Chemistry notes

1979 Biochemistry and Physiology Examination (Examination Released in 1980) | Home | Part I Index |

Question 1 of 100

Iodine is primarily important in the biochemical synthesis of

A. ACTH.

B. thyroxin.

C. adrenalin.

D. calcitonin.

E. parathyroid hormone.

Question 2 of 100

The vitamin that promotes the synthesis of prothrombin by the liver is

A. carotene.

B. vitamin C.

C. vitamin K.

D. folic acid.

E. vitamin B12

Question 3 of 100

The most generally accepted mechanism of fluoride action in reducing dental decay is the result of an increase in the hardness of the tooth.

A. an increase in remineralization of enamel.

B. a decrease in exchange of ions between body fluids and the hard tissues.

C. a reduction of solubility of the enamel as the fluoride content increases.

D. a decrease in carbohydrate metabolism in the oral cavity as a result of enzyme inhibition.

Question 4 of 100

Ear aches may develop as a result of blockage of the eustachian tube because

A. the ossicles can no longer vibrate.

B. fluid in the middle ear cannot escape.

C. pressure on the round window distorts the basement membrane.

D. pressure in the middle earis not equalized with atmospheric pressure.

E. blockage of the eustachian tube usually means the presence of an infection in the middle ear.

Question 5 of 100

The primary site of action of antidiuretic hormone is on the distal tubules and collecting ducts in the kidney.

A. afferent arterioles of the glomeruli.

B. thirst center in the hypothalamus.

C. osmoreceptors in the hypothalamus.

D. adrenal cortex.

Question 6 of 100

Administration of heparin to a human results in symptoms similar to vitamin K deficiency in that both conditions result in

A. release of lipoprotein lipase to the blood and rapid clearance of chylomicrons.

B. an increase in bleeding time due to lack of thrombin formation.

C. retardation of fibrinogen synthesis by the liver.

D. elevated non-esterified fatty acids which elevate serum caleium, thus retarding blood clotting.

Question 7 of 100

The greatest part of CO2 carried in the blood is carried in the form of

A. simple solution in the blood plasma.

B. carbamino compound with hemoglobin.

C. bicarbonate.

D. carbonic acid.

Question 8 of 100

The generation of the spike or action potential is attributed to

A. a rapid but brief increase in Na+ conductance.

B. a rapid but brief increase in K+ conductance.

C. a rapid but brief decrease in Cl- shift.

D. equal but opposite movements of K+ and Na+.

Question 9 of 100

In severe diabetic acidosis, one would expect an increase in plasma

A. carbonic acid.

B. keto acids.

C. cations.

D. chloride.

E. sodium.

Question 10 of 100

Norepinephrine is stored at the

A. preganglionic parasympathetic nerve endings.

B. postganglionic parasympathetic nerve endings.

C. preganglionic sympathetic nerve endings.

D. postganglionie sympathetic nerve endings.

Question 11 of 100

Edema may be caused by

A. constriction of arterioles.

B. increased permeability of capillaries.

C. reduced blood pressure in the capillaries.

D. a tissue osmotic pressure that is lower than that of the plasma.

Question 12 of 100

Fasting for three hours leads to

A. increased storage fat.

B. decreased liver glycogen.

C. elevated blood sugar level.

D. suppression of gluconeogenesis.

Question 13 of 100

The rate of fluoride incorporation into bone depends upon the

A. water mineral ratio.

B. age of the individual.

C. rate of bone remodeling or turnover.

D. amount of ionizable fluoride in the diet.

E. All of the above

Question 14 of 100

In a parathyroid deficiency state, there is

A. an increase in serum calcium and a decrease in serum phosphate.

B. a decrease in serum calcium and an increase in serum phosphate.

C. an increase in serum calcium and a normal serum phosphate.

D. a normal serum calcium and an increase in serum phosphate.

Question 15 of 100

Oxygen removal from the alveoli of the lung may be facilitated by

A. low PO2 of pulmonary artery blood.

B. increased total alveolar surface area.

C. increased blood flow through alveolar capillaries.

D. all of the above.

E. none of the above.

Question 16 of 100

An action potential in a nerve fiber is considered to be related to

A. the changed orientation of molecules in the membrane giving rise to a static potential difference.

B. the entry of sodium ion followed by the exit of potassium ion.

C. a breakdown of metabolic products resulting in different concentrations of potassium across the membrane.

D. the flow of electrons across the membrane following change in membrane permeability.

Question 17 of 100

Carbonic anhydrase in the kidney tubular cells is known to be associated with the reabsorption of

