GENERAL PHYSIOLOGY | Multiple-Choice Questions in Medical Physiology | mcqs


In each of the following questions, select the

single best response unless instructed otherwise.

1.         The water content of lean body mass is about: A. 30 ml/100 g

B. 50 ml/100 g

C. 70 ml/100 g

D. highly variable

2.         Body mass index is calculated as:

A.        weight in pounds by height in meters

B.         weight in kg by height in meters

C.         weight in kg divided by square of height in meter squared

D.        weight in kg divided by body surface area

3.         The most abundant cation in ICF is

A.        Sodium

B.         Potassium

C.         Magnesium

D.        Calcium

4.         The most abundant anion in ECF is

A.        bicarbonate

B.         chloride

C.         phosphate

D.        protein anion

5.         ECF volume is determined by:

A.        plasma [Na]

B.         plasma protein concentration

C.         the amount of sodium in the ECF

6.         The body fluid compartment that contains more osmotically active particles (in relation to other fluid compartments in the same individual) is:

A.        intracellular fluid

B.         plasma

C.         interstitial fluid

7.         The following values are obtained on a sample of serum from a child that has clinical evidence of dehydration.

Serum [Na] = 135 mmol/L Serum [glucose] = 540 mg/dL

Serum [urea nitrogen] = 56 mg/dL

The osmolality of serum is expected to be close to:

A.        290 mOsm/kg H2O

B.         300 mOsm/kg H2O

C.         310 mOsm/ kg H2O

D.        320 mOsm/kg H2O

E.         330 mOsm/kg H2O

8.         The following values are obtained on a sample of serum from a child that has clinical evidence of dehydration.

Serum [Na] = 130 mmol/L Serum [glucose] = 540 mg/dL

Serum [urea nitrogen] = 56 mg/dL

Assuming there are no toxins in ECF, the effective serum osmolality is approximately:

A.        290 mOsm/kg H2O

B.         300 mOsm/kg H2O

C.         310 mOsm/ kg H2O

D.        320 mOsm/kg H2O

E.         330 mOsm/kg H2O

9.         What percentage of osmolality of plasma in a healthy, well hydrated individual is attributable to sodium and its accompanying anions?

A. 30 %

B.  50 %

C.  70 %

D. 90 %

10.       Which of the following contributes least to the osmolality of plasma?

A.        Glucose

B.         Proteins

C.         Sodium

D.        Urea

11.       The osmolar concentration of sodium in normal human plasma is approximately:

A. 275 – 295 mOsm/L

B. 135 – 145 mOsm/L

C. 240 – 250 mOsm/L

D. 95 – 110 mOsm/L

12.       In the steady state, the value of which of the following variables is the same in ICF and ECF?

A.        pH

B.         Osmolality

C.         Concentration of proteins

D.        Number of osmoles

13.       Which compartment does the term “sucrose space” refer to?

A.        Extracellular fluid (ECF)

B.         Interstitial fluid (ISF)

C.         Intracellular fluid (ICF)

D.        Plasma

14.       The volume of distribution of intravenously administered sucrose in a healthy well hydrated 70-kg man is about:

A.        3.5 liters

B.         10.5 liters

C.         14 liters

D.        28 liters

15.       In a healthy adult, ECF volume constitutes what fraction of body weight?

A. 10%

B. 20%

C. 30%

D. 40%

16.       In a healthy adult male weighing 70 kg, the total volume of fluid present in the transcellular compartment does not normally exceed:

A.        1 liter

B.         3 liters

C.         5 liters

D.        7 liters

17.       Which of the following markers administered intravenously distributes exclusively in intracellular fluid?

A.        Evans blue dye

B.         Heavy water

C.         Sucrose

D.        None of the above

18.       Which of the following substances can be used as a marker for the ECF compartment?

A.        Nonmetabolizable sugars

B.         Glucose

C.         Radio-iodinated albumin

D.        D2O

19.       Which of the following markers is incorrectly

matched with its volume of distribution?

