Free physiology MCQ exam model for basic medical & preclinical students

Explanation:

• Sinoatrial node → Correct because it initiates electrical impulses of the heart.

• Atrioventricular node → Incorrect because it delays impulse conduction.

• Bundle of His → Incorrect because it conducts impulses to ventricles.

• Purkinje fibers → Incorrect because they distribute impulses in ventricles.

• Ventricular myocardium → Incorrect because it contracts but does not initiate rhythm.

Explanation:

• Buffer systems → Correct because bicarbonate buffer is the primary regulator.

• Lungs only → Incorrect because they assist but are not primary buffers.

• Kidneys only → Incorrect because they regulate long-term pH.

• Liver only → Incorrect because it has a minor role.

• Digestive system → Incorrect because it is not involved in pH regulation.

Explanation:

• Proximal convoluted tubule → Correct because glucose is actively reabsorbed here.

• Glomerulus → Incorrect because it filters plasma only.

• Loop of Henle → Incorrect because it concentrates urine.

• Distal convoluted tubule → Incorrect because it fine-tunes electrolytes.

• Collecting duct → Incorrect because it regulates water balance.

Explanation:

• Functions of the human body → Correct because physiology explains how organs and systems work.

• Structure of tissues → Incorrect because this is studied in histology.

• Chemical composition of cells → Incorrect because this is biochemistry.

• Microorganisms → Incorrect because this is microbiology.

• Development before birth → Incorrect because this is embryology.

Explanation:

• −70 mV → Correct because it is the typical resting membrane potential of neurons.

• +30 mV → Incorrect because this occurs during depolarization.

• 0 mV → Incorrect because resting membrane is polarized.

• −40 mV → Incorrect because it is closer to threshold potential.

• −90 mV → Incorrect because it is closer to potassium equilibrium potential.

Explanation:

• Vitamin A → Correct because it forms retinal, essential for vision.

• Vitamin B₁ → Incorrect because it is involved in carbohydrate metabolism.

• Vitamin C → Incorrect because it is required for collagen synthesis.

• Vitamin D → Incorrect because it regulates calcium metabolism.

• Vitamin K → Incorrect because it is involved in clotting.

Explanation:

• Fetal hemoglobin → Correct because it binds oxygen more strongly than adult hemoglobin.

• Deoxyhemoglobin → Incorrect because it lacks bound oxygen.

• Oxyhemoglobin → Incorrect because it has normal affinity.

• Carbaminohemoglobin → Incorrect because it carries carbon dioxide.

• Methemoglobin → Incorrect because it cannot bind oxygen effectively.

Explanation:

• Beta cells of pancreas → Correct because they secrete insulin.

• Alpha cells of pancreas → Incorrect because they secrete glucagon.

• Delta cells of pancreas → Incorrect because they secrete somatostatin.

• Acinar cells → Incorrect because they secrete digestive enzymes.

• Ductal cells → Incorrect because they secrete bicarbonate-rich fluid.

Explanation:

• Residual volume → Correct because it remains in lungs after maximal expiration.

• Tidal volume → Incorrect because it is easily measured.

• Inspiratory reserve volume → Incorrect because it is measurable by spirometry.

• Expiratory reserve volume → Incorrect because it can be measured.

• Vital capacity → Incorrect because it is the sum of measurable volumes.

Explanation:

• Potassium → Correct because high membrane permeability to K⁺ determines resting potential.

• Sodium → Incorrect because Na⁺ permeability is low at rest.

• Calcium → Incorrect because it plays a role in signaling, not resting potential.

• Chloride → Incorrect because it has a minor role.

• Magnesium → Incorrect because it is not involved in membrane potential generation.