Practice questions-set-1

Q.1- A 73-year-old woman is transferred to an intensive care unit after she is found to be in septic shock. It is believed that she originally had a urinary tract infection and that the bacteria seeded her bloodstream. The critical care fellow is concerned she may not have an adequate stress response in this situation. He orders a cosyntropin test, which evaluates the body’s ability to produce which of the following hormones?

a) Oxytocin

b) Vasopressin

c) Cortisol

d) Corticotropin-releasing hormone

e) Adrenocorticotropic hormone (ACTH)

Q.2- A 75-year-old man complains of increased urinary frequency, especially at night. he has difficulty starting to urinate and often dribbles urine when he finishes. His urologist suspects benign hyperplasia and places him on a 5-α-Reductase inhibitor. This would decrease which of the following?

a) Conversion of c-AMP to adenosine

b) Release of calcium from endoplasmic reticulum

c) Prostaglandin synthesis

d) Conversion of Angiotensin I to Angiotensin II

e) Conversion of testosterone to dihydrotestosterone (DHT)

Q.3- A 56-year -old diabetic with end-stage renal disease receives a kidney transplant from his son. His nephrologist is concerned for the possibility of transplant rejection and puts the patient on mycophenolic acid, which inhibits which of the following enzyme in the synthesis of nucleotides?

a) PRPP synthetase

b) IMP dehydrogenase

c) Adenylo succinate synthetase

d) Ribonucleotide reductase

e) Adenylosuccinase                               

Q.4- A patient presents with very high levels of serum cholesterol. After a series of tests, it is concluded that the patient has high circulating levels of LDL cholesterol but has normal levels of the liver LDL receptor. One possible explanation for this observation is which of the following?

a) The patient has a mutated form of apoprotein B-100.

b) The inability to selectively remove cholesterol from the LDL complex.

c) The absence of the enzyme lipoprotein lipase.

d) Decreased levels of acyl-CoA: cholesterol acyltransferase.

e) Altered phosphorylation of the LDL receptor.

Q.5- A 25-year-old female was referred to a lipid research center for the investigation of moderate hypertriglyceridemia because the plasma lipid and lipoprotein profiles showed abnormalities. Both HDL and LDL were more buoyant and showed elevations in TG content with the mass of TG approximately the same as that of cholesterol. A deficiency in which of the following is the most likely cause of this patient’ s lipid abnormality?

a) Lecithin-cholesterol acyltransferase (LCAT)

b) Lipoprotein lipase

c) Apoprotein C-II

d) Hepatic lipase

e) Apoprotein B-100               

Q.6- An 18- year -old cricket player sustains a compound fracture on the field. He is taken for surgery, during which anesthesiologist notes a significantly increased body temperature (104OF). There is suspicion of malignant hyperthermia. Which of the following components of ETC is likely to be responsible for this phenomenon?

a) Complex I

b) Complex II

c) Complex III

d) Complex IV

e) ATP synthase complex                               

Q.7- A 43- year-old woman diagnosed with early-stage breast cancer elects to have a lumpectomy followed by radiation therapy because this regimen has been shown to be equivalent to mastectomy in such patients. Radiations work in part by-

a) Inhibiting NADH – cytochrome C reductase

b) Inhibiting cytochrome b-c1 complex

c) Generating reactive oxygen species

d) Oxidizing glutathione

e) Inhibiting ATP synthase complex                               

Q.8- A 47 -year- old man, with no known family history of cancer, develops changes in his bowel habits, including occasional blood in his stools. Colonoscopy and biopsy confirm the diagnosis of adenocarcinoma of the colon. Furthermore, the tumor is found to have a mutation in the ras protein. Which of the following best describes the protein?

a) A non-receptor tyrosine kinase

b) A nuclear transcription factor

c) A receptor kinase

d) A GTP binding protein

e) A polypeptide growth factor                               

Q.9-A 23-year-old man was diagnosed with metastatic liver disease. The grain storage facility outside his house was contaminated with aflatoxin B. In addition, which of the following might act as a co carcinogen in the development of a patient’s cancer?

a) Human T cell lympho-trophic virus (HTLV-1)

b) Hepatitis B virus

c) Asbestos

d) Epstein Barr virus

e) Aniline dyes.                               

Q.10- A 24 -year old bride prepares for her wedding day. After her manicure and pedicure, her hairdresser uses rollers to create a new style for her hair. To create a “permanent wave”, the stylist then applies thioglycollate to break apart the-S-S- bonds in cystine units, reducing them to -SH groups. Which level of protein structure is most greatly affected by this treatment?

a) Primary structure

b) Secondary structure

c) Tertiary structure

d) Quaternary structure

e) Super secondary structure.                               

Q.11- A 27 –year-old female with epilepsy has been taking Phenytoin to control her seizures. She is pregnant and considering the risk of potential bleeding episodes in the infant, her physician is considering changing her medicine. What biochemical activity might be deficient in the baby if her medication is continued as such?

a) Hydroxylation of proline

b) Gamma carboxylation of glutamic acid residues

c) Glucuronidation of bilirubin

d) Oxidation of lysine

e) Oxidation of glutathione.                               

Q.12- A 12- year-old Asian girl presents with nausea, vomiting and non-localizing neurological signs. She has been using brightly colored facial cosmetics obtained from Abroad.

Which biochemical investigation should be appropriate?

a) Liver function tests

b) Brain scan

c) Blood protoporphyrin level

d) Estimation of zinc levels

e) Estimation of arsenate levels                               

Q.13- As electrons are received and passed down the transport chain, the electron carriers are first reduced with the acceptance of the electron and then oxidized with loss of the electron. A patient poisoned by which of the following compounds has the most highly reduced state of most of the respiratory chain carriers?

a) Antimycin A

b) Rotenone

c) Carbon monoxide

d) Puromycin

e) Chloramphenicol                               

Q.14- A 6-month-old infant is seen in the emergency room with a fractured rib and subdural hematoma.  His serum copper level is 4.5 nM/L (Normal range is 5-11 nM/L). Developmental delay is apparent. Which of the following enzyme activity is most affected corresponding to the symptoms?

a) Lysyl oxidase

b) Carboxy peptidase

c) Tyrosinase

d) Superoxide dismutase

e) Xanthine oxidase.

Q.15- Oral contraceptives are known to lower blood levels of folate and B6. Which of the following conversion processes would be directly affected?

a) Glutamate to N-Acetyl Glutamate by NAG synthase

b) Glutamate to Glutamine by Glutamine synthase

c) Glutamine to Glutamate by Glutaminase

d) Glutamate to Alpha-ketoglutarate by Glutamate dehydrogenase

e) Glutamate to GABA by Glutamate decarboxylase.

 

Key to answers

1)- (c) ; 2)- (e); 3)- (b); 4)- (a); 5) –(d); 6)- (e); 7)- (c); 8)- (d); 9)- (b); 10)- (c); 11)- (b);12)- (e);13)- (c);14)- (a);15)- (e)