A.        Antipyrine – total body water

B.         Inulin – ECF volume

C.         Evans blue – plasma volume

D.        I125 albumin – blood volume

20.       100 mg of sucrose is injected intravenously into an adult male weighing 70 kg. The plasma concentration of sucrose after mixing is 0.01 mg/ml. If 5 mg of sucrose has been metabolized during this period, the ECF volume in this individual is approximately:

A.        6 liters

B.         9.5 liters

C.         14 liters

D.        17.5 liters

21.       A known amount of heavy water and inulin are injected intravenously into a healthy 35 year old male. The volume of distribution of heavy water and inulin were 36 liters and 12 liters respectively. Which of the following estimations is most likely?

A.        Plasma volume is 6 liters.

B.         Interstitial fluid volume is 6 liters.

C.         ICF volume is 28 liters.

D.        ECF volume is 12 liters.

22.       In a healthy adult weighing 70 kg, plasma volume was estimated to be 3000 ml. His hematocrit was 40%. His blood volume is approximately:

A.        5000 ml

B.         5200 ml

C.         5400 ml

D.        5600 ml

23.       What fraction of total body potassium is present in plasma?

A. 0.4%

B. 8.2%

C. 12%

D. 88%

24.       A substance injected intravenously was found to be distributed through 35% of total body water. Which of the following is most likely?

A.        It did not pass through blood capillaries.

B.         It entered neurons and cerebral ventricles.

C.         It did not enter cells.

D.        It was excluded from ‘third spaces’.

25.       Of the following substances, the lipid bilayer per se (i.e., without proteins) is most permeable to:

A.        sodium ions

B.         urea

C.         glucose

D.        water

26.       Red blood cells from a healthy individual were placed in each of the following solutions and observations were made after 1 hour. Cells would have most likely have lysed when placed in:

A.        0.3% NaCl

B.         0.9% NaCl

C.         1.2% NaCl

27.       Which of the following solutions is hypertonic?

A.        0.9 % NaCl

B.         5% dextrose

C.         20% mannitol

D.        Distilled water

28.       The volume of RBC placed in a NaCl solution with an osmolality of 280 mOsm/Kg H2O is 100 femtoliters. What will be the steady state volume when they are placed in a NaCl solution with an osmolality of 350 mOsm/Kg H2O?

A.        120 fL

B.         80 fL

C.         50 fL

D.        Data inadequate

29.       ICF volume does not change when dehydration is:

A.        isotonic

B.         hypertonic

C.         hypotonic

30.       Two liters of 0.9% NaCl is administered to a 12-year old boy with moderate isotonic dehydration. What is the expected change in ICF volume after NaCl administration?

A.        No change

B.         Increase by 0.5 liter

C.         Increase by 2 liters

D.        Decrease by 0.5 liter

E.         Decrease by 2 liters

31.       ICF volume decreases when dehydration is:

A.        isotonic

B.         hypertonic

C.         hypotonic

32.       If the intent is to replenish total body water in a dehydrated individual which of the following should be administered intravenously?

A.        0.9% NaCl

B.         5% dextrose solution

C.         Albumin

D.        10% glucose solution

E.         Distilled water

33.       Cell volume and pressure is mainly dependent upon activity of:

A.        Na glucose cotransporter

B.         Na-K pump

C.         glucose transporter

D.        Na-Ca exchanger

34.       Which of the following exerts the greatest osmotic effect across capillaries on a mole-mole basis?

A.        Sodium

B.         Chloride

C.         Dextran

D.        Hydroxyethyl starch

E.         Albumin

F.         Fibrinogen

35.       The rate of diffusion of a substance across the cell membrane is inversely proportional to:

A.        concentration gradient for the substance

B.         diffusion coefficient

C.         surface area available for diffusion

D.        thickness of the membrane

36.       Which of the following modes of transport across the cell membrane is quantitatively more important for flux of ions?

A.        Diffusion

B.         Filtration

C.         Vesicular transport

37.       Amongst plasma proteins, albumin makes the greatest contribution to the colloid osmotic pressure of plasma proteins because, relative to most plasma proteins, albumin:

A.        is the most abundant plasma protein

B.         has the longest half-life

C.         has the lowest molar mass

D.        exits the capillary fastest

38.       Osmotic pressure of crystalloids is not included in the Starling’s equation describing fluid exchange across capillaries because:

