkage |
| B. | -1,6 linkages |
| C. | -1,4 and -1,6 linkages |
| D. | -1,4 and -1,6 linkage |
| Answer» D. -1,4 and -1,6 linkage | |
| 19. |
The active form of glycogen phosphorylase is phosphorylated, while the dephosphorylation of which active form occurs? |
| A. | Glycogen synthase |
| B. | Glycogen semisynthase |
| C. | Glycogen hydrolase |
| D. | Glycogen dehydrogenase |
| Answer» B. Glycogen semisynthase | |
| 20. |
The amount of energy received from one ATP is |
| A. | 76 kcal |
| B. | 7.3 kcal |
| C. | 760 kcal |
| D. | 1000 kcal |
| Answer» C. 760 kcal | |
| 21. |
The enzymes of glycolysis in a eukaryotic cell are located in the |
| A. | intermembrane space |
| B. | plasma membrane |
| C. | cytosol |
| D. | mitochondrial matrix |
| Answer» D. mitochondrial matrix | |
| 22. |
Fructose-2,6-bisphosphate |
| A. | activates fructose-1,6-bisphosphatase |
| B. | activates phosphofructokinase |
| C. | inhibits fructose-1,6-bisphosphatase |
| D. | both (b) and (c) |
| Answer» E. | |
| 23. |
Glucose from the breakdown of glycogen is obtained in |
| A. | the liver by phosphorolysis |
| B. | the muscles by phosphorolysis |
| C. | the muscles by hydrolysis |
| D. | both (a) and (b) |
| Answer» E. | |
| 24. |
During glycolysis, the major energy generating step involves |
| A. | pyruvate kinase |
| B. | phosphoglycerate kinase |
| C. | glyceraldehyde-3 -dehydrogenase |
| D. | Phosphofructokinase |
| Answer» D. Phosphofructokinase | |
| 25. |
Glycolytic pathway regulation involves |
| A. | allosteric stimulation by ADP |
| B. | allosteric inhibition by ATP |
| C. | feedback, or product, inhibition by ATP |
| D. | all of the above |
| Answer» E. | |
| 26. |
During catabolism, only about 40% of the energy available from oxidizing glucose is used to synthesize ATP. Remaining 60% |
| A. | is lost as heat |
| B. | is used to reduce NADP |
| C. | remains in the products of metabolism |
| D. | is stored as fat. |
| Answer» B. is used to reduce NADP | |
| 27. |
A kinase is an enzyme that |
| A. | removes phosphate groups of substrates |
| B. | uses ATP to add a phosphate group to the substrate |
| C. | uses NADH to change the oxidation state of the substrate |
| D. | removes water from a double bond |
| Answer» C. uses NADH to change the oxidation state of the substrate | |
| 28. |
The released energy obtained by oxidation of glucose is stored as |
| A. | a concentration gradient across a membrane |
| B. | ADP |
| C. | ATP |
| D. | NAD |
| E. | <sup>+</sup> |
| Answer» D. NAD | |
| 29. |
When concentration of the reactants is higher than the equilibrium concentration then |
| A. | the gibbs free energy will be positive |
| B. | the gibbs free energy will be negative |
| C. | more products will be formed |
| D. | both (b) and (c) |
| Answer» E. | |
| 30. |
Why does the glycolytic pathway continue in the direction of glucose catabolism? |
| A. | There are essentially three irreversible reactions that act as the driving force for the pathway |
| B. | High levels of ATP keep the pathway going in a forward direction |
| C. | The enzymes of glycolysis only function in one direction |
| D. | Glycolysis occurs in either direction |
| Answer» B. High levels of ATP keep the pathway going in a forward direction | |
| 31. |
ATP is from which general category of molecules? |
| A. | Polysaccharides |
| B. | Proteins |
| C. | Nucleotides |
| D. | Amino acids |
| Answer» D. Amino acids | |