COMLEX-USA Biomedical Sciences

Question 1

Which enzyme is deficient in Tay-Sachs disease, leading to accumulation of GM2 ganglioside?

Accepted Answer

Hexosaminidase A

Answer

Glucocerebrosidase

Answer

Sphingomyelinase

Answer

Alpha-galactosidase A

Question 2

A mutation in which gene is most commonly associated with hereditary breast and ovarian cancer syndrome?

Accepted Answer

BRCA1/2

Answer

TP53

Answer

APC

Answer

RB1

Question 3

The 'watershed' area between the superior and inferior mesenteric artery territories, most vulnerable to ischemia, is located at:

Accepted Answer

Splenic flexure

Answer

Hepatic flexure

Answer

Sigmoid colon

Answer

Cecum

Question 4

Which complement pathway is activated by antibody-antigen complexes and begins with C1q binding?

Accepted Answer

Classical pathway

Answer

Alternative pathway

Answer

Lectin pathway

Answer

Terminal pathway

Question 5

During which phase of the cell cycle does DNA replication occur?

Accepted Answer

S phase

Answer

G1 phase

Answer

G2 phase

Answer

M phase

Question 6

The sliding filament theory of muscle contraction states that sarcomere shortening results from:

Accepted Answer

Myosin heads pulling actin toward the M line

Answer

Shortening of actin and myosin filaments

Answer

Z-disc disintegration

Answer

Titin protein contraction