Physician Assistant Scientific Knowledge 2

Question 1

Which enzyme is responsible for the rate-limiting step in cholesterol biosynthesis?

Accepted Answer

HMG-CoA reductase

Answer

HMG-CoA reductase catalyzes the conversion of HMG-CoA to mevalonate, the committed and rate-limiting step in cholesterol synthesis, and is the target of statins.

Question 2

The Fick principle is used to calculate cardiac output. Which formula correctly represents it?

Accepted Answer

CO = VO2 / (CaO2 - CvO2)

Answer

The Fick principle states cardiac output equals oxygen consumption divided by the arteriovenous oxygen content difference.

Question 3

Which cell type produces surfactant in the lung?

Accepted Answer

Type II pneumocytes

Answer

Type II pneumocytes synthesize and secrete pulmonary surfactant, which reduces alveolar surface tension and prevents collapse.

Question 4

During oxidative phosphorylation, the chemiosmotic gradient drives ATP synthesis through which complex?

Accepted Answer

Complex V (ATP synthase)

Answer

Complex V (ATP synthase) uses the proton-motive force generated by the electron transport chain to synthesize ATP from ADP and inorganic phosphate.

Question 5

Which blood group system determines the Rh factor, and what antigen is most clinically significant?

Accepted Answer

Rh system; D antigen

Answer

The Rh blood group system's D antigen is the most immunogenic and clinically important, particularly in hemolytic disease of the newborn.

Physician Assistant Practice Test

Physician Assistant Practice Test

Physician Assistant Scientific Knowledge 2