/* === PHYSL 210 — question bank (keyed by module id) === */ // { q, options:[4], a:correctIndex, e:explanation } const QUESTIONS = { cell: [ { q:'The ___ performs oxidative reactions that produce H₂O₂, while the ___ is the site of cellular respiration.', options:['Lysosome; nucleus','Rough endoplasmic reticulum; nucleus','Peroxisome; mitochondrion','Mitochondrion; lysosome'], a:2, e:'Peroxisomes use oxygen to oxidise fatty acids and toxins, generating H₂O₂ that is detoxified by catalase. Mitochondria carry out cellular respiration and produce the cell\'s ATP.' }, { q:'Which of the following is an amphipathic molecule?', options:['Peripheral membrane protein','Phospholipid only','Integral membrane protein only','Both phospholipid and integral membrane protein'], a:3, e:'Both phospholipids (polar head, nonpolar fatty-acid tails) and integral membrane proteins (nonpolar transmembrane segments, polar extracellular/cytoplasmic regions) are amphipathic. Peripheral proteins are not amphipathic.' }, { q:'Which of the following statements about desmosomes is correct?', options:['Desmosomes are composed of connexons','Desmosomes are communicating junctions','Desmosomes are composed of cadherins','Desmosomes form nearly impermeable junctions'], a:2, e:'Desmosomes use cadherin proteins to link adjacent cells and are anchored intracellularly by intermediate filaments (keratin), giving tissues mechanical strength. Connexons form gap junctions; tight junctions are the nearly impermeable junctions.' }, { q:'Which of the following is NOT true of simple diffusion?', options:['Involves a net flux from higher to lower concentration','Is a passive process','Requires energy input from ATP to transport molecules across the membrane','Allows lipid-soluble molecules to cross the membrane'], a:2, e:'Simple diffusion is entirely passive — molecules move spontaneously down their concentration gradient with no energy input. ATP is required only for active transport.' }, { q:'Which of the following statements about the Na⁺/K⁺ pump is correct?', options:['Pumps 3 Na⁺ into the cell and 2 K⁺ out of the cell','Is an example of secondary active transport','Maintains a high concentration of K⁺ in the extracellular fluid','Hydrolyses one ATP molecule per transport cycle'], a:3, e:'Each cycle of the Na⁺/K⁺ pump hydrolyses one ATP, using that energy to move 3 Na⁺ out and 2 K⁺ in (not the reverse). It is primary — not secondary — active transport, and it maintains high intracellular K⁺.' }, { q:'Na⁺ channels and the Na⁺/K⁺ pump are both examples of:', options:['Primary active transport','Carrier-mediated facilitated diffusion','Mediated transport','Passive transport'], a:2, e:'Mediated transport means any transport process that uses a membrane protein. Na⁺ channels (passive, channel-mediated) and the Na⁺/K⁺ pump (active, carrier-mediated) both use membrane proteins, so both are mediated transport.' }, { q:'A white blood cell takes in bacteria by:', options:['Pinocytosis','Receptor-mediated endocytosis','Carrier-mediated facilitated diffusion','Phagocytosis'], a:3, e:'Phagocytosis ("cell eating") is the process by which leukocytes use pseudopods to engulf large particles such as bacteria into a phagosome, which then fuses with lysosomes for digestion.' }, { q:'Some organelles have their own DNA distinct from nuclear DNA. This is true of which organelle?', options:['Ribosomes','Mitochondria','Peroxisomes','Lysosomes'], a:1, e:'Mitochondria contain their own circular double-stranded DNA, a remnant of their endosymbiotic bacterial ancestry. No other mammalian organelle has its own genome.' }, { q:'Which of the following is NOT a function of the plasma membrane?', options:['Synthesis of phospholipids in the cell','Contains specialised connections between cells','Regulates what enters and leaves the cell','Acts as a boundary between the cell and its environment'], a:0, e:'Phospholipid synthesis occurs primarily in the smooth endoplasmic reticulum, not the plasma membrane. The plasma membrane functions as a physical barrier, contains cell junctions, mediates selective transport, and carries receptors.' }, { q:'Which intercellular connections force transcellular (through-cell) transport to occur?', options:['Tight junctions','Desmosomes','Gap junctions','Desmosomes and gap junctions'], a:0, e:'Tight junctions (occludins) seal the paracellular space between epithelial cells, preventing molecules from passing between cells; all transport must therefore occur transcellularly through the cell.' }, { q:'Two ATP molecules could provide energy for the Na⁺/K⁺ pump to move ___ ions out for every ___ ions moved in.', options:['6 Na⁺ out; 4 K⁺ in','4 Na⁺ out; 2 K⁺ in','3 Na⁺ out; 2 K⁺ in','2 Na⁺ out; 3 K⁺ in'], a:0, e:'Each ATP cycle moves 3 Na⁺ out and 2 K⁺ in. Two cycles (two ATP) therefore move 6 Na⁺ out and 4 K⁺ in.' }, { q:'Sodium ions do not freely cross the membrane by simple diffusion — they require an ion channel. What determines the direction they move?', options:['The