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.
| 501. |
Normal values for renal function include all of the following EXCEPT: |
| A. | filtration fraction =0.2 |
| B. | 22% of cardiac output |
| C. | GFR = 180 litres/day |
| D. | RPF = 900 litres/day |
| E. | Tm glucose = 450 mg/minute |
| Answer» F. | |
| 502. |
When considering fluid balance, which of the following is INCORRECT? |
| A. | the minimum daily fluid output may normally be estimated by measuring the urine output and adding 500ml |
| B. | urine output is always the single largest contributor to fluid output |
| C. | fluid intake and output may be altered in response to a change in extracellular osmolarity |
| D. | fluid intake and output may be altered in response to a change in extracellular volume |
| E. | the hypothalamus is an important regulator of fluid intake |
| Answer» C. fluid intake and output may be altered in response to a change in extracellular osmolarity | |
| 503. |
Regarding heterotrimeric G proteins |
| A. | GDP is bound to the B subunit |
| B. | They are not serpentine receptors |
| C. | The delta unit separates from the other subunits to bring about the biological effect |
| D. | The intrinsic GTPase activity of the alpha subunit converts GTP to GDP |
| E. | They span the membrane seven times |
| Answer» F. | |
| 504. |
Erythropoietin: |
| A. | is produced in the juxtaglomerular cells of the kidney |
| B. | production is stimulated by theophylline |
| C. | secretion is facilitated by the acidosis that develops at high altitude |
| D. | has a half-life in the circulation of about 5 hours |
| E. | is produced predominantly in the spleen in neonates |
| Answer» E. is produced predominantly in the spleen in neonates | |
| 505. |
Normal urinary values include all of the following EXCEPT: |
| A. | albumin 150mg/day |
| B. | pH = 4.5 to 8.0 |
| C. | volume = 0.5 to 2.4 litres/day |
| D. | specific gravity = 1.010 to 1.035 |
| E. | osmolality = 3 to 1400 millismol/litres |
| Answer» B. pH = 4.5 to 8.0 | |
| 506. |
Regarding the function of the heart: |
| A. | at increased heart rates, diastole is shortened more than systole |
| B. | the pericardial sac normally contains about 50ml of fluid |
| C. | during the cardiac cycle, left ventricular ejection begins before right ventricular ejection |
| D. | during expiration, the aortic valve closes before the pulmonary valve |
| E. | the end diastolic ventricular volume is about 170ml |
| Answer» B. the pericardial sac normally contains about 50ml of fluid | |
| 507. |
Regarding gas exchange in the lungs: |
| A. | N2O is diffusion limited |
| B. | CO is perfusion limited |
| C. | O2 is between N2O and CO but at rest, is perfusion limited |
| D. | diffusing capacity of the lung for a gas is inversely proportionate to the surface area of the alveolocapillary membrane and directly proportional to its thickness |
| E. | at rest, it takes blood 0.25secs to traverse the pulmonary capillaries |
| Answer» D. diffusing capacity of the lung for a gas is inversely proportionate to the surface area of the alveolocapillary membrane and directly proportional to its thickness | |
| 508. |
The surface area of the lungs is: |
| A. | three times the area of skin |
| B. | ten times the area of skin |
| C. | 30 times the area of skin |
| D. | 100 times the area of skin |
| E. | none of the above |
| Answer» D. 100 times the area of skin | |
| 509. |
Inhibitory post synaptic potentials involve: |
| A. | localised increase in membrane permeability to Na+ |
| B. | localised decrease in membrane permeability to Cl- |
| C. | localised increase in membrane permeability to PO4 |
| D. | localised increase in membrane permeability to Cl- |
| E. | localised decrease in membrane permeability to K+ |
| Answer» E. localised decrease in membrane permeability to K+ | |
| 510. |
With regard to the effect of hormones on renal tubules, which is CORRECT? |
| A. | aldosterone increases K reabsorption from the distal tubule |
| B. | angiotensin II increases H+ secretion from the proximal tubules |
