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+
