Medical Chemistry (Problem Based Questions)
Medical Chemistry (Problem Based Questions)
Medical Chemistry (Problem Based Questions)
MEDICAL CHEMISTRY
(Problem based questions)
Department of Medical Chemistry introduces this activity on
multiple choice questions-Problems based in Medical Chemistry
as a part of its commitment to continuous education and
learning. Medical students are encouraged to read this short
book to improve their knowledge and direct their reading for
written examinations. The range of subjects included in this
short book is based on the content outline of what is thought in
medical schools today. It covers topics that have formed the
core of such courses that are still valid today.
DIRECTIONS: Each of the questions or incomplete statements below is KEY TO ANSWERS
followed by four-five suggested answers or completions. Choose the most Question Answer Question Answer Question Answer Question Answer
appropriate single answer in each case 1 C 24 B 47 E 70 C
2 B 25 A 48 C 71 E
3 C 26 A 49 B 72 B
Enzymes 4 B 27 E 50 A 73 C
Q1) A 54 –year-old male was rushed to emergency when he collapsed 5 A 28 C 51 B 74 A
in the middle of a business meeting. Examination revealed excessive 6 B 29 C 52 C 75 D
7 A 30 A 53 B 76 B
sweating and high blood pressure. ECG chest was conclusive of Acute
8 C 31 D 54 C 77 B
Myocardial Infarction. Which biochemical investigation out of the 9 C 32 A 55 C 78 C
following would be of no help in the confirmation of diagnosis? 10 B 33 E 56 B 79 D
11 C 34 D 57 C 80 D
A. Cardiac troponins
12 A 35 D 58 C
B. Serum myoglobin
13 E 36 A 59 B
C. Lactate dehydrogenase 14 A 37 B 60 B
D. Creatine Phospho kinase-MB(CPK-MB) 15 B 38 E 61 A
16 A 39 D 62 D
17 A 40 C 63 B
Q2) A 42-year-old obese female presented to the emergency center 18 D 41 B 64 C
with complaints of worsening nausea, vomiting, and abdominal pain. 19 B 42 D 65 D
Her pain was located in the mid epigastric area and right upper 20 D 43 A 66 D
21 C 44 D 67 C
quadrant. Blood biochemistry revealed high serum amylase level.
22 D 45 C 68 C
What is the probable diagnosis for this patient? 23 B 46 C 69 B
A. Viral hepatitis
References
B. Acute pancreatitis
1. Textbook of Biochemistry for Medical Students, 7th Edition
C. Renal colic
2. Multiple Choice Questions, Biochemistry for Medics-Lecture Notes
D. Acute gastritis
3. Multiple Choice Questions on Clinical Chemistry in Diagnosis and
Treatment.
D. 11 hydroxylase deficiency Q3) A 60-year-old chronic alcoholic was brought to the hospital with
E. 17 hydroxylase deficiency complaints of protuberant abdomen (ascites) and edema feet. He also
had history of hemorrhages. Blood biochemistry revealed- High serum
Q79) A physician want top order thyroid function tests on an acutely transaminases, low serum total proteins, Albumin and a prolonged
ill, hospitalized patient suspected of being hypothyroid. The beast prothrombin time. Urine analysis was normal. What could be the
advice would be: possible diagnosis?
rd
A. Order a 3 generation TSH test A. Renal failure
B. Order measurements of free T3 B. Protein malnutrition
C. Order a TRH challenge test C. Cirrhosis of liver
D. Wait until the illness is over before performing the thyroid D. Heart failure
investigation
E. Immediately treat with thyroid replacement therapy Q4) A 52-year-old man had a myocardial infarction 8 hour ago. Which
of the following pairs of plasma enzyme activity measurements is most
room by paramedics, and the strong odor of better almond is present. A. Creatine kinase-MB and lactate dehydrogenase
The differential diagnosis must include the possibility of poisoning by B. Creatine kinase-MB and aspartate aminotransferase
C. carbon monoxide
D. cyanide Q5) One out of the following enzymes has absolute specificity for its
Q6) A 23-year-old male, golden gloves boxing contender presents with following conditions in a 65 year old female:
metabolic disorder. He describes his training regimen that involves A. Insulin resistance
consuming a dozen raw eggs a day for a protein. Raw eggs contain a B. Hyperosmolar coma
protein called Avidin; with an extremely high affinity for a cofactor, C. Hyperlipidemia
cofactors?
