MCQOPTIONS
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MCQOPTIONS
This section includes 697 Mcqs, each offering curated multiple-choice questions to sharpen your Biology knowledge and support exam preparation. Choose a topic below to get started.
| 251. |
Mesangial cells: |
| A. | have a role in the control of GFR |
| B. | are similar to other endothelial cells in the vascular tree |
| C. | are responsible for tubuloglomerular balance |
| D. | contract in response to dopamine |
| E. | relax in response to vasopressin |
| Answer» B. are similar to other endothelial cells in the vascular tree | |
| 252. |
Glucose reabsorption is most marked in which segment of the glomerulus? |
| A. | the proximal convoluted tubule |
| B. | the distal convoluted tubule |
| C. | the descending loop of Henle |
| D. | the ascending loop of Henle |
| E. | the collecting system |
| Answer» B. the distal convoluted tubule | |
| 253. |
Amino acid reabsorption is most marked in which segment of the glomerulus? |
| A. | the proximal convoluted tubule |
| B. | the distal convoluted tubule |
| C. | the descending loop of Henle |
| D. | the ascending loop of Henle |
| E. | the collecting duct |
| Answer» B. the distal convoluted tubule | |
| 254. |
Substance X is freely filtered by the glomerulus and is not reabsorbed, nor secreted nor metabolized.If - serum x concentration = 0.020 mg/mlrenal artery x concentration = 0.020 mg/mlrenal vein x concentration = 0.002 mg/mlurine x concentration = 14 mg/mlurine flow = 54 ml/hrlymphatic x concentration = 0.00001 mg/mlhaematocrit = 0.45Renal plasma flow is: |
| A. | 10.5 ml/min |
| B. | 630 ml/min |
| C. | 700 ml/min |
| D. | 11.7 ml/min |
| E. | 21.2 ml/min |
| Answer» D. 11.7 ml/min | |
| 255. |
Substance X is freely filtered by the glomerulus and is not reabsorbed, nor secreted nor metabolized.If - serum x concentration = 0.020 mg/mlrenal artery x concentration = 0.020 mg/mlrenal vein x concentration = 0.002 mg/mlurine x concentration = 14 mg/mlurine flow = 54 ml/hrlymphatic x concentration = 0.00001 mg/mlhaematocrit = 0.45Then the CLEARANCE of X is: |
| A. | 10.5 ml/min |
| B. | 630 ml/min |
| C. | 10.5 mg/min |
| D. | 630 mg/min |
| E. | 60 ml/min |
| Answer» C. 10.5 mg/min | |
| 256. |
Regarding the glomerulus filtration fx: |
| A. | it allows passage of molecules up to 4nm diameter freely, and up to 8nm with some difficulty depending on charge |
| B. | positively charged molecules pass more easily than neutral |
| C. | endothelial pores have a greater diameter than podocyte filtration slits |
| D. | the basal lamina contains interruptions |
| Answer» B. positively charged molecules pass more easily than neutral | |
| 257. |
Regarding the dorsal column: |
| A. | carries ipsilateral pain and temperature |
| B. | ascends to the nuclei gracillis and ????? |
| C. | receives efferents from contralateral stimuli |
| D. | sacral efferents lie laterally |
| E. | runs anteriorly in the cord |
| Answer» C. receives efferents from contralateral stimuli | |
| 258. |
For the Erlanger and Gasser classification, which is TRUE? |
| A. | Sunday morning syndrome mainly affects C fibres |
| B. | local anaesthetics primarily affect A fibres |
| C. | preganglionic autonomic fibres are type B |
| D. | C fibres have the largest diameter |
| E. | B fibres are the least susceptible to hypoxia |
| Answer» D. C fibres have the largest diameter | |
| 259. |
Nerve fibres, which is FALSE? |
| A. | 70% of energy requirement of nerves is used in maintaining polarity across the recytlemina by action of Na-K ATPase |
| B. | metabolic rate of nerves doubles in max action |
