Biochemistry-Physiology 1

The heteropolysaccharide that prevents formation of active thrombin is
1. Heparin
2. Hyaluronic acid
3. Keratin sulfate
4. Dermatan sulfate
5. Chondroitin sulfate

Oxygen passes from alveolar air into blood by
1. Diffusion
2. Perfusion
3. Adsorption
4. Active transport
5. Facilitated transport

A fall in blood pressure causes
1. Increase activity of both vasoconstrictor  and cardio inhibitory centers
2. Decreased activity of both vasoconstrictor and cardioinhibitory centers
3. Increased activity of the vasoconstrictor center and decreased activity of the cardioinhibitory center
4. Decreased activity of the vasoconstrictor center and increased activity of the cardio inhibitory center

Hyperparathyroidism is marked by
1. Chronic tetany
2. A high blood calcium level
3. Retention of phosphates by the kidneys
4. Storage of excess minerals by the bones
5. Increased irritability of excitable tissues

Biological oxidative-phosphorylation enzymes occur in the cell primarily as
1. Components of the cell wall
2. Components of the nuclear membrane
3. Soluble enzymes of the cytoplasm
4. Enzymes partly in microsomes and partly in the mitochondria
5. Highly organized multy-enzyme units in the mitochondria

A diet deficient in calcium will result in 
1. Stimulation of the thyroid gland
2. Increased ability to cross link fibrin
3. Production of calcitonin and a low blood calcium level
4. Production of parathyroid hormone and bone resorption

In sickle cell anemia, a variation in an amino acid of the hemoglobin is detected.  This substitution of valine for glutamic acid
1. Results in no change in solubility
2. Results in no change in isoelectric pH
3. Is a result of a change in DNA coding
4. Has no noticeable effect in the O2 transport behavior of the erythrocyte

The parasympathetic nervous system regulates
1. Heart rate
2. Venous tone
3. Arteriolar tone
4. Renal blood flow
5. Pulmonary blood flow

The most abundant protein (by weight) in the human body is
1. Elastin
2. Keratin
3. Albumin
4. Collagen
5. Chondroitin

A net water loss that results from sweating causes an increase in
1. Urine formation
2. Antidiuretic hormone
3. Glomerular filtration
4. Tubular excretion of electrolytes

The organic matrix of bone is composed largely of collagen and
1. Lipids
2. Citrate
3. Dextrans
4. Glycosaminoglycans

Fasting for five hours leads to
1. Increase storage fat
2. Decreased liver glycogen
3. Elevated blood sugar level
4. Suppression of gluconeogenesis

Colloid osmotic pressure of the blood is important because it 
1. Aids in blood clotting
2. Nourishes blood cells
3. Prevents loss of erythrocytes from the blood
4. Prevents excess loss of fluid from capillaries
5. Prevents entrance of tissue fluid into capillaries

Failure of cardiac muscle to exhibit tetany results from its
1. Automaticity
2. Long chronaxie
3. Intercalated disks
4. Long refractory period
5. Protoplasm in bridges between fibers

Release of glucocorticosteroid is controlled by
1. Adrenocorticotropic hormone
2. Preganglionic adrenergic nerves
3. Postganglionic adrenergic nerves
4. Preganglionic cholinergic nerves
5. Postganglionic cholinergic nerves

A common intermediate of metabolism of carbohydrates, fatty acids and amino acids is
1. Glycerol
2. Acetyl CoA
3. Acetoacetate
4. Oxaloacetate
5. Acetylcholine

The end product of glycolysis under anaerobic conditions is 
1. Lactic acid
2. Pyruvic acid
3. Acetoacetic acid
4. Oxaloacetic acid

During respiration, carbon dioxide and oxygen are exchanged at the junction of cloud and alveolar spaces and the junction of blood and tissue. The actual diffusion of gases is primarily controlled by the 
1. Atmospheric pressure
2. Elasticity of blood capillaries
3. Bicarbonate content of the blood
4. Hemoglobin content of erythrocytes
5. Differentials in partial pressures of the gases

Preganglionic fibers at exclusively 
1. Somatic
2. Adrenergic
3. Sympathetic
4. Cholinergic
5. Parasympathetic

Energy for glomerular filtration is derived from
1. Intratubular pressure
2. Osmotic pressure of the blood
3. Hydrostatic pressure of the blood
4. Interstitial pressure of the tubules