A. Cobalamine Q77) A person having an abnormally low serum cortisol baseline level
B. Biotin is given ACTH. A subsequent serum cortisol measurement taken 1
C. Folic acid hour after ACTH shows no change in the serum cortisol level. The
D. Pyridoxal phosphate most probable diagnosis of the patient
E. Thiamin pyrophosphate A. Cushing's syndrome
B. Addison's disease
Q7) A 20-year-old female, a known alcoholic has been brought to the C. Adrenal tumor
emergency department with respiratory distress. Bilateral crepitations D. Hypopituitarism
are felt in the lungs, neek veins are engorged and x-ray chest shows E. Hypoactive hypothalamus
dilated heart. She has been diagnosed with ‘Cardiac Beri-Beri. Which
of the following reactions might have been affected? Q78) A new born female child is born with ambiguous genitalia and
A. Pyruvate to Acetyl CoA develops hyponatremia, hyperkalemia, and hypotension shortly after
B. Pyruvate to Oxaloacetate birth. Which of the following is (are) the most likely cause for her
C. Pyruvate to lactate problem?
D. Pyruvate to Alanine A. autoimmune destruction of the adrenal gland
E. Pyruvate to Malic acid B. infarction of the adrenal gland
C. 21 hydroxylase deficiency
Q73) In the male, increased FSH and LH and decreased testosterone is Q8) A bone marrow aspirate of a strictly vegetarian female, confirms
most likely associated with: the suspicion that she has a megaloblastic anemia because it showed a
A. primary hypergonadism greater than normal number of red and white blood cell precursors,
B. Secondary hypergonadism most of which were larger than normal. What is the cause of
C. Primary hypogonadism megaloblastic anemia in this patient?
D. Secondary hypogonadism A. Vitamin C deficiency
E. Normal function B. Folate toxicity
C. Vitamin B12 deficiency
Q74) A diagnosis of hemolytic anemia in an 11-year-old boy would be D. B6-P deficiency
supported by the following findings: E. Vitamin K toxicity
A. Urinary urobilinogen excretion increased
B. Increased plasma ALP Q9) A45-year-old female presents to her primary care doctor with
C. Increased plasma ALT fatigue and tingling/numbness in her extremities (bilateral).
D. Increased plasma haptoglobin Examination reveals a beefy red and fissured tongue. Further
E. Hypoalbuminemia evaluation reveals a low Glutathione reductase activity in the red blood
cells. Which of the following vitamin deficiencies could have caused
Q75) A45-year-old patient presents with hypertension, central obesity, her symptoms?
abdominal striate, muscle weakness, and moon face. Which of the A. Vitamin C deficiency
following test would be? most useful perform first? B. Niacin deficiency
A.ACTH C. Vitamin B2 deficiency
B. Aldosterone D. B6-P deficiency
C. Random serum cortisol E. Biotin deficiency
D. 1 mg overnight dexamethasone suppression test
E.CRH stimulation test
Q10) A 12-year-old boy develops convulsions. After running an Special Topics
encephalogram (EEG), a neurologist determines that he has epilepsy. Q70) A three year old boy was brought unconscious into emergency
He is prescribed with Benzodiazepine which promotes the activity of room. Blood gases were performed PH 7.26, PCO2 54 mmHg, HCO3
Gamma-amino butyric acid (GABA); GABA is derived from glutamic 38 mmol/l, Base excess +14 mmol/l ,this patient demonstrates:
acid via which of the following biochemical reactions? A. Metabolic alkalosis
A. Deamination B. Metabolic acidosis
B. Decarboxylation C. Respiratory acidosis
E. Hydroxylation
Q71) A patient's blood urea is 30 mg/dl and his creatinine is 5.0 mg/dl.
What conclusion would you draw from these results?
