Repeated USMLE Questions Step 1- Review- 34

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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

C- Glucose-6-phasphatase

D- Myophosphorylase

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)?

A- Enterococcus

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.

 

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