📝 Step 6 — 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 child with a lysosomal enzyme defect accumulates sphingomyelin in tissues. Which normal biochemical step is primarily impaired?
Options:
Conversion of sphingosine into ceramide
Hydrolysis of sphingomyelin to ceramide
Addition of glucose to ceramide
Formation of phosphatidylcholine from choline
Oxidation of fatty acids in mitochondria
Correct Answer:
Hydrolysis of sphingomyelin to ceramide
Explanation:
Sphingomyelinase normally breaks sphingomyelin into ceramide and phosphocholine. Its deficiency causes sphingomyelin accumulation.
MCQ 2
Question:
A membrane lipid is abundant in myelin and contains sphingosine rather than glycerol as its backbone. Which structural feature best identifies this lipid class?
Options:
Steroid nucleus with hydroxyl group
Glycerol backbone with two fatty acids
Sphingosine backbone with fatty acid
Isoprene units with phosphate group
Amino acid chain with glucose residue
Correct Answer:
Sphingosine backbone with fatty acid
Explanation:
Sphingolipids are built on sphingosine. Addition of fatty acid forms ceramide, the central intermediate.
MCQ 3
Question:
A researcher blocks formation of ceramide in a neuronal cell culture. Which downstream lipid would be directly reduced?
Options:
Cholesterol ester
Triacylglycerol
Cardiolipin
Sphingomyelin
Prostaglandin
Correct Answer:
Sphingomyelin
Explanation:
Ceramide is the precursor for sphingomyelin. Phosphocholine is added to ceramide to form sphingomyelin.
MCQ 4
Question:
In a neuron-rich tissue, sphingomyelin contributes mainly to which functional property?
Options:
Rapid glucose entry into cells
Structural stability of myelin
Storage of excess amino acids
Synthesis of peptide hormones
Transport of oxygen in plasma
Correct Answer:
Structural stability of myelin
Explanation:
Sphingomyelin is abundant in neuronal membranes and myelin, supporting membrane integrity and nerve conduction.
MCQ 5
Question:
A patient develops slow movement and rigidity due to degeneration of pigmented neurons in the midbrain. Which neurotransmitter becomes deficient in the striatum?
Options:
Acetylcholine
Dopamine
GABA
Glutamate
Noradrenaline
Correct Answer:
Dopamine
Explanation:
Substantia nigra pars compacta neurons provide dopaminergic input to the striatum. Their degeneration causes dopamine deficiency.
MCQ 6
Question:
A lesion damages the pathway connecting the substantia nigra to the striatum. Which motor effect is most expected?
Options:
Excessive sensory loss
Impaired voluntary movement initiation
Loss of lower motor neurons
Complete flaccid paralysis
Isolated pain pathway damage
Correct Answer:
Impaired voluntary movement initiation
Explanation:
The nigrostriatal dopaminergic pathway regulates basal ganglia motor circuits. Loss of dopamine produces difficulty initiating movement.
MCQ 7
Question:
A patient has rhythmic hand movement while sitting quietly. The tremor decreases when he reaches for an object. Which system is most likely involved?
Options:
Cerebellar coordination system
Basal ganglia motor circuit
Peripheral sensory receptor system
Anterior horn motor system
Vestibular balance pathway
Correct Answer:
Basal ganglia motor circuit
Explanation:
A tremor present at rest and reduced by voluntary movement is typical of Parkinsonian tremor due to basal ganglia dysfunction.
MCQ 8
Question:
During finger-nose testing, a patient’s tremor becomes more prominent as the finger approaches the target. Which mechanism best explains this finding?
Options:
Failure of dopamine synthesis
Failure of movement coordination
Failure of neuromuscular transmission
Failure of sensory pain conduction
Failure of spinal reflex arc
Correct Answer:
Failure of movement coordination
Explanation:
Cerebellar tremor is an intention tremor. It worsens during goal-directed movement due to impaired coordination and error correction.
MCQ 9
Question:
A patient with Parkinson’s disease is started on a drug that crosses the blood-brain barrier and is converted into dopamine. Which drug is being used?
Options:
Carbidopa
Selegiline
Entacapone
Levodopa
Benztropine
Correct Answer:
Levodopa
Explanation:
Levodopa crosses the blood-brain barrier and is converted into dopamine in the brain.
MCQ 10
Question:
A drug is added to levodopa to reduce nausea and hypotension caused by peripheral dopamine formation. Which mechanism explains this benefit?
Options:
Peripheral dopa decarboxylase inhibition
Central dopamine receptor blockade
Brain monoamine oxidase activation
Striatal acetylcholine stimulation
Peripheral COMT activation
Correct Answer:
Peripheral dopa decarboxylase inhibition
Explanation:
Carbidopa inhibits peripheral dopa decarboxylase, reducing peripheral dopamine formation and increasing levodopa delivery to the brain.
MCQ 11
Question:
A Parkinson’s patient has wearing-off symptoms before the next levodopa dose. A drug is prescribed to prolong levodopa action by reducing its peripheral metabolism. Which class is most appropriate?
