Free biochemistry MCQ exam model for basic & preclinical students

Explanation:

• Stomach → Correct because pepsin functions optimally in acidic pH.

• Mouth → Incorrect because salivary amylase acts here.

• Esophagus → Incorrect because no digestion occurs.

• Small intestine → Incorrect because trypsin acts here.

• Large intestine → Incorrect because no protein digestion occurs.

Explanation:

• Phospholipid → Correct because it forms the bilayer of cell membranes.

• Triglyceride → Incorrect because it is a storage lipid.

• Cholesterol → Incorrect because it stabilizes membranes but is not the main component.

• Glycogen → Incorrect because it is a carbohydrate.

• Waxes → Incorrect because they are protective lipids.

Explanation:

• Vitamin D → Correct because it dissolves in fats and is stored in the body.

• Vitamin B₁ → Incorrect because it is water-soluble.

• Vitamin B₆ → Incorrect because it is water-soluble.

• Vitamin C → Incorrect because it is water-soluble.

• Vitamin B₁₂ → Incorrect because it is water-soluble.

Explanation:

• Carbohydrates → Correct because glucose is the main energy source for cells.

• Proteins → Incorrect because they are mainly structural and functional.

• Lipids → Incorrect because they are long-term energy storage.

• Nucleic acids → Incorrect because they store genetic information.

• Vitamins → Incorrect because they act as coenzymes, not energy sources.

Explanation:

• Amino acids → Correct because proteins are polymers of amino acids.

• Fatty acids → Incorrect because they are components of lipids.

• Nucleotides → Incorrect because they form nucleic acids.

• Monosaccharides → Incorrect because they form carbohydrates.

• Triglycerides → Incorrect because they are lipids.

Explanation:

• Cellulase → Correct because humans cannot digest cellulose.

• Hexokinase → Incorrect because it phosphorylates glucose.

• Catalase → Incorrect because it breaks down hydrogen peroxide.

• Amylase → Incorrect because it digests starch.

• Trypsin → Incorrect because it digests proteins.

Explanation:

• 7.4 → Correct because normal blood pH is tightly regulated around 7.35–7.45.

• 6.8 → Incorrect because it is too acidic for survival.

• 7.0 → Incorrect because it indicates acidosis.

• 7.2 → Incorrect because it is below normal range.

• 7.6 → Incorrect because it indicates alkalosis.

Explanation:

• Insulin → Correct because it promotes glucose uptake by cells.

• Glucagon → Incorrect because it raises blood glucose.

• Adrenaline → Incorrect because it increases blood glucose during stress.

• Cortisol → Incorrect because it increases gluconeogenesis.

• Thyroxine → Incorrect because it increases metabolic rate.

Explanation:

• ATP → Correct because it provides energy for cellular processes.

• ADP → Incorrect because it has less energy than ATP.

• AMP → Incorrect because it has minimal energy.

• NADH → Incorrect because it is an electron carrier.

• FADH₂ → Incorrect because it is also an electron carrier.

Explanation:

• Chemical processes in living organisms → Correct because biochemistry deals with chemical reactions occurring in cells.

• Structure of tissues → Incorrect because this is histology.

• Functions of organs → Incorrect because this is physiology.

• Microorganisms only → Incorrect because this is microbiology.

• Genetic inheritance only → Incorrect because this is genetics.