MCQOPTIONS
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MCQOPTIONS
This section includes 199 Mcqs, each offering curated multiple-choice questions to sharpen your Biochemistry knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
The deficiency of which of the following enzyme leads to galactosemia? |
| A. | Galactokinase |
| B. | Pyruvate kinase |
| C. | PFK-1 |
| D. | PFK-2 |
| Answer» B. Pyruvate kinase | |
| 52. |
Which out of the following is not a flavoprotein? |
| A. | Succinate dehydrogenase |
| B. | Cytochrome c |
| C. | Xanthine oxidase |
| D. | NADH dehydrogenase-Qreductase |
| Answer» C. Xanthine oxidase | |
| 53. |
What is the main source of natural fluoride? |
| A. | Mushrooms |
| B. | Potatoes |
| C. | Meat |
| D. | Water |
| Answer» E. | |
| 54. |
Which of the following mineral is involved in protein metabolism and oxidation reactions? |
| A. | Molybdenum |
| B. | Manganese |
| C. | Magnesium |
| D. | calcium |
| Answer» B. Manganese | |
| 55. |
One of the following statements is correct about pentose phosphate pathway |
| A. | It generates 6 moles of CO₂ for each mole of glucose consumed |
| B. | It generates 38 mol of ATP per mole of glucose consumed |
| C. | It is a reductive pathway that consumes NADH |
| D. | Present in plants but not in animals |
| Answer» B. It generates 38 mol of ATP per mole of glucose consumed | |
| 56. |
Which of the following statements about the control of glycogen synthesis from blood glucose in myocytes is incorrect? |
| A. | Insulin affects three of five steps in this pathway |
| B. | The effects on transport and hexokinase activity increase the flux towards glycogen |
| C. | The change in glycogen synthase activity increases the flux towards glycogen |
| D. | Hexokinase enzyme is involved |
| Answer» D. Hexokinase enzyme is involved | |
| 57. |
Iodine is a part of thyroid hormone and is essential for the prevention of |
| A. | goiter |
| B. | osteoporosis |
| C. | muscle weakness |
| D. | diarrhea |
| Answer» B. osteoporosis | |
| 58. |
Which of the following statements is true about the control of muscle glycogen phosphorylase? |
| A. | It is activated by phosphorylation by an active phosphorylase kinase |
| B. | It is allosterically activated by ATP |
| C. | It is allosterically activated by cAMP |
| D. | Normally it exists in active form |
| Answer» B. It is allosterically activated by ATP | |
| 59. |
Which of the following enzyme’s gene expression is slowed by insulin? |
| A. | Hexokinase II |
| B. | Hexokinase IV |
| C. | PEP carboxykinase |
| D. | Pyruvate kinase |
| Answer» D. Pyruvate kinase | |
| 60. |
Selenium deficiency leads to |
| A. | liver necrosis |
| B. | diarrhea |
| C. | multiple sclerosis |
| D. | Crohn's disease |
| Answer» B. diarrhea | |
| 61. |
∆G° is defined as the |
| A. | Residual energy present in the reactants at equilibrium |
| B. | Residual energy present in the products at equilibrium |
| C. | Difference in the residual energy of reactants and products at equilibrium |
| D. | Energy required in converting one mole of reactants to one mole of products |
| Answer» E. | |
| 62. |
Which of the following is required as a component of blood hemoglobin? |
| A. | Iron |
| B. | Magnesium |
| C. | Calcium |
| D. | Copper |
| Answer» B. Magnesium | |
| 63. |
Which is an example for chemical to osmotic energy conversion that occurs in living organisms? |
| A. | ATP-driven muscle contraction |
| B. | ATP-dependent photon emission in fireflies |
| C. | light-induced electron flow in chloroplasts |
| D. | ATP-driven active transport across a membrane |
| Answer» E. | |
| 64. |
Ethanol is oxidized to acetaldehyde in the liver cytoplasm by |
| A. | Alcohol dehydrogenase |
| B. | Alcohol carboxylase |
| C. | Pyruvate carboxylase |
| D. | Pyruvate kinase |
| Answer» B. Alcohol carboxylase | |
| 65. |
The mineral which aids in the utilization of iron and in hemoglobin synthesis is |
| A. | calcium |
| B. | phosphorus |
| C. | cobalt |
| D. | copper |
| Answer» E. | |
| 66. |
The product formed in the isomerization of mannose 6-phosphate |
| A. | Fructose 6-phosphate |
