MCQOPTIONS
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MCQOPTIONS
This section includes 181 Mcqs, each offering curated multiple-choice questions to sharpen your Biochemistry knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Storage polysaccharide made by animals is |
| A. | amylopectin |
| B. | glycogen |
| C. | cellulose |
| D. | collagen |
| Answer» C. cellulose | |
| 2. |
Gluconeogenesis uses |
| A. | 3 ATPs and 2 GTPs per glucose |
| B. | 2 ATPs and 1 GTPs per glucose |
| C. | 3 ATPs and 3 GTPs per glucose |
| D. | 4 ATPs and 2 GTPs per glucose |
| Answer» E. | |
| 3. |
Under aerobic condition pyruvate is converted by pyruvate dehydrogenase to |
| A. | phosphoenol pyruvate |
| B. | acetyl CoA |
| C. | lactate |
| D. | glyceraldehyde 3 phosphate |
| Answer» C. lactate | |
| 4. |
Gluconeogenesis requires a higher amount of ATP equivalents as compared to that produced by glycolysis because |
| A. | gluconeogenesis releases energy as heat |
| B. | glycolysis releases energy as heat |
| C. | glycolysis occurs in the mitochondria while gluconeogenesis occurs in the cytosol |
| D. | all of the above |
| Answer» C. glycolysis occurs in the mitochondria while gluconeogenesis occurs in the cytosol | |
| 5. |
The process not involved in the formation of glucose by gluconeo-genesis is |
| A. | the conversion of oxaloacetate to glucose |
| B. | the conversion of lactate to pyruvate |
| C. | the dephosphorylation of glucose-6-phosphate |
| D. | all of the above |
| Answer» B. the conversion of lactate to pyruvate | |
| 6. |
In the Glycolysis reaction, for each glucose conversion how many ATP's are produced? |
| A. | 4 |
| B. | 2 |
| C. | 1 |
| D. | 3 |
| Answer» C. 1 | |
| 7. |
The molecule which acts directly on an enzyme to lower its catalytic rate is __________ |
| A. | Repressor |
| B. | Inhibitor |
| C. | Modulator |
| D. | Regulator |
| Answer» C. Modulator | |
| 8. |
The proteolysis rate enhancement by chymotrypsin (~10¹⁰ folds) corresponds to a reduction in activation energy of about |
| A. | 40 kJ/mol |
| B. | 49 kJ/mol |
| C. | 58 kJ/mol |
| D. | 88 kJ/mol |
| Answer» D. 88 kJ/mol | |
| 9. |
Fructose is metabolized by |
| A. | fructose 1-phosphate pathway |
| B. | fructose 6-phosphate pathway |
| C. | glyceraldehyde 3-phosphate pathway |
| D. | both (a) and (b) |
| Answer» E. | |
| 10. |
Which of the following would be considered a part of metabolism? |
| A. | Biosynthetic pathways that build DNA |
| B. | Catabolic pathways that break down complex carbohydrates |
| C. | The capture of light energy for use in making glucose |
| D. | All of the above |
| Answer» E. | |
| 11. |
Humans are unable to digest |
| A. | starch |
| B. | complex carbohydrates |
| C. | denatured proteins |
| D. | cellulose |
| Answer» E. | |
| 12. |
Gluconeogenesis is the |
| A. | formation of glycogen |
| B. | breakdown of glucose to pyruvate |
| C. | breakdown of glycogen to glucose |
| D. | synthesis of glucose from non-carbohydrate precursors |
| Answer» E. | |
| 13. |
Which of the following is not involved in the biosynthesis of DNA? |
| A. | Energy from ATP |
| B. | Mononucleotides |
| C. | Carbonic anhydrase |
| D. | Enzymes |
| Answer» D. Enzymes | |
| 14. |
Patients suffering from Von Gierke's disease are unable to perform gluconeogeneis because they have a defective |
| A. | lactate dehydrogenase |
| B. | glucose 6 phosphatase |
| C. | pyruvate carboxylase |
| D. | none of these |
| Answer» C. pyruvate carboxylase | |
| 15. |
What is the consensus N-glycosylation site in a protein sequence? |
| A. | Asn-Xaa-(Ser or Thr) |
| B. | (Ser or Thr)-Asn-Ala |
| C. | Thr-(Asn or Gln)-Ala |
| D. | None of these |
| Answer» B. (Ser or Thr)-Asn-Ala | |
| 16. |
Which of the following characteristic enzymes of gluconeogensis is not found in the cytosol? |
| A. | Pyruvate carboxlyase |
| B. | Fructose-l,6-bisphosphatase |
| C. | Both (a) and (b) |
| D. | Glucose-6-phosphatase |
| Answer» B. Fructose-l,6-bisphosphatase | |
| 17. |
The conversion of pyruvate to lactate is catalysed by |
| A. | pyruvate carboxylase |
| B. | lactate dehydrogenase |
| C. | pyruvate dismutase |
| D. | pyruvate decarboxylase |