A.        they were discovered after Starling described the forces

B.         crystalloids carry electric charges

C.         crystalloids diffuse freely across the capillary endothelium

D.        the quantity of crystalloids in plasma is negligible compared to plasma proteins

39.       The term oncotic pressure is applied to osmotic pressure exerted by:

A.        albumin and other plasma proteins across the capillary wall

B.         crystalloids across the cell membrane

C.         hemoglobin across the capillary wall

D.        substances such as urea, lactate, glucose across the cell membrane

40.       Which of the following is matched


A.        Microfilaments: actin, myosin

B.         Intermediate filaments: vimentin, keratin

C.         Microtubules: clathrin

D.        Cytoskeleton: spectrin, ankyrin

41.       The mitotic spindle is made up of a protein called:

A.        tubulin

B.         caveolin

C.         connexin

D.        annexin

42.       The mitochondrial genome is absent from:

A.        sperm cells

B.         ovum

C.         mature red blood cells

D.        white blood cells

43.       Cytosolic calcium concentration in unexcited cells is about:

A.        2.5 mM

B.         10 mM

C.         150 µM

D.        100 nM

44.       Most of the calcium in the endoplasmic reticulum is sequestered by:

A.        calmodulin

B.         caldesmin

C.         calbindin

D.        calsequestrin

45.       Which of the following statements regarding regulation of cell cycle is incorrect?

A.        This serves to regulate transition of the cell from one phase of the cell cycle to the next.

B.         At restriction points, cyclins always promote transition from G0 to S phase.

C.         Defects in DNA synthesis normally allow progression from G2 to M phase.

D.        Deficiency of p53 allows progression to M phase.

46.       Which of the following is an example of primary active transport?

A.        Ca extrusion from cells by the Na-Ca exchanger

B.         Glucose entry into cells through glucose transporter 2 (GLUT-2)

C.         H2O flux across cell membranes through aquaporins

D.        Glucose uptake into intestinal epithelial cells by Na-glucose cotransporter 1 (SGLT-1)

E.         Ca sequestration in sarcoplasmic reticulum by Ca-ATPase

47.       Sodium-glucose cotransport in the intestine and kidney is an example of:

A.        primary active transport

B.         secondary active transport

C.         facilitated diffusion

D.        passive transport

48.       Which of the following is / are active transport processes? (Select all correct answers).

A.        Extrusion of calcium into ECF

B.         Efflux of K during repolarization

C.         Entry of chloride into neurons

D.        Transcytosis (vesicular transport)

49.       Which of the following processes is ATP dependent? (Select all correct answers).

A.        Acidification of lysosomes

B.         Actin-myosin cross bridge cycling

C.         Exocytosis

D.        Micropinocytosis

50.       Which of the following transport processes is mediated by a carrier protein in the plasma membrane? (Select all correct answers).

A.        Glucose uptake through SGLT-1

B.         Na influx through Na channels

C.         Na-K ATPase

D.        Water fluxes through aquaporins

51.       Which of the following processes does not

exhibit ‘saturation kinetics’?

A.        Facilitated diffusion

B.         Na+-Ca2+ exchanger

C.         Simple diffusion

D.        Na+ coupled active transport

52.       Na-K-2Cl transporter in the apical membrane of the thick ascending limb of the loop of Henle is an example of:

A.        primary active transport

B.         secondary active transport

C.         passive transport

D.        countertransport

53.       Which of the following is an example of passive transport?

A.        Calcium efflux by calcium pump

B.         Na-Ca exchanger

C.         Potassium efflux through potassium leak channels

D.        Calcium sequestration in sarcoplasmic reticulum

54.       Which of the following ions is not transported across the cell membrane by a primary active transport mechanism?

A.        Na

B.         Cl

C.         K

D.        Ca

55.       Figures A and B given below depict the relationship between transport rates (in Y-axis, in arbitrary units) and concentration gradients (in X- axis, in arbitrary units) of two substances A and B respectively.

Fig A    Fig B

Which of the following statements is correct?

