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Repeated USMLE Questions Step 1- Review- 53- Pharmacology

Q- A patient represents to the ER with anaphylactic shock. Epinephrine is given to the patient. Which one of the following adrenoreceptors mainly mediates bronchial muscle relaxation?

A- Alpha-1 receptor

B- Alpha-2 receptor

C- Beta-1 receptor

D- Beta-2 receptor

D- Beta-2 receptor- Epinephrine is used in anaphylactic shock. It causes vasoconstriction and bronchodilation. Vasoconstriction is mediated by alpha-1 receptor while bronchodilation is mediated by beta-2 receptor.

 

Q- Folic acid is given to pregnant women to decrease the risk of having a fetus with a neural tube defect. This treatment is a cofactor of which one of the following processes?

A- Active electron transport

B- Biosynthesis of nucleotides

C- Glycolysis

D- Triglyceride lipolysis

B- Biosynthesis of nucleotides- Folic acid play an important role in the synthesis of DNA, methionine from homocysteine and modification of DNA and RNA.

 

Q- Gentamicin is added to penicillin in the treatment of infections caused by viridans streptococci. Which of the following is the mechanism of action of this antibiotic?

A- Binding to the 30S subunit of bacterial ribosome

B- Blocking the attachment of charged tRNA at the P site peptide chain

C- Inhibiting synthesis of the peptidoglycan layer of the bacterial cell wall

D- Inhibiting type II topoisomerase (DNA gyrase)

A- Binding to the 30S subunit of bacterial ribosome- B is the mechanism of action of tetracycline. C is cefalexin and D is ciprofloxacin.

 

More Pharmacology MCQs

Read The Topics on First Aid USMLE Step 1 

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