| C. | ADH increases water reabsorption in the proximal tubule |
| D. | atrial naturetic peptide decreases Na+ reabsorption from the proximal tubules |
| E. | parathyroid hormone increases phosphate reabsorption |
| Answer» C. ADH increases water reabsorption in the proximal tubule | |
| 511. |
With regard to the normal Hb-ox-y-en dissociation curve, which is the most likely to be CORRECT? |
| A. | when arterial PO2 = 60mmHg, Hb saturation is 80% |
| B. | when arterial PO2 = 40mmHg, Hb saturation is 75% |
| C. | when arterial PO2 = 30mmHg, Hb saturation is 40% |
| D. | acidosis shifts the curve to the left |
| E. | decreased PCO2 shifts the curve to the right |
| Answer» C. when arterial PO2 = 30mmHg, Hb saturation is 40% | |
| 512. |
With regard to CO2 carriage in the blood: |
| A. | dissolved CO2 has an insignificant role in the carriage of CO2 in the blood |
| B. | HCO3 production is fast in plasma |
| C. | ionic dissociation of carbonic acid in the red cell is fast without an enzyme |
| D. | the CO2 concentration in blood is independent of the saturation of haemoglobin with oxygen |
| E. | the majority of CO2 is carried in the blood in the forms of dissolved CO2 and carbamino-compounds |
| Answer» D. the CO2 concentration in blood is independent of the saturation of haemoglobin with oxygen | |
| 513. |
Regarding the vomiting reflex, which is INCORRECT? |
| A. | it is integrated by the medilla |
| B. | breath is held in expiration |
| C. | the glottis closes |
| D. | it involves salivation |
| E. | there are afferents from vestibular nuclei |
| Answer» C. the glottis closes | |
| 514. |
Which drug is NOT involved in facilitating Cl- conductance? |
| A. | benzodiazepines |
| B. | progesterone |
| C. | oestrogen |
| D. | barbiturates |
| E. | alcohol |
| Answer» D. barbiturates | |
| 515. |
Which of the following does NOT increases synthesis of 2, 3-DPG? |
| A. | growth hormone |
| B. | phosphate deficiency |
| C. | thyroid hormone |
| D. | exercise for one hour |
| E. | androgens |
| Answer» C. thyroid hormone | |
| 516. |
With respect to the EEG and brain wave activity which is FALSE? |
| A. | the rhythm (adults) has a frequency of 18-30/second |
| B. | infants have a faster rhythm than adults |
| C. | the frequency of the rhythm can be decreased with hypoglycaemia, hypothermia and increased ??? |
| D. | young adult 25% sleep is REM sleep |
| E. | REM sleep is characterised by no muscle tone, but increased extraocular movement |
| Answer» C. the frequency of the rhythm can be decreased with hypoglycaemia, hypothermia and increased ??? | |
| 517. |
All of the following are features of acclimatisation to high altitude EXCEPT: |
| A. | shift to the right of the oxygen dissociation curve |
| B. | increased number of capillaries in peripheral tissues |
| C. | pulmonary vasodilation |
| D. | polycythaemia |
| E. | increased maximum breathing capacity |
| Answer» D. polycythaemia | |
| 518. |
Considering conduction rates in myocardial cells, which statement is TRUE? |
| A. | Perkinje fibres are subepicardial and are the largest fibres, 4-7 times the width of other fibres |
| B. | Perkinje fibres are fast fibres , and can conduct a wave of depolarisation at a speed of 4m/sec |
| C. | the duration of the action potential and refractory period in fast fibres is shorter than slow fibres |
| D. | initial depolarisation occurs in fast fibres with a rapid influx of Ca2+ ions from the sarcoplasmic reticulum |
| E. | none of the above statements are true |
| Answer» C. the duration of the action potential and refractory period in fast fibres is shorter than slow fibres | |
| 519. |
Regarding the heart, which is TRUE? |
| A. | the right and left ventricles perform the same amount of work, because the same volume of blood is pumped by each |
| B. | the cross sectional shape of both ventricles is approximately cylindrical |
| C. | the right ventricle pumps by a bellows type mechanism |
| D. | the left ventricle pump action is via reducing cross-sectional area, as a function of radius cubed |