electrochemical gradient of potassium','The configuration of membrane phospholipids','The electrochemical gradient of sodium','The amount of cholesterol in the plasma membrane'], a:2, e:'Ions move through channels down their own electrochemical gradient (a combination of concentration gradient and electrical gradient). For Na⁺, both the chemical gradient (high outside) and the electrical gradient (inside negative) drive Na⁺ into the cell.' }, { q:'Which one of the following is NOT a component of a phospholipid?', options:['Saturated fatty acids','Glycerol backbone','Cholesterol','Phosphate group'], a:2, e:'A phospholipid consists of a glycerol backbone, a phosphate-containing polar head (with a nitrogen-containing group), and two fatty acid chains. Cholesterol is a separate membrane lipid — it is not part of the phospholipid structure.' }, { q:'Which of the following is NOT a function of membrane proteins?', options:['Some act as channels','They determine the fluidity of the membrane','Some transport glucose','Some act as enzymes'], a:1, e:'Membrane fluidity is determined primarily by the degree of fatty acid saturation in phospholipids and by cholesterol content — not by membrane proteins. Membrane proteins function as channels, carriers, receptors, enzymes, and structural anchors.' }, { q:'Molecules exit cells by:', options:['Phagocytosis','Exocytosis','Receptor-mediated endocytosis','Pinocytosis'], a:1, e:'Exocytosis is the process by which membrane vesicles fuse with the plasma membrane to release their contents to the extracellular space. Phagocytosis, receptor-mediated endocytosis, and pinocytosis all bring material into the cell.' }, { q:'Which of the following statements about G proteins is correct?', options:['They bind ATP/ADP','They contain binding sites for the first messenger','They are activated by adenylate cyclase','They may alter the activity of an ion channel'], a:3, e:'The activated GTP-bound α-subunit moves to its effector protein, which can be an enzyme (e.g. adenylate cyclase) or an ion channel. The receptor — not the G-protein — binds the first messenger. G-proteins bind GDP/GTP, not ATP/ADP.' }, { q:'Which of the following has the fastest rate of simple diffusion across the plasma membrane?', options:['Charged ions','Small, nonpolar molecules','Large, uncharged polar molecules','Large, charged molecules'], a:1, e:'Simple diffusion through the lipid bilayer is fastest for small, nonpolar molecules (e.g. O₂, CO₂) because they dissolve readily into the hydrophobic core. Charged and large polar molecules cannot cross by simple diffusion.' }, { q:'Adenylate cyclase catalyses a reaction in which:', options:['A protein is phosphorylated','Calmodulin is activated','ATP is converted to cAMP','GTP is converted to GDP'], a:2, e:'Adenylate cyclase (adenylyl cyclase) is the effector enzyme activated by the Gα-subunit; it catalyses the conversion of ATP into cyclic AMP (cAMP), the second messenger that activates cAMP-dependent protein kinase A.' }, { q:'Facilitated diffusion occurs:', options:['Into the cell only','Out of the cell only','In either direction depending on temperature','In either direction depending on the concentration gradient of the molecule'], a:3, e:'Facilitated diffusion is passive — carriers and channels transport molecules down their concentration gradient, which can be in either direction depending on where the solute is more concentrated at any given time.' }, { q:'Carrier-mediated facilitated diffusion:', options:['Involves a specific membrane protein','Moves substances against a concentration gradient','Requires energy in the form of ATP','Uses the same carrier protein for all solutes'], a:0, e:'Carrier-mediated facilitated diffusion uses a specific transport protein for each solute. It is passive (no ATP required), moves solutes down their concentration gradient, and is selective and saturable.' }, ], blood: [ { q:'The site of destruction of aging red blood cells is the:', options:['Small intestine','Liver','Spleen','Bone marrow'], a:2, e:'Old and damaged RBCs are phagocytosed by macrophages in the spleen (and to a lesser extent the liver). The heme is converted to bilirubin and iron is recycled; the globin is broken down to amino acids.' }, { q:'Which process directs white blood cells to the pathogens once WBCs have crossed the blood vessel wall?', options:['Opsonisation','Margination','Diapedesis','Chemotaxis'], a:3, e:'Chemotaxis is the directed migration of WBCs along a concentration gradient of chemotactic factors (C5a, IL-8, bacterial products) toward the site of infection, after diapedesis (transmigration through the vessel wall).' }, { q:'Which one of the following statements about red blood cells is INCORRECT?', options:['Mature RBCs lack nuclei','RBCs contain haemoglobin','Deoxyhemoglobin carries oxygen','RBCs are biconcave in shape'], a:2, e:'Deoxyhemoglobin is haemoglobin that has already unloaded its oxygen — it does NOT carry oxygen. Oxygen is carried by