Đề thi, bài tập trắc nghiệm online Hóa sinh lipid – Đề 3

1. What is the function of waxes in biological systems?

A. Primary energy storage in animals.

B. Structural component of cell membranes in bacteria.

C. Protective coating on leaves, fruits, and animal skin.

D. Precursor for steroid hormones in vertebrates.

2. What is the role of bile salts in lipid digestion?

A. To hydrolyze triacylglycerols into fatty acids and glycerol.

B. To emulsify dietary fats, increasing the surface area for enzymatic digestion.

C. To transport fatty acids across the intestinal membrane.

D. To synthesize triacylglycerols in the intestinal cells.

3. Which type of lipid is the most abundant component of cell membranes?

A. Triacylglycerols

B. Phospholipids

C. Steroids

D. Fatty acids

4. Lipids are a diverse group of biomolecules that are largely hydrophobic. Which of the following is NOT a primary function of lipids in living organisms?

A. Long-term energy storage

B. Structural components of cell membranes

C. Catalysis of biochemical reactions

D. Signaling molecules (hormones)

5. Which of the following lipids is a precursor for steroid hormones?

A. Cholesterol

B. Palmitic acid

C. Glycerol

D. Sphingosine

6. What is the primary difference between saturated and unsaturated fatty acids?

A. Saturated fatty acids contain phosphate groups, while unsaturated fatty acids do not.

B. Saturated fatty acids contain only single bonds between carbon atoms, while unsaturated fatty acids contain at least one double bond.

C. Unsaturated fatty acids are solid at room temperature, while saturated fatty acids are liquid.

D. Saturated fatty acids are synthesized in plants, while unsaturated fatty acids are synthesized in animals.

7. Gaucher disease is a lysosomal storage disorder caused by a deficiency in the enzyme glucocerebrosidase. Which type of lipid accumulates in this disease?

A. Cholesterol esters

B. Triacylglycerols

C. Glucocerebroside

D. Gangliosides

8. What is the condition called that is characterized by elevated levels of ketone bodies in the blood?

A. Hyperglycemia

B. Ketoacidosis

C. Hypoglycemia

D. Hyperlipidemia

9. What are sphingolipids primarily synthesized from?

A. Glycerol and fatty acids

B. Sphingosine and fatty acids

C. Cholesterol and fatty acids

D. Isoprenoids

10. How many ATP molecules (approximately) can be generated from the complete oxidation of one molecule of palmitic acid (a 16-carbon saturated fatty acid)?

A. 10

B. 32

C. 106

D. 256

11. Which lipoprotein is primarily responsible for transporting cholesterol from the liver to peripheral tissues?

A. HDL (High-Density Lipoprotein)

B. LDL (Low-Density Lipoprotein)

C. VLDL (Very-Low-Density Lipoprotein)

D. Chylomicrons

12. Which lipid is a major component of myelin sheath, insulating nerve fibers?

A. Triacylglycerol

B. Cholesterol

C. Sphingomyelin

D. Phosphatidylserine

13. What is the role of phospholipase A2 (PLA2)?

A. To synthesize phospholipids from fatty acids and glycerol.

B. To hydrolyze phospholipids at the sn-2 position, releasing arachidonic acid.

C. To transport phospholipids between organelles.

D. To degrade sphingolipids in lysosomes.

14. In fatty acid biosynthesis, which molecule is the primary building block for fatty acid chains?

A. Glucose

B. Acetyl-CoA

C. Amino acids

D. Glycerol-3-phosphate

15. Eicosanoids are derived from polyunsaturated fatty acids. Which polyunsaturated fatty acid is the primary precursor for most eicosanoids in humans?

A. Oleic acid

B. Palmitic acid

C. Arachidonic acid

D. Stearic acid

16. What is the role of carnitine in fatty acid oxidation?

A. To activate fatty acids in the cytoplasm.

B. To transport long-chain fatty acids into the mitochondrial matrix.

C. To inhibit beta-oxidation when energy is abundant.

D. To synthesize fatty acids in the mitochondria.

17. Which of the following is NOT a ketone body?

A. Acetoacetate

B. Beta-hydroxybutyrate

C. Acetone

D. Pyruvate

18. Ketogenesis is the process of producing ketone bodies. Under what metabolic condition is ketogenesis typically increased?

A. High carbohydrate intake

B. Well-fed state

C. Fasting or starvation

D. Insulin-stimulated conditions

19. Which lipid-derived molecule is involved in visual signal transduction?

A. Retinal

B. Tocopherol (Vitamin E)

C. Phylloquinone (Vitamin K)

D. Calciferol (Vitamin D)

20. Which enzyme is the key regulatory enzyme in fatty acid biosynthesis?

A. HMG-CoA reductase

B. Acetyl-CoA carboxylase

C. Carnitine acyltransferase

D. Lipoprotein lipase

21. What is the role of HDL (High-Density Lipoprotein)?

A. Transporting triacylglycerols from the liver to adipose tissue.

B. Transporting cholesterol from peripheral tissues back to the liver.

C. Delivering dietary lipids from the intestine to the liver.

D. Synthesizing cholesterol in peripheral tissues.

22. Which enzyme is the target of statin drugs, commonly used to lower cholesterol levels?

A. Acetyl-CoA carboxylase

B. HMG-CoA reductase

C. Fatty acid synthase

D. Cholesterol ester transfer protein (CETP)

23. Which of the following is a characteristic feature of lipid rafts in cell membranes?

A. They are composed primarily of unsaturated fatty acids.

B. They are highly fluid and disordered regions of the membrane.

C. They are enriched in cholesterol and sphingolipids, making them more ordered and less fluid than surrounding membrane regions.

D. They are devoid of membrane proteins.

24. Which organ is primarily responsible for ketogenesis?

A. Brain

B. Liver

C. Muscle

D. Adipose tissue

25. Which lipid derivative acts as a local hormone and is involved in inflammation and pain?

A. Cholesterol

B. Prostaglandins

C. Triacylglycerols

D. Phosphatidylcholine

26. Which enzyme primarily hydrolyzes triacylglycerols in the small intestine?

A. Amylase

B. Lipase

C. Protease

D. Nuclease

27. What are chylomicrons?

A. Enzymes that digest cholesterol in the small intestine.

B. Lipoprotein particles that transport dietary lipids from the intestine to other parts of the body.

C. Hormones that regulate lipid metabolism.

D. Structural components of cell membranes made of carbohydrates and lipids.

28. Which of the following is an essential fatty acid that must be obtained from the diet?

A. Palmitic acid

B. Stearic acid

C. Linoleic acid (omega-6)

D. Oleic acid (omega-9)

29. What is the impact of trans-fatty acids on human health?

A. They are beneficial for cardiovascular health.

B. They have no significant impact on health.

C. They increase LDL cholesterol and decrease HDL cholesterol, increasing the risk of cardiovascular disease.

D. They primarily affect liver function but not cardiovascular health.

30. Where does fatty acid oxidation (beta-oxidation) primarily occur in eukaryotic cells?

A. Cytoplasm

B. Endoplasmic reticulum

C. Mitochondria

D. Golgi apparatus