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.
| 151. |
Vitamins are essential because the organism |
| A. | can't synthesize these compounds at all |
| B. | can synthesize these compounds partially |
| C. | can't synthesize these compounds in the adequate amounts |
| D. | none of the above |
| Answer» B. can synthesize these compounds partially | |
| 152. |
Common feature in all serine proteases is a |
| A. | hydrophobic specificity pocket |
| B. | hydrophilic specificity pocket |
| C. | cluster of reactive serine residues |
| D. | single reactive serine residue |
| Answer» E. | |
| 153. |
Which of the common features are shared between serine and aspartate proteases? |
| A. | Both require water to complete the catalytic cycle |
| B. | Both use a base to activate the nucleophile |
| C. | Both show specificity for certain amino acid sequences |
| D. | All of the above |
| Answer» E. | |
| 154. |
Before they can react, many molecules need to be destabilized. This state is typically achieved through |
| A. | changing the three-dimensional shape of the molecule |
| B. | oxidizing the molecules by removing electrons |
| C. | changing the reaction from a biosynthetic to a catabolic pathway |
| D. | the input of a small amount of activation energy |
| Answer» E. | |
| 155. |
The E.coli pyruvic acid dehydrogenase complex is reported to |
| A. | decatalyze the oxidation of pyruvic acid to acetyl Co A and CO₂ |
| B. | Catalyze the oxidation of pyruvic acid to acetyl Co A and CO₂ |
| C. | retard the reduction of pyruvic acid to acetyl Co A and CO₂ |
| D. | Catalyze the reduction of pyruvic acid to acetyl Co A and CO₂ |
| Answer» C. retard the reduction of pyruvic acid to acetyl Co A and CO₂ | |
| 156. |
The most prominent role that tocopherol has in in-vitro systems is as a strong |
| A. | antioxidants |
| B. | reducing agent |
| C. | oxidizing agent |
| D. | all of these |
| Answer» B. reducing agent | |
| 157. |
The cleavage specificity of trypsin and chymotrypsin depend in part on the |
| A. | proximity of Ser 195 to the active site or specificity pocket |
| B. | size, shape, and charge of the active site or specificity pocket |
| C. | presence of a low-barrier hydrogen bond in the active site or specificity pocket |
| D. | absence of water in the active site |
| Answer» C. presence of a low-barrier hydrogen bond in the active site or specificity pocket | |
| 158. |
Acyl carrier protein (ACP) plays an important role in the biosynthesis of |
| A. | fatty acids |
| B. | amino acids |
| C. | sugars |
| D. | carbohydrates |
| Answer» B. amino acids | |
| 159. |
A deficiency of thiamin produces the disease known as |
| A. | beri-beri |
| B. | scurvy |
| C. | cataract |
| D. | anemia |
| Answer» B. scurvy | |
| 160. |
Main function of insulin hormone is to |
| A. | increase glycogen in liver |
| B. | decrease glycogen in liver |
| C. | increase blood sugar |
| D. | decrease blood sugar |
| Answer» E. | |
| 161. |
Ascorbic acid acts as an |
| A. | reducing agent |
| B. | oxidizing agent |
| C. | oxidizing and reducing agent both |
| D. | none of the above |
| Answer» B. oxidizing agent | |
| 162. |
The symptoms of retinol excess are |
| A. | bone fragility |
| B. | nausea |
| C. | weakness |
| D. | all of these |
| Answer» E. | |
| 163. |
The vitamin riboflavin is part of the __________ molecule. |
| A. | ferredoxin |
| B. | FAD |
| C. | pyridoxal phosphat |
| D. | pyrophosphate |
| Answer» C. pyridoxal phosphat | |
| 164. |
In the co-enzyme B₁₂ the position occupied by a cyanide ion in vitamin B12 is bonded directly to the __________ of the ribose of adenosine. |