oxyhemoglobin (Hb with O₂ bound).' }, { q:'Which statement about the destruction of red blood cells is INCORRECT?', options:['Bilirubin is secreted into bile and enters the small intestine','Macrophages in the spleen phagocytose dead and degenerating RBCs','Iron obtained from the breakdown of heme is recycled in the urine','The globin portion is broken down to amino acids'], a:2, e:'Iron released from heme is recycled back to the bone marrow via transferrin for new haemoglobin synthesis or stored in the liver — it is NOT excreted in the urine. Bilirubin (from heme) is excreted in bile.' }, { q:'What is the function of transferrin?', options:['Contributes to the colloid osmotic pressure of plasma','Functions as a clotting factor','Carries oxygen in the blood','Transports iron in the blood'], a:3, e:'Transferrin is a plasma protein synthesised by the liver that binds and transports iron in the blood. It should not be confused with haemoglobin (O₂ transport) or albumin (osmotic pressure).' }, { q:'A person with type AB blood would have ___ antigens on their red cells and ___ antibodies in their plasma.', options:['Neither A nor B; both anti-A and anti-B','A and B antigens; neither anti-A nor anti-B','B antigen only; anti-A antibodies','A antigen only; anti-B antibodies'], a:1, e:'Type AB individuals express both A and B carbohydrate antigens on their RBCs and therefore have neither anti-A nor anti-B antibodies in their plasma — they are the universal recipients for red cell transfusion.' }, { q:'Choose the correct order of steps for haemostasis:', options:['Vasoconstriction → platelet plug → blood coagulation','Vasoconstriction → blood coagulation → platelet plug','Platelet plug → blood coagulation → vasoconstriction','Platelet plug → vasoconstriction → blood coagulation'], a:0, e:'Haemostasis proceeds in three sequential steps: (1) vascular spasm (vasoconstriction), (2) primary haemostasis — formation of the platelet plug, and (3) secondary haemostasis — blood coagulation forming the fibrin clot.' }, { q:'Pernicious anaemia is caused by:', options:['Increased breakdown of RBCs due to abnormal shape','Chronic kidney disease causing reduced EPO','Increased blood loss','Lack of intrinsic factor or vitamin B12'], a:3, e:'Pernicious anaemia results from deficiency of intrinsic factor (secreted by gastric parietal cells) or dietary vitamin B12, impairing the absorption of B12 needed for normal DNA synthesis and RBC maturation.' }, { q:'Which of the following characteristics applies to acquired (adaptive) immunity?', options:['Non-specific and no memory of foreign body','Major cells involved are phagocytes (neutrophils, macrophages)','Major cells involved are lymphocytes (B and T cells)','Is fast to develop, within seconds to hours'], a:2, e:'Acquired immunity is specific, has immunological memory, and is mediated by lymphocytes (B cells for humoral immunity; T cells for cell-mediated immunity). Innate immunity is non-specific, fast, and relies on phagocytes.' }, { q:'T lymphocytes are unique compared to other white blood cells because:', options:['They arise from stem cells located in the bone marrow','They are activated in secondary lymphoid tissue such as lymph nodes','They migrate to and reside in the thymus where they become mature','Cytokines are essential for their maturation'], a:2, e:'T cell precursors (pre-T cells) leave the bone marrow and travel to the thymus — a primary lymphoid organ — where they undergo maturation and education (positive and negative selection). This thymic residency distinguishes them from B cells.' }, { q:'Erythropoietin (EPO) stimulates RBC production. Where is EPO produced?', options:['Bone marrow','Spleen','Kidney','Liver'], a:2, e:'The kidney produces erythropoietin in response to decreased O₂ delivery (hypoxia, anaemia, low blood volume, pulmonary disease). EPO then stimulates erythroid precursors in the bone marrow to differentiate into red blood cells.' }, { q:'Opsonins:', options:['Facilitate the attachment and phagocytosis of bacteria by phagocytic cells','Form pores on the surface of bacteria, killing them','Are produced by the invading bacteria themselves','Bind iron so that bacteria cannot grow'], a:0, e:'Opsonins (mainly antibodies and complement fragment C3b) coat the surface of pathogens and are recognised by specific receptors on phagocytes (neutrophils and macrophages), greatly enhancing the rate of phagocytosis.' }, { q:'Which of the following causes DECREASED platelet aggregation?', options:['Nitric oxide (NO)','Prostacyclin (PGI₂)','Thromboxane A₂ (TXA₂)','Both nitric oxide and prostacyclin'], a:3, e:'Nitric oxide and prostacyclin (PGI₂) are released by intact endothelial cells and act as anti-platelet signals, inhibiting aggregation and causing vasodilation to restrict clot formation to the site of injury. TXA₂ (from activated platelets) promotes aggregation.' }, { q:'Von Willebrand factor (vWF):', options:['Is found only in the plasma, not in platelets','Prevents platelets from