| E. | in pulmonary disease the right ventricle hypertrophies and assumes a crescented shape in cross section |
| Answer» D. the left ventricle pump action is via reducing cross-sectional area, as a function of radius cubed | |
| 520. |
Regarding buffers in the body |
| A. | Initial correction of pH disturbance is achieved by the kidneys |
| B. | The phosphate buffer system is the predominant buffer in the blood |
| C. | Bones contribute to buffering by taking up bicarbonate |
| D. | Hb is an important buffer in the blood |
| E. | All of the above are true |
| Answer» E. All of the above are true | |
| 521. |
Regarding the neural control of breathing, which statement is INCORRECT? |
| A. | medullary centres are close to but separate from central chemoreceptors |
| B. | during quiet respiration, expiration is a passive event |
| C. | inspiratory medullary neurons supply both phrenic nerves |
| D. | ventral medullary neurons are expiratory and do not discharge spontaneously |
| E. | inspiratory medullary neurons discharge spontaneously at a rate of 12-15 times/minute |
| Answer» E. inspiratory medullary neurons discharge spontaneously at a rate of 12-15 times/minute | |
| 522. |
Which of the following statements regarding erythropoietin is INCORRECT in an adult? |
| A. | half-life of about 5 hours |
| B. | hypoxia can increase secretion within minutes |
| C. | is secreted by spleen and salivary glands |
| D. | is secreted in adequate amounts by liver in absence of kidneys |
| E. | is a glycoprotein |
| Answer» E. is a glycoprotein | |
| 523. |
Regarding body fluid compartments |
| A. | About 2/3 TBW is extracellular |
| B. | ECF / intracellular fluid volume ratio is larger in infants than in adults |
| C. | Plasma volume in a 70 kg male is approximately 5 litres |
| D. | A 30 year old male has 40% water as a percentage of body weight |
| E. | Transcellular fluid has a greater volume than intracellular fluids |
| Answer» C. Plasma volume in a 70 kg male is approximately 5 litres | |
| 524. |
Which factor increases renal blood flow? |
| A. | 1 adrenergic stimulation |
| B. | 2 adrenergic stimulation |
| C. | reduced systemic blood pressure |
| D. | exercise |
| E. | lying down |
| Answer» F. | |
| 525. |
Coronary circulation: |
| A. | left coronary artery has greater flow in 50% of people |
| B. | thebesian veins connect arterioles to the heart chambers |
| C. | cusps of the aortic valve occlude orifices of coronary arteries during LV ejection |
| D. | coronary flow at rest is 250ml/min |
| E. | at rest, heart extracts 50% O2 / unit of blood delivered |
| Answer» E. at rest, heart extracts 50% O2 / unit of blood delivered | |
| 526. |
Which of the following is inhibitory neurotransmitter? |
| A. | gallamine |
| B. | acetylcholine |
| C. | glutamate |
| D. | glycine |
| E. | aspartate |
| Answer» E. aspartate | |
| 527. |
Substances cleared from the circulation by the lungs include all the following EXCEPT: |
| A. | angiotensin H |
| B. | serotonin |
| C. | leukotrienes |
| D. | bradykinin |
| E. | prostaglandin |
| Answer» B. serotonin | |
| 528. |
Hypoxia at high altitudes: |
| A. | is a form of stagnant hypoxia |
| B. | causes symptoms of cyanosis |
| C. | causes severe symptoms in an unacclimatised person at 3,000m |
| D. | can always be reversed with 100% O2 |
| E. | increased H+ concentration |
| Answer» C. causes severe symptoms in an unacclimatised person at 3,000m | |
| 529. |
With regard to the metabolism of carbohydrates: |
| A. | in the absence of liver glycogen stores, glycogen administration does not cause hyperglycaemia |
| B. | glucocorticoids have a minor effect on gluconeogenesis |
| C. | growth hormone causes increased use of glucose for energy |
| D. | glucose is absorbed by most cells by active sodium glucose co-transport |
| E. | during starvation, stores last for less than 24 hours |
| Answer» F. | |
| 530. |
With regard to lipid metabolism: |
| A. | only HDL is formed in the liver |
| B. | fatty acids in the plasma form 1:1 complexes with albumin |