Inhibition of acetylcholinesterase at a neuromuscular junction causes
1. Prolongation of the endplate potential
2. Increased liberation of acetylcholine from neuronal terminals
3. The resting potential of the muscle fiber to increase in magnitude
4. The critical membrane potential of the muscle fiber to move to a value nearer the resting potential

The function of vitamin K is involved directly with
1. Synthesis of prothrombin
2. Activation of the Stuart factor
3. Regulation of calcium in the blood
4. Conversion of fibrinogen to fibrin
5. Transcriptional control for fibrinogen synthesis

Active transport systems generally involved specific binding molecules that are
1. Lipids
2. Proteins
3. Carbohydrates
4. Nucleic acids
5. Polyphosphates

Sympathetic stimulation affects carbohydrate metabolism because
1. Peripheral tissues esquire epinephrine to take up glucose
2. Sympathetic nerves top the pancreas regulates insulin release
3. Insulin cannot act on the liver in the absence of epinephrine
4. Epinephrine increases liver glycogenolysis
5. None of the above

In the absence of compensatory changes, a drop in blood pressure results from
1. Vasoconstriction
2. Increased hematocrit
3. Increased stroke volume
4. Increased cardiac output
5. Decreased venous return

Certain viruses has been isolated in crystalline form and have been found to be
1. Nucleotides
2. Polypeptides
3. Phospholipids
4. Scleroproteins
5. Nucleoproteins

In the presence of a constant heart rate,  changes in blood pressure may be attributed mainly to alterations in resistance offered by
1. Veins 
2. Arteries
3. Arterioles
4. Capillaries

Velocity of nerve impulse conduction in a sensory nerve fiber is related to
1. Intensity of the stimulus
2. Presence of a myelin sheath
3. Nature of the applied stimulus
4. Cross-sectional area of the axon

According to the Henderson-Hasselbach equation, the pH of a buffer system depends on the pK of the weak acid and the
1. PK of the salt
2. Molar concentration of weak acid present
3. Molar concentration of salt of the weak acid present
4. Ratio of molar concentration of salt and weak acid

Normally, the rate of the heartbeat in a human is determined by
1. The bundle of His
2. All cardiac muscle
3. The sinoatrial node
4. The cervical ganglion
5. nerve impulses from the cardiac center of the medulla

The process by which genetic information flows from RNA to protein is
1. Mutation
2. Replication
3. Translation
4. Transcription

One essential feature of the  Watson-Crick-Wilkins model for the double stranded DNA molecule concerns the nitrogenous base pairing on complementary strands. This involves the specific pairing of
1. Adenine with guanine
2. Adenine with thymine
3. Cytosine with thymine
4. Cytosine with adenine

The function of hypophyseal portal vessels is to
1. drain blood from the adenohypophysis Into the median eminence
2. Supply blood to a small fraction of the adenohypophysis
3. Carry hypothalamic releasing factors to the adenohypophysis
4. Carry blood from the adenohypophysis

Glycosaminoglycans function as important structural components of 
1. Glycogen
2. nucleic acids
3. Hyaluronidase
4. Connective tissue

Stimulation of the sympathetic nervous supply to the gastrointestinal tract generally causes
1. Inhibition of motility
2. Increase in HCl secretonin
3. Secretion by pancreatic acini
4. An increase in the rate of colonic evacuation

Hydrolysis of thyroglobulin Liberates a number of iodinated compounds. Two are considered thyroid hormones.  These are
1. Tyrosine and thyronine
2. Tyrosine and diiodotyrosine
3. Thyroxin and triiodothyronine
4. Thyroxin And triiodotyrosine

FSH exerts its action on
1. Epididymis
2. Endometrium
3. Interstitial cells
4. Germinal epithelium
5. Juxtaglomerular apparatus

Alpha cells in the islands of Langerhans are the source of 
1. Insulin 
2. Glucagon
3. Glycogen
4. Secretin
5. Thiamine

The diffusion coefficient for the transfer of each gas through the respiratory membrane depends upon
1. Solubility only
2. Molecular weight only
3. Both solubility and molecular weight
4. Concentration gradient

The low serum phosphate level in hyperparathyroidism is caused by
1. Decreased absorption of phosphate
2. Increased renal loss of phosphate
3. Increased deposition of calcium phosphate in bone
4. Increased reabsorption of calcium phosphate from bone

A local, cold stimulus applied to an extremity but not leading to lowering of body temperature evokes reflex shivering.  This is principally a result of
1. Axon reflexes
2. Spinal reflexes
3. Reflexes involving the precentral gyrus of the hemisphere
4. Reflexes involving the post central gyrus of the hemisphere