adhering to the vessel wall','Is involved in haematopoiesis in the bone marrow','Is derived from platelets and forms a bridge between platelets and the damaged vessel wall'], a:3, e:'vWF is stored in platelet α-granules and in subendothelial tissue. When a vessel is damaged, vWF is released and bridges platelet surface glycoproteins to exposed collagen, initiating platelet adhesion at the injury site.' }, { q:'Which statement about macrophages is NOT correct?', options:['They are large phagocytic cells found in tissues','They arise from monocytes in the blood','They present foreign antigens to T cells on MHC class II proteins','Macrophages — not neutrophils — are responsible for oxygen-dependent killing using free radicals'], a:3, e:'In the lectures, oxygen-dependent killing using corrosive free radical products (reactive oxygen species) is specifically described for neutrophils. While macrophages do phagocytose pathogens, free radical-based killing was attributed to neutrophils in this course.' }, { q:'If bacteria are carried in the blood and exposed to B cells in the spleen, they will initiate:', options:['An inflammatory response','Activation of the complement system only','A cell-mediated immune response','A humoral immune response'], a:3, e:'B cells in secondary lymphoid tissue (spleen, lymph nodes) recognise antigens via surface antibodies, then undergo clonal expansion and differentiate into plasma cells that secrete circulating antibodies — this is the humoral immune response.' }, { q:'Three statements about diapedesis: (1) It is a crucial feature of innate immunity. (2) Impairment of diapedesis would lead to persistent bacterial infections. (3) It is preceded by margination, rolling and adhesion, and followed by chemotaxis and phagocytosis. Which are correct?', options:['Statement 1 only','Statements 1 and 2 only','Statements 2 and 3 only','All three statements are correct'], a:3, e:'All three are correct. Diapedesis (emigration of WBCs through vessel walls) is a key step of innate immunity; impairment causes susceptibility to infection; and the sequence is margination → rolling → adhesion → diapedesis → chemotaxis → phagocytosis.' }, { q:'Three statements about plasma proteins: (1) Mainly produced by the liver. (2) Transport of oxygen is a major function. (3) Removal of fibrinogen and clotting factors from plasma produces serum. Which are correct?', options:['Statements 1 and 2 correct; Statement 3 not correct','Statements 1 and 3 correct; Statement 2 not correct','All three statements are correct','Only Statement 3 is correct'], a:1, e:'Statements 1 and 3 are correct. Plasma proteins are mainly liver-derived, and serum is plasma minus fibrinogen and clotting factors. Statement 2 is incorrect: oxygen is transported by haemoglobin inside RBCs, not by plasma proteins.' }, ], nms: [ { q:'Which stage of the nerve action potential is described by: voltage-gated K⁺ channels are open; Na⁺ channels are closed and in the resting state?', options:['Depolarisation phase','Resting membrane potential','Repolarisation phase','Relative refractory period'], a:3, e:'During the relative refractory period, K⁺ channels are still open (causing after-hyperpolarisation) while only some Na⁺ channels have recovered to the resting (closed but activatable) state. A larger-than-normal stimulus can still fire an AP.' }, { q:'At the peak of an action potential, the neuronal membrane potential:', options:['Is impermeable to sodium ions','Approaches the equilibrium potential of sodium (+55 mV)','Is sitting at the threshold potential (−50 mV)','Approaches the equilibrium potential of potassium (−90 mV)'], a:1, e:'At the peak (~+30 mV), Na⁺ permeability is maximal and the membrane potential is driven toward ENa⁺ (+55 mV). It does not reach +55 mV because Na⁺ channels begin to inactivate and K⁺ channels start opening.' }, { q:'The gap between two communicating neurons is termed the:', options:['Cytoplasm','Node of Ranvier','Neuromuscular junction','Synaptic cleft/gap'], a:3, e:'The synaptic cleft (or synaptic gap, ~40 nm wide) is the fluid-filled space between the presynaptic membrane and postsynaptic membrane at a chemical synapse.' }, { q:'Select the correct statement about nerve impulse conduction:', options:['An AP is a large change in membrane potential occurring over a period of several seconds','Saltatory conduction involves Schwann cells and occurs at greater speed than in unmyelinated fibres','The AP in nerves is generated by voltage-gated Na⁺ and Ca²⁺ channels','The resting membrane potential is primarily determined only by Na⁺ permeability'], a:1, e:'Saltatory conduction occurs in myelinated axons (myelinated by Schwann cells in the PNS); current jumps between nodes of Ranvier, giving speeds of 12–130 m/s compared to 0.5–2 m/s for unmyelinated axons. The AP lasts milliseconds and is generated by Na⁺ and K⁺ channels.' }, { q:'Which of the following is correctly matched?', options:['Glutamate — inhibitory neurotransmitter','Glycine — excitatory neurotransmitter','GABA — binding to receptor opens Na⁺ channels','Glycine — binding to receptor opens Cl⁻ channels'], a:3, e:'Glycine is an inhibitory neurotransmitter that binds receptors opening Cl⁻ channels, causing Cl⁻ influx and an IPSP (hyperpolarisation). Glutamate is excitatory; GABA also opens Cl⁻ channels (not Na⁺).' }, { q:'Which is correctly matched regarding neuron types?', options:['Interneurons — carry information from periphery to spinal cord','Afferent neurons — carry information from spinal cord to periphery','Interneurons — carry information between neurons','Efferent neurons — found entirely in the CNS'], a:2, e:'Interneurons are located entirely within the CNS and carry information between neurons (afferent to efferent, or between interneurons). Afferent neurons carry information to the CNS; efferent neurons carry information from the CNS to the periphery.' }, { q:'Which of the following is NOT a graded potential?', options:['An excitatory postsynaptic potential (EPSP)','An inhibitory postsynaptic potential (IPSP)','An action potential','A receptor potential'], a:2, e:'The action potential is all-or-none — it either fires fully or not at all. EPSPs, IPSPs, and receptor potentials are all graded potentials whose amplitude is proportional to stimulus strength.' }, { q:'At resting potential, the ion distribution of a neuron is such that ___ ions are most abundant inside the cell, while ___ ions are most abundant outside.', options:['K⁺ inside; Na⁺ outside','Na⁺ inside; K⁺ outside','Ca²⁺ inside; Na⁺ outside','Ca²⁺ inside; K⁺ outside'], a:0, e:'K⁺ ≈ 150 mM intracellularly vs 5 mM extracellularly. Na⁺ ≈ 150 mM extracellularly vs 15 mM intracellularly. These gradients are maintained by the Na⁺/K⁺-ATPase and set the resting membrane potential.' }, { q:'A refractory period:', options:['Is the same as the resting potential','Is a brief period when a neuron is unable to conduct an impulse','Occurs during the depolarising phase of an action potential','Continues until voltage-gated Ca²⁺ channels close'], a:1, e:'The refractory period is the brief interval after an AP during which another AP cannot be generated (absolute refractory period) or requires a larger stimulus (relative refractory period). It enforces unidirectional propagation.' }, { q:'Cell bodies of sensory neurons of spinal nerves are located in:', options:['The dorsal root ganglion of the spinal cord','The hypothalamus','The lateral horn of the spinal cord','The ventral root ganglion'], a:0, e:'Afferent (sensory) neuron cell bodies are located in the dorsal root ganglion, just outside the spinal cord. Their peripheral axon extends to the receptor; their central axon enters the dorsal horn of the spinal cord.' }, { q:'Myelin:', options:['Is formed by oligodendrocytes in the peripheral nervous system','Is formed by Schwann cells in the central nervous system','Decreases the speed of electrotonic conduction','Is discontinuous, interrupted by nodes of Ranvier'], a:3, e:'Myelination is discontinuous — unmyelinated gaps called nodes of Ranvier occur between myelin segments. Voltage-gated Na⁺ channels concentrate at the nodes, allowing saltatory conduction. Schwann cells myelinate in the PNS; oligodendrocytes in the CNS.' }, { q:'A motor unit:', options:['Is the same as a neuromuscular junction','Consists of a motor neuron, its axon, and all the muscle fibres it innervates','Is the same as a sarcomere, the basic contractile unit','Consists of an afferent neuron and all the muscle fibres it innervates'], a:1, e:'The motor unit is the functional unit of the motor system: one motor neuron, its axon, and all the skeletal muscle fibres it innervates. It is the smallest increment of force the nervous system can generate.' }, { q:'The smallest contractile unit of skeletal muscle is a:', options:['Motor unit','Synapse','Motor end plate','Sarcomere'], a:3, e:'The sarcomere is the structural and functional unit of contraction, defined as the region between two Z-lines. It contains overlapping thick (myosin) and thin (actin/troponin/tropomyosin) filaments that slide past each other during contraction.' }, { q:'In muscle, neurotransmitter receptors are located:', options:['On the motor neuron axon terminals','On the motor neuron axon','Freely floating in the synaptic cleft','On the motor end plate of the muscle fibre'], a:3, e:'Nicotinic acetylcholine receptors are concentrated on the motor end plate — the specialised region of the muscle fibre membrane at the neuromuscular junction. They are on the postsynaptic (muscle) side, not the presynaptic (nerve) side.' }, { q:'In a resting muscle, which of the following is NOT chemically associated with the others?', options:['Actin','Myosin','Troponin','Tropomyosin'], a:1, e:'At rest, tropomyosin covers the myosin-binding sites on actin, and troponin holds tropomyosin in that position — actin, troponin, and tropomyosin are all associated in the thin filament. Myosin (thick filament) is physically separated