1. Which respiratory volume represents the volume of air remaining in the lungs even after a forcible expiration?
Correct Answer: C (Residual Volume)
Residual Volume (RV) averages 1100 mL to 1200 mL and cannot be forcibly expelled from the lungs or measured directly using a simple spirometer.
Residual Volume (RV) averages 1100 mL to 1200 mL and cannot be forcibly expelled from the lungs or measured directly using a simple spirometer.
2. Vital Capacity (VC) of the lung is defined as:
Correct Answer: B (ERV + TV + IRV)
Vital Capacity is the maximum volume of air a person can inhale after a forced expiration, comprising ERV + TV + IRV (approx. 3500–4500 mL).
Vital Capacity is the maximum volume of air a person can inhale after a forced expiration, comprising ERV + TV + IRV (approx. 3500–4500 mL).
3. What is the partial pressure of oxygen (pO2) in atmospheric air and alveoli respectively (in mm Hg)?
Correct Answer: A (159 and 104)
According to NCERT data, atmospheric pO2 is 159 mm Hg while alveolar pO2 is 104 mm Hg, establishing the concentration gradient for gas exchange.
According to NCERT data, atmospheric pO2 is 159 mm Hg while alveolar pO2 is 104 mm Hg, establishing the concentration gradient for gas exchange.
4. Nearly what percentage of carbon dioxide is transported in the blood as bicarbonate ions (HCO3-)?
Correct Answer: C (70%)
Approximately 70% of CO2 is transported as bicarbonate ions (HCO3-) with the help of the enzyme carbonic anhydrase, 20–25% bound to hemoglobin as carbamino-hemoglobin, and 7% dissolved in blood plasma.
Approximately 70% of CO2 is transported as bicarbonate ions (HCO3-) with the help of the enzyme carbonic anhydrase, 20–25% bound to hemoglobin as carbamino-hemoglobin, and 7% dissolved in blood plasma.
5. Which of the following conditions shifts the oxygen-hemoglobin dissociation curve to the right?
Correct Answer: B (High pCO2, high H+ concentration, and high temperature)
High pCO2, elevated H+ (acidic conditions/low pH), and high temperature lower hemoglobin’s affinity for O2 (Bohr Effect), shifting the dissociation curve to the right to promote oxygen unloading in active tissues.
High pCO2, elevated H+ (acidic conditions/low pH), and high temperature lower hemoglobin’s affinity for O2 (Bohr Effect), shifting the dissociation curve to the right to promote oxygen unloading in active tissues.
6. The primary respiratory rhythm center is located in which part of the brain?
Correct Answer: B (Medulla oblongata)
A specialized neural center located in the medulla oblongata is primarily responsible for regulating respiratory rhythm, while the pneumotaxic center in the pons fine-tunes it.
A specialized neural center located in the medulla oblongata is primarily responsible for regulating respiratory rhythm, while the pneumotaxic center in the pons fine-tunes it.
7. Emphysema is a chronic respiratory disorder characterized by:
Correct Answer: B (Damage to alveolar walls leading to decreased respiratory surface area)
In emphysema, alveolar walls break down and lose elasticity, drastically reducing the surface area available for gas exchange. Cigarette smoking is its major cause.
In emphysema, alveolar walls break down and lose elasticity, drastically reducing the surface area available for gas exchange. Cigarette smoking is its major cause.
8. Silicosis and asbestosis are classic examples of:
Correct Answer: C (Occupational respiratory disorders)
Workers in stone-grinding, silica, or asbestos industries inhale fine dust particles over long periods, leading to severe inflammation, pulmonary fibrosis, and irreversible lung damage.
Workers in stone-grinding, silica, or asbestos industries inhale fine dust particles over long periods, leading to severe inflammation, pulmonary fibrosis, and irreversible lung damage.
9. Which plasma protein is primarily responsible for maintaining the osmotic balance of human blood?
Correct Answer: B (Albumin)
Albumin maintains blood colloidal osmotic pressure. Globulins participate in immunity (defense mechanisms), and fibrinogens are essential for blood clotting.
Albumin maintains blood colloidal osmotic pressure. Globulins participate in immunity (defense mechanisms), and fibrinogens are essential for blood clotting.
10. Erythroblastosis fetalis can occur when:
Correct Answer: B (An Rh- mother carries an Rh+ fetus during subsequent pregnancies)
Rh incompatibility occurs when an Rh- negative mother is exposed to Rh+ positive fetal blood during a first delivery. In subsequent Rh+ pregnancies, maternal anti-Rh antibodies cross the placenta and destroy fetal red blood cells.