| Answer» C. pyruvate dismutase | |
| 18. |
The ultimate source of energy that sustains living systems is |
| A. | glucose |
| B. | oxygen |
| C. | sunlight |
| D. | carbon dioxide |
| Answer» D. carbon dioxide | |
| 19. |
How many types of enzymatic regulation mechanism occurs in the cells? |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | 5 |
| Answer» E. | |
| 20. |
Where does inhibitor binds on enzyme in mixed inhibition? |
| A. | At active site |
| B. | Allosteric site |
| C. | Does not bind on enzyme |
| D. | Binds on substrate |
| Answer» C. Does not bind on enzyme | |
| 21. |
Aldolases splits fructose 1,6 biphosphate into |
| A. | glyceraldehyde 3- phosphate |
| B. | glyceraldehyde 3- phosphate and dihydroxyacetone phosphate |
| C. | dihydroxyacetone phosphate |
| D. | none of the above |
| Answer» C. dihydroxyacetone phosphate | |
| 22. |
Metabolic reactions that break down complex molecules into smaller compounds, thereby releasing usable energy for the cell, are best described as |
| A. | biosynthetic |
| B. | catabolic |
| C. | catalytic |
| D. | photosynthetic |
| Answer» C. catalytic | |
| 23. |
The active site of chymotrypsin consists of a catalytic triad of which of the following amino acid residues? |
| A. | Serine, histidine and aspartate |
| B. | Serine, histidine and glutamate |
| C. | Threonine, histidine and aspartate |
| D. | Methionine, histidine and aspartate |
| Answer» B. Serine, histidine and glutamate | |
| 24. |
Regulated metabolic pathways are |
| A. | compartmentalized in eukaryotes |
| B. | usually regulated at the first step |
| C. | committed after the first step |
| D. | all of these |
| Answer» E. | |
| 25. |
The function of gluconeogenesis is |
| A. | maintenance of blood glucose levels during starvation or a low carbohydrate diet |
| B. | recovery of lactate from fermentation and glycerol from fat breakdown |
| C. | a pathway for the utilization of amino acids |
| D. | all of the above |
| Answer» E. | |
| 26. |
Boat and chair conformations are found |
| A. | in pyranose sugars |
| B. | in any sugar without axial -OH groups |
| C. | in any sugar without equatorial -OH groups |
| D. | only in D-glucopyranose |
| Answer» B. in any sugar without axial -OH groups | |
| 27. |
What is the cause of the genetic disease known as Galactosemia? |
| A. | Deficiency in lactase |
| B. | Absence of galactose 1-P uridyl transferase |
| C. | Absence of lactose synthetase |
| D. | Non functioning of semnase |
| Answer» C. Absence of lactose synthetase | |
| 28. |
A catabolic intermediate which stimulates phosphofructokinase would stimulate |
| A. | gluconeogenesis |
| B. | glycolysis |
| C. | glycogen synthesis |
| D. | none of these |
| Answer» C. glycogen synthesis | |
| 29. |
Which of the following is false statement with regard to comparison between Serine and HIV proteases? |
| A. | Both use nucleophilic attack to hydrolyze the peptide bond |
| B. | Both require water to complete the catalytic cycle |
| C. | Both forms an acyl-enzyme intermediate |
| D. | Both show specificity for certain amino acid sequences |
| Answer» D. Both show specificity for certain amino acid sequences | |
| 30. |
The polypeptide chains in chymotrypsin are linked by ___________ |
| A. | Hydrogen bonds |
| B. | Ionic bonds |
| C. | Disulfide bond |
| D. | SH-SH bond |
| Answer» D. SH-SH bond | |
| 31. |
What is present in the stomach to prevent self-digestion? |
| A. | Mucus |
| B. | acid |
| C. | Enzymes |
| D. | hormones |
| Answer» B. acid | |
| 32. |
Which of the following does not occur during gluconeogenesis? |
| A. | The carboxylation of pyruvate to oxaloacetate |
| B. | The conversion of pyruvate to phosphoenolpyruvate (PEP) |
| C. | The decarboxylation of oxaloacetate to phosphoenolpyruvate |
| D. | The conversion of PEP to fructose bisphosphate |
| Answer» C. The decarboxylation of oxaloacetate to phosphoenolpyruvate | |
| 33. |
Which of the following statements about enzymes or their function is true? |
| A. | Enzymes do not alter the overall change in free energy for a reaction |
| B. | Enzymes are proteins whose three-dimensional form is key to their function |
