Question 1

Which of the following best describes the structure shown in the first image (Image 1)?

Accepted Answer

A diacylglycerol, consisting of a glycerol backbone esterified to two fatty acids and a free hydroxyl group.

Question 2

Which of the following statements about pulmonary surfactant is CORRECT?

Accepted Answer

Its main lipid component is lecithin (phosphatidylcholine), which constitutes 70-80% of the surfactant lipids.

Question 3

A newborn presents with respiratory distress syndrome (RDS). Which of the following laboratory findings would most likely be observed in the amniotic fluid?

Accepted Answer

A low L/S ratio (less than 1.5)

Question 4

Which enzyme is responsible for maintaining the asymmetry of phospholipids in the plasma membrane by moving phosphatidylserine from the outer to the inner leaflet?

Accepted Answer

Flippase

Question 5

Which of the following is the only significant sphingophospholipid in humans and is a major component of myelin?

Accepted Answer

Sphingomyelin

Question 6

A patient with obstructive jaundice is found to have increased bile acids in the urine. Which of the following is the most likely explanation for this finding?

Accepted Answer

Impaired excretion of bile acids into the intestine, leading to their accumulation and spillover into the urine

Question 7

Which of the following best describes the role of cholesterol in the body?

Accepted Answer

It is a precursor for bile acids, steroid hormones, and vitamin D.

Question 8

Which of the following is the rate-limiting enzyme in the synthesis of bile acids from cholesterol?

Accepted Answer

7α-hydroxylase

Question 9

A patient with cholelithiasis (gallstones) is found to have a mole ratio of bile salts and phospholipids to cholesterol less than 10:1. What is the significance of this finding?

Accepted Answer

It suggests a lithogenic (stone-forming) bile composition, predisposing to cholesterol gallstones.

Question 10

Which of the following statements about the antioxidant defense system in the lungs of premature infants is CORRECT?

Accepted Answer

The antioxidant defense system includes superoxide dismutase, glutathione peroxidase, and catalase.

Question 11

Which of the following best explains why administration of glucocorticoids to pregnant women at risk of preterm delivery accelerates fetal lung maturation?

Accepted Answer

Glucocorticoids stimulate the synthesis of surfactant lipids, particularly lecithin.

Question 12

Which of the following is a function of glycosphingolipids in the plasma membrane?

Accepted Answer

They are involved in cell recognition and signal transduction.

Question 13

A patient with a deficiency in flippase activity would most likely exhibit which of the following abnormalities in their cell membranes?

Accepted Answer

Accumulation of phosphatidylserine on the outer leaflet of the plasma membrane

Question 14

Which of the following is a direct precursor of sphingomyelin in its biosynthetic pathway?

Accepted Answer

Ceramide

Question 15

Which of the following best describes the fate of bile acids after their secretion into the intestine?

Accepted Answer

They are reabsorbed in the ileum and returned to the liver via the enterohepatic circulation.

Question 16

Which of the following is a toxic secondary bile acid that can cause hemolysis and fever if it accumulates?

Accepted Answer

Lithocholic acid

Question 17

A patient with a genetic defect in the enzyme 7α-hydroxylase would most likely have which of the following abnormalities?

Accepted Answer

Decreased synthesis of bile acids from cholesterol

Question 18

Which of the following best explains why a low L/S ratio in amniotic fluid is associated with an increased risk of neonatal respiratory distress syndrome?

Accepted Answer

It reflects insufficient synthesis of lecithin (phosphatidylcholine), a key component of surfactant.

Question 19

Which of the following is a major function of phospholipids in cellular membranes?

Accepted Answer

They act as precursors for eicosanoids and participate in signal transduction.

Phospholipids, Glycosphingolipids, and Cholesterol: Structure, Function, and Clinical Relevance

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