Đề 10 – Bài tập, đề thi trắc nghiệm online Hóa sinh lipid

1. Phospholipids are amphipathic molecules crucial for cell membrane structure. What does `amphipathic` mean in this context?

A. Having a hydrophobic tail and a hydrophilic head

B. Having only hydrophobic regions

C. Having only hydrophilic regions

D. Being composed of only fatty acids

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

A. Hydrolyzing triacylglycerols

B. Emulsifying dietary fats

C. Transporting fatty acids into intestinal cells

D. Synthesizing cholesterol

3. How does the concentration of malonyl-CoA affect fatty acid beta-oxidation?

A. Activates beta-oxidation

B. Inhibits beta-oxidation

C. Has no effect on beta-oxidation

D. Required as a substrate for beta-oxidation

4. In the context of membrane fluidity, how does the presence of unsaturated fatty acids in phospholipids affect the membrane?

A. Decreases membrane fluidity by allowing tighter packing

B. Increases membrane fluidity by disrupting packing

C. Has no significant effect on membrane fluidity

D. Solidifies the membrane at room temperature

5. What is the primary function of brown adipose tissue, compared to white adipose tissue?

A. Long-term energy storage as triacylglycerols

B. Heat generation (thermogenesis)

C. Hormone secretion (e.g., leptin)

D. Insulation and protection of organs

6. Which lipid-derived hormone plays a crucial role in regulating blood glucose levels?

A. Cortisol

B. Insulin

C. Glucagon

D. Prostaglandins

7. What is the role of phospholipase C (PLC) in cell signaling?

A. Hydrolyzes triacylglycerols to release fatty acids for energy

B. Cleaves phosphatidylinositol bisphosphate (PIP2) to generate second messengers IP3 and DAG

C. Synthesizes phospholipids for membrane biogenesis

D. Transports phospholipids between organelles

8. Lipoproteins are responsible for transporting lipids in the bloodstream. Which lipoprotein is primarily involved in transporting cholesterol from the liver to peripheral tissues, potentially contributing to plaque formation in arteries?

A. HDL (High-Density Lipoprotein)

B. LDL (Low-Density Lipoprotein)

C. VLDL (Very-Low-Density Lipoprotein)

D. Chylomicrons

9. What is the role of Acyl Carrier Protein (ACP) in fatty acid synthesis?

A. To transport fatty acids into mitochondria

B. To carry the growing fatty acid chain during synthesis

C. To activate fatty acids for beta-oxidation

D. To regulate acetyl-CoA carboxylase activity

10. Which of the following is NOT a major class of lipids?

A. Proteins

B. Triacylglycerols

C. Phospholipids

D. Steroids

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

A. High carbohydrate diet

B. Well-fed state

C. Fasting or starvation

D. Insulin-stimulated state

12. Which of the following lipids is NOT found in significant amounts in animal cell membranes?

A. Phospholipids

B. Cholesterol

C. Triacylglycerols

D. Sphingolipids

13. Which of the following statements about lipid digestion and absorption is INCORRECT?

A. Pancreatic lipase hydrolyzes triacylglycerols into monoacylglycerols and fatty acids.

B. Bile salts aid in the emulsification of dietary lipids.

C. Short-chain fatty acids are absorbed directly into the bloodstream.

D. Chylomicrons transport lipids from the liver to the intestine.

14. Cholesterol is an essential lipid with diverse roles. Which of the following is a key function of cholesterol in animal cells?