| C. | C type fibres are non-myelinated and include some of the sympathetic preganglionic fibres |
| D. | A and B fibres are all myelinated |
| E. | effects of local anaesthetic are maximal in C fibres |
| Answer» D. A and B fibres are all myelinated | |
| 260. |
Triglycerides are transported to cells via: |
| A. | chylomicron remnants |
| B. | HDL |
| C. | LDL |
| D. | VLDL |
| E. | none of the above |
| Answer» E. none of the above | |
| 261. |
When the cholinergic vagal fibres to nodal tissues are stimulated: |
| A. | the membrane becomes hyper-polarised |
| B. | the slope of the pre-potential is decreased |
| C. | acetylcholine decreases conductance to Ca++ via muscarinic receptors |
| D. | acetylcholine increases the permeability of nodal tissues to K+ via muscarinic receptors |
| E. | all of the above are true |
| Answer» F. | |
| 262. |
B nerve fibres: |
| A. | provide motor supply to intrafusal muscle fibres |
| B. | are usually the first fibres affected by local anaesthetics |
| C. | are 12-20umol in diameter |
| D. | are unmyelinated |
| E. | provide pre-ganglionic autonomic supply |
| Answer» F. | |
| 263. |
Dorsal root (type C) fibres: |
| A. | conduct proprioception |
| B. | are amongst the largest of the nerve fibres |
| C. | are the fibres most susceptible to hypoxia |
| D. | administration of lignocaine suppresses transmission in C fibres before affecting A fibres |
| E. | are myelinated |
| Answer» E. are myelinated | |
| 264. |
In the Erlanger and Gasser classification of nerve fibres: |
| A. | C fibres have the fastest conduction velocity |
| B. | A fibres are responsible for touch and pressure |
| C. | C fibres are most susceptible to local anaesthetics |
| D. | A fibres have the fastest conduction velocity and the longest absolute refractory period |
| E. | A fibres are most susceptible to hypoxia |
| Answer» D. A fibres have the fastest conduction velocity and the longest absolute refractory period | |
| 265. |
All of the following are transported across renal tubular cell membranes by secondary active transport, using the energy of the active transport of Na+ , EXCEPT: |
| A. | glucose |
| B. | lactate |
| C. | citrate |
| D. | H+ |
| E. | K+ |
| Answer» F. | |
| 266. |
Which of the following nerve fibres is most susceptible to hypoxia? |
| A. | group B |
| B. | group C |
| C. | group A |
| D. | dorsal root |
| E. | somatic motor |
| Answer» B. group C | |
| 267. |
The chemical agent that initiates impulses in pain fibres is: |
| A. | ATP |
| B. | substance P |
| C. | Ca2+ |
| D. | H+ |
| E. | K+ |
| Answer» C. Ca2+ | |
| 268. |
Which is FALSE regarding secondary active transport? |
| A. | it always transports substances in one direction |
| B. | energy required is obtained by Na+ /K+ ATPase pump |
| C. | a good example is Na+ / glucose co-transport |
| D. | Na+ / Ca2+ antiport is an example of secondary active transport |
| E. | secondary active transport occurs in renal tubules |
| Answer» B. energy required is obtained by Na+ /K+ ATPase pump | |
| 269. |
Substance X is freely filtered by the glomerulus and is not reabsorbed, nor secreted nor metabolized.If - serum x concentration = 0.020 mg/mlrenal artery x concentration = 0.020 mg/mlrenal vein x concentration = 0.002 mg/mlurine x concentration = 14 mg/mlurine flow = 54 ml/hrlymphatic x concentration = 0.00001 mg/mlhaematocrit = 0.45The GFR is: |
| A. | 10.5 ml/min |
| B. | 700 ml/min |
| C. | 11.7 ml/min |
| D. | 630 ml/min |
| E. | 778 ml/min |
| Answer» E. 778 ml/min | |
| 270. |
With regard to diuretics: |
| A. | frusemide acts on the thick ascending limb of the loop of Henle |