and not bound to actin.' }, { q:'What role do calcium ions play in muscle contraction?', options:['Bind to the myosin cross-bridge to cause the power stroke','Cause the release of Na⁺ from the sarcoplasmic reticulum','Bind to troponin to move tropomyosin off the binding sites on actin','Bind to tropomyosin to move troponin off the binding sites on actin'], a:2, e:'Ca²⁺ released from the SR binds to troponin, causing a conformational change in the troponin–tropomyosin complex that moves tropomyosin away from the myosin-binding sites on actin, allowing cross-bridge attachment and contraction.' }, { q:'The dorsal horn of the spinal cord consists of:', options:['White matter containing astrocytes and sensory axon terminals','White matter containing oligodendrocytes and motor neuron terminals','Grey matter containing astrocytes and axon terminals of peripheral sensory neurons','Grey matter containing astrocytes and axon terminals of motor neurons'], a:2, e:'The dorsal horn is grey matter (cell bodies, unmyelinated processes, synapses) and receives axon terminals of afferent (sensory) neurons entering via the dorsal root. Grey matter also contains astrocytes and interneurons.' }, { q:'Place the following events in the correct sequence of synaptic transmission: (1) vesicles fuse with presynaptic membrane, (2) ions flow across postsynaptic membrane, (3) voltage-gated Ca²⁺ channels open, (4) AP arrives in presynaptic terminal, (5) transmitter released and diffuses to bind receptors.', options:['4 → 3 → 2 → 5 → 1','4 → 3 → 1 → 5 → 2','3 → 4 → 1 → 5 → 2','2 → 4 → 3 → 1 → 5'], a:1, e:'Sequence: AP arrives (4) → terminal depolarises, Ca²⁺ channels open (3) → Ca²⁺ influx causes vesicles to fuse (1) → transmitter released by exocytosis and diffuses to bind receptors (5) → ion channels open, PSP generated (2).' }, ], cns: [ { q:'Fine touch and proprioception are carried to the brain by the:', options:['Spinothalamic tract','Dorsal column pathway','Corticospinal tract','Rubrospinal tract'], a:1, e:'The dorsal columns carry fine touch, vibration and proprioception; the spinothalamic tract carries pain and temperature.' }, { q:'The main descending pathway for voluntary movement is the:', options:['Spinothalamic tract','Dorsal column','Corticospinal tract','Spinocerebellar tract'], a:2, e:'The corticospinal (pyramidal) tract carries voluntary motor commands from cortex to spinal cord.' }, { q:'Which structure is essential for forming new declarative memories?', options:['Amygdala','Hippocampus','Cerebellum','Hypothalamus'], a:1, e:'The hippocampus is critical for consolidating new declarative (explicit) memories.' }, { q:'In the CNS, white matter is composed primarily of:', options:['Neuronal cell bodies','Myelinated axon tracts','Glial cell nuclei','Blood vessels'], a:1, e:'White matter is made of myelinated axons; grey matter contains cell bodies.' }, { q:'Arousal and the sleep–wake cycle are governed by the:', options:['Reticular activating system','Basal ganglia','Choroid plexus','Limbic cortex'], a:0, e:'The reticular activating system in the brainstem regulates wakefulness and arousal.' }, ], ans: [ { q:'All autonomic preganglionic neurons release which neurotransmitter?', options:['Noradrenaline','Acetylcholine','Adrenaline','Dopamine'], a:1, e:'Both sympathetic and parasympathetic preganglionic neurons release ACh onto nicotinic receptors.' }, { q:'Postganglionic sympathetic neurons typically release ____ onto ____ receptors.', options:['ACh; muscarinic','Noradrenaline; adrenergic','ACh; nicotinic','Adrenaline; nicotinic'], a:1, e:'Most postganglionic sympathetic neurons release noradrenaline onto adrenergic receptors (sweat glands are an ACh/muscarinic exception).' }, { q:'The adrenal medulla is best described as:', options:['An endocrine gland unrelated to the ANS','A modified sympathetic ganglion','A parasympathetic ganglion','Part of the somatic motor system'], a:1, e:'The adrenal medulla is a modified sympathetic ganglion that secretes adrenaline into the blood.' }, { q:'Which response is characteristic of parasympathetic activation?', options:['Increased heart rate','Pupil dilation','Increased gut motility','Bronchodilation'], a:2, e:'Parasympathetic ("rest and digest") activity increases GI motility and secretion while slowing the heart.' }, { q:'The sympathetic division arises from which regions of the spinal cord?', options:['Cranial and sacral','Thoracolumbar','Cervical only','Lumbosacral'], a:1, e:'Sympathetic outflow is thoracolumbar (T1–L2); parasympathetic outflow is craniosacral.' }, ], ss: [ { q:'Photoreceptors respond to light by:', options:['Depolarising and increasing glutamate release','Hyperpolarising and decreasing glutamate release','Releasing acetylcholine','Firing action potentials directly'], a:1, e:'Light hyperpolarises photoreceptors, reducing their tonic glutamate release — an unusual feature of phototransduction.' }, { q:'Which receptors provide high-acuity colour vision?', options:['Rods','Cones','Bipolar