Rh incompatibility occurs when an Rh- negative mother is exposed to Rh+ positive fetal blood during a first delivery. In subsequent Rh+ pregnancies, maternal anti-Rh antibodies cross the placenta and destroy fetal red blood cells.
11. Which inorganic ion plays a critical role as a cofactor at multiple steps in the blood coagulation cascade?
Correct Answer: C (Ca2+)
Calcium ions (Clotting Factor IV) play a vital role in several steps of blood clotting, including the activation of prothrombin activator.
Calcium ions (Clotting Factor IV) play a vital role in several steps of blood clotting, including the activation of prothrombin activator.
12. The Sinoatrial Node (SAN) is designated as the pacemaker of the human heart because it:
Correct Answer: B (Generates the maximum rate of action potentials (70–75 per minute) and initiates cardiac rhythm)
The SAN is auto-excitable and generates impulses at the highest rate (70–75 beats/min), dictating the rhythm of the entire heart.
The SAN is auto-excitable and generates impulses at the highest rate (70–75 beats/min), dictating the rhythm of the entire heart.
13. During a standard cardiac cycle lasting 0.8 seconds, the duration of joint diastole is approximately:
Correct Answer: C (0.4 second)
In a normal 0.8-second cardiac cycle: Atrial systole takes 0.1 s, Ventricular systole takes 0.3 s, and Complete Joint Diastole (all four chambers relaxed) lasts 0.4 s.
In a normal 0.8-second cardiac cycle: Atrial systole takes 0.1 s, Ventricular systole takes 0.3 s, and Complete Joint Diastole (all four chambers relaxed) lasts 0.4 s.
14. On a standard Electrocardiogram (ECG) trace, what does the T-wave represent?
Correct Answer: C (Repolarization of ventricles)
The P-wave indicates atrial depolarization; the QRS complex represents ventricular depolarization; and the T-wave represents ventricular repolarization (return to resting state).
The P-wave indicates atrial depolarization; the QRS complex represents ventricular depolarization; and the T-wave represents ventricular repolarization (return to resting state).
15. If a person has a stroke volume of 70 mL and a heart rate of 72 beats per minute, their cardiac output is:
Correct Answer: A (~5040 mL (approx. 5 Liters))
Cardiac Output = Stroke Volume x Heart Rate = 70 mL x 72 bpm = 5040 mL/min (approximately 5 Liters/min).
Cardiac Output = Stroke Volume x Heart Rate = 70 mL x 72 bpm = 5040 mL/min (approximately 5 Liters/min).
16. Atherosclerosis (Coronary Artery Disease) is caused by deposits of:
Correct Answer: B (Calcium, fat, cholesterol, and fibrous tissues in coronary arteries)
Atherosclerosis results from plaque deposits (calcium, fats, cholesterol) lining the lumen of coronary arteries, reducing blood flow to cardiac muscle.
Atherosclerosis results from plaque deposits (calcium, fats, cholesterol) lining the lumen of coronary arteries, reducing blood flow to cardiac muscle.
17. Which of the following groups of animals is strictly uricotelic?
Correct Answer: C (Reptiles, birds, and land snails)
Uricotelic animals excrete nitrogenous wastes as semi-solid uric acid pellets with minimal water loss, an evolutionary adaptation for terrestrial water conservation.
Uricotelic animals excrete nitrogenous wastes as semi-solid uric acid pellets with minimal water loss, an evolutionary adaptation for terrestrial water conservation.
18. The Malpighian body (renal corpuscle) of a human nephron consists of:
Correct Answer: A (Glomerulus and Bowman’s capsule)
The glomerulus along with its surrounding cup-shaped Bowman’s capsule forms the Malpighian body or renal corpuscle.
The glomerulus along with its surrounding cup-shaped Bowman’s capsule forms the Malpighian body or renal corpuscle.
19. Maximum reabsorption of essential electrolytes (70–80%) and nutrients from glomerular filtrate takes place in the:
Correct Answer: A (Proximal Convoluted Tubule (PCT))
The PCT is lined by simple cuboidal brush-border epithelium, which provides a large surface area for reabsorbing nearly all nutrients and 70–80% of electrolytes and water.
The PCT is lined by simple cuboidal brush-border epithelium, which provides a large surface area for reabsorbing nearly all nutrients and 70–80% of electrolytes and water.
20. The descending limb of Henle’s loop is:
Correct Answer: A (Permeable to water but almost impermeable to electrolytes)
The descending limb allows water to exit into the hypertonic medullary interstitium, concentrating the urine as it flows downward.