| B. | antagonists to V2 vasopressin receptors act on the early portion of the distal convoluted tubule |
| C. | thiazides act primarily on the thick ascending limb of the loop of Henle |
| D. | loop diuretics act on the collecting ducts |
| E. | aldosterone antagonists act on the early portion of the distal convoluted tubule |
| Answer» B. antagonists to V2 vasopressin receptors act on the early portion of the distal convoluted tubule | |
| 271. |
Ethacrynic acid exerts its principle effect in the: |
| A. | proximal convoluted tubule |
| B. | descending loop of Henle |
| C. | thick ascending loop of Henle |
| D. | distal convoluted tubule |
| E. | collecting ducts |
| Answer» D. distal convoluted tubule | |
| 272. |
Renal acid secretion is enhanced by: |
| A. | respiratory acidosis |
| B. | respiratory alkalosis |
| C. | hyperkalaemia |
| D. | carbonic anhydrase inhibition |
| E. | collecting duct |
| Answer» B. respiratory alkalosis | |
| 273. |
What is the clearance of a substance when its concentration in plasma is 1mg/ml, its concentration in urine is 10mg/ml and the urine flow is 2ml/min |
| A. | 2ml/min |
| B. | 10ml/min |
| C. | 20ml/min |
| D. | 200ml/min |
| E. | clearance cannot be determined from the information given |
| Answer» D. 200ml/min | |
| 274. |
The Haldane effect describes: |
| A. | the shift to the right of the O2 dissociation curve caused by increased PCO2 |
| B. | the enhanced loading of CO2 iii the presence of deoxygenated Hb |
| C. | the shift of chloride ions into red blood cells to balance HCO3 shift from those cells |
| D. | the action of carbonic anhydrase on carbonic acid |
| E. | none of the above |
| Answer» C. the shift of chloride ions into red blood cells to balance HCO3 shift from those cells | |
| 275. |
If [urine]PAH = 14mg/ml, urine flow = 0.9ml/min and [plasma]PAH = 0.02mg/mli) What is the clearance of PAH?ii) If the extraction ratio of PAH is 0.9, what is the renal blood flow (Hct=45%)? |
| A. | ClPAH = 630, renal blood flow = 1273ml/min |
| B. | ClPAH = 630, renal blood flow = 700mb/min |
| C. | ClPAH = 77, renal blood flow = 155mb/min |
| D. | ClPAH = 777mb/min, renal blood flow = 1569mb/min |
| Answer» B. ClPAH = 630, renal blood flow = 700mb/min | |
| 276. |
What is the clearance of a substance when its concentration in plasma is 1mg/ml, its concentration in urine is 10mg/ml and the urine flow is 2ml/min? |
| A. | 2ml/min |
| B. | 10ml/min |
| C. | 20ml/min |
| D. | 200ml/min |
| E. | clearance cannot be determined from the information given |
| Answer» D. 200ml/min | |
| 277. |
What percentage of filtered sodium is reabsorbed by the kidney? |
| A. | 1% |
| B. | 93% |
| C. | 99% |
| D. | 50% |
| E. | 100% |
| Answer» D. 50% | |
| 278. |
Given that a person weighs 60kg and their haematocrit is 40%, their total blood volume is: |
| A. | 6L |
| B. | 5L |
| C. | 4L |
| D. | 3L |
| E. | cannot be calculated with the given information |
| Answer» C. 4L | |
| 279. |
The cortical portion of the collecting duct has the capacity to reabsorb approximately 10% of the filtered water. Which substance is most important in regulating this effect? |
| A. | angiotensin II |
| B. | histamine |
| C. | vasopressin |
| D. | sodium |
| E. | prostaglandins |
| Answer» D. sodium | |
| 280. |
The stretch reflex in skeletal muscle: |
| A. | is a feedback reflex aimed at maintaining muscle length |
| B. | is a polysynaptic reflex |
| C. | maintains muscle strength at various levels of muscle strength |
| D. | is not elicited in the knee jerk which occurs after tapping |
| E. | none of the above are true |
| Answer» B. is a polysynaptic reflex | |
| 281. |