A.        B is transported by facilitated diffusion

B.         Transport of B is ATP dependent

C.         There is a ‘transport maximum’ for B

D.        Substance A would move in one direction only

56.       Emiocytosis requires an increase in the intracellular concentration of:

A.        Na

B.         K

C.         Ca

D.        Cl

57.       How many transmembrane domains do G- protein coupled receptors have?

A.        2

B.         3

C.         7

D.        12

58.       How many subunits do G proteins have?

A.        One

B.         Two

C.         Three

D.        Four

59.       Which G protein activates adenylyl cyclase?

A.        Gs

B.         Gq

C.         Gi

D.        Gl

60.       Which subunit of G proteins has intrinsic GTPase activity?

A.        Alpha

B.         Beta

C.         Gamma

D.        Delta

61.       Which of the following hormones does not act via a G-protein coupled receptor in the cell membrane?

A.        Thyrotropin releasing hormone

B.         Angiotensin II

C.         Antidiuretic hormone

D.        Thyroxine

62.       Which toxin inhibits the function of Gi?

A.        Cholera toxin

B.         Pertussis toxin

C.         Forskolin

D.        Saxitoxin

63.       Which receptor does not span the cell membrane seven times?

A.        Rhodopsin

B.         Beta-adrenergic receptor

C.         Insulin receptor

D.        M2 receptor

64.       The second messengers in the phosphatidyl inositol cascade are:

A.        IP3, DAG and calcium

B.         protein kinases A (PKA) and C

C.         cAMP and cAMP dependent PKA

D.        cGMP and calcium

65.       Which of the following stimulates the release of calcium from the endoplasmic reticulum?

A.        IP3

B.         PTH

C. 1, 25 (OH)2 D3


66.       Protein kinase C is activated by:

A.        IP3

B.         diacylglycerol (DAG)

C.         cAMP

D.        guanylyl cyclase

67.       Which of the following is not a second messenger in a signal transduction pathway?

A.        cAMP

B.         Guanylyl cyclase

C.         Inositol trisphosphate

D.        Diacyclglycerol

E.         Steroid hormone – receptor complex

68.       The smooth muscle relaxing effects of endothelium derived relaxing factor nitric oxide are mediated by an increase in intracellular level of:

A.        cAMP

B.         cGMP

C.         calcium

D.        endothelin

69.       Which of the following hormones or growth factors does not signal via receptor tyrosine kinases?

A.        Insulin

B.         ANP

C.         Epidermal growth factor

D.        Platelet derived growth factor

70.       Guanylyl cyclases are activated by:

A.        CO, NO and ANP

B.         NO, ANP and ET1

C.         AII, NO and ANP

D.        ANP, ET1 and AII

71.       Which of the following hormone(s) mediate(s) its effects by activating nuclear / cytosolic receptors? (Select all correct answers).

A.        Thyroxine

B.         Retinoic acid

C.         Estradiol

D.        Progesterone

E.         Aldosterone

F.         Cortisol

G. 1, 25 (OH)2 D3

72.       Which intercellular junctions directly allow the passage of small molecules and ions between the cytosol of one cell and its neighbor without movement into interstitial fluid?

A.        Gap junctions

B.         Focal adhesions

C.         Zonula occludens

D.        Desmosomes

73.       Gap junctions are made up of a protein called:

A.        connexin

B.         clathrin

C.         cadherin

D.        calcineurin

74.       Connexins do not allow the passage of:

A.        polypeptides

B.         Na ions

C.         Ca ions

D.        inositol trisphosphate

E.         amino acids

75.       The philosophy that all vital mechanisms are directed toward maintaining constancy of composition of the internal environment and that this is necessary for the sustenance of life was first propounded by:

A.        Claude Bernard

B.         Walter B Cannon

C.         William Harvey

D.        Alan Hodgkin

76.       The term ‘homeostasis’ was coined by:

A.        Claude Bernard

B.         Walter B Cannon

C.         Homer Smith

D.        William Harvey

77.       The core body temperature of an experimental animal is raised from 98ºF to 106ºF by passive heating. Eventually, it dropped to 99ºF. What is the gain of the temperature regulation system in this instance?

