MCQs on Role of Coenzymes in Metabolic Reactions
1. What is the primary role of coenzymes in metabolic reactions?
a) Structural support for enzymes
b) Acting as catalysts
c) Transporting electrons or groups
d) Inhibiting enzyme activity
Answer: c) Transporting electrons or groups
2. Which of the following is a coenzyme involved in redox reactions?
a) ATP
b) NAD+
c) DNA
d) Hemoglobin
Answer: b) NAD+
3. FAD (Flavin Adenine Dinucleotide) acts as a coenzyme in:
a) Glycolysis
b) Electron transport chain
c) Citric acid cycle
d) Photosynthesis
Answer: c) Citric acid cycle
4. Which vitamin is a precursor for coenzyme A?
a) Vitamin B1
b) Vitamin B2
c) Vitamin B5
d) Vitamin B12
Answer: c) Vitamin B5
5. Coenzymes are usually:
a) Inorganic ions
b) Proteins
c) Small organic molecules
d) Lipids
Answer: c) Small organic molecules
6. NADH is a reduced form of:
a) NADP+
b) NAD+
c) FADH2
d) ATP
Answer: b) NAD+
7. What is the role of coenzyme A in metabolism?
a) Transporting oxygen
b) Activating fatty acids
c) Synthesizing proteins
d) Breaking down carbohydrates
Answer: b) Activating fatty acids
8. Which coenzyme is essential for carboxylation reactions?
a) Biotin
b) FAD
c) NAD+
d) Coenzyme Q
Answer: a) Biotin
9. The coenzyme FMN (Flavin Mononucleotide) is derived from which vitamin?
a) Vitamin B1
b) Vitamin B2
c) Vitamin B6
d) Vitamin B12
Answer: b) Vitamin B2
10. Coenzyme Q, also known as ubiquinone, plays a crucial role in:
a) Glycolysis
b) Electron transport chain
c) Lipid biosynthesis
d) Protein synthesis
Answer: b) Electron transport chain
11. Which coenzyme is vital for transamination reactions?
a) Coenzyme A
b) Pyridoxal phosphate (PLP)
c) NAD+
d) FAD
Answer: b) Pyridoxal phosphate (PLP)
12. Thiamine pyrophosphate (TPP) acts as a coenzyme in:
a) Decarboxylation reactions
b) Oxidation-reduction reactions
c) Hydrolysis reactions
d) Phosphorylation reactions
Answer: a) Decarboxylation reactions
13. Which coenzyme is involved in one-carbon transfer reactions?
a) Biotin
b) Tetrahydrofolate (THF)
c) Coenzyme A
d) NADPH
Answer: b) Tetrahydrofolate (THF)
14. The coenzyme responsible for lipid synthesis is:
a) NAD+
b) NADP+
c) FAD
d) Biotin
Answer: b) NADP+
15. Which of the following is a prosthetic group acting as a coenzyme?
a) NAD+
b) ATP
c) Heme
d) Vitamin C
Answer: c) Heme
16. Coenzymes typically bind to enzymes:
a) Irreversibly
b) Temporarily and reversibly
c) Via covalent bonds
d) To denature the enzyme
Answer: b) Temporarily and reversibly
17. The coenzyme associated with energy transfer is:
a) NAD+
b) ATP
c) Coenzyme Q
d) FMN
Answer: b) ATP
18. Which coenzyme is critical in the Calvin cycle?
a) NADPH
b) FAD
c) Coenzyme A
d) Thiamine pyrophosphate
Answer: a) NADPH
19. Lipoic acid serves as a coenzyme in:
a) Glycolysis
b) Fatty acid metabolism
c) Pyruvate dehydrogenase complex
d) Photosynthesis
Answer: c) Pyruvate dehydrogenase complex
20. What is the primary role of NADP+ in metabolism?
a) Generating ATP
b) Providing reducing power for biosynthesis
c) Transporting oxygen
d) Hydrolyzing proteins
Answer: b) Providing reducing power for biosynthesis
21. Coenzymes differ from enzymes because they are:
a) Catalytic proteins
b) Organic non-protein molecules
c) Mineral cofactors
d) Structural proteins
Answer: b) Organic non-protein molecules
22. Which of the following is a coenzyme for pyruvate carboxylase?
a) Biotin
b) Coenzyme Q
c) FAD
d) NADPH
Answer: a) Biotin
23. Coenzyme A primarily transfers:
a) Phosphate groups
b) Acyl groups
c) Amino groups
d) Hydrogen ions
Answer: b) Acyl groups
24. Which coenzyme is involved in oxidative decarboxylation?
a) NAD+
b) TPP (Thiamine pyrophosphate)
c) Biotin
d) ATP
Answer: b) TPP (Thiamine pyrophosphate)
25. Coenzyme FAD is reduced to:
a) FMN
b) FADH2
c) NADPH
d) ATP
Answer: b) FADH2
26. The precursor molecule for NAD+ synthesis is:
a) Glucose
b) Niacin (Vitamin B3)
c) Riboflavin
d) Pantothenic acid
Answer: b) Niacin (Vitamin B3)
27. Which coenzyme is central to the synthesis of neurotransmitters?
a) PLP (Pyridoxal phosphate)
b) Coenzyme A
c) NAD+
d) Biotin
Answer: a) PLP (Pyridoxal phosphate)
28. Coenzymes involved in redox reactions primarily carry:
a) Electrons and protons
b) Acyl groups
c) Phosphate groups
d) Amino groups
Answer: a) Electrons and protons
29. NADPH is a coenzyme primarily used in:
a) Catabolic pathways
b) Anabolic pathways
c) ATP synthesis
d) Electron transport chain
Answer: b) Anabolic pathways
30. The coenzyme involved in glycolysis is:
a) NAD+
b) Coenzyme A
c) FMN
d) ATP
Answer: a) NAD+