Q11) A3-year-old girl has been brought for consultation. She is well
A. Patient is normal
below the 5th percentile for both height and weight with multiple
B. Patient is in early stage of renal failure
rachitic deformities of the skeleton to include severe bowing of the
C. Patient protein intake is quite low
tibias bilaterally, pigeon chest and thickened/widened wrists
D. Patient has suffered muscle deterioration
bilaterally. Which of the following vitamins can be recommended as a
E. One of the values is in error
part of treatment?
A. Biotin
Q72) Liver function tests can vary depending on a number of factors,
B. Folic acid
but which of the following would be LAST likely to occur after
C. Vitamin D
obstruction of the common bile duct?
D. Pyridoxal phosphate
A. Elevation of serum conjugated bilirubin
E. TPP
B. Elevation of serum unconjugated bilirubin
C. Elevation of serum alkaline phosphatase
D. Appearance of bilirubin in urine
E. Decrease of urine urobilinogen
C. Competitively inhibit the metabolism of methanol Q12) A2- year-old child presented with chronic cough and Bronchitis,
D. Promote the excretion of metabolite of methanol growth failure and passage of light-colored, foul-smelling stools.
E. All of the above Mother of the child reported that the child was finding it difficult to
locate things in the dim light and during night-time. Which of the
Q68) In physiological jaundice of new-born, due to less availability of following vitamins might be deficient in this child?
substrate and immature enzyme system, there is an impaired A. Vitamin A
formation of soluble, non-toxic form of bilirubin which is: B. Vitamin D
A. Bilirubin sulphate C. Vitamin C
B. Bilirubin phosphate D. Vitamin E
C. Bilirubin diglucuronate E. Vitamin K
D. Bilirubin acetate
E. Methylated Bilirubin Q13) A term infant is born and does well with breast-feeding. Two
days later, the mother calls frantically because baby is bleeding from
Q69) In phenylketonuria (a congenital disorder of phenylalanine the umbilical cord and nostrils. Which of the following vitamins might
metabolism that occurs due to deficiency of phenylalanine be deficient in this baby?
hydroxylase), there is impaired conversion of phenylalanine to A. Vitamin A
tyrosine. The excess phenylalanine is detoxified and excreted in urine. B. Vitamin D
Which of the following conjugating agents is used for detoxification of C. Vitamin C
phenylalanine? D. Vitamin E
A. Glutathione E. Vitamin K
B. Glutamine
C. S-Adenosyl Methionine
D. Active sulfate(PAPS)
E. D-Glucuronic acid
Q14) A45-year-old male has been brought to the emergency D. Increased gluconeogenesis
department after a family member found him extremely confused and E. Decreased liver glycogen store
disoriented. He has an unsteady gait and strange irregular eye
movements. Upon extensive work up, he has been diagnosed with Q66) A 75-year-old woman with osteoporosis complains of back pain.
Wernicke-Korsakoff syndrome. Which of the following vitamins might A magnetic resonance imaging (MRI) scan for her back confirms a
be deficient? compressing fracture of the L3 vertebra. The attending physician
A. TPP begins treating the patient with morphine for pain control. Morphine
B. Biotin is an analgesic that works similarly to which of the following
C. Folic acid endogenously produced substances?
D. Pyridoxal phosphate A. ACTH
E. Niacin B. POMC
C. MSH
Carbohydrate Metabolism D. Endorphin
Q15) A30-year-old man has been fasting for religious reason for E. Lipotropin
several days. His brain has reduced its need for glucose by using which
of the following substances as an alternate source of energy? Detoxification
A. Fatty acids
Q67) A 3-year-old girl was brought into the Emergency Room. She was
B. Beta hydroxy butyrate
cold and clammy and was breathing rapidly. She was obviously
C. Glycerol
confused and lethargic. Her mother indicated that she had accidentally
D. Beta carotene
ingested automobile antifreeze while playing in the garage. Following
E. Alanine
gastrointestinal lavage and activated charcoal administration, a
nasogastric tube for ethanol was administered. How will ethanol help
Q16) A7-year-old girl is brought to emergency department by her
in reliving the symptoms?
parents with complaints of severe polyuria and polydipsia. Laboratory
A. Conjugate with methanol to form a soluble compound
examination reveals ketones in the urine. Which of the following is the
B. Induce the alcohol dehydrogenase enzyme
most likely source of ketones?
