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.
| 101. |
How is the enzyme COX-1 important in human health? |
| A. | It helps to transport carbon dioxide in the blood |
| B. | It is critical for the biosynthesis of DNA |
| C. | It is a chemical derivative of aspirin |
| D. | It catalyzes the production of hormones that maintain the stomach lining |
| Answer» E. | |
| 102. |
Which of the following is false about lysozyme? |
| A. | It is an antibacterial agent found in tears and egg white |
| B. | The substrate of lysozyme is peptidoglycan |
| C. | Lysozyme cleaves (β1 → 4) glycosidic C-O bonds between two types of sugar residue in the molecule NAM and NAG |
| D. | It is a bisubstrate enzyme |
| Answer» E. | |
| 103. |
Fructose diphosphate accumulation would |
| A. | inhibit glycolysis and gluconeogenesis |
| B. | stimulate glycolysis and gluconeogenesis |
| C. | stimulate glycolysis and inhibit gluconeogenesis |
| D. | inhibit glycolysis and stimulate gluconeogenesis |
| Answer» D. inhibit glycolysis and stimulate gluconeogenesis | |
| 104. |
Glucagon and epinephrine |
| A. | inhibits gluconeogenesis and stimulates glycolysis |
| B. | stimulates gluconeogenesis and glycolysis |
| C. | stimulates gluconeogenesis and inhibits glycolysis |
| D. | inhibits gluconeogenesis and glycolysis |
| Answer» D. inhibits gluconeogenesis and glycolysis | |
| 105. |
Glycogen degradation requires the enzyme namely |
| A. | glycogen phosphorylase and phosphoglucomutase |
| B. | glycogen phosphorylase and glycogen-debranching enzyme |
| C. | glycogen synthase and phosphorylase |
| D. | none of the above |
| Answer» C. glycogen synthase and phosphorylase | |
| 106. |
When all the monosaccharides in a polysaccharide are same type, such type of a polysaccharide is called a ___________ |
| A. | Glycogen |
| B. | Homoglycan |
| C. | Heteroglycan |
| D. | Oligosaccharide |
| Answer» C. Heteroglycan | |
| 107. |
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 | |
| 108. |
Which of the following has reducing properties? |
| A. | Glucuronic acid |
| B. | Gluconic acid |
| C. | Glucaric acid |
| D. | Mucic acid |
| Answer» B. Gluconic acid | |
| 109. |
Which of the following carbohydrates is a triose? |
| A. | Glucose |
| B. | Ribose |
| C. | Ribulose |
| D. | Glyceraldehyde |
| Answer» E. | |
| 110. |
In the enzyme-catalyzed reaction shown below, what will be the effect on substances A, B, C, and D of inactivating the enzyme labeled E2? A ---(E1)---> B ---(E2)---> C ---(E3)---> |
| A. | A, B, C, and D will all still be produced |
| B. | A, B, and C will still be produced, but not D |
| C. | A and B will still be produced, but not C or D |
| D. | A will still be produced, but not B, C, or D |
| Answer» D. A will still be produced, but not B, C, or D | |
| 111. |
Glycolysis reactions take place in |
| A. | cytoplasm |
| B. | cell membrane |
| C. | cell wall |
| D. | plasmids |
| Answer» B. cell membrane | |
| 112. |
Which of the following are the structural polysaccharides? |
| A. | Glycogen |
| B. | Starch |
| C. | Chitin |
| D. | Glucose |
| Answer» D. Glucose | |
| 113. |
Which of the following is an example of bacterial and yeast polysaccharide? |
| A. | Starch |
| B. | Glycogen |
| C. | Cellulose |
| D. | Dextrans |
| Answer» E. | |
| 114. |
The cells dependent solely on glucose as an energy source are |
| A. | muscle cells |
| B. | brain cells |
| C. | kidney cells |
| D. | liver cells |
| Answer» C. kidney cells | |
| 115. |
During vigorous exercise, pyruvate produced by glycolysis is converted to |
| A. | acetate |
| B. | lactate |
| C. | monosodium phosphate |
| D. | pyruvic acid |
| Answer» C. monosodium phosphate | |
| 116. |
Vitamin-C is considered as a |
| A. | water soluble |
| B. | fat soluble |
| C. | fat and water soluble |
| D. | none of these |
| Answer» B. fat soluble | |
| 117. |
Which of the following is carried out when cAMP functions as a second messenger? |