A. urea.

B. chloride.

C. bicarbonate ion.

D. carbohydrate.

Question 18 of 100

Toxic effects of carbon monoxide are best explained by the fact that carbon monoxide

A. depresses the rate of respiration.

B. prevents dissociation of oxyhemoglobin.

C. competes with O2 for hemoglobin binding sites.

D. poisons oxidative catalysts of the tissue cells.

E. combines irreversibly with hemoglobin forming methemoglobin.

Question 19 of 100

Hypoactivity of the posterior pituitary gland leads to

A. dwarfism.

B. cretinism.

C. acromegaly.

D. diabetes mellitus.

E. diabetes insipidus.

Question 20 of 100

The first heart sound relates to

A. closure of the A-V valves.

B. opening of the A-V valves.

C. excitation of the auricles.

D. closure of the aortic valve.

E. opening of the aortic valve.

Question 21 of 100

Removal of a molecule of water between the carboxyl group of one amino acid and the amino group of a second amino acid results in formation of a

A. zwitterion.

B. polypeptide.

C. peptide bond.

D. hydrogen bond.

E. glycosidic bond.

Question 22 of 100

Augmented flow from the gallbladder during feeding results in part from

A. a conditioned reflex.

B. the release of enterocrinin.

C. the release of cholecystokinin.

D. a reflex by way of the splanchnic nerves.

E. the stimulatory effect of bile salts by way of enterohepatic circulation.

Question 23 of 100

The hemodynamics of flow in the tooth pulp are most likely analogous to those in the

A. heart.

B. lungs.

C. cranium.

D. liver.

E. gut.

Question 24 of 100

Muscle glycogen does not yield blood glucose directly but liver glycogen does because

A. hexokinase is not present in liver.

B. muscle cells are impermeable to glucose.

C. muscle does not contain phosphoglucomutase.

D. muscle glycogen differs in structure from liver glycogen.

E. glucose-6-phosphatase is not present in muscle.

Question 25 of 100

A 0.85 per cent solution of sodium chloride is isotonic with respect to blood. This solution would also be

A. isosmotic.

B. hyposmotic.

C. hyperosmotic.

D. none of the above.

Question 26 of 100

Glomerular filtration rate may be measured by

A. creatinine.

B. a substance filtered and secreted.

C. a substance filtered but not reabsorbed or secreted.

D. none of the above.

Question 27 of 100

An important nutrient present in low concentration in milk is

A. carbohydrate.

B. calcium.

C. protein.

D. iron.

Question 28 of 100

In the relationship between the concentrations of substrate and the rate of an enzyme catalyzed reaction, the existence of a limited value (Vmax) of the reaction rate is due primarily to the

A. exhaustion of the substrate supply.

B. saturation of the enzyme with substrate.

C. inhibition of the enzyme by the reaction products.

D. denaturation of the enzyme at higher substrate concentrations.

E. balance between the increase in reaction rate with increasing substrate concentrations and accelerated destruction of the enzyme at higher substrate concentrations.

Question 29 of 100

The absolute refractory period of skeletal muscle is an interval during which

A. the stimulus is more than normally effective.

B. the threshold is lowered.

C. the muscle is relaxed.

D. no stimulus is effective.

Question 30 of 100

The primary function of the cerebellum is

A. coordination of spinal reflexes.

B. coordination of autonomic activity.

C. coordination of voluntary movement.

D. regulation of the internal environment of the body.

Question 31 of 100

An important lipotropic substance is

A. choline.

B. tyrosine.

C. hemoglobin.

D. oxaloacetic acid.

E. 8-hydroxybutyric acid.

Question 32 of 100

Transcription is the cellular process of making

A. new DNA.

B. RNA from DNA.

C. proteins from amino acids by way of RNA.

D. none of the above.

Question 33 of 100

Immediately following the closure of the A-V valves is the period of

A. isotonic contraction.

B. isometric contraction.

C. isometric relaxation.

D. isotonic relaxation.

Question 34 of 100

A component of the coenzyme required in a transamination process is

A. niacin.

B. thiamine.

C. folic acid.

D. pyridoxine.

E. riboflavin.

Question 35 of 100

A marked fall in the oxygen tension in arterial blood would stimulate the receptors in the