A. Primary energy source

B. Precursor for steroid hormones

C. Structural component of plant cell walls

D. Major component of RNA

15. Which of the following is a potential consequence of a deficiency in carnitine?

A. Increased synthesis of fatty acids

B. Impaired transport of long-chain fatty acids into mitochondria

C. Enhanced beta-oxidation of fatty acids

D. Accumulation of ketone bodies in the blood

16. What is the consequence of inhibiting HMG-CoA reductase, the target of statin drugs?

A. Increased fatty acid synthesis

B. Decreased cholesterol synthesis

C. Increased triacylglycerol synthesis

D. Decreased ketone body synthesis

17. How do trans fatty acids, often found in processed foods, affect lipid metabolism and health?

A. They are metabolized like saturated fatty acids and have no adverse health effects.

B. They raise LDL cholesterol and lower HDL cholesterol levels, increasing the risk of cardiovascular disease.

C. They are essential fatty acids and beneficial for heart health.

D. They are rapidly metabolized and do not accumulate in the body.

18. How does insulin primarily affect fatty acid metabolism?

A. Stimulates fatty acid breakdown (beta-oxidation)

B. Inhibits fatty acid synthesis

C. Stimulates fatty acid synthesis and storage

D. Has no significant effect on fatty acid metabolism

19. Lipid rafts are specialized microdomains within cell membranes. What is the main characteristic of lipid rafts regarding their lipid composition?

A. Enriched in polyunsaturated fatty acids

B. Depleted in cholesterol

C. Enriched in cholesterol and sphingolipids

D. Composed primarily of glycerophospholipids

20. Beta-oxidation is a crucial metabolic pathway for energy production from lipids. Where does beta-oxidation of fatty acids primarily occur in eukaryotic cells?

A. Cytoplasm

B. Endoplasmic reticulum

C. Mitochondria

D. Lysosomes

21. Which enzyme is responsible for hydrolyzing triacylglycerols stored in adipose tissue, releasing fatty acids and glycerol into the bloodstream?

A. Lipoprotein lipase

B. Hormone-sensitive lipase

C. Pancreatic lipase

D. Phospholipase A2

22. Which enzyme catalyzes the committed step in fatty acid synthesis?

A. Acetyl-CoA carboxylase

B. Fatty acid synthase

C. Thiolase

D. Enoyl-CoA hydratase

23. Essential fatty acids are those that cannot be synthesized by the human body and must be obtained from the diet. Which of the following is an example of an essential fatty acid?

A. Palmitic acid

B. Oleic acid

C. Linoleic acid

D. Stearic acid

24. Which of the following is a characteristic feature of sphingolipids that distinguishes them from glycerophospholipids?

A. Presence of a glycerol backbone

B. Presence of fatty acid chains

C. Presence of a sphingosine backbone

D. Presence of a phosphate group

25. How do omega-3 and omega-6 fatty acids differ in their chemical structure?

A. Omega-3 fatty acids are saturated, while omega-6 are unsaturated.

B. Omega-3 fatty acids have the first double bond at the 3rd carbon from the omega end, while omega-6 have it at the 6th carbon.

C. Omega-3 fatty acids contain more double bonds than omega-6 fatty acids.

D. Omega-6 fatty acids are essential, while omega-3 are non-essential.

26. Which of the following is a characteristic of lipid storage diseases (lysosomal storage disorders)?

A. Increased breakdown of lipids in lysosomes

B. Accumulation of specific lipids within lysosomes due to enzyme deficiencies

C. Enhanced transport of lipids across cell membranes

D. Decreased synthesis of lipids in the endoplasmic reticulum

27. Lipids are a diverse group of biomolecules with various functions. 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)

28. Which type of fatty acid contains no carbon-carbon double bonds and is typically solid at room temperature?

A. Unsaturated fatty acid

B. Polyunsaturated fatty acid

C. Saturated fatty acid

D. Monounsaturated fatty acid

29. What is the key difference between waxes and triacylglycerols (fats and oils)?

A. Waxes contain glycerol, while triacylglycerols do not.

B. Waxes are esters of fatty acids with long-chain alcohols, while triacylglycerols are esters of fatty acids with glycerol.

C. Waxes are hydrophilic, while triacylglycerols are hydrophobic.

D. Waxes are used for energy storage, while triacylglycerols are for structural components.

30. Eicosanoids, such as prostaglandins and leukotrienes, are signaling lipids derived from polyunsaturated fatty acids. What is a primary role of eicosanoids in the body?

A. Long-term energy storage

B. Structural component of cell membranes

C. Regulation of inflammation and pain

D. Digestion of dietary fats