cells','Ganglion cells'], a:1, e:'Cones mediate colour and high-acuity vision; rods serve dim-light and peripheral vision.' }, { q:'In the cochlea, high-frequency sounds are detected best at the:', options:['Apex of the basilar membrane','Base of the basilar membrane','Round window','Tectorial membrane tip'], a:1, e:'The basilar membrane is tonotopically organised: the stiff base responds to high frequencies, the flexible apex to low frequencies.' }, { q:'The decline in receptor response to a sustained, constant stimulus is called:', options:['Summation','Adaptation','Facilitation','Transduction'], a:1, e:'Adaptation is the decrease in receptor potential/firing during a maintained stimulus.' }, { q:'Sensory transduction converts a stimulus into a:', options:['Muscle contraction','Graded receptor potential','Hormone release','Reflex arc'], a:1, e:'Receptors transduce stimulus energy into a graded receptor potential that may trigger action potentials.' }, ], cardio: [ { q:'Cardiac output is the product of:', options:['Heart rate × stroke volume','Preload × afterload','Blood pressure × resistance','Stroke volume × ejection fraction'], a:0, e:'Cardiac output = heart rate × stroke volume.' }, { q:'The plateau phase of the ventricular (fast-type) action potential is maintained by:', options:['Na⁺ influx','Ca²⁺ influx balancing K⁺ efflux','Cl⁻ influx','K⁺ influx'], a:1, e:'During the plateau, Ca²⁺ entry roughly balances K⁺ exit, prolonging depolarisation and allowing contraction.' }, { q:'Baroreceptors that buffer short-term changes in arterial pressure are located in the:', options:['Renal arterioles','Carotid sinus and aortic arch','Pulmonary veins','Coronary sinus'], a:1, e:'Carotid sinus and aortic arch baroreceptors sense stretch and adjust pressure via the autonomic nervous system.' }, { q:'Net fluid movement across a capillary wall is determined by:', options:['Starling (hydrostatic and oncotic) forces','The cardiac cycle alone','Action potential frequency','Surfactant levels'], a:0, e:'Starling forces — the balance of hydrostatic and oncotic pressures — govern capillary filtration and reabsorption.' }, { q:'The normal pacemaker of the heart is the:', options:['AV node','Bundle of His','SA node','Purkinje fibres'], a:2, e:'The SA node has the fastest intrinsic rate and sets the heart rhythm.' }, ], gi: [ { q:'Which cells of the gastric glands secrete hydrochloric acid?', options:['Chief cells','Parietal cells','G cells','Mucous neck cells'], a:1, e:'Parietal (oxyntic) cells secrete HCl and intrinsic factor; chief cells secrete pepsinogen.' }, { q:'Segmentation contractions in the small intestine primarily serve to:', options:['Propel chyme toward the anus','Mix chyme with digestive juices','Trigger swallowing','Close the lower oesophageal sphincter'], a:1, e:'Segmentation mixes contents for digestion and absorption, whereas peristalsis propels them.' }, { q:'Dietary fats are absorbed across the intestinal epithelium after forming:', options:['Monosaccharides','Micelles','Amino acids','Bicarbonate'], a:1, e:'Bile salts emulsify fat into micelles; the absorbed lipids are reassembled into chylomicrons.' }, { q:'The hormone that stimulates pancreatic bicarbonate secretion in response to acid in the duodenum is:', options:['Gastrin','Secretin','Cholecystokinin','Insulin'], a:1, e:'Secretin, released in response to duodenal acid, stimulates bicarbonate-rich pancreatic and biliary secretion.' }, { q:'From innermost to outermost, the layers of the GI tract wall are:', options:['Serosa, muscularis, submucosa, mucosa','Mucosa, submucosa, muscularis externa, serosa','Submucosa, mucosa, serosa, muscularis','Mucosa, muscularis, submucosa, serosa'], a:1, e:'The wall layers from the lumen outward are mucosa, submucosa, muscularis externa and serosa.' }, ], resp: [ { q:'Pulmonary surfactant reduces the work of breathing by:', options:['Increasing surface tension','Lowering surface tension and increasing compliance','Thickening the respiratory membrane','Constricting the airways'], a:1, e:'Surfactant from type II pneumocytes lowers alveolar surface tension, raising compliance and preventing collapse.' }, { q:'A rightward shift of the oxygen–haemoglobin dissociation curve occurs with:', options:['Decreased CO₂ and H⁺','Increased CO₂, H⁺ and temperature','Decreased temperature','Increased pH'], a:1, e:'The Bohr effect: ↑CO₂, ↑H⁺ (↓pH) and ↑temperature shift the curve right, unloading O₂ to active tissues.' }, { q:'During quiet breathing, expiration is normally:', options:['Active, using internal intercostals','Passive, due to elastic recoil','Driven by the diaphragm contracting','Dependent on abdominal muscles'], a:1, e:'Quiet expiration is passive elastic recoil; the diaphragm and external intercostals drive (active) inspiration.' }, { q:'Central chemoreceptors that regulate ventilation respond most directly to:', options:['Arterial O₂','CO₂/H⁺ in the cerebrospinal fluid','Plasma glucose','Blood pressure'], a:1, e:'Central