📝 Step 5 — KMU Past Papers & Exam Learning

This section contains KMU-style past paper questions designed to strengthen conceptual understanding. Focus on understanding explanations rather than memorizing answers.

🎯 How to Study KMU Past Papers

• Read the question carefully.
• Think about the answer before looking.
• Read the explanation slowly.
• Understand the reasoning behind the correct answer.
• Revise difficult questions again.

MCQ 1

Question:
A patient with acute inflammation develops pain and fever after tissue injury. Which mediator group most directly explains these findings?

Options:
Leukotrienes
Prostaglandins
Thromboxanes
Lipoxins
Catecholamines

Correct Answer:
Prostaglandins

Explanation:
Prostaglandins, especially PGE₂, mediate pain sensitization and fever during inflammation.

MCQ 2

Question:
Arachidonic acid is released from membrane phospholipids before eicosanoid synthesis. Which enzyme is mainly responsible for this release?

Options:
Cyclo-oxygenase
5-lipoxygenase
Phospholipase A₂
Thromboxane synthase
Prostacyclin synthase

Correct Answer:
Phospholipase A₂

Explanation:
Phospholipase A₂ releases arachidonic acid from membrane phospholipids, providing substrate for COX and LOX pathways.

MCQ 3

Question:
A patient taking long-term ibuprofen develops epigastric pain and occult GI bleeding. Which protective mechanism has most likely been reduced?

Options:
Gastric mucus and bicarbonate secretion
Gastric pepsinogen activation
Gastric histamine breakdown
Gastric bile salt neutralization
Gastric leukotriene formation

Correct Answer:
Gastric mucus and bicarbonate secretion

Explanation:
NSAIDs inhibit COX-1, reducing protective gastric prostaglandins that maintain mucus, bicarbonate, and mucosal blood flow.

MCQ 4

Question:
Low-dose aspirin is prescribed to reduce risk of coronary thrombosis. Its antiplatelet effect is mainly due to reduced synthesis of:

Options:
Prostacyclin
Thromboxane A₂
Leukotriene B₄
Prostaglandin F₂α
Lipoxin A₄

Correct Answer:
Thromboxane A₂

Explanation:
Aspirin irreversibly inhibits platelet COX-1, reducing thromboxane A₂ and platelet aggregation.

MCQ 5

Question:
A patient with asthma develops bronchospasm after taking aspirin. Which shift in arachidonic acid metabolism best explains this response?

Options:
Reduced leukotriene receptor sensitivity
Increased prostacyclin production
Increased leukotriene formation
Reduced phospholipase A₂ activity
Increased thromboxane degradation

Correct Answer:
Increased leukotriene formation

Explanation:
COX inhibition may divert arachidonic acid toward the LOX pathway, increasing leukotrienes that cause bronchospasm.

MCQ 6

Question:
Which enzyme is most closely associated with formation of leukotrienes from arachidonic acid?

Options:
COX-1
COX-2
5-lipoxygenase
Phospholipase C
Acetyl-CoA carboxylase

Correct Answer:
5-lipoxygenase

Explanation:
5-lipoxygenase converts arachidonic acid into leukotriene intermediates, especially in inflammatory cells.

MCQ 7

Question:
A drug blocks cysteinyl leukotriene receptors in bronchial smooth muscle. Which clinical effect is expected?

Options:
Reduced platelet aggregation
Reduced bronchoconstriction
Reduced gastric acid secretion
Reduced prostanoid catabolism
Reduced thromboxane synthesis

Correct Answer:
Reduced bronchoconstriction

Explanation:
Leukotriene receptor antagonists such as montelukast reduce leukotriene-mediated bronchoconstriction in asthma.

MCQ 8

Question:
A patient receiving corticosteroids shows marked reduction in both prostaglandin and leukotriene production. Which step is inhibited?

Options:
Release of arachidonic acid
Conversion of PGH₂ to TXA₂
Binding of LTD₄ to receptor
Degradation of prostanoids
Activation of platelet COX-1

Correct Answer:
Release of arachidonic acid

Explanation:
Corticosteroids inhibit phospholipase A₂ activity, reducing arachidonic acid release and suppressing both COX and LOX pathways.

MCQ 9

Question:
Which pair correctly matches mediator with major function?

Options:
PGI₂ — platelet aggregation
TXA₂ — vasodilation
LTB₄ — neutrophil chemotaxis
PGE₂ — bronchial relaxation
LTD₄ — gastric protection

Correct Answer:
LTB₄ — neutrophil chemotaxis

Explanation:
LTB₄ is a strong chemotactic mediator for neutrophils during inflammation.

MCQ 10

Question:
Selective inhibition of COX-2 is expected to reduce inflammation mainly by decreasing:

Options:
Constitutive gastric prostaglandins
Inflammation-induced prostaglandins
Platelet thromboxane release
Leukotriene receptor binding
Arachidonic acid release

Correct Answer:
Inflammation-induced prostaglandins

Explanation:
COX-2 is induced at inflammatory sites and produces prostaglandins responsible for pain, fever, and swelling.