| C. | Enzymes speed up reactions by lowering activation energy |
| D. | All of the above |
| Answer» E. | |
| 34. |
a-amylose is similar to |
| A. | β-sheets |
| B. | β-turned coils |
| C. | α-helices |
| D. | the hydrophobic core |
| Answer» D. the hydrophobic core | |
| 35. |
Which of the following is not a disaccharide? |
| A. | Amylose |
| B. | Cellobiose |
| C. | Lactose |
| D. | None of these |
| Answer» B. Cellobiose | |
| 36. |
Which of the following statements about the energy needs of cells is false? |
| A. | Without a continuous input of energy, cell disorder will increase |
| B. | The laws of thermodynamics force cells to acquire energy |
| C. | Many cellular reactions have an associated activation energy |
| D. | The most usable energy for cells comes from the rapid combustion of glucose |
| Answer» E. | |
| 37. |
Which of the following is an example of reversible inhibitor? |
| A. | DIPF |
| B. | Penicillin |
| C. | Iodoacetamide |
| D. | Protease inhibitors |
| Answer» E. | |
| 38. |
Which of the following statements are true about the reactions at the active center of chymotrypsin? |
| A. | The aspartate residue gives an electron to histidine |
| B. | The aspartate residue gives a proton to histidine |
| C. | The aspartate residue keeps the histidine in the correct direction |
| D. | A proton moves from the aspartate to serine to histidine in the catalytic triad of chymotrypsin |
| Answer» D. A proton moves from the aspartate to serine to histidine in the catalytic triad of chymotrypsin | |
| 39. |
When the velocity of enzyme activity is plotted against substrate concentration, which of the following is obtained? |
| A. | Hyperbolic curve |
| B. | Parabola |
| C. | Straight line with positive slope |
| D. | Straight line with negative slope |
| Answer» B. Parabola | |
| 40. |
When living organisms are cooled below some critical body temperature, the metabolic reactions within their cells cease to function properly. This malfunction occurs because |
| A. | their enzymes lose the proper three-dimensional shape |
| B. | enzyme active sites become permanently bound to substrates |
| C. | the activation energy for the reaction is raised |
| D. | there is insufficient molecular motion for substrates to interact |
| Answer» E. | |
| 41. |
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 | |
| 42. |
An intermediate which inhibits the activity of fructose 1,6 diphos-phatase would inhibit |
| A. | glycolysis |
| B. | pyrolysis |
| C. | gluconeogenesis |
| D. | none of these |
| Answer» D. none of these | |
| 43. |
Enzyme-driven metabolic pathways can be made more efficient by |
| A. | concentrating enzymes within specific cellular compartments |
| B. | grouping enzymes into free-floating, multienzyme complexes |
| C. | fixing enzymes into membranes so that they are adjacent to each other |
| D. | All of the above |
| Answer» E. | |
| 44. |
The role of Asp 102 and His 57 during trypsin catalysis is to |
| A. | neutralize the charge on the other's side chain |
| B. | keep the specificity pocket open |
| C. | function as a proton shuttle |
| D. | clamp the substrate into the active site |
| Answer» D. clamp the substrate into the active site | |
| 45. |
Which of the following catalyzes the reversible degradation of 2-phosphoglycerate to phosphoenolpyruvate? |
| A. | Chymotrypsin |
| B. | Hexokinase |
| C. | Enolase |
| D. | Trypsin |
| Answer» D. Trypsin | |
| 46. |
Which of the following is true about the structure of hexokinase? |
| A. | U-shaped |
| B. | T-shaped |
| C. | E-shaped |
| D. | G-shaped |
| Answer» B. T-shaped | |
| 47. |
Which of the following is false about chymotrypsin? |
| A. | Hydrolytic cleavage of a peptide bond by chymotrypsin has two phases |
| B. | It is activated in the presence of trypsin |
| C. | It is synthesized in the thyroid gland |
| D. | Polypeptide chains in chymotrypsin are linked by S-S bonds |
| Answer» D. Polypeptide chains in chymotrypsin are linked by S-S bonds | |
| 48. |
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 | |
| 49. |
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 | |
| 50. |
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 | |