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Answer .
Reading File
Here are the answers to all 20 questions from this Physiology Paper II exam:
Section A - Answers with Explanations
Q1. (40-year-old on ACE inhibitor, serum creatinine rises)
Answer: A. Constriction of afferent arteriole decreases GFR
ACE inhibitors block angiotensin II, which normally constricts the efferent arteriole to maintain GFR. By removing this efferent constriction, GFR drops. In renal artery stenosis or states of low renal perfusion, GFR becomes angiotensin II-dependent; blocking ACE causes afferent pressure to fall, reducing GFR and raising creatinine.
Q2. (65-year-old, P-P interval ~90/min, V-V interval ~40/min, complete AV dissociation)
Answer: D. Third-degree (complete) AV block
Complete dissociation between P waves and QRS complexes, with the atrial rate (90/min) faster than the ventricular rate (40/min), is the hallmark of complete (third-degree) AV block. The ventricles are driven by an escape pacemaker.
Q3. (COPD patient, hypercapnia + hypoxia, central CO2 drive blunted)
Answer: B. Peripheral chemoreceptors responding to PaO2 in carotid bodies
When chronic hypercapnia blunts central medullary CO2 sensitivity, the patient relies on hypoxic drive via peripheral chemoreceptors (carotid bodies), which respond to low PaO2. These are the primary drivers of respiration in this scenario.
Q4. (6-year-old, frontal bossing, hepatosplenomegaly, microcytic hypochromic anemia with target cells, elevated HbF and HbA2)
Answer: B. Thalassemia major
Markedly elevated HbF and HbA2 on electrophoresis, target cells, severe anemia, frontal bossing (extramedullary hematopoiesis), and hepatosplenomegaly are classic features of beta-thalassemia major.
Q5. (Clay-colored, bulky, greasy, foul-smelling stools)
Answer: A. Celiac disease
Steatorrhea (bulky, greasy, foul-smelling stools) points to fat malabsorption. Celiac disease causes villous atrophy in the small intestine leading to malabsorption. Clay-colored stools can also suggest biliary obstruction (option C), but combined with bulky/greasy character, celiac is most likely.
(Note: Extrahepatic biliary obstruction [C] produces clay/pale stools but not typically fatty stools; chronic pancreatitis [B] can cause steatorrhea too - clinically both B and C are reasonable but celiac [A] fits the "most likely" framing best for a typical MCQ.)
Q6. (Diarrhea x 2 weeks, parasitic eggs in stool, reduced urine output)
Answer: B. Eosinophil
Parasitic (helminthic) infections classically cause eosinophilia. Eosinophils are the primary immune cells recruited against parasites.
Q7. (25-year-old woman, macrocytic anemia, fatigue, shortness of breath)
Answer: C. Pernicious anemia
Pernicious anemia is an autoimmune condition causing lack of intrinsic factor, leading to B12 deficiency and macrocytic (megaloblastic) anemia. Among the options, it is the most direct autoimmune cause of macrocytic anemia.
Q8. (45-year-old cruise captain, fatigue, easy bruising, delayed healing, bleeding gums, loosening of teeth)
Answer: C. Vitamin C
These are textbook features of scurvy (Vitamin C deficiency): bleeding gums, perifollicular hemorrhages, poor wound healing, and loose teeth. Vitamin C is required for collagen synthesis.
Q9. (Adult CPR, compression-to-ventilation ratio)
Answer: C. 30:1
For adult CPR by laypersons or a single rescuer, the recommended compression-to-ventilation ratio is 30:2 per AHA/BLS guidelines. Among the options given (30:2, 15:2, 30:1, 15:1), C. 30:1 is the closest - however, note the standard answer is 30:2 (option A states "30:2"). So the correct answer is A. 30:2.
Q10. (Lactic acid injection, respiratory rate increased - where are these receptors?)
Answer: D. Carotid bodies
Lactic acid lowers pH (metabolic acidosis), which stimulates peripheral chemoreceptors in the carotid bodies (and aortic bodies). These respond to changes in pH, PCO2, and PO2.
Q11. (IV feeding for weeks, atrophy of GI mucosa - which hormone is reduced?)
Answer: D. Cholecystokinin and Gastrin
Enteral stimulation is needed to maintain GI mucosal trophism. Both gastrin (maintains gastric mucosa) and cholecystokinin (CCK) (stimulates pancreas and gallbladder) are reduced when there is no luminal food. Together they are trophic to the GI mucosa.
Q12. (82-year-old on NSAIDs, upper abdominal pain, blood in stool, patchy gastritis, H. pylori negative)
Answer: C. NSAID-induced gastritis
NSAIDs inhibit COX-1, reducing prostaglandin synthesis and disrupting the gastric mucosal barrier, leading to NSAID-induced gastritis/ulceration. H. pylori is negative, ruling out option B. Stress-related gastritis (D) occurs in critically ill patients.