A. aortic arch and the carotid sinus.

B. walls of the great veins.

C. aortic and carotid bodies.

D. respiratory center.

Question 36 of 100

In terms of its origin and its function, the adrenal medulla is comparable to

A. the adrenal cortex.

B. a preganglionic sympathetic nerve.

C. a postganglionic sympathetic nerve.

D. a preganglionic parasympathetic nerve.

E. a postganglionic parasympathetic nerve.

Question 37 of 100

Sodium taurocholate and glycocholate are necessary for the absorption of

A. sucrose.

B. glycerol.

C. amino acids.

D. fatty acids.

E. nucleic acids.

Question 38 of 100

The rate of diffusion of oxygen across the alveolar-capillary membrane is

A. directly proportional to the alveolar volume.

B. directly proportional to the functional diffusion surface area.

C. indirectly proportional to the alveolar oxygen tension.

D. indirectly proportional to the oxygen tension gradient across the diffusion membrane.

Question 39 of 100

The belief that the secretion of saliva is an active process is supported by the observation that

A. during secretion, there is vasodilation within the gland.

B. during secretion, blood flow through the gland is increased.

C. during secretion, blood flow through the gland is decreased.

D. secretion stops if the pressure within the salivary duct is the same as the blood pressure.

E. secretion continues even when the pressure within the salivary duct is higher than the blood pressure.

Question 40 of 100

The subliminal fringe of a motor neuron pool is a useful concept in explaining the phenomenon of

A. direct inhibition.

B. reciprocal innervation.

C. central facilitation.

D. monosynaptic conduction.

Question 41 of 100

The largest volume flow of blood through the left coronary artery occurs

A. during systole.

B. during diastole.

C. during rapid ventricular ejection.

D. during isovolumetric contraction.

E. between first and second heart sounds.

Question 42 of 100

After being absorbed from the intestine, iron is carried through the blood in the form of

A. ferritin.

B. transferrin.

C. hemosiderin.

D. apotransferrin.

E. ceruloplasmin.

Question 43 of 100

In humans, the site for production of ketone bodies in blood appears to be

A. the liver.

B. the kidney.

C. the adrenal.

D. the pancreas.

E. adipose tissue.

Question 44 of 100

The main function of plasma globulins is to

A. maintain colloid osmotic pressure.

B. provide the body with both natural and acquired immunity.

C. act as a framework on which clot formation may occur.

D. None of the above

Question 45 of 100

During exercise, muscle tissue accumulates lactic acid. As a result, erythrocytes passing through capillaries in the muscle

A. release more CO2.

B. absorb more CO2.

C. release more O2.

D. Both (1) and (3) above

E. Both (2) and (3) above

Question 46 of 100

The enterogastric reflex produces

A. an increase in gastric secretion.

B. an increase in gastric motility.

C. a decrease in gastric motility.

D. a decrease in intestinal motility.

E. an increase in intestinal motility.

Question 47 of 100

Section of the pyramidal tracts produces

A. hypertonia.

B. sympathetic hyperactivity.

C. parasympathetic hyperactivity.

D. loss of fine voluntary movements.

E. complete loss of temperature regulation.

Question 48 of 100

The best criterion for the effectiveness of breathing is

A. tidal volume.

B. minute volume.

C. rate of respiration.

D. alveolar ventilation.

E. a careful measurement of the dead space.

Question 49 of 100

The effect on basal heart rate of cutting successively the vagus and the sympathetic nerves in an animal reveals

A. predominance of vagal over svmpathetic innervation in determining heart rate.

B. predominance of sympathetic over vagal innervation in determining heart rate.

C. that effects of the vagi and the sympathetics on heart rate are equal and opposite.

D. none of the above.

Question 50 of 100

Saltatory conduction depends largely upon the

A. presence of Golgi bodies in the some.

B. internal concentration of sodium.

C. presence of nodes of Ranvier.

D. presence of Schwann cells.

Question 51 of 100

In helping to control the rhythm of respiration, the vagus nerves in the lungs are stimulated by receptors detecting changes in the