| C. | plasma cholesterol levels rise considerably with an increase in daily ingestion |
| D. | free fatty acids are metabolised in preference to glucose in a non-exercising individual |
| E. | utilisation of fatty acids is stimulated by glucocorticoids |
| Answer» F. | |
| 531. |
In regard to pH |
| A. | pH of a solution is the log to base 10 of the reciprocal hydrogen ion concentration |
| B. | Is the negative log of the concentration of hydrogen ions |
| C. | For each pH unit less than 7 the concentration of hydrogen ion is increased 10 fold |
| D. | A pH of 7 is equal to a hydrogen ion concentration of 10-7 mmol/l |
| E. | All of the above are true |
| Answer» F. | |
| 532. |
With respect to protein synthesis: |
| A. | each amino acid found in human protein has its own individual single transfer RNA |
| B. | pre mRNA processing occurs in the cytoplasm prior to binding to ribosomes on the endoplasmic retic??? |
| C. | each gene has regulatory, promoter, coding and non coding regions which are all transcribed into pre mRNA |
| D. | introns no recognised physiological function |
| E. | the promoter site of a gene is the site where RNA polymerase binds |
| Answer» F. | |
| 533. |
With respect to the loop of Henle: |
| A. | the ascending limb is highly permeable to water |
| B. | the descending limb is impermeable to water |
| C. | the thick ascending limb co-transports sodium, potassium and chloride out of the lumen |
| D. | tubular fluid becomes concentrated as it passes through the ascending limb |
| E. | the ascending limb removes approximately 15% of filtered water |
| Answer» D. tubular fluid becomes concentrated as it passes through the ascending limb | |
| 534. |
Renal blood pressure: |
| A. | the pressure drop across the glomerulus is about 20mmHg |
| B. | pressure in the renal vein is about 15mmHg |
| C. | the glomerular capillary pressure is about 80% that of arterial |
| D. | the greatest drop in pressure (percentage wise) is from the efferent arteriole to the peritubular capillary |
| Answer» E. | |
| 535. |
Which of the following is NOT involved in the control of ventilation? |
| A. | peripheral chemoreceptors |
| B. | lung stretch receptors |
| C. | basal ganglia |
| D. | pons |
| E. | respiratory muscles |
| Answer» D. pons | |
| 536. |
Regarding movement to high altitude, which statement is INCORRECT? |
| A. | hyperventilation occurs due to hypoxic stimulation of peripheral chemoreceptors |
| B. | pro-erythroblasts mature into erythrocytes more rapidly than normal |
| C. | renal bicarbonate excretion increases |
| D. | increased numbers of mitochondria appear in the tissues |
| E. | FiO2 decreases with increasing altitude |
| Answer» F. | |
| 537. |
For transmembrane movement, which is TRUE? |
| A. | exocytosis requires Ca2+ and energy |
| B. | Na+ -K+ -ATPase is an example of facilitated diffusion |
| C. | amiloride activates epithelial Na+ channels |
| D. | clathrin is essential for vesicle exocytosis |
| E. | water can only enter cells via water channels |
| Answer» B. Na+ -K+ -ATPase is an example of facilitated diffusion | |
| 538. |
The righting reflex is pronounced after sectioning of the neural axis above which level: |
| A. | spinal cord |
| B. | medulla |
| C. | mid-brain |
| D. | subcortical nuclei |
| E. | all above intact but decerebellate |
| Answer» D. subcortical nuclei | |
| 539. |
In a polysynaptic reflex, which of the following happen when the strength of the adequate stimulus is increased? |
| A. | the amplitude of the motor response is increased |
| B. | the motor response spreads to include other muscles and even other limbs |
| C. | there is increased inhibition of stretch reflexes |
| D. | the duration of the motor response increases |
| E. | all of the above are true |
| Answer» B. the motor response spreads to include other muscles and even other limbs | |
| 540. |
Regarding muscle spindles: |
| A. | are composed of extrafusal fibres |
| B. | receive efferents |
| C. | all subtypes send afferents via flower spray ended 1a nerves |
