Repeated USMLE Questions Step 1- Review- 78

Q- Increased concentration of malonyl-CoA most likely inhibits which one of the following biochemical processes?

A- Fatty acid oxidation

B- Fatty acid synthesis

C- Glycolysis

D- Oxidative phosphorylation

A- Fatty acid oxidation- The rate limiting step in the fatty acid oxidation is inhibited by increased concentration of malonyl-CoA.

Q- A patient presents with biliary colic for a week with pain in his right shoulder after eating a fatty meal. Examination reveals marked right upper quadrant tenderness with inspiration. Which one of the following nerves is responsible for his right shoulder pain?

A- Axillary nerve

B- Intercostal nerve

C- Phrenic nerve

D- Vagus nerve

C- Phrenic nerve- This is most likely a case of cholecystitis confirmed by positive Murphy’s sign. Inflammation of the gall bladder causes irritation of the4 diaphragmatic pleura which is innervated by the phrenic nerve. Nerve root of the phrenic nerve includes the right shoulder.

Q- Which one of the following cardiac conditions presents with an opening snap and a diastolic murmur on auscultation?

A- Aortic stenosis

B- Mitral stenosis

C- Pulmonary valve stenosis

D- Ventricular septal defect

B- Mitral stenosis- Opening snap of the mitral valve and low pitch, rumbling murmur heard at the apex are characteristic of mitral stenosis.

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