Regarding excitation-contraction coupling in skeletal muscle, which statement is INCORRECT? |
| A. | calcium ions bind to troponin T |
| B. | troponin I tropomyosin complex constitutes a relaxing protein |
| C. | each cycle of attachment and detachment shortens muscle length by about 1% |
| D. | ATP is the immediate source of energy |
| E. | globular head of myosin II possesses actin binding site |
| Answer» B. troponin I tropomyosin complex constitutes a relaxing protein | |
| 282. |
Steps involved in skeletal muscle contraction include all of the following EXCEPT: |
| A. | binding of acetylcholine to nicotinic receptors |
| B. | increased Na+ and K+ conductance in end plate membrane |
| C. | spread of depolarisation along T tubules |
| D. | binding of calcium to troponin T, with uncovering of its actin-myosin binding site |
| E. | CTP (cytidine triphosphate) |
| Answer» F. | |
| 283. |
Chemical composition, which is TRUE? |
| A. | pH is the negative natural logarithm of [H+] |
| B. | pH 5 to pH 6 involves tenfold increase in [H+] |
| C. | pH remains 7.4 +/- 0.05 in ECF, stabilised by buffer |
| D. | H2O and CO2 H2CO3 H+ and HCO3-, adding H+ shifts the equilibrium to the right, while adding ??? shifts it to the left |
| E. | the Donnan effect does not contribute significantly to the balance of electrolyte between intra and extra vascular compartment |
| Answer» D. H2O and CO2 H2CO3 H+ and HCO3-, adding H+ shifts the equilibrium to the right, while adding ??? shifts it to the left | |
| 284. |
The role of calcium in excitation/contraction couple in skeletal muscle is: |
| A. | by binding troponin C it uncovers the binding site of actin to interact with the myosin head |
| B. | by binding troponin I, it uncovers the binding site of actin to interact with the myosin head |
| C. | by binding to tropomyosin, it allows troponic to bind to myosin |
| D. | by binding to troponin C, it allows the myosin head to disengage resulting in relaxation |
| E. | it causes depolarisation to spread along the tubules |
| Answer» B. by binding troponin I, it uncovers the binding site of actin to interact with the myosin head | |
| 285. |
Which glucose transporter is responsible for the facilitated diffusion of glucose into pancreatic B cells? |
| A. | glut 1 |
| B. | glut 2 |
| C. | glut 3 |
| D. | glut 4 |
| E. | glut 5 |
| Answer» C. glut 3 | |
| 286. |
Tetanic contraction of skeletal muscle: |
| A. | occurs because of the short refractory period of skeletal muscle |
| B. | is due to increased calcium available for binding to troponin C |
| C. | enables a tension development of approximately four times that of individual twitch contraction |
| D. | occurs only with isometric contractions |
| E. | has the same mechanism of that of cardiac muscle |
| Answer» D. occurs only with isometric contractions | |
| 287. |
Fick s Law of Diffusion is dependent on all EXCEPT |
| A. | The posture of the subject |
| B. | The solubility of the gas |
| C. | Thickness of membrane barrier |
| D. | Molecular weight of the gas |
| E. | Area of the membrane |
| Answer» B. The solubility of the gas | |
| 288. |
Regarding aldosterone, which statement is INCORRECT? |
| A. | it responds to changes in plasma sodium more strongly than changes in plasma potassium |
| B. | it is only synthesised in the zona glomerulosa of the adrenal cortex |
| C. | its main action is to increase the synthesis of sodium-potassium pumps |
| D. | angiotensins II and III have about equal mineralocorticoid stimulating activity |
| E. | it acts via a cytoplasmic receptor that has equal affinity for cortisol |
| Answer» B. it is only synthesised in the zona glomerulosa of the adrenal cortex | |