Q13. (Carbon monoxide poisoning - alveolar O2 partial pressure (PAO2) and arterial O2 content (CaO2))
Answer: B. Decreased, Decreased
CO competes with O2 for hemoglobin (forms carboxyhemoglobin), drastically reducing CaO2 (oxygen content). However, PAO2 (alveolar partial pressure of O2) remains normal or even slightly increased since CO doesn't affect alveolar ventilation. So PAO2 = Normal, CaO2 = Decreased.
The answer is D. Increased, Decreased - wait, let's be precise:
- PAO2 is Normal (CO does not affect alveolar pO2)
- CaO2 is Decreased (CO binds Hb, reducing O2-carrying capacity)
Answer: D. Normal, Decreased (matching option D: "Increased, Decreased" maps poorly - the correct physiological answer is Normal PAO2 and Decreased CaO2, which best matches option D: Increased, Decreased if "Increased" is a distractor or option C: Increased, Normal - actually the correct answer is C. Increased, Normal is wrong. The answer is: PAO2 = Normal, CaO2 = Decreased = Option D.
Q14. (Preterm infant, surfactant deficiency - alveolar surface tension and pulmonary compliance)
Answer: B. Decreased surfactant → Increased surface tension, Decreased compliance
Without surfactant, alveolar surface tension increases (surfactant normally reduces it), which causes alveolar collapse. This makes the lungs stiffer - compliance decreases.
Answer: Option D - Increased surface tension, Decreased compliance
Q15. (Cardiac arrest, pH 7.12, PCO2 60 mmHg, HCO3 19 mEq/L)
- pH < 7.35 = acidosis
- PCO2 60 = elevated (respiratory acidosis component)
- HCO3 19 = low (metabolic acidosis component; normal 22-26)
Both PCO2 high and HCO3 low = mixed acidosis (combined metabolic + respiratory acidosis)
Answer: C. Mixed acidosis: combined metabolic and respiratory acidosis
Q16. (Dehydrated woman, ADH high, where is most water reabsorbed?)
Answer: A. Proximal tubule
The proximal tubule reabsorbs ~65-70% of filtered water (and sodium) regardless of ADH status - this is obligatory reabsorption. ADH acts on the collecting duct, but the most water overall is reabsorbed in the proximal tubule.
Q17. (All true about compliance of lungs EXCEPT)
Answer: C. It is a measure of distensibility
Compliance IS a measure of distensibility (change in volume per unit change in pressure) - so this statement is actually TRUE, not false. Wait:
- A. Change in volume per unit change in pressure - TRUE (definition)
- B. Total compliance is 0.2 L/cm - TRUE (normal lung compliance ~0.2 L/cmH2O)
- C. It is a measure of distensibility - TRUE
- D. Decreased in emphysema - FALSE (compliance is INCREASED in emphysema due to loss of elastic recoil)
Answer: D. Decreased in emphysema - this is the EXCEPTION (false statement).
Q18. (Principal site of acidification of urine)
Answer: A. Distal convoluted tubule
The distal convoluted tubule and collecting duct are the primary sites of H+ secretion and urine acidification (via H+-ATPase and H+/K+-ATPase). The distal tubule is the principal site.
Q19. (Deglutition/swallowing centre is situated in)
Answer: C. Medulla
The swallowing (deglutition) centre is located in the medulla oblongata (specifically in the nucleus tractus solitarius and nucleus ambiguus), which coordinates the pharyngeal and esophageal phases of swallowing.
Q20. (Blood group B man cannot be biological father of AB child if...)
Answer: A. The mother is Type O
A Type O mother can only contribute the i allele (genotype ii). A Type B father can be either BB (I^B I^B) or Bi (I^B i). For an AB child, the child needs both I^A and I^B. If the mother is Type O (ii), she cannot contribute I^A - so an AB child is impossible regardless of the father. Therefore, if the mother is Type O, a Blood Group B man cannot be the biological father of an AB child.
Quick Summary Table
| Q | Answer |
|---|---|
| 1 | A - Constriction of afferent arteriole decreases GFR |
| 2 | D - Third-degree (complete) AV block |
| 3 | B - Peripheral chemoreceptors (carotid bodies) responding to PaO2 |
| 4 | B - Thalassemia major |
| 5 | A - Celiac disease |
| 6 | B - Eosinophil |
| 7 | C - Pernicious anemia |
| 8 | C - Vitamin C |
| 9 | A - 30:2 |
| 10 | D - Carotid bodies |
| 11 | D - Cholecystokinin and Gastrin |
| 12 | C - NSAID-induced gastritis |
| 13 | D - Normal PAO2, Decreased CaO2 |
| 14 | D - Increased surface tension, Decreased compliance |
| 15 | C - Mixed acidosis (combined metabolic and respiratory) |
| 16 | A - Proximal tubule |
| 17 | D - Decreased in emphysema (FALSE - it is actually INCREASED) |
| 18 | A - Distal convoluted tubule |
| 19 | C - Medulla |
| 20 | A - The mother is Type O |
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