A. stretch of the lung parenchyma.

B. PCO2 and PO2 of the blood.

C. PCO2 of the alveolar air.

D. PO2 of the alveolar air.

E. pH of the blood.

Question 52 of 100

In third degree heart block, the electrocardiograph shows

A. an increased PQ interval.

B. an increase in the height of the R wave.

C. an increase in the height of the QRS complex.

D. the P wave and the QRS complex are dissociated.

Question 53 of 100

The most biologically important physicochemical property of connective tissue which is regulated by its mucopolysaccharide molecules is

A. viscosity.

B. buffering capacity.

C. solubility in dilute acids.

D. supersaturation with calcium ions.

Question 54 of 100

A substance that alters the rate of an enzymatic reaction by interacting with the enzyme at a site other than the active site is

A. an allosteric modifier.

B. a competitive inhibitor.

C. a non-competitive inhibitor.

D. none of the above.

Question 55 of 100

Homogentisic acid accumulates in the urine in

A. ketonuria.

B. cystinuria.

C. alkaptonuria.

D. phenyl ketonuria.

Question 56 of 100

An enzyme that is activated by epinephrine is

A. hexokinase.

B. glucokinase.

C. adenyl cyclase.

D. phosphofructokinase.

E. none of the above.

Question 57 of 100

Cyclic 3', 5'-AMP increases the rate of glycogenolysis by

A. promoting the formation of a phosphorylated form of glycogen phosphorylase.

B. serving as a substrate for glycogen phosphorylase.

C. serving as a precursor of 5'AMP which is a cofactor for glycogen phosphorylase.

D. furnishing phosphate for the phosphorolysis of glycogen.

Question 58 of 100

A proportionate increase in resistance of afferent and efferent arterioles of the kidney would result in a decrease in

A. both filtration fraction and glomerular filtration rate.

B. renal blood flow with no change in glomerular filtration rate.

C. glomerular filtration rate with no change in renal blood flow.

D. urine output.

Question 59 of 100

The depolarization of the skeletal muscle cell membrane by motor nerves is directly produced by the

A. shift of Na ions out of the end-plate.

B. activation of muscle contractile proteins.

C. increased concentration of neuromuscular cholinesterase.

D. change in end-plate potential level to a critical value.

Question 60 of 100

Vagal stimulation in the mammalian heart has primarily a rate effect because

A. acetylcholine has little direct effect on contractility of heart muscle.

B. there are few vagal endings distributed to the mammalian ventricles.

C. acetylcholine is not liberated in effective amounts at vagal endings in the mammalian ventricles.

D. sympathetic effects cancel those of the vagus.

Question 61 of 100

The osmotic pressure of the filtrate at the end of the proximal convoluted tubule is

A. greater than that of plasma.

B. much less than that of plasma.

C. about the same as that of plasma.

D. greater than that of the filtrate in the descending portion of the loop of Henle.

Question 62 of 100

Osteoblasts form the organic matrix of bone prior to calcification of the tissue. This process requires vitamins

A. A and B12.

B. A and C.

C. A and D.

D. C and E.

E. D and E.

Question 63 of 100

Albinism is caused by a deficiency of an enzyme involved in the metabolism of

A. tyrosine.

B. arginine.

C. histidine.

D. methionine.

E. tryptophan.

Question 64 of 100

The main factors directly involved in the maintenance of systemic arterial blood pressure are

A. cardiac output, blood volume, peripheral resistance and respiratory rate.

B. cardiac output, blood volume, blood viscosity and peripheral resistance.

C. heart rate, ventricular filling, blood viscosity and peripheral resistance.

D. plasma colloid osmotic pressure, capillary blood pressure, tissue hydrostatic pressure and tissue colloid osmotic pressure.

Question 65 of 100

The buffer system most important in maintaining the physiological pH of plasma is

A. protein/proteinate.

B. acetic acid/acetate.

C. carbonic acid/bicarbonate.

D. phosphoric acid/phosphate.

E. hydroxybutyric acid/hydroxybutyrate.

Question 66 of 100

Pieces of dog parotid gland and of pancreas are transplanted under the skin of the donor animal. After re-establishment of a circulation, ingestion of food will result in secretion from