The descending limb allows water to exit into the hypertonic medullary interstitium, concentrating the urine as it flows downward.
21. What trigger stimulates Juxtaglomerular (JG) cells to release the enzyme Renin?
Correct Answer: B (A fall in glomerular filtration rate (GFR) or renal blood pressure)
A drop in glomerular blood flow/GFR triggers JG cells to release Renin, initiating the RAAS mechanism (converting angiotensinogen to Angiotensin I and II) to elevate GFR.
A drop in glomerular blood flow/GFR triggers JG cells to release Renin, initiating the RAAS mechanism (converting angiotensinogen to Angiotensin I and II) to elevate GFR.
22. Which hormone acts as a natural check/antagonist to the Renin-Angiotensin-Aldosterone System (RAAS)?
Correct Answer: C (Atrial Natriuretic Factor (ANF))
Secreted by the atrial walls of the heart when blood pressure increases, ANF induces vasodilation and causes Na+ excretion, counteracting RAAS.
Secreted by the atrial walls of the heart when blood pressure increases, ANF induces vasodilation and causes Na+ excretion, counteracting RAAS.
23. Diabetes insipidus is caused by hyposecretion or deficiency of:
Correct Answer: C (Antidiuretic Hormone (ADH / Vasopressin))
Deficiency of ADH impairs water reabsorption in distal nephron segments, causing excretion of large volumes of dilute urine (polyuria) and extreme thirst (polydipsia).
Deficiency of ADH impairs water reabsorption in distal nephron segments, causing excretion of large volumes of dilute urine (polyuria) and extreme thirst (polydipsia).
24. Renal calculi are insoluble mass deposits formed in the kidney, predominantly made of:
Correct Answer: A (Calcium oxalates)
Renal calculi (kidney stones) consist of insoluble crystalline salts, most commonly calcium oxalates formed within the renal pelvis.
Renal calculi (kidney stones) consist of insoluble crystalline salts, most commonly calcium oxalates formed within the renal pelvis.
25. Ciliary movement in the human body is prominently observed in the:
Correct Answer: B (Trachea and female Fallopian tubes)
Ciliated epithelium lining the respiratory tract helps propel inhaled dust particles outward, and in fallopian tubes, it helps move the ovum toward the uterus.
Ciliated epithelium lining the respiratory tract helps propel inhaled dust particles outward, and in fallopian tubes, it helps move the ovum toward the uterus.
26. What essential role do Ca2+ ions play during skeletal muscle contraction?
Correct Answer: B (Bind to troponin to unmask active myosin-binding sites on actin)
Ca2+ released from the sarcoplasmic reticulum binds to troponin C, shifting tropomyosin and uncovering active myosin-binding sites on actin filaments.
Ca2+ released from the sarcoplasmic reticulum binds to troponin C, shifting tropomyosin and uncovering active myosin-binding sites on actin filaments.
27. According to the Sliding Filament Theory, during skeletal muscle contraction:
Correct Answer: B (The I-band shortens while the A-band retains its length)
During muscle contraction, thin actin filaments slide over thick myosin filaments toward the center of the sarcomere: the I-band and H-zone shorten, while the dark A-band maintains its original length.
During muscle contraction, thin actin filaments slide over thick myosin filaments toward the center of the sarcomere: the I-band and H-zone shorten, while the dark A-band maintains its original length.
28. How many pairs of “true ribs” are present in the human thoracic skeleton?
Correct Answer: A (First 7 pairs (1st to 7th))
True ribs (pairs 1–7) attach dorsally to thoracic vertebrae and ventrally directly to the sternum via hyaline cartilage. Pairs 8–10 are false ribs, and pairs 11–12 are floating ribs.
True ribs (pairs 1–7) attach dorsally to thoracic vertebrae and ventrally directly to the sternum via hyaline cartilage. Pairs 8–10 are false ribs, and pairs 11–12 are floating ribs.
29. The joint located between the atlas (C1) and axis (C2) vertebrae is a:
Correct Answer: C (Pivot joint)
The atlantoaxial joint between the atlas and axis is a pivot synovial joint allowing rotational movement of the head side to side.
The atlantoaxial joint between the atlas and axis is a pivot synovial joint allowing rotational movement of the head side to side.
30. Myasthenia gravis is an autoimmune disorder affecting the neuromuscular junction that leads to:
Correct Answer: B (Fatigue, weakening, and paralysis of skeletal muscles)
Myasthenia gravis is an autoimmune condition where antibodies block or destroy acetylcholine receptors at the neuromuscular junction, impairing muscle stimulation.