| B. | Glucose 6-phosphate |
| C. | 2-phosphoglycerate |
| D. | 3-phosphoglycerate |
| Answer» B. Glucose 6-phosphate | |
| 67. |
Which one out of the following enzymes acts in pentose phosphate pathway? |
| A. | Aldolase |
| B. | Glycogen phosphorylase |
| C. | Pyruvate kinase |
| D. | 6-phosphogluconate dehydrogenase |
| Answer» E. | |
| 68. |
Which of the following mineral is involved in the enzyme -controlled energy yielding reactions of metabolism? |
| A. | Calcium |
| B. | Phosphorus |
| C. | Iron |
| D. | Copper |
| Answer» C. Iron | |
| 69. |
Glucagon and epinephrine stimulate glycogen breakdown to glucose 6-phosphate |
| A. | Directly by binding to glycogen phosphorylase |
| B. | Indirectly by first stimulating adenylate cyclase to make cAMP |
| C. | Only in the liver |
| D. | Only in muscle cells |
| Answer» C. Only in the liver | |
| 70. |
Which of the following is involved in pentose phosphate pathway? |
| A. | Glucose 6-phosphate dehydrogenase |
| B. | Acyl co-A glycerol transferases |
| C. | PFK-2/FBPase-2 |
| D. | Pyruvate dehydrogenase |
| Answer» B. Acyl co-A glycerol transferases | |
| 71. |
When one molecule of glucose is oxidized to two molecules of lactate during anaerobic glycolysis, which of the following statements is false? |
| A. | Glyceraldehyde 3-P dehydrogenase reaction produces 2 ATP molecules |
| B. | Lactate dehydrogenase reaction produces no ATP |
| C. | Pyruvate kinase reaction produces 2 ATP molecules |
| D. | Phosphofructokinase-1 reaction uses 1 ATP molecule |
| Answer» B. Lactate dehydrogenase reaction produces no ATP | |
| 72. |
Examples of goitrogenic foods are __________ and __________ . |
| A. | turnips and corn |
| B. | rutabagas and okra |
| C. | raw cabbage and turnips |
| D. | cassava and lettuce |
| Answer» D. cassava and lettuce | |
| 73. |
Hydrolysis of lactose yields |
| A. | D-galactose and D-glucose |
| B. | D-glucose and D-glucose |
| C. | D-galactose and D-fructose |
| D. | D-fructose and D-glucose |
| Answer» B. D-glucose and D-glucose | |
| 74. |
Glucose 6-phosphatase is present only in |
| A. | Liver |
| B. | Muscle |
| C. | Epithelial tissues |
| D. | Kidneys |
| Answer» B. Muscle | |
| 75. |
Which of the following is true about the enzyme producing NADH from a triose phosphate in the glycolytic pathway? |
| A. | It produces 1, 3-biphosphoglycerate and NADH |
| B. | It catalyzes irreversible reaction |
| C. | It uses NAD⁺ and dihydroxyacetone phosphate as substrates |
| D. | It uses FADH₂ and glyceraldehyde 3-phosphate as substrates |
| Answer» B. It catalyzes irreversible reaction | |
| 76. |
When blood sugar levels fall, glycolysis is halted in liver to allow _________ |
| A. | Homeostasis |
| B. | Anaerobic respiration |
| C. | Aerobic respiration |
| D. | Gluconeogenesis |
| Answer» E. | |
| 77. |
Which of the following statements is correct about reductive pentose phosphate pathway? |
| A. | It is not reversible |
| B. | Transketolase transfers 3 carbon units |
| C. | Transaldose transfers 2 carbon units |
| D. | Pentoses can provide glycolytic intermediates |
| Answer» E. | |
| 78. |
Which of the following type of metabolite is used for generating glucose under severe starvation conditions? |
| A. | Amino acids |
| B. | Fats |
| C. | Glycogen |
| D. | Starch |
| Answer» B. Fats | |
| 79. |
Anabolism and catabolism are chemically linked in the form of |
| A. | ADP |
| B. | ATP |
| C. | Phosphodiester linkage |
| D. | ASP |
| Answer» C. Phosphodiester linkage | |
| 80. |
Which of the following enzymes is involved in the positive regulation of glycolysis/gluconeogenesis? |
| A. | Hexokinase II |
| B. | Hexokinase IV |
| C. | PFK-2/FBPase-2 |
| D. | Pyruvate kinase |
| Answer» D. Pyruvate kinase | |
| 81. |
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 | |
| 82. |
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 | |
| 83. |
The released energy obtained by oxidation of glucose is stored as |
| A. | a concentration gradient across a membrane |
| B. | ADP |
| C. | ATP |
| D. | NAD+ |
| Answer» D. NAD+ | |
| 84. |
Which trace mineral is a component of the enzyme that activates vitamin A in the eye? |