Infusion of hypertonic NaCl solution will
1. Increase extracellular osmolarity only
2. Decrease intracellular Osmolarity only
3. Decrease intracellular volume and increase extracellular volume
4. Increase both intracellular and extracellular volumes
5. Decrease both intracellular and extracellular volumes

The final step in the complete metabolism of fat is carried out by means of
1. Anaerobic glycolysis
2. The tricarboxylic acid cycle
3. The reductive fixation of CO2
4. The hexose monophosphate shunt
5. The Krebs-Henselet (urea) cycle

The optimum pH for an enzyme is the
1. Isoelectric point of the enzyme
2. pH of most rapid reaction rate
3. pH at which the enzyme is most soluble
4. pH of most rapid denaturation of the enzyme

the center of the brain regulating body temperature is in the
1. Pons
2. Medulla
3. Thalamus
4. Hypothalamus
5. Cerebral cortex

Local autoregulation of blood flow in skeletal muscle is determined chiefly by
1. Axon reflexes
2. Acetylcholine
3. Spinal reflexes
4. Muscle metabolites

Transport of iron in plasma is almost entirely in the form of 
1. Ferritin
2. Cytochrome
3. Hemoglobin
4. Transferrin
5. Hemosiderin

Intracellular and interstitial body fluids have similar
1. Total osmotic pressures
2. Colloid osmotic pressure
3. Chloride ion concentrations
4. Potassium ion concentrations

Carotid body receptors are simulated most effectively by
1. Elevated pH
2. Low oxygen tension
3. High oxygen tension
4. Low carbon dioxide tension
5. Increased arterial blood pressure

The most important function of hydrochloride acid in the stomach is
1. Destruction of bacteria
2. Neutralization of chyme
3. Activation of pepsinogen
4. Hydrolysis of dietary protein
5. Stimulation of pancreatic secretion

The countercurrent theory is used to explain the functioning of 
1. The kidney
2. Nerve fibers
3. Muscle fibers
4. The cerebral cortex
5. The basilar membrane in the cochlea

Regeneration of severed axons does not take place in the central nervous system because of the
1. Absence of a neurilemma
2. Presence of spinal fluid
3. Absence of a myelin sheath
4. Impediment of scar tissue to grow

The continuous flow of blood in arteries during diastole is made possible by
1. The thoracic pump
2. Relaxation of arterioles
3. The pumping action of skeletal muscle
4. Energy stored in arteries during systole

Intrapleural pressure during normal respiration is
1. Subatmospheric
2. Positive during expiration
3. Positive during inspiration
4. Zero at the end of expiration
5. Zero at the end of inspiration

In relation to it's effect upon movement of water between vascular and extra vascular space, plasma colloid osmotic pressure acts in the same direction as
1. Tissue pressure
2. Venous pressure
3. Capillary pressure
4. Arteriolar pressure
5. Tissue colloid osmotic pressure

The amino acid that contributes to the tertiary structure of a protein by causing a bend when it occurs in the primary sequence is 
1. Leucine
2. Alanine
3. Proline
4. Tyrosine
5. Aspartic acid

The plasma protein subtraction that contains antibodies found bathing mucous surfaces (mouth, bronchial passages, small intestine) is
1. IgA
2. IgD
3. IgE
4. IgG
5. IgM

Under normal conditions, the resting potential across a muscle cell membrane is lower that the equilibrium potential for potassium because
1. Sodium permeability is equal to potassium permeability 
2. Sodium permeability exceeds potassium permeability
3. The membrane has a low permeability to the sodium ion
4. The membrane has a low permeability to the chloride ion

Two enzymes that have been postulated to play very important roles in calcification are
1. Enolase and phosphorylase
2. Alkaline phosphatase and catalase 
3. Pyrophosphatase and carbonic anhydrase
4. Pyrophosphatase and alkaline phosphatase
5. Carbonic anhydrase and alkaline phosphatase

Free fatty acids are transported in blood plasma as
1. Sodium salts
2. undissociated acids
3. A complex with albumin
4. A Micelle complexed with bile salts
5. A major constituent of plasma lipoproteins

Removal of huge anterior lobe of the pituitary gland results in
1. Diabetes
2. Loss of capacity to oxidize fat
3. Loss of capacity to store sugar
4. Increased sensitivity to insulin

Most abundant calcium is transported in blood as
1. Calcium phosphate
2. A globulin complex
3. An albumin complex
4. An associate with hemoglobin