A. parotid and pancreatic transplants.

B. the fragment of the parotid only.

C. the fragment of the pancreas only.

D. neither fragment.

Question 67 of 100

The products of hydrolysis of lecithin are

A. glycerol, fatty acids, phosphoric acid, serine.

B. glycerol, fatty acids, phosphoric acid, choline.

C. sphingosine, acetic acid, phosphoric acid, inositol.

D. glyceraldehyde, fatty acids, phosphoric acid, choline.

E. glyceraldehyde, fatty acids, phosphoric acid, ethanolamine.

Question 68 of 100

If the anticodon on transfer RNA is ACG, the codon on messenger RNA is

A. CGT.

B. GCA.

C. CGA.

D. UAG.

E. UGC.

Question 69 of 100

Two hormones which act similarly to increase glycogen and lipid breakdown as well as cyclic AMP synthesis are

A. insulin and calcitonin.

B. glucagon and epinephrine.

C. aldosterone and testosterone.

D. parathyroid hormone and glucagon.

Question 70 of 100

An injection of epinephrine into the left ventricular wall causes an increase in care output. This is an example of

A. positive inotropic activity.

B. heterometric autoregulation.

C. Starling's Law of the Heart.

D. homeometric autoregulation .

Question 71 of 100

The amino acid composition of a protein having an isoelectric pH of 10 has

A. no acidic amino acids.

B. no basic amino acids.

C. no neutral amino acids.

D. more basic than acidic amino acids.

E. more acidic than basic amino acids.

Question 72 of 100

The recommended daily dietary allowances for Ca and P provide a Ca/P intake of approximately

A. 0.5.

B. 1.0.

C. 2.0.

D. 3.0.

E. 4.0.

Question 73 of 100

Other factors being equal, one should expect N2O-O2 sedation to be induced more slowly than normal in a person having a

A. tidal volume larger than normal.

B. vital capacity smaller than normal.

C. residual volume smaller than normal.

D. functional residual capacity larger than normal.

E. None of the above

Question 74 of 100

Capillary diameter is directly influenced by

A. parasympathetic nerve impulses.

B. by products of metabolism.

C. sympathetic nerve impulses.

D. axon reflexes.

Question 75 of 100

Coenzymes used in pyruvate debydrogenase reactions are: (a) thiamine pyrophosphate; (b) pyridoxal phosphate; (c) lipoic acid; (d) biotin; (e) NAD+.

A. (a) and (b) only

B. (a), (b) and (e)

C. (a), (c) and (e)

D. (b) and (d)

E. (c) and (d)

Question 76 of 100

A person injured in an automobile accident has lost two pints of blood and is now in shock. Which of the following are likely to occur? (a) A decrease in glomerular filtration rate; (b) A decrease in the reabsorption of H2O in the distal convoluted tubule; (c) A decrease in urine formation; (d) A decrease in the release of an antidiuretic hormone.

A. (a) and (c)

B. (a) and (d)

C. (b) and (c)

D. (b) and (d)

E. (c) and (d)

Question 77 of 100

Which of the following is an essential fatty acid?

A. Acetic

B. Stearic

C. Myristic

D. Palmitic

E. Arachidonic

Question 78 of 100

Which of the following functions of bone could be considered the most prominent?

A. Buffering

B. Phosphate source

C. Sodium reservoir

D. Fluoride reservoir

E. Calcium reservoir

Question 79 of 100

A number of substances yield energy to the body when a phosphate group is transferred to a suitable acceptor. Which of the following compounds yields the most energy per mole?

A. Creatine

B. Pyruvic acid

C. Glucose-1-phosphate

D. Adenosine triphosphate

E. Fructose-1,6-diphosphate

Question 80 of 100

Which of the following is the direct precursor of urea?

A. Glutamic acid

B. Citrulline

C. Ornithine

D. Glutamide

E. Arginine

Question 81 of 100

Which of the following enzymes is involved in the termination of neuromuscular transmission?

A. Acetylcholine esterase

B. Methyltransferase

C. Monoamine oxidase

D. Choline acetylase

E. Adenyl cyclase

Question 82 of 100

To which of the following avitaminoses is the gingiva most susceptible?

A. A

B. B2

C. B6

D. C

E. Niacin

Question 83 of 100

Which of the following ions is especially required in the blood clotting process?

A. Fe++

B. Na+

C. Ca++

D. Mg++

E. K+

Question 84 of 100

In the metabolic conversion of glycogen to lactic acid, which of the following is an intermediate?

