Repeated USMLE Questions Step 1- Review-176

Q- A drug that increases GABA activity in the central nervous system is prescribed for anxiety. Which class of drugs acts by increasing the frequency of chloride channel opening at the GABA-A receptor?

A- Barbiturates

B- Benzodiazepines

C- Selective serotonin reuptake inhibitors

D- Tricyclic antidepressants

B- Benzodiazepines- Benzodiazepines increase the frequency of chloride channel opening at GABA-A receptors, enhancing inhibitory neurotransmission.

 

Q- A woman has heavy menstrual bleeding and prolonged bleeding time. Platelet count is normal. Which disorder is most likely?

A- Bernard-Soulier syndrome

B- Hemophilia A

C- Von Willebrand disease

D- Vitamin K deficiency

C- Von Willebrand disease- vWF disease causes mucosal bleeding with ↑ bleeding time and normal platelet count (often ↑ PTT too).

 

Q- A newborn develops jaundice and hepatomegaly within the first week of life. Laboratory studies show elevated galactose-1-phosphate levels. Which enzyme deficiency is most likely responsible?

A- Galactokinase

B- Galactose-1-phosphate uridyltransferase

C- Glucose-6-phosphate dehydrogenase

D- Pyruvate dehydrogenase

B- Galactose-1-phosphate uridyltransferase- Classic galactosemia results from deficiency of galactose-1-phosphate uridyltransferase, leading to accumulation of galactose-1-phosphate, liver damage, cataracts, and failure to thrive.

 

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Dr Ray Makar

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