The main effect of aldosterone is to cause
1. Increased secretion of antidiuretic hormone
2. Inhibition of the micturition reflex
3. Increased blood flow into the vasa recta
4. Increased permeability of sodium in the proximal tubule and Henle's loop
5. Increased permeability of sodium in the distal tubule and the collecting duct

In a state of water intoxication, the extra volume of water is found primarily 
1. In potential spaces
2. In the interstitial compartment
3. In the intracellular compartment
4. In the intravascular compartment
5. Equally distributed among all compartments

The major end product of carbohydrate ingestion is
1. Xylose
2. Glucose
3. Mannose
4. Fructose
5. Galactose

The discharge of impulses in small motor (fusimotor) neurons inner sting muscle spindles serves to
1. Inhibit extrafusal muscle contraction
2. Sustain extrafusal muscle contraction
3. Protect the muscle from excessive strain
4. inhibit the discharge of impulses in large motor fibers
5. Inhibit the discharge of impulses in small motor fibers

the greatest concentration of carbonic anhydrase is found
1. In plasma
2. In platelets
3. In leukocytes
4. In erythrocytes
5. Equally distributed between plasma and erythrocytes

Electronegativity in living cells requires that 
1. A potential for charge separation exists
2. Biological water assumes a crystalline pattern at the membrane
3. Negative charges outnumber positive charges within the cell's cytoplasm 
4. None of the above

The rate of fluoride incorporation into bones of an animal depends upon
1. Age of the animal
2. Water-mineral ratio of the bone
3. Rate of bone remodeling or turnover
4. Amount of ionizable fluoride in the diet
5. All of above
6. Only 2 and 3

In mammals, the last stage of biological oxidation is accomplished with
1. NAD+
2. Ubiquinon
3. Flavoprotein
4. Cytochrome c
5. Cytochrome oxidase

Inhibition of lipolysis, stimulation of protein synthesis and increased entry of glucose into muscles and adipose tissues are biological actions of the hormone
1. Insulin
2. Cortisol
3. Glucagon
4. Epinephrine
5. Testosterone

Phosphorylation of some enzymes by ATP results in conversion of the enzyme from an active to an inactive form.  This is illustrated by the conversion of
1. Pepsinogen to pepsin
2. Trypsinogen to trypsin
3. Glycogen synthetase I to glycogen synthetase D
4. None of the above

In untreated diabetes mellitus, polyuria is related to 
1. The osmotic effect of glucosuria
2. Decreased secretion of antidiuretic hormone
3. Increased active transport of sodium by renal tubules
4. The direct effect of insulin on tubular reabsorption of water

During passage of an impulse across either normal muscle or nerve fibers, which of the following phenomena are exhibited?
A) an electrical response
B) an increase in consumption of intracellular glucose
C) a loss of impulse strength cause by resistance
D) an inflow of extracellular sodium
E) an increase in permeability of the cell membrane

Which of the following are energy rich phosphate carriers?
a) glucose-6-phosphate
b) 1,3-diphosphoglyceric acid
c) Creatine phosphate
d) 3-phosphoglyceric acid
e) adenosine monophosphate

Which of the following phospholipids would most likely be found in the outer lamella of the plasma membrane?
a) sphingomyelin
b) phosphatidylcholine
c) phosphatidylethanolamine

Which of the following describe an asymmetric model of membrane assembly?
a) some membrane proteins may have their N-terminal residues predominately on one side of the membrane
b) the polar head groups of the phospholipids may be primarily oriented toward one side of the membrane
c) the membrane has an inverted orientation

A diet rich in tryptophan offsets a deficiency of which of the following vitamins?
1. Niacin
2. Thiamine
3. Riboflavin
4. None of the above

The effect of vitamin C deficiency on the developing tooth is primarily on the calcification of dentin and cementum.  This can best be explained by which of the following statements.
1. This thus happen but the reason is obscure
2. Dentin is the most sensitive tissue inthe body to a vitamin C deficiency
3. Vitamin C influences the formation of collagen, the organic matrix found in dentin and cementum
4. vitamin C has metabolic interrelations with Other vitamins that have a greater influence on dentin and cementum than on enamel
5. The vascular system is more important to these tissues than to enamel and, in an avitaminosis C, the vascular system is subject to hemorrhage

Which of the following is a vitamin?
1. Adenine
2. Inosine
3. Xanthine
4. Thyroxin
5. Pyridoxine