| D. | nuclear chain fibres show dynamic response |
| E. | afferent discharge decreased with muscle stretch |
| Answer» C. all subtypes send afferents via flower spray ended 1a nerves | |
| 541. |
Regulation of renal blood flow which is FALSE? |
| A. | angiotensin II constricts the afferent arteriole and efferent arteriole |
| B. | noradrenaline constricts intertubular arteries and afferent arterioles |
| C. | dopamine causes vasodilation in renal vessels and natriuresis |
| D. | ACh renal vasodilation |
| E. | prostaglandins increase blood flow to the cortex and decrease it in the medulla |
| Answer» B. noradrenaline constricts intertubular arteries and afferent arterioles | |
| 542. |
Regarding body temperature: |
| A. | humans are poikilothermic |
| B. | oral temperature is usually higher than rectal temperature |
| C. | it is usually lowest at 6am |
| D. | children have more precise temperature regulation |
| E. | emotion has no effect on core temperature |
| Answer» F. | |
| 543. |
The tympanic reflex : |
| A. | is activated by foreign bodies in the external auditory canal |
| B. | results in vertigo |
| C. | is activated by high-pitched sounds only |
| D. | results in the decreased transmission of sound |
| E. | none of the above |
| Answer» E. none of the above | |
| 544. |
Regarding compliance, which statement is INCORRECT? |
| A. | functional residual capacity is the equilibrium volume when elastic recoil of lung is balanced by normal tendency for chest wall to spring out |
| B. | hysteresis is due to frictional resistance to air movement |
| C. | compliance is greater in expiration than in inspiration |
| D. | compliance is increased in emphysema |
| E. | compliance is a dynamic measure of lung and chest wall recoil |
| Answer» F. | |
| 545. |
The neurotransmitter secreted by primary afferent fibres for severe pain is: |
| A. | glutamate |
| B. | acetylcholine |
| C. | substance P |
| D. | opioid peptides |
| E. | noradrenaline |
| Answer» E. noradrenaline | |
| 546. |
Temperature sensation: |
| A. | respond to compartitive temp gradient ??? skin |
| B. | cold receptors predominate |
| C. | warm receptors respond 30 - 100 |
| D. | afferents carried via the dorsal column |
| E. | warm and cold afferents carried via Ad fibre |
| Answer» C. warm receptors respond 30 - 100 | |
| 547. |
The stretch reflex: |
| A. | is classically initiated by tapping on the quadriceps muscle |
| B. | is initiated by stretch of the muscle |
| C. | involves impulses being conducted from the muscle spindle to the motor cortex |
| D. | involves extrafusal fibres stimulating annulospiral and flowerspray sensory fibres |
| E. | involves gamma afferents of leksell |
| Answer» C. involves impulses being conducted from the muscle spindle to the motor cortex | |
| 548. |
With regard to ascending to high altitudes: |
| A. | there is a linear decrease in inspired oxygen pressures with increasing altitude |
| B. | the partial pressure of water vapour in moist inspired air decreases with PiO2 |
| C. | at 19,200m, barometric pressure = 47mmHg, PiO2 then is approx 9mmHg |
| D. | at peak at Mt Everest, barometric pressure = 380mmHg, PiO2 is approx 70mmHg |
| E. | in permanent residents of the Andes, arterial and venous PO2 is half normal levels |
| Answer» E. in permanent residents of the Andes, arterial and venous PO2 is half normal levels | |
| 549. |
The thick ascending limb of the loop of Henle: |
| A. | is impermeable to water |
| B. | has maximal permeability to NaCl |
| C. | is relatively permeable to water |
| D. | is impermeable to NaCl |
| E. | is a site where there is no active transport of sodium |
| Answer» B. has maximal permeability to NaCl | |
| 550. |
The thin ascending loop of Henle is: |
| A. | relatively permeable to water |
| B. | relatively impermeable to sodium ion |
| C. | permeable to both water and sodium ion |
| D. | relatively impermeable to water |
| E. | relatively impermeable to both water and sodium ion |
| Answer» E. relatively impermeable to both water and sodium ion | |