MCQ 11

Question:
A patient taking a COX inhibitor develops reduced renal perfusion during dehydration. Which normal prostaglandin function has been impaired?

Options:
Maintenance of renal blood flow
Activation of neutrophil migration
Inhibition of leukotriene synthesis
Formation of platelet fibrin
Degradation of thromboxane

Correct Answer:
Maintenance of renal blood flow

Explanation:
Renal prostaglandins help maintain renal blood flow, especially during stress states such as dehydration.

MCQ 12

Question:
Aspirin has a prolonged antiplatelet effect because platelets:

Options:
Store aspirin in granules
Lack nuclei for new enzyme synthesis
Convert aspirin into thromboxane
Increase prostacyclin breakdown
Block leukotriene receptors

Correct Answer:
Lack nuclei for new enzyme synthesis

Explanation:
Platelets cannot synthesize new COX enzyme after irreversible aspirin inhibition because they lack nuclei.

MCQ 13

Question:
Which mediator balance is most important in regulating platelet aggregation and vascular tone?

Options:
PGE₂ and LTB₄
TXA₂ and PGI₂
LTC₄ and LTD₄
COX-1 and 5-LOX
Histamine and bradykinin

Correct Answer:
TXA₂ and PGI₂

Explanation:
TXA₂ promotes platelet aggregation and vasoconstriction, while PGI₂ inhibits platelet aggregation and causes vasodilation.

MCQ 14

Question:
A drug inhibits 5-lipoxygenase in a patient with asthma. Which mediator production is most directly reduced?

Options:
Thromboxanes
Prostacyclin
Leukotrienes
Prostaglandins
Bradykinin

Correct Answer:
Leukotrienes

Explanation:
5-lipoxygenase inhibition by drugs such as zileuton reduces leukotriene synthesis.

MCQ 15

Question:
Which statement best explains why eicosanoids act mainly near their site of synthesis?

Options:
They are stored in vesicles
They circulate bound to albumin
They are rapidly degraded
They require endocrine glands
They are secreted as zymogens

Correct Answer:
They are rapidly degraded

Explanation:
Eicosanoids have short half-lives and are rapidly catabolized, so they act locally as paracrine or autocrine mediators.

MCQ 16

Question:
A patient with chronic inflammatory joint pain improves after NSAID therapy. The most likely biochemical basis is decreased formation of:

Options:
Arachidonic acid from glucose
Prostaglandins from arachidonic acid
Leukotrienes from histamine
Thromboxane from cholesterol
Prostanoids from amino acids

Correct Answer:
Prostaglandins from arachidonic acid

Explanation:
NSAIDs inhibit COX enzymes, reducing prostaglandin synthesis from arachidonic acid and decreasing pain and inflammation.

MCQ 17

Question:
Which adverse effect is most directly related to long-term systemic corticosteroid use rather than simple COX inhibition?

Options:
Bronchospasm
Gastric mucosal bleeding
Osteoporosis
Reduced platelet aggregation
Aspirin sensitivity

Correct Answer:
Osteoporosis

Explanation:
Long-term corticosteroids cause systemic effects such as osteoporosis, hyperglycemia, muscle wasting, and infection susceptibility.

MCQ 18

Question:
During inflammation, COX-2 expression increases mainly in response to:

Options:
Cytokines and tissue injury
Insulin and glucagon
Bile salts and enzymes
Oxygen and carbon dioxide
Calcium and phosphate

Correct Answer:
Cytokines and tissue injury

Explanation:
COX-2 is inducible and increases during inflammation due to cytokines and tissue injury signals.

MCQ 19

Question:
A patient with allergic asthma has airway narrowing mainly due to LTC₄, LTD₄, and LTE₄. Which tissue response is most likely?

Options:
Relaxation of bronchial smooth muscle
Contraction of bronchial smooth muscle
Inhibition of mucus secretion
Reduction of vascular permeability
Suppression of immune cell activation

Correct Answer:
Contraction of bronchial smooth muscle

Explanation:
Cysteinyl leukotrienes cause bronchial smooth muscle contraction, mucus secretion, and increased airway resistance.

MCQ 20

Question:
Which drug action occurs most upstream in the arachidonic acid pathway?

Options:
Aspirin inhibition of COX
Zileuton inhibition of 5-LOX
Montelukast receptor blockade
Steroid inhibition of phospholipase A₂
NSAID inhibition of prostaglandin synthesis

Correct Answer:
Steroid inhibition of phospholipase A₂

Explanation:
Steroids act upstream by reducing arachidonic acid release, thereby decreasing both prostaglandin and leukotriene synthesis.

📌 Important Exam Strategy

KMU examinations often test integrated understanding rather than isolated facts. Focus on linking anatomy, embryology, histology, and clinical concepts when reviewing questions.

✅ Revision Tip

If you can explain the reason behind the correct answer without looking at notes, your concept is strong.