Reactions that have unfavorable energetically (i.e., +∧G°) in metabolic pathways may be driven to completion by which of the following processes?
1. Coupling
2. Allosterism
3. Modification
4. Microscopic reversibility

The primary structure of protein is best described by which of the following statements?
1. Proteins are amino acids 
2. Proteins are polymers of dextrorotatory monomers
3. Proteins include all nitrogen compounds of tissues
4. Proteins are polymers formed by hydrogen bonding between amino acids
5. Proteins are polymers formed by Maude linkages between alpha-carboxylgroups and alpha-amino groups

Which of the following is a source of transferable methyl groups in metabolism?
1. Valine
2. Choline
3. Leucine
4. Isoleucine

Protein content of enamel from mature teeth is approximately what percent of enamel weight?
1. 0.1-1%
2. 5-10%
3. 15-20%
4. 25-30%
5. 50-55%

Starting from the receptor, which of the following best represents the arc of the Hering- Breuer reflex.
1. Lung-vagus-medulla-vagus -bronchial muscles
2. Carotid body-vagus-medulla-spinal cord-bronchial muscles
3. Lung-vagus-medulla-spinal cord-respiratory muscles
4. Lung-glossopharyngeal nerve-spinal cord-bronchial muscles
5. Carotid body-glossopharyngeal nerve-medulla-spinal cord-respiratory muscles

In which segment of the nephron does tubular fluid have the highest osmolality?
1. Henle's loop
2.  Distal tubule
3. Proximal tubule
4. Collecting duct
5. Bowman's capsule

Which tissue is metabolically inert (not in dynamic equilibrium with blood and metabolites)?
1. Bone
2. Dentin
3. Adipoose
4. Connective
5. None of the above

By which of the following mechanisms does the presence of fats in the small intestine influence the rate of gastric emptying?
1 fat in the small intestine hastens gastric emptying through activity of the hormone, enterogastrone
2. Fat in the small intestine inhibits gastric emptying through activity of the hormone, enterogastrone
3. Fat in the small intestine initiates the enterobacter in reflex that inhibits further gastric emptying
4. Fat in the small intestine initiates the enterobacter if reflex that stimulates further gastric emptying

Which of the following portions of an ECG is related to propagation of the cardiac impulse between the SA node and the AV node?
1. QRS complex
2. PR interval
3. QS interval
4. QR interval
5. T wave

Which of the following vitamin is necessary as a coenzyme in the initial steps of fatty acid synthesis?
1. Biotin
2.Thiamin
3. Vitamin A
4. Vitamin D
5. Riboflavin

A patient has cheilosis, angular stomatitis, glossitis and red, itching eyes.  The periodontal surgery that was performed one week ago has not healed properly.  Deficiency of which of the following vitamins is most likely?
1. Thiamine
2. Riboflavin
3. Tocopherol
4. Calciferol
5. Pantothenic acid

Which of the following is NOT a part of accommodation for near vision?
1. Constriction of pupils
2. Convergence of eyeballs
3. Release of visual purple
4. Contraction of ciliary muscle

Which of the following is NOT a reflex mediated by the medulla oblongata?
1. Blinking
2. Coughing
3. Vomiting
4. Patellar
5. Swallowing

Which of the following agents is NOT likely to be found in plasma?
1. Thrombin
2. Fibrinogen
3. Prothrombin
4. Calcium ion
5. Ascorbic acid

Which of the following is NOT a function of the liver
1. Detoxification
2. Gluconeogenesis
3. Formation of plasma protein
4. Secretion of digestive enzymes
5. Regulation of blood sugar level

Which of the following does NOT occur when anesthetics are applied to a neural membrane?
1. K+ flux remains unchanged
2. Pores of the membrane becomes "frozen"
3. there is Ca++ flux through the membrane
4. Resting potential drops to a more negative value

Which of the following is not involved as a cofactors in formation of acetyl CoA from pyruvate?
1. NAD+
2. FAD
3. Pyridoxine
4. Lipoid acid
5. Thiamine pyrophosphate

Which of the following statements concerning collagen is incorrect?
1. Collagen has a tribe licks structure
2. The molecular weight of collagen is above 100.000
3. Hydroxyproline is incorporated into the molecule by tRNA
4. Destruction of collagen can be caused by collagenases
5. Collagen contains both hydroxyproline and hydroxylysine residues

Which of the following hormones exerts the least effect on calcium metabolism of bone tissue?
1. Androgen
2. Estrogen
3. Norepinephrine
4. Thyroid hormone
5. Parathyroid hormone