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WorksheetsPCS 1 December 2025
Total questions: 12
Worksheet time: 6mins
A 3-year-old child presents with hepatomegaly, fasting hypoglycaemia, and lactic acidosis. Genetic testing confirms a deficiency of glucose-6-phosphatase. Liver biopsy shows marked accumulation of a highly branched carbohydrate polymer composed of α-1,4-linked glucose chains with α-1,6 branch points.
Which carbohydrate structure is accumulating in this disease?
A - Cellulose
B - Glycogen
C - Amylose
D - Amylopectin
E - Pectin
A patient presents with painful blistering of the skin after minimal friction. Biopsy shows that the keratinocytes remain attached to the basement membrane, but adjacent keratinocytes have separated from each other, forming intraepidermal clefts.
Direct immunofluorescence demonstrates autoantibodies targeting a cadherin-type adhesion protein that normally links cells together through intermediate filaments.
Which structure is primarily affected?
Gap Junction
Hemidesmosome
Desmosome
Adherens Junction
Tight Junction
Which ion is MOST responsible for establishing the resting membrane potential of neurons?
Na⁺
K⁺
Ca²⁺
Cl⁻
HCO₃⁻
Which bone is correctly matched to its classification?
Vertebra — long bone
Patella — irregular bone
Sternum — flat bone
Scapula — short bone
Metacarpal — sesamoid bone
Which best describes the ionic basis of an IPSP?
Opening of Na⁺ channels → depolarisation
Opening of Ca²⁺ channels → depolarisation
Opening of Cl⁻ channels → hyperpolarisation
Closing of K⁺ efflux channels → hyperpolarisation
Which structural feature is unique to cardiac muscle when compared with skeletal and smooth muscle?
Multinucleated fibres
Intercalated discs
Absence of striations
Spindle-shaped cells
Involuntary control
Which process produces the majority of ATP in aerobic respiration?
Glycolysis
Citric acid cycle
Substrate level phosphorylation in the cytosol
Oxidative phosphorylation
β-oxidation of fatty acids
During intense exercise, which metabolic change occurs first to meet the sudden increase in energy demand?
Rapid increase in muscle glycolysis
Activation of gluconeogenesis in the liver
Increased ketone body synthesis
Inhibition of glycogen phosphorylase
Increased conversion of pyruvate to acetyl-CoA
What tissue is shown in this image?
Skeletal muscle
Fibrocartilage
Dense regular connective tissue
Elastic cartilage
Smooth muscle
During strenuous exercise, lactate production increases. What is the primary metabolic purpose of this shift?
To generate extra ATP in the mitochondria
To increase Krebs cycle activity
To allow glycolysis to continue by regenerating NAD
To act as a fuel that can be used by the heart
To promote glycogen storage
Which process occurs in the mitochondrial matrix during aerobic respiration?
Glycolysis
Lactate fermentation
Electron transport chain
Krebs cycle
Pyruvate export to cytosol
Which statement best describes smooth muscle contraction?
It requires troponin to regulate tropomyosin
It occurs more rapidly than skeletal muscle contraction
Myosin is activated by phosphorylation via MLCK
It depends primarily on intracellular calcium stored in the sarcoplasmic reticulum
It cannot maintain tension for prolonged periods