Options:
Anticholinergic drug
COMT inhibitor
NMDA blocker
Muscarinic agonist
GABA enhancer
Correct Answer:
COMT inhibitor
Explanation:
COMT inhibitors reduce levodopa metabolism and prolong its action, helping wearing-off symptoms.
MCQ 12
Question:
A patient receiving Parkinson’s treatment develops hallucinations and excessive daytime sleepiness. Which drug group is most likely responsible?
Options:
Dopamine agonists
Anticholinergics
COMT inhibitors
Cholinesterase inhibitors
Beta blockers
Correct Answer:
Dopamine agonists
Explanation:
Dopamine agonists stimulate dopamine receptors and may cause hallucinations, sleepiness, hypotension, and impulse-control problems.
MCQ 13
Question:
A young patient with Parkinsonian tremor is treated with a drug that reduces relative cholinergic activity in the striatum. Which drug group matches this action?
Options:
MAO-B inhibitors
COMT inhibitors
Dopamine precursors
Dopamine agonists
Anticholinergics
Correct Answer:
Anticholinergics
Explanation:
Anticholinergics reduce relative acetylcholine excess in the striatum and are more useful for tremor than bradykinesia.
MCQ 14
Question:
Which paired relationship best explains the clinical difference between Parkinsonian and cerebellar tremor?
Options:
Resting tremor — basal ganglia dysfunction
Action tremor — spinal cord dysfunction
Postural tremor — peripheral nerve lesion
Intention tremor — substantia nigra lesion
Pill-rolling tremor — cerebellar lesion
Correct Answer:
Resting tremor — basal ganglia dysfunction
Explanation:
Parkinsonian tremor is a resting tremor caused by basal ganglia dysfunction, while cerebellar tremor is an intention tremor.
MCQ 15
Question:
A patient has bradykinesia, reduced arm swing, and masked facial expression. Which pathological process best explains these features?
Options:
Demyelination of posterior columns
Degeneration of nigral dopaminergic neurons
Infarction of lower motor neurons
Compression of peripheral nerves
Damage to cerebellar Purkinje cells
Correct Answer:
Degeneration of nigral dopaminergic neurons
Explanation:
Parkinson’s disease results from degeneration of dopaminergic neurons in substantia nigra pars compacta, causing basal ganglia imbalance.
MCQ 16
Question:
A drug used in Parkinson’s disease reduces dopamine breakdown in the brain by inhibiting monoamine oxidase-B. Which example belongs to this group?
Options:
Entacapone
Trihexyphenidyl
Pramipexole
Selegiline
Carbidopa
Correct Answer:
Selegiline
Explanation:
Selegiline is an MAO-B inhibitor. It prolongs dopamine action by reducing its breakdown in the brain.
MCQ 17
Question:
A drug directly stimulates dopamine receptors without requiring enzymatic conversion into dopamine. Which drug best fits this mechanism?
Options:
Tolcapone
Ropinirole
Carbidopa
Benztropine
Entacapone
Correct Answer:
Ropinirole
Explanation:
Ropinirole is a dopamine agonist. It directly stimulates dopamine receptors in basal ganglia circuits.
MCQ 18
Question:
A Parkinson’s patient improves after treatment, but the disease continues to progress. Which statement best explains this observation?
Options:
Treatment mainly restores myelin synthesis
Treatment mainly improves symptoms
Treatment mainly removes Lewy bodies
Treatment mainly regenerates nigral neurons
Treatment mainly prevents lipid storage
Correct Answer:
Treatment mainly improves symptoms
Explanation:
Current Parkinson’s drug therapy is mainly symptomatic. It improves dopaminergic function but does not stop neurodegeneration.
MCQ 19
Question:
A biochemical disorder affects sphingomyelin breakdown, while Parkinson’s disease affects dopamine-producing neurons. What common principle links these conditions?
Options:
Both primarily affect plasma proteins
Both show biochemical basis of neurological disease
Both arise from steroid hormone failure
Both involve defective hemoglobin synthesis
Both mainly damage renal tubules
Correct Answer:
Both show biochemical basis of neurological disease
Explanation:
Sphingolipid metabolism supports neuronal structure, while dopamine supports motor function. Both illustrate biochemical causes of nervous system dysfunction.
MCQ 20
Question:
A patient has resting tremor, rigidity, and bradykinesia. Which integrated treatment strategy most directly targets the underlying functional defect?
Options:
Reduce cerebellar output to cortex
Increase dopaminergic activity in basal ganglia
Block sensory impulses from muscle spindle
Stimulate acetylcholine release in striatum
Increase sphingomyelin degradation in myelin
Correct Answer:
Increase dopaminergic activity in basal ganglia
Explanation:
Parkinson’s disease involves dopamine deficiency in basal ganglia circuits. Drug treatment aims to increase dopaminergic activity and improve movement control.
📌 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.