Myasthenia gravis is an autoimmune condition where antibodies block or destroy acetylcholine receptors at the neuromuscular junction, impairing muscle stimulation.
31. Sustained involuntary muscle contractions (tetany) occur primarily due to:
Correct Answer: B (Low Ca2+ levels in body fluids (hypocalcemia))
Tetany is characterized by painful muscle spasms resulting from hypocalcemia, which dramatically increases neuronal excitability.
Tetany is characterized by painful muscle spasms resulting from hypocalcemia, which dramatically increases neuronal excitability.
32. Gout is a metabolic joint condition caused by the accumulation and inflammation of:
Correct Answer: B (Uric acid crystals in joint cavities)
Gout involves joint inflammation resulting from the precipitation of uric acid crystals due to impaired purine metabolism or excretion.
Gout involves joint inflammation resulting from the precipitation of uric acid crystals due to impaired purine metabolism or excretion.
33. In a resting, non-conducting neuron, the axonal membrane is:
Correct Answer: A (Comparatively more permeable to K+ and nearly impermeable to Na+)
At rest, potassium leak channels make the axonal membrane significantly more permeable to K+ than Na+, maintaining a resting potential of approx -70 mV.
At rest, potassium leak channels make the axonal membrane significantly more permeable to K+ than Na+, maintaining a resting potential of approx -70 mV.
34. The sodium-potassium pump (Na+/K+ ATPase) maintains the resting membrane potential by actively pumping:
Correct Answer: B (3 Na+ outwards for 2 K+ into the cell)
The electrogenic Na+/K+ pump hydrolyzes ATP to export 3 Na+ ions out of the axon and import 2 K+ ions back in, maintaining ionic gradients.
The electrogenic Na+/K+ pump hydrolyzes ATP to export 3 Na+ ions out of the axon and import 2 K+ ions back in, maintaining ionic gradients.
35. Depolarization during nerve impulse propagation occurs due to a rapid influx of:
Correct Answer: B (Na+ ions into the axoplasm)
When a threshold stimulus arrives, voltage-gated Na+ channels open rapidly, causing an influx of Na+ that reverses membrane polarity from negative to positive (+30 mV).
When a threshold stimulus arrives, voltage-gated Na+ channels open rapidly, causing an influx of Na+ that reverses membrane polarity from negative to positive (+30 mV).
36. Unipolar neurons (with a cell body and a single neurite process) are primarily found in:
Correct Answer: C (Embryonic stage)
Unipolar neurons are predominantly present during the embryonic developmental stage. Bipolar neurons are found in the retina, and multipolar neurons occur in the cerebral cortex.
Unipolar neurons are predominantly present during the embryonic developmental stage. Bipolar neurons are found in the retina, and multipolar neurons occur in the cerebral cortex.
37. At a chemical synapse, neurotransmitters released from presynaptic vesicles bind to specific receptors located on the:
Correct Answer: B (Post-synaptic membrane)
Neurotransmitters cross the synaptic cleft and bind to receptor proteins on the post-synaptic membrane, opening ligand-gated ion channels.
Neurotransmitters cross the synaptic cleft and bind to receptor proteins on the post-synaptic membrane, opening ligand-gated ion channels.
38. Which cerebral structure acts as the major relay station for sensory and motor signaling in the forebrain?
Correct Answer: B (Thalamus)
The cerebrum wraps around the thalamus, which serves as a crucial sensory and motor relay hub connecting lower brain regions to the cerebral cortex.
The cerebrum wraps around the thalamus, which serves as a crucial sensory and motor relay hub connecting lower brain regions to the cerebral cortex.
39. The autonomic nervous system consists of sympathetic and parasympathetic divisions. Sympathetic neural stimulation acts to:
Correct Answer: A (Increase heart rate and cardiac output)
The sympathetic nervous system drives the “fight or flight” response, increasing heart rate, ventricular force of contraction, and overall cardiac output.
The sympathetic nervous system drives the “fight or flight” response, increasing heart rate, ventricular force of contraction, and overall cardiac output.
40. The large band of myelinated nerve fibers connecting the left and right cerebral hemispheres is the:
Correct Answer: B (Corpus callosum)
The left and right cerebral hemispheres are interconnected internally by a prominent transverse tract of nerve fibers called the corpus callosum.
The left and right cerebral hemispheres are interconnected internally by a prominent transverse tract of nerve fibers called the corpus callosum.