| A. | Acts second in importance to AMP |
| B. | Activates all cytosolic protein kinases |
| C. | Activates the cAMP-dependent protein kinase |
| D. | Acts outside the cell to influence cellular processes |
| Answer» D. Acts outside the cell to influence cellular processes | |
| 118. |
Saliva contains all of the following except |
| A. | hormones |
| B. | amylase |
| C. | bacteria-killing enzymes |
| D. | antibodies |
| Answer» B. amylase | |
| 119. |
Which of the following compounds is responsible for coordinated regulation of glucose and glycogen metabolism? |
| A. | NAD+ |
| B. | Fructose 2,6 bisphosphate |
| C. | Acetyl-CoA |
| D. | Fructose 1,6 bisphosphate |
| Answer» C. Acetyl-CoA | |
| 120. |
Dihydroorotate dehydrogenase contains |
| A. | 4 flavins and 4 atoms of iron per molecule |
| B. | 2 flavins and 4 atoms of iron per molecule |
| C. | 2 flavins and 2 atoms of iron per molecule |
| D. | 4 flavins and 2 atoms of iron per molecule |
| Answer» B. 2 flavins and 4 atoms of iron per molecule | |
| 121. |
Which of the following is an oligosaccharide linked to protein? |
| A. | Glycolipid |
| B. | Glycoprotein |
| C. | Ganglioside |
| D. | Galactoside |
| Answer» B. Glycoprotein | |
| 122. |
Which of the following catalyzes the reversible reaction of β-D-Glucose to glucose 6-phosphate? |
| A. | Chymotrypsin |
| B. | Hexokinase |
| C. | Enolase |
| D. | Trypsin |
| Answer» C. Enolase | |
| 123. |
Which of the following is the correct Line weaver-Burk equation? |
| A. | a |
| B. | b |
| C. | c |
| D. | d |
| Answer» B. b | |
| 124. |
The hormones, glucagon and epinephrine, stimulate glycogen breakdown to G-6-P |
| A. | only in the liver |
| B. | using ATP as the phosphoryl donor |
| C. | directly, by binding to glycogen phosphorylase |
| D. | indirectly, by first stimulating adenylate cyclase to make cAMP |
| Answer» E. | |
| 125. |
The sugar which forms major component of nucleic acids is |
| A. | ribose |
| B. | galactose |
| C. | mannose |
| D. | maltose |
| Answer» B. galactose | |
| 126. |
Which of the following is true about Michaelis-Menten kinetics? |
| A. | Kₘ, the Michaelis constant, is defined as that concentration of substrate at which enzyme is working at maximum velocity |
| B. | It describes single substrate enzymes |
| C. | Kₘ, the Michaelis constant is defined as the dissociation constant of the enzyme-substrate complex |
| D. | It assumes covalent binding occurs between enzyme and substrate |
| Answer» C. Kₘ, the Michaelis constant is defined as the dissociation constant of the enzyme-substrate complex | |
| 127. |
In lysozyme catalysis, which of the following does not contribute? |
| A. | The abnormally high pKa of Glu35 |
| B. | The strained conformation of the D sugar |
| C. | Formation of a covalent intermediate at Asp52 |
| D. | Formation of a covalent intermediate at Ser195 |
| Answer» E. | |
| 128. |
Which of the following enzymes plays an important role in the Cori " cycle? |
| A. | Glucokinase |
| B. | Glucose-6-phosphate dehydrogenase |
| C. | Lactate dehydrogenase |
| D. | Glucose isomerase |
| Answer» D. Glucose isomerase | |
| 129. |
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 | |
| 130. |
Tryprotophan synthetase of E.coli, a typical bifunctional oligomeric enzyme consist of |
| A. | a protein designated A |
| B. | two proteins designated A and B |
| C. | a protein A and one-subunit a |
| D. | a protein designated B |
| Answer» C. a protein A and one-subunit a | |
| 131. |
How many ATP equivalents per mole of glucose input are required for gluconeogenesis? |
| A. | 2 |
| B. | 6 |
| C. | 8 |
| D. | 4 |
| Answer» C. 8 | |
| 132. |
E.coli ACP has its molecular weight as around |
| A. | 9000 |
| B. | 19000 |
| C. | 39000 |
| D. | 90,000 |
| Answer» B. 19000 | |
| 133. |
Which of the following (s) is/are serine proteases? |
| A. | Chymotrypsin |
| B. | Trypsin |
| C. | Elastase |
| D. | all of these |
| Answer» E. | |
| 134. |
