Repeated USMLE Questions Step 1- Review- 34

Q- Which one of the following enzymes is most likely deficient in a case of McArdle disease (type V of glycogen storage diseases)?

A- α-1,4- glucosidase

B-Debranching enzyme



D-Myophosphorylase- It is skeletal muscle glycogen phosphorylase. Its deficiency leads to accumulation of glycogen in muscles. 3M, McArdle, Myophosphorylase and Muscle. Blood glucose level is not affected.

Q- Which one of the following organisms is the leading cause of urinary tract infections (UTI)?


B-Escherichia coli

C-Proteus mirabilis

D-Pseudomonas aeruginosa

B-Escherichia coli- E coli is the leading cause of UTI. Nitrite test is positive (reduction of urinary nitrates).

Q- Paradoxical splitting of heart sounds can be heard in which one of the following cardiac conditions?

A-Aortic stenosis

B-Atrial septal defect

C-Pulmonary stenosis

D-Right bundle branch block

A-Aortic stenosis- P2 sound occurs before delayed A2 sound so, it reversed the normal order of valve closure. Wide splitting occurs in pulmonary stenosis and RBBB while fixed splitting occurs in ASD.

More Repeated USMLE Step 1 Questions 

Leave a Comment