| A. | adenine |
| B. | 5-6 dimethylbenzimidazole |
| C. | hydroxycobalamin |
| D. | cyanocobalamin |
| Answer» B. 5-6 dimethylbenzimidazole | |
| 165. |
β-carotene together with α-carotene, γ-carotene and cryptoxanthine are synthesized by |
| A. | plants |
| B. | animal |
| C. | plants and animals both |
| D. | none of these |
| Answer» B. animal | |
| 166. |
Lipoic acid is a co-factor of the |
| A. | pyruvic dehydrogenase |
| B. | α-ketoglutaric dehydrogenase |
| C. | both (a) and (b) |
| D. | di-hydroorotate dehydrogenase |
| Answer» D. di-hydroorotate dehydrogenase | |
| 167. |
Which of these molecules is vitamin H? |
| A. | Biotin |
| B. | Carnitine |
| C. | Folic acid |
| D. | None of these |
| Answer» B. Carnitine | |
| 168. |
Biotin occurs mainly in combined forms bound to protein through |
| A. | ε-N-lysine moiety |
| B. | ε-S-lysine moiety |
| C. | ε-N-biotinyl-L-lysine |
| D. | ε-N-lipoyl - L-lysine |
| Answer» B. ε-S-lysine moiety | |
| 169. |
In one iron-metalloflavoprotein, the iron is present as a |
| A. | heme-protein |
| B. | nonheme type |
| C. | both (a) and (b) |
| D. | flavin moiety |
| Answer» B. nonheme type | |
| 170. |
Which of these is a vitamin A precursor? |
| A. | Cobalamin |
| B. | Pyridoxine |
| C. | Beta-Carotene |
| D. | Thiamine |
| Answer» D. Thiamine | |
| 171. |
A fat-soluble vitamin that regulates blood clotting is |
| A. | vitamin A |
| B. | vitamin K |
| C. | vitamin C |
| D. | niacin |
| Answer» C. vitamin C | |
| 172. |
Lipoic acid exists in |
| A. | oxidized form |
| B. | reduced form |
| C. | oxidized and reduced form both |
| D. | none of these |
| Answer» D. none of these | |
| 173. |
The reductant, NADH, transfers the electrons via a flavo-proteins to the specific disulfide (S-S) protein to form a dithiol (SH,SH) protein which converts vitamin |
| A. | B₁₂(Co²⁺)to B₁₂(Co) |
| B. | B₁₂(Co) to B₁₂(Co²⁺) |
| C. | B₁₂(Co²⁺)to B₁₂(Co⁺) |
| D. | B₁₂(Co⁺)to B₁₂(Co²⁺) |
| Answer» D. B₁₂(Co⁺)to B₁₂(Co²⁺) | |
| 174. |
An example of a digestive hormone is |
| A. | lipase |
| B. | pepsin |
| C. | amylase |
| D. | gastrin |
| Answer» E. | |
| 175. |
Vitamin B₁₂ is useful in the prevention and treatment of |
| A. | pernicious anemia |
| B. | scurvy |
| C. | cataract |
| D. | beri-beri |
| Answer» B. scurvy | |
| 176. |
Which of the following glycoprotein functions as a lubricant and protective agent? |
| A. | Collagens |
| B. | Mucins |
| C. | Transferrins |
| D. | Immunoglobulins |
| Answer» C. Transferrins | |
| 177. |
Which of these is a symptom of vitamin A deficiency? |
| A. | Osteoporosis |
| B. | Impaired taste perception |
| C. | Blindness |
| D. | Impaired blood clotting |
| Answer» D. Impaired blood clotting | |
| 178. |
What compound of raw egg white causes a syndrome similar to vitamin B deficiency? |
| A. | Avidin |
| B. | Betabindin |
| C. | Ovalbumin |
| D. | Albumin |
| Answer» B. Betabindin | |
| 179. |
The disease Beriberi is due to a dietary deficiency in |
| A. | vitamin B1 (thiamine) |
| B. | vitamin B2 (riboflavin) |
| C. | vitamin B6 (pyridoxine) |
| D. | vitamin B12 |
| Answer» B. vitamin B2 (riboflavin) | |
| 180. |
An enzyme, L-folate reductase reduces folic acid to |
| A. | hydrofolic acid |
| B. | dihydrofolic acid |
| C. | trihydrofolic acid |
| D. | tetrahydrofolic acid |
| Answer» C. trihydrofolic acid | |
| 181. |
An early sign of retinol deficiencies in man is |
| A. | night blindness |
| B. | keratinization |
| C. | xeropthalmia |
| D. | none of these |
| Answer» B. keratinization | |