What would be the molecular formula for a polymer made by linking ten glucose molecules together by dehydration synthesis, if molecular formula for glucose is C6H,206? |
| A. | C60H100O50 |
| B. | C60H120O60 |
| C. | C60H102O51 |
| D. | (C6H12O6)10 |
| Answer» D. (C6H12O6)10 | |
| 135. |
What is the general mechanism of an enzyme? |
| A. | It acts by reducing the activation energy |
| B. | It acts by increasing the activation energy |
| C. | It acts by decreasing the pH |
| D. | It acts by increasing the pH |
| Answer» B. It acts by increasing the activation energy | |
| 136. |
Who discovered vitamin C (ascorbic acid)? |
| A. | Paul Berg |
| B. | Linus Pauling |
| C. | Albert Szent-Gyorgyi |
| D. | Kerry Mull is |
| Answer» D. Kerry Mull is | |
| 137. |
The catalytic efficiency of two distinct enzymes can be compared based on which of the following factor? |
| A. | Kₘ |
| B. | Product formation |
| C. | Size of the enzymes |
| D. | pH of optimum value |
| Answer» B. Product formation | |
| 138. |
Selenium is an essential component of the enzyme glutathione peroxidase which |
| A. | scavenges toxic hydoperoxycompounds in tissues |
| B. | reduces toxic hydoperoxycompounds in tissues |
| C. | oxidizes toxic hydoperoxycompounds in tissues |
| D. | none of the above |
| Answer» B. reduces toxic hydoperoxycompounds in tissues | |
| 139. |
Models of end-linked Osaka VI Fibrinogen dimers, a bilayer dimer is linked at |
| A. | both ends by one disulfide bond |
| B. | either end via two disulfide bonds |
| C. | either end via a single disulfide bond |
| D. | both ends by two disulfide bonds |
| Answer» E. | |
| 140. |
A deficiency of niacin causes |
| A. | pellagra |
| B. | scurvy |
| C. | cataract |
| D. | anemia |
| Answer» B. scurvy | |
| 141. |
The occurrence of metals such as iron or molybdenum in some flavoproteins can |
| A. | stabilize the semiquinone |
| B. | de-stabilize the semiquinone |
| C. | form chelation |
| D. | all of these |
| Answer» B. de-stabilize the semiquinone | |
| 142. |
What metal ion is specifically bound by vitamin B12? |
| A. | Cobalt |
| B. | Copper |
| C. | Zinc |
| D. | Iron |
| Answer» B. Copper | |
| 143. |
Which of the following compounds/(s) belong/(s) to the vitamin B6 group? |
| A. | Pyridoxal |
| B. | Pyridoxine |
| C. | Pyridoxamine |
| D. | All of these |
| Answer» E. | |
| 144. |
A deficiency of Vitamin K results in a decreased level of |
| A. | prothrombin |
| B. | thrombin |
| C. | fibrin |
| D. | fibrinogen |
| Answer» B. thrombin | |
| 145. |
The vitamin riboflavin, which occurs as a yellow pigment in egg yolk and milk become |
| A. | colorless on reduction with Zn in acid and regained its color on re-oxidation |
| B. | colorless on oxidation and regained its color on reduction with Zn in acid |
| C. | more deep in color on reduction with Zn in acid and regained its color on re-oxidation |
| D. | more deep in color on oxidation and regained its color on reduction with Zn in acid |
| Answer» B. colorless on oxidation and regained its color on reduction with Zn in acid | |
| 146. |
Vitamin-D deficiency can cause |
| A. | rickets |
| B. | pernicious anemia |
| C. | cataract |
| D. | beri-beri |
| Answer» B. pernicious anemia | |
| 147. |
The absence of ascorbic acid in the human diet gives rise to |
| A. | rickets |
| B. | pernicious anemia |
| C. | cataract |
| D. | beri-beri |
| Answer» C. cataract | |
| 148. |
Which of the following are reduced coenzymes? |
| A. | NADH and FADH₂ |
| B. | NAD⁺ and FAD |
| C. | ATP and GTP |
| D. | Coenzyme A and ubiquinone |
| Answer» B. NAD⁺ and FAD | |
| 149. |
Vitamin B12 (Cobalamin) is only synthesized by |
| A. | fishes |
| B. | micro-organisms |
| C. | plants |
| D. | animals |
| Answer» C. plants | |
| 150. |
The prosthetic group biotin is a carrier of which type of molecule? |
| A. | Activated carbon dioxide (CO₂) |
| B. | Ammonia |
| C. | Methyl group |
| D. | Sulfhydryl group |
| Answer» B. Ammonia | |