| A. | Zinc |
| B. | Iron |
| C. | Iodine |
| D. | Chromium |
| Answer» B. Iron | |
| 85. |
Which of the following vitamin is essential for the absorption of calcium from the intestinal tract? |
| A. | Vitamin D |
| B. | Vitamin E |
| C. | Vitamin B12 |
| D. | Vitamin B6 |
| Answer» B. Vitamin E | |
| 86. |
Which of the following enzyme catalyzes the first step of glycolysis? |
| A. | Hexokinase |
| B. | Pyruvate kinase |
| C. | Glucokinase |
| D. | Phosphofructokinase-1 |
| Answer» B. Pyruvate kinase | |
| 87. |
The rate of breakdown of metabolites is termed as |
| A. | Metabolic state |
| B. | Metabolism |
| C. | Steady state |
| D. | Homeostasis |
| Answer» D. Homeostasis | |
| 88. |
The substrate used in the last step of glycolysis is |
| A. | Glyceraldehyde 3-phosphate |
| B. | Pyruvate |
| C. | Phosphoenolpyruvate |
| D. | 1, 3-bisphosphoglycerate |
| Answer» D. 1, 3-bisphosphoglycerate | |
| 89. |
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. | |
| 90. |
Which of the following enzyme catalyses the direct transfer and incorporation of O₂ into a substrate molecule is |
| A. | Reductase |
| B. | Oxidase |
| C. | Oxygenase |
| D. | Peroxidase |
| Answer» D. Peroxidase | |
| 91. |
What does first law of thermodynamics state? |
| A. | Energy can neither be destroyed nor created |
| B. | Energy cannot be 100 percent efficiently transformed from one type to another |
| C. | All living organisms are composed of cells |
| D. | Input of heat energy increases the rate of movement of atoms and molecules |
| Answer» B. Energy cannot be 100 percent efficiently transformed from one type to another | |
| 92. |
Which One of the following statements about the control of enzyme activity by phosphorylation is correct |
| A. | Phosphorylation of an enzyme results in conformational change |
| B. | Phosphorylation of an enzyme occurs only at specific tyrosine residues |
| C. | Phosphorylation of an enzyme is carried out by phosphoprotein phosphatases |
| D. | Enzyme control by phosphorylation is irreversible |
| Answer» B. Phosphorylation of an enzyme occurs only at specific tyrosine residues | |
| 93. |
Which of the following ion is required for the development of sound teeth with resistance to tooth decay? |
| A. | Fluoride ion |
| B. | Sodium ion |
| C. | Chloride ion |
| D. | Magnesium ion |
| Answer» B. Sodium ion | |
| 94. |
Which of the following is necessary for the clotting of blood, functions of certain enzymes and control of fluids through cell membranes? |
| A. | Calcium |
| B. | Magnesium |
| C. | Copper |
| D. | Cobalt |
| Answer» B. Magnesium | |
| 95. |
The enzyme which catalyzes the conversion of pyruvate to oxaloacetate |
| A. | Pyruvate carboxylase |
| B. | Pyruvate dehydrogenase |
| C. | Pyruvate kinase |
| D. | Phosphofructokinase-1 |
| Answer» B. Pyruvate dehydrogenase | |
| 96. |
How many steps are catalyzed by different enzymes in glycolysis and gluconeogenesis? |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | 5 |
| Answer» C. 4 | |
| 97. |
Which of the following statements is incorrect about oxidase? |
| A. | They catalyze reactions involving hydrogen peroxide |
| B. | They catalyze reaction using O₂ as a hydrogen acceptor |
| C. | They catalyze reactions using niacin as coenzyme |
| D. | They catalyze reactions of direct incorporation of O₂ into the substrate |
| Answer» C. They catalyze reactions using niacin as coenzyme | |
| 98. |
Hydrolysis of sucrose yields |
| A. | D-galactose and D-glucose |
| B. | D-glucose and D-glucose |
| C. | D-galactose and D-fructose |
| D. | D-fructose and D-glucose |
| Answer» E. | |
| 99. |
Conversion of xylulose 5-phosphate to ribulose 5-phosphate is catalyzed by |
| A. | Phosphopentose epimerase |
| B. | Transaldolase |
| C. | Transketolase |
| D. | Phosphopentose isomerase |
| Answer» B. Transaldolase | |
| 100. |
Which of the following conversions is not catalyzed by hexokinase? |
| A. | D-Glucose to glucose 6-phosphate |
| B. | D-Fructose to fructose 6-phosphate |
| C. | D-Mannose to mannose 6-phosphate |
| D. | D-Fructose to fructose 1-phosphate |
| Answer» E. | |