41. Hormones that interact with intracellular receptors and regulate gene expression directly are typically:
Correct Answer: B (Steroid hormones (e.g., Estrogen, Cortisol) and Iodothyronines)
Lipid-soluble steroid hormones and thyroid hormones easily pass through cell membranes to bind intracellular/nuclear receptors and directly regulate target gene expression.
Lipid-soluble steroid hormones and thyroid hormones easily pass through cell membranes to bind intracellular/nuclear receptors and directly regulate target gene expression.
42. Which endocrine gland secretes Melatonin to regulate 24-hour diurnal sleep-wake cycles?
Correct Answer: C (Pineal gland)
Located on the dorsal side of the forebrain, the pineal gland secretes melatonin, which regulates circadian rhythms, body temperature, and sleep cycles.
Located on the dorsal side of the forebrain, the pineal gland secretes melatonin, which regulates circadian rhythms, body temperature, and sleep cycles.
43. Hypersecretion of Growth Hormone (GH) in adults leads to severe physical disfigurement, especially of facial bones, called:
Correct Answer: B (Acromegaly)
Excess GH in childhood causes gigantism, whereas hypersecretion in adults after epiphyseal plates close leads to acromegaly (thickening of facial and limb bones).
Excess GH in childhood causes gigantism, whereas hypersecretion in adults after epiphyseal plates close leads to acromegaly (thickening of facial and limb bones).
44. Cretinism (characterized by stunted mental and physical growth in infants) is caused by:
Correct Answer: A (Hypothyroidism during pregnancy)
Maternal thyroid hormone deficiency during pregnancy severely disrupts fetal brain development, leading to cretinism, low IQ, deaf-mutism, and stunted growth.
Maternal thyroid hormone deficiency during pregnancy severely disrupts fetal brain development, leading to cretinism, low IQ, deaf-mutism, and stunted growth.
45. Exophthalmic goiter (Grave’s disease) is an autoimmune hyperthyroid condition characterized by:
Correct Answer: B (Enlarged thyroid gland, protrusion of eyeballs, and increased BMR)
Graves’ disease causes thyroid hyperfunction, resulting in goiter, protruding eyeballs (exophthalmos), elevated BMR, and significant weight loss.
Graves’ disease causes thyroid hyperfunction, resulting in goiter, protruding eyeballs (exophthalmos), elevated BMR, and significant weight loss.
46. Parathyroid Hormone (PTH) increases blood Ca2+ levels (hypercalcemic effect) by:
Correct Answer: B (Stimulating bone resorption, renal Ca2+ reabsorption, and intestinal Ca2+ absorption)
PTH elevates circulating blood Ca2+ levels by stimulating bone breakdown (resorption), renal tubular reabsorption of Ca2+, and intestinal absorption from food.
PTH elevates circulating blood Ca2+ levels by stimulating bone breakdown (resorption), renal tubular reabsorption of Ca2+, and intestinal absorption from food.
47. Which pair of pancreatic hormones acts antagonistically to maintain blood glucose homeostasis?
Correct Answer: B (Insulin and Glucagon)
Insulin (from beta-cells) lowers blood glucose levels (hypoglycemic factor), whereas glucagon (from alpha-cells) raises blood glucose levels (hyperglycemic factor).
Insulin (from beta-cells) lowers blood glucose levels (hypoglycemic factor), whereas glucagon (from alpha-cells) raises blood glucose levels (hyperglycemic factor).
48. Addison’s disease is caused by:
Correct Answer: A (Hyposecretion of adrenal cortex hormones (glucocorticoids & mineralocorticoids))
Underproduction of corticoid hormones alters carbohydrate metabolism and electrolyte balance, causing severe weakness, fatigue, and skin bronzing.
Underproduction of corticoid hormones alters carbohydrate metabolism and electrolyte balance, causing severe weakness, fatigue, and skin bronzing.
49. The catecholamine hormones Epinephrine and Norepinephrine are produced and secreted by the:
Correct Answer: C (Adrenal Medulla)
The adrenal medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline), commonly referred to as emergency or fight-or-flight hormones.
The adrenal medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline), commonly referred to as emergency or fight-or-flight hormones.
50. Which anterior pituitary hormone acts directly on Leydig cells to stimulate androgen synthesis in males?
Correct Answer: B (Luteinizing Hormone (LH / ICSH))
In males, LH (Interstitial Cell Stimulating Hormone) targets testicular Leydig cells to induce testosterone secretion, whereas FSH acts on Sertoli cells to support spermatogenesis.
In males, LH (Interstitial Cell Stimulating Hormone) targets testicular Leydig cells to induce testosterone secretion, whereas FSH acts on Sertoli cells to support spermatogenesis.