A. Maltose

B. Glycerol

C. Phosphocreatine

D. Acetoacetic acid

E. Glucose-1-phosphate

Question 85 of 100

Which of the following is most likely to promote depolymerization of the ground substance?

A. Cortisone

B. Collagenase

C. Chymotrypsin

D. Hyaluronidase

E. Ammonium phosphate

Question 86 of 100

Where in the cell does most protein synthesis occur?

A. In the nucleus

B. Within lysosomes

C. Within the mitochondria

D. On polyribosomes

E. In soluble cytoplasm

Question 87 of 100

What changes in the extracellular fluid compartment are caused by prolonged sweating?

A. A decrease in volume and an increase in osmotic pressure

B. A decrease in volume and a decrease in osmotic pressure

C. An increase in volume and an increase in osmotic pressure

D. An increase in volume and a decrease in osmotic pressure

Question 88 of 100

Which of the following statements concerning salivary gland function or its control is correct?

A. Epinephrine inhibits parotid amylase secretion by decreasing cyclic AMP levels.

B. Salivary flow is inhibited by the presence of dry food in the mouth.

C. Some chemicals, such as potassium iodid' and mercury, are excreted in part by the saliva.

D. Mucoproteins are the most important buffers in the saliva.

Question 89 of 100

Which of the situations below characterizes the exchange of chloride and bicarbonate ion between the red cell and plasma in the lungs?

A. The passage of chloride ion into the cell from the plasma and the passage of bicarbonate ion from the cell into the plasma.

B. The passage of chloride ion into the plasma from the cell and the passage of bicarbonate ion from the plasma into the cell.

C. The passage of chloride ion and bicarbonate ion into the cell from the plasma so that carbon dioxide can escape

D. The passage of chloride ion and bicarbonate ion from the cell into the plasma

Question 90 of 100

Which of the following amino acids is a thio-ether?

A. Leucine

B. Threonine

C. Isoleucine

D. Methionine

E. Thiolhistidine

Question 91 of 100

Which of the following processes is most important in preventing a decrease of more than 0.2 units in the pH of the blood when CO2 enters?

A. Urea formation following amino acid deamination

B. NH4+ formation in the kidney

C. Formation of ketone bodies

D. Excretion of acidic urine

E. Conversion of HbO2 to Hb

Question 92 of 100

Which of the following is most commonly associated with transport of free fatty acids in human blood?

A. Albumin

B. Globulin

C. Cholesterol

D. Sphingolipid

E. Mucopolysaccharide

Question 93 of 100

Which of the following reflexes is monosynaptic?

A. Stretch reflex

B. Withdrawal reflex

C. Crossed extensor reflex

D. Positive supporting reaction

E. Labyrin shine righ tiny reflex

Question 94 of 100

In which of the following combinations is the name of the hormone, its chemical type and its tissue of origin correctly matched?

A. Aldosterone--peptide--pancreas

B. Glucagon--peptide--adrenal cortex

C. Epinephrine--steroid--adrenal medulla

D. ACTH--polypeptide--adrenal cortex

E. Vasopressin--peptide--posterior pituitary

Question 95 of 100

Which of the following is considered to be the least important in producing enamel hypoplasia in developing teeth?

A. Rickets

B. Prolonged vitamin A deficiency

C. Prolonged vitamin D deficiency

D. Fluoride intake of less than 0.2 ppm in the water

E. Inadequate calcium intake for a prolonged period

Question 96 of 100

Which of the following is NOT a type of connective tissue fiber?

A. Chitin

B. Elastin

C. Collagen

D. Reticulin

Question 97 of 100

Which of the following digestive enzymes is NOT derived from an inactive zymogen precursor?

A. Pepsin

B. Trypsin

C. Amylase

D. Chymotrypsin

Question 98 of 100

The hypothalamus-pituitary complex does NOT control hormonal secretions of the

A. thyroid.

B. parathyroids.

C. corpora lutea.

D. ovarian follicles.

E. interstitial cells of the testes.

Question 99 of 100

An enzyme which is found in the succus entericus but NOT in the pancreatic juice is

A. lipase.

B. trypsin.

C. chymotrypsin.

D. enterokinase.

Question 100 of 100

Proprioceptors are found in each of the following EXCEPT the

A. gingiva.

B. skeletal muscles.

C. pulp of the tooth.

D. periodontal ligament.

E. temporomandibular joint.