A. Converts xanthine to uric acid A. Fatty acid breakdown
B. Converts ribonucleotides to deoxy ribonucleotides B. Protein break down
C. Degrades guanine to xanthine C. Glycogenolysis
D. Degrades AMP to IMP D. Gluconeogenesis
E. Converts PRPP to phosphoribosylamine E. Side chain of cholesterol
Q64) A58-year-old man is a woken by throbbing ach in his great toe. Q17) A breast-fed infant began to vomit frequently and lose weight.
He had a similar attack earlier also, after indulging in a rich meal. On Several days later she developed jaundice, hepatomegaly and bilateral
examination, he is noted to have an angry inflamed great toe and cataract. What is the possible cause for these symptoms?
several nodules on the antihelix of his ear. Inhibition of which of the A. Galactosemia
following enzymes might prevent the occurrence of such symptoms? B. Von-Gierke’s disease
A. Amido transferase C. Type 1 diabetes Mellitus
B. PRPP synthetase D. Hereditary Fructose intolerance
C. Xanthine oxidase E. Gaucher disease
D. Orotate phosphoribosyl transferase
Q18) The major metabolic product produced under normal
E. Carbamoyl phosphate synthetase 11
circumstances by erythrocytes and by muscle cells during intense
exercise is recycled through liver in the Cori cycle. The metabolite is-
Hormones
A. Oxaloacetate
Q65) A23-year-old woman has been referred from an endocrinologist
B. Alanine
for weight gain especially around the waist. She also striae over the
C. Glycerol
abdomen and s rounded appearance to her face. She is found to have
D. Lactate
Cushing disease. Which of the following is found in this patient?
E. NADH
A. Decreased absorption of glucose from intestine
B. Decreased lipolysis
C. Increased protein synthesis
Q19) A3-month-old infant presents with hepatosplenomegaly and Q61) The diet of a child suffering from Maple syrup disease (an amino
failure to thrive. A liver biopsy reveals glycogen with an abnormal, acid disorder), should be low, in which out of the following amino acids
amylopectin like structure with long outer chains and missing content?
branches. Which of the following enzymes would most likely be A. Branched chain amino acids
deficient? B. Phenylalanine
A. Alpha Amylase C. Methionine
B. Branching enzyme D. Tryptophan
C. Debranching enzyme E. Histidine
D. Glycogen phosphorylase
E. Glucose-6-phosphatase Nucleotides Metabolism
Q62) A 7-year-old boy suffers from mental retardation and self-
Q20) Prior to a race, many marathon runners will try to increase their mutilation and has increased levels of serum uric acid. These
glycogen concentrations by loading up with foods with high starch symptoms are characteristics of Lesch Nyhan syndrome, which is due
content, such as pasta, Alpha amylase secreted by the pancreas will to defective-
digest the starch into which of the following major products? A. Salvage pathway for pyrimidine biosynthesis
A. Amylose, amylopectin, and maltose B. Denovo synthesis of pyrimidines
B. Glucose, galactose, and fructose C. Xanthine oxidase
C. Glucose, sucrose, and maltotriose D.HGPRT (Hypoxanthine Guanine Phospho Ribosyle Transferase)
D. Limit dextrin, maltose, and maltotriose E. Formyl transferase
E. Maltose, glucose, and fructose
Q63) A physician evaluates a 32-year-old patient for fatigue. The
Q21) Which of the following substances CANNOT contribute to net patient is found to have an elevated white blood cell count (WBC) and
Gluconeogenesis in mammalian liver? an enlarged spleen. A referral to an oncologist results in a diagnosis of
A. Alanine Chronic Myelogenous Leukemia (CML). Treatment with hydroxyurea,
B. Glutamate a ribonucleotide reductase inhibitor is begun. The normal functioning
C. Palmitate of this enzyme is to do which of the followings?
Q58) In a new born presenting with refusal to feeds and irritability, a D. Pyruvate
deficiency of Cystathionine-B-synthase has been diagnosed, which of E. Odd chain fatty acid
the following compounds is expected to be elevated in blood?
Q22) Which of the following complications is less likely to occur in type
A. Serine
2 diabetics, as opposed to type 1 diabetics?