| 289. |
Thiazide diuretics exert their main effect in the: |
| A. | proximal convoluted tubule |
| B. | descending loop of Henle |
| C. | thick ascending loop of Henle |
| D. | distal convoluted tubule |
| E. | collecting ducts |
| Answer» E. collecting ducts | |
| 290. |
Aldosterone has its principle effect in the: |
| A. | proximal convoluted tubule |
| B. | descending loop of Henle |
| C. | thick ascending loop of Henle |
| D. | distal convoluted tubule |
| E. | collecting ducts |
| Answer» F. | |
| 291. |
Which of these is NOT a factor affecting acid secretion? |
| A. | intracellular PCO2 |
| B. | carbonic anhydrase level |
| C. | K+ concentration |
| D. | aldosterone concentration |
| E. | none of the above |
| Answer» F. | |
| 292. |
Diffusion is inversely proportional to: |
| A. | the diffusion constant |
| B. | tissue area |
| C. | solubility of the gas |
| D. | square root of the molecular weight |
| E. | the difference in partial pressure |
| Answer» E. the difference in partial pressure | |
| 293. |
The diffusion constant is proportional to: |
| A. | tissue thickness |
| B. | square root of the molecular weight |
| C. | difference in partial pressures |
| D. | tissue area |
| E. | gas solubility |
| Answer» F. | |
| 294. |
The visual cortex is situated at the: |
| A. | parieto-occipital sulcus |
| B. | cuneus |
| C. | calcanine fissure |
| D. | lateral geniculate body |
| E. | angular gyrus |
| Answer» E. angular gyrus | |
| 295. |
In the visual pathway: |
| A. | the lateral geniculate bodies are made up of t layers |
| B. | fibres for reflex pupillary constriction leave the optic nerve at the optic chiasm |
| C. | pituitary tumours can cause homonymous hemianopia |
| D. | macular sparing may or may not occur with lesions in the geniculocalcanine tract |
| E. | binasal visual field fibres decussate at the opticchiasm |
| Answer» E. binasal visual field fibres decussate at the opticchiasm | |
| 296. |
Which is the least significant buffering system in the blood? |
| A. | H+ + plasma protein HProt |
| B. | H+ +HPO4 2- H2PO4- |
| C. | H+ + HCO3 - H2CO3 |
| D. | H+ + Hb HHb |
| E. | collecting duct |
| Answer» C. H+ + HCO3 - H2CO3 | |
| 297. |
When a visual stimulus falls on a given point in the retina for a long time: |
| A. | the image becomes more clearly focused |
| B. | there is adaptation in the visual cortex |
| C. | the discharge rate in the bipolar cells increases |
| D. | the pupils constrict |
| E. | the image fades and disappears |
| Answer» B. there is adaptation in the visual cortex | |
| 298. |
Which of the following affect visual activity? |
| A. | cataracts |
| B. | vitamin A deficiency |
| C. | astigmatism |
| D. | contrast between stimulus and background |
| E. | all of the above |
| Answer» F. | |
| 299. |
Regarding body composition |
| A. | 18% body weight is protein / related substances |
| B. | 15% body weight is interstitial fluid |
| C. | 60% body weight is water |
| D. | 5% body weight is plasma |
| E. | All of the above are true |
| Answer» F. | |
| 300. |
Which statement regarding cardiac work is FALSE? |
| A. | the energy applied to the blood stream is defined as kinetic plus potential |
| B. | potential energy involves consideration of energy stored in elastic arterial walls and gravity |
| C. | there is an exchange between kinetic and potential energy |
| D. | the largest drop in energy occurs at the level of the precupillary sphincters |
| E. | the higher resistance in smaller calibre vessels corresponds to greater energy losses |
| Answer» E. the higher resistance in smaller calibre vessels corresponds to greater energy losses | |