chemoreceptors sense CO₂ (via H⁺) in the CSF; peripheral chemoreceptors respond mainly to low arterial O₂.' }, { q:'Optimal gas exchange requires ventilation and perfusion to be:', options:['Completely independent','Matched (V/Q ≈ 0.8)','Maximally mismatched','Equal to zero'], a:1, e:'Ventilation–perfusion matching (V/Q ≈ 0.8) maximises the efficiency of gas exchange.' }, ], renal: [ { q:'The three basic renal processes are:', options:['Filtration, reabsorption and secretion','Diffusion, osmosis and active transport','Filtration, digestion and excretion','Secretion, storage and release'], a:0, e:'Urine is formed by glomerular filtration, tubular reabsorption and tubular secretion.' }, { q:'Antidiuretic hormone (ADH) concentrates urine by:', options:['Increasing Na⁺ reabsorption in the loop','Inserting aquaporins in the collecting duct','Dilating the afferent arteriole','Inhibiting aldosterone'], a:1, e:'ADH increases water permeability of the collecting duct by inserting aquaporin channels, concentrating the urine.' }, { q:'Aldosterone acts on the distal nephron to:', options:['Increase Na⁺ reabsorption and K⁺ secretion','Increase K⁺ reabsorption','Decrease water reabsorption','Increase glucose reabsorption'], a:0, e:'Aldosterone promotes Na⁺ (and water) reabsorption and K⁺ secretion in the distal tubule and collecting duct.' }, { q:'Glucose normally does not appear in the urine until plasma glucose exceeds the:', options:['Filtration fraction','Transport maximum (Tm)','Osmotic gradient','Renal threshold for sodium'], a:1, e:'Filtered glucose is fully reabsorbed until the transporters begin to saturate. Glucosuria actually begins once plasma glucose exceeds the renal threshold for glucose, which is slightly below the average Tm; Tm is the closest available option here.' }, { q:'The medullary osmotic gradient that allows urine concentration is generated by the:', options:['Glomerulus','Countercurrent multiplier in the loop of Henle','Bowman’s capsule','Macula densa'], a:1, e:'The loop of Henle acts as a countercurrent multiplier, building the medullary gradient that drives water reabsorption.' }, ], endo: [ { q:'Steroid hormones differ from peptide hormones in that they:', options:['Act through surface receptors and cAMP','Cross the cell membrane to act on nuclear receptors','Cannot enter target cells','Are stored in large secretory vesicles'], a:1, e:'Lipid-soluble steroid (and thyroid) hormones cross the membrane and bind intracellular/nuclear receptors to alter transcription.' }, { q:'Which hormone is released by the posterior pituitary?', options:['ACTH','Growth hormone','Antidiuretic hormone (ADH)','TSH'], a:2, e:'The posterior pituitary stores and releases ADH and oxytocin made in the hypothalamus; ACTH, GH and TSH are anterior pituitary hormones.' }, { q:'Parathyroid hormone (PTH) raises blood calcium by all of the following EXCEPT:', options:['Stimulating bone resorption','Increasing renal Ca²⁺ reabsorption','Activating vitamin D','Stimulating calcitonin release'], a:3, e:'PTH raises Ca²⁺ via bone, kidney and vitamin-D activation; calcitonin (from the thyroid) opposes PTH by lowering Ca²⁺.' }, { q:'Insulin lowers blood glucose mainly by:', options:['Stimulating glycogen breakdown','Promoting glucose uptake and storage','Inhibiting glucose use by cells','Stimulating gluconeogenesis'], a:1, e:'Insulin promotes cellular glucose uptake and storage as glycogen/fat; glucagon opposes it.' }, { q:'Most endocrine axes are regulated chiefly by:', options:['Positive feedback','Negative feedback','Feed-forward only','Random secretion'], a:1, e:'Negative feedback predominates — for example, thyroid hormone inhibits TSH and TRH release.' }, ], repro: [ { q:'Development of the testis is driven by the:', options:['Second X chromosome','SRY gene on the Y chromosome','Maternal oestrogen','Aromatase enzyme'], a:1, e:'The SRY gene on the Y chromosome initiates testis development; without it the gonad becomes an ovary.' }, { q:'Ovulation is triggered by a mid-cycle surge of:', options:['FSH','Luteinising hormone (LH)','Progesterone','hCG'], a:1, e:'A sharp LH surge around day 14 triggers ovulation.' }, { q:'After implantation, the corpus luteum is maintained early in pregnancy by:', options:['FSH','LH','Human chorionic gonadotropin (hCG)','Oxytocin'], a:2, e:'Embryonic hCG sustains the corpus luteum, which keeps secreting progesterone until the placenta takes over.' }, { q:'Which hormone is chiefly responsible for milk ejection (let-down)?', options:['Prolactin','Oxytocin','Oestrogen','Progesterone'], a:1, e:'Oxytocin causes contraction of myoepithelial cells for milk ejection; prolactin drives milk production.' }, { q:'In both sexes, gametogenesis is driven primarily by which pituitary hormones?', options:['ACTH and TSH','FSH and LH','GH and prolactin','ADH and oxytocin'], a:1, e:'FSH and LH (the gonadotropins) drive gametogenesis and sex-steroid production in both males and females.' }, ], }; Object.assign(window, { QUESTIONS });