B. Glutamate
A. Retinopathy
C. Homocysteine
B. Weight gain
D. Valine
C. Cardiovascular disease
E. Threonine
D. Hypoglycemic coma
E. Non ketotic hyperosmolar coma
Q59) Histamine, a chemical mediator of allergies and anaphylaxis, is
synthesized from amino acid Histidine by which of the following
Q23) A30-year-old male presents with severe muscle cramps. He is
processes?
found to have muscle glycogen phosphorylase deficiency (Me Ardle’s
A. Deamination
disease< Glycogen storage type 5). Glycogen phosphorylase degrades
B. Decarboxylation
glycogen to produce-
C. Transamination
A. Glucose
D. Dehydration
B. Glucose-1-P
E. Hydroxylation
C. Glucose-6-P
D. UDP Glucose
Q60) The synthesis of all of the following compounds except one is
E. Glycogen primer
deficient in a patient suffering from phenylketonuria-
A. Melanin
Q24) A15-year-old type 1 diabetic faints after injecting himself with
B. Melatonin
insulin. He is administered Glucagon and rapidly recovers
C. Catecholamines
consciousness. Glucagon induces activity of:
D. Thyroid Hormone
A. Glycogen synthase
B. Glycogen phosphorylase
C. Glucokinase A. DOPA
D. Hexokinase B. Glutamine
E. UDP Glucose phosphorylase C. Tyrosine
D. Tryptophan
Q25) A30-year-old presents with intractable vomiting and inability to
E. Threonine
eat or drink for the past 3 days. His blood glucose level is normal.
Which of the following is most important for maintenance of blood Q56) A 59-year-old woman develops gait and a pin-rolling tremor. She
glucose? is referred to a neurologist for evaluation. After a through workup, a
A. Liver diagnosis of Parkinson disease is made and the patient is placed on
B. Heart Mono amine oxidase inhibitor. The drug in this case, is given to
C. Skeletal muscle decrease the degradation of which of the followings?
D. Lysosome A. Serotonin
E. Spleen B. Dopamine
C. Nicotinamide
Q26) A15-year-old male presents with increased thirst, hunger, D. Melatonin
urination, and weight loss. His fasting blood glucose level is 400 mg/dl E. Nitric oxide
and is diagnosed with type 1 diabetes mellitus. What is the reason for
the patient’s inability to maintain a normal blood glucose level? Q57) A55-year-old man suffers from cirrhosis of liver. Toxins such
A. Decreased uptake of glucose by peripheral cells ammonia are not properly metabolized by the liver and can damage
B. Abnormal response to glucagon brain. Which of the following compounds is expected to be highest
Q30) A56-year-old, obese man complains of polydipsia, polyuria and Q51) A5-year-old boy presents with altered mental status, heart
fatigue. A glucose tolerance test confirms the diagnosis of diabetes. He failure, and muscle weakness. His serum level of ketones and glucose
is placed on Metformin, which works by which of the following are abnormally low. He is diagnosed with primary carnitine deficiency.
Q34) In cystic fibrosis, the pancreatic ducts become obstructed by and hepatomegaly (enlarged liver). His triglyceride level is 1500 mg/dl.
viscous mucus. Consequently digestion of which of the following He is diagnosed with type V hyperlipidemia Triglycerides are
substances would be most impaired? primarily synthesized in which of the following tissues?
C. Cellulose C. Liver
D. lipids D. Spleen
Q44) A23-year-old female presents with low red blood cell count,
Q37) A deficiency of Apo protein C-II results in the disease
corneal opacities and kidney insufficiency. She is diagnosed with
hyperlipoproteinaemia type 1, in which there is a significant increase
lecithin: cholesterol acyl transferase (LACT) deficiency. In which of
in the concentration of plasma triacylglycerol. Which of the following
the following reactions LACT is involved?
is true about the condition?
A. Transfer of cholesterol esters from HDL to VLDL
A. VLDL and HDL increase
B. Hydrolysis of HDL
B. Plasma appears milky
C. Uptake of cholesterol from liver cells
C. There is a risk for premature IHD
D. Converting cholesterol to Cholesterol esters
D. Serum cholesterol increases
E. Promoting uptake of HDL in to liver cells
E. Apo C-11 acts as an activator of LACT enzyme.