A.        Zero

B.         One

C.         -7

D.        Infinity

78.       Which of the following statements about negative feedback control systems is incorrect?

A.        Output is one of the inputs to the system.

B.         It is based on a ‘set-point’ for the controlled variable.

C.         The system corrects “errors”.

D.        The ‘set point’ of the system cannot be changed by inputs other than the controlled variable.

79.       The SI unit of pressure is:

A.        mm Hg

B.         cm H2O

C.         Pascal

D.        Torr

80.       The diameter of a red blood cell is approximately:

A. 7 × 10-3 m

B. 7 × 10-6 m

C. 7 × 10-9 m

D. 7 × 10-10 m

81.       The volume of a red blood cell is approximately:

A.        8 × 10-10 liter

B.         80 cubic microliter

C.         85 microns

D.        90 femtoliter

82.       Which of the following quantities is dimensionless?

A.        Specific gravity of plasma

B.         Osmolality of urine

C.         Resistance to air flow

D.        Ejection fraction

E.         Filtration fraction

F.         Diffusion coefficient

83.       If an individual is breathing 15 times per minute, respiratory frequency is approximately:

A.        0.1 Hz

B.         0.15 Hz

C.         0.2 Hz

D.        0.25 Hz

E.         0.3 Hz

84.       If intracellular and extracellular calcium are 2 millimoles per liter and 100 nanomoles per liter, the ratio of intracellular and extracellular calcium is approximately:

A. 200

B. 2000

C. 20000

D. 200000

85.       The mass of 1 mole of potassium is 39 g. If the potassium chloride concentration of a solution is 39 mg %, the concentration of potassium in this solution is closest to:

A.        1 mmol/L

B.         3.9 mmol/L

C.         10 mmol/L

D.        100 mmol/L

86.       If the pH of a urine sample is 5.4, and the pH of arterial plasma is 7.4, the ratio of concentration of hydrogen ions in the urine sample and plasma is approximately:

A. 0.8

B. 2

C. 10

D. 100

87.       What is the ratio of the concentration of hydrogen ions in gastric juice (pH 1.4) and arterial plasma (pH 7.4)?

A. 103

B. 104

C. 105

D. 106

88.       The [H+] of arterial plasma is normally about:

A.        20 nmol/L

B.         30 nmol/L

C.         40 nmol/L

D.        50 nmol/L

89.       In each of the options below, [H+] is expressed in nanomoles/L, PaCO2 is in mm Hg and [HCO3] in mmol/L. Which of the following is true?

A.        PaCO2 = [H+] × [HCO3]

B. [H+] = 24 [PaCO2] / [HCO3]

90.       Normally, the ratio of PaCO2 and plasma HCO3 is:

A. 1.2

B.  1.4

C.  1.6

D. 1.8

91.       The Henderson-Hasselbalch equation states that when a buffer acid is half dissociated the pH of the solution is equal to:

A.        pKa

B. 7.0

C. 2 pKa

D. 0.5 pKa

92.       A buffer is most effective when the pH of the solution is close to:

A.        0.5 pKa

B.         pKa

C.         2 pKa

93.       The most abundant protein in mammalian cells is:

A.        actin

B.         collagen

C.         titin

D.        dystrophin

94.       The diameter of which of the following cytoskeletal components is the least?

A.        Microfilaments

B.         Intermediate filaments

C.         Microtubules

95.       Which of the following is an example of a ligand-gated ion channel?

A.        Nicotinic Ach receptor (nAchR)

B.         Beta-2 adrenergic receptor

C.         5 HT receptor

D.        Histamine 2 receptor

96.       Which of the following is an example of juxtacrine communication?

A.        Cell-cell anchors caused by interactions between TGF and TGF receptors on adjacent cells

B.         Passage of ions and small molecules between the cytosols of adjacent cells through connexons.

C.         Attachment of cell membrane to basal lamina via integrins.

97.       We speak of second messengers in signal transduction pathways. In the case of epinephrine acting on beta-1 adrenergic receptors in the SA node, the first messenger is:

A.        epinephrine

B.         beta-1 adrenergic receptor

C.         the alpha subunit of Gs protein

D.        adenylyl cyclase

98.       Activation of which of the following enzymes leads to formation of diacylglycerol and inositol 1,4,5 trisphosphate?

A.        Cyclooxygenase

B.         Hormone sensitive lipase

C.         Lipocortin

D.        Phospholipase A2

E.         Phospholipase C

99.       Which of the following is not known to act via a G-protein coupled receptor in target cell membranes?

A.        Acetylcholine

B.         Aldosterone

C.         Epinephrine

D.        Histamine

100.     Dimerization of which of the following hormone receptors is essential for signaling?

A.        Acetylcholine receptor

B.         Beta-2 adrenergic receptor

C.         Growth hormone receptor

D.        Histamine receptor

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