250+ TOP MCQs on Lipid Metabolism and Answers Quiz Exam

This set of Life Sciences Multiple Choice Questions on “Lipid Metabolism”.

1. Name the most active organs in the animal body which have the ability to synthesize triacylglycerol?
A. Spleen
B. Kidney
C. Liver and intestines
D. Adipose tissues

Answer: C
Clarification: In general, all plants and animals have the ability to synthesize triacylglycerol (TAG). In animals, liver and intestines are two most active sites for TAG synthesis. Adipose tissues are the storage site for fat.

2. Triacylglycerol stored in the body as cytoplasmic lipid droplets.
A. True
B. False

Answer: A
Clarification: Triacylglycerol is stored as the cytoplasmic lipid droplets like fat globules, oil bodies, lipid particles, adiposomes etc. These triacylglycerols are enclosed by a monolayer of phospholipids and hydrophobic proteins.

3. Which of the following pathway is not used for triacylglycerol synthesis?
A. Glycerol 3-phosphate pathway
B. Glyoxylate pathway
C. Monoacylglycerol pathway
D. Kennedy pathway

Answer: B
Clarification: Except glyoxylate pathway, all three pathways have been used for the synthesis of triacylglycerol. Kennedy pathway and glycerol 3-phosphate pathway are same which predominates in the liver and adipose tissue while the monoacylglycerol pathway used in intestines.

4. Which of the following enzyme is not used in the synthesis of triacylglycerol?
A. Glycerol-3-phosphate acyltransferase
B. Acylglycerophophate acyltransferase
C. Phosphatidic acid phosphohydrolase
D. Glycogen phosphorylase

Answer: D
Clarification: Triacylglycerol biosynthetic pathway involves the formation of triacylglycerol by glycerol-3-phosphate. It involves four steps catalyzed by all the above enzymes except glycogen phosphorylase. The fourth enzyme is Diacylglycerol acyltransferase which converts diacylglycerol to triacylglycerol.

5. What is lipolysis?
A. Hydrolysis of triacylglycerol
B. Formation of lipids
C. Breakdown of ketone bodies
D. Formation of ketone bodies

Answer: A
Clarification: Hydrolysis of triacylglycerol by lipase is called lipolysis. Triacylglycerol stored in adipose tissues of animals in an insoluble form where they constantly synthesized and broken down again.

6. Which of the following hormone is not used in the hydrolysis of triacylglycerol into the fatty acids in adipose tissues?
A. Epinephrine
B. Norepinephrine
C. Glucagon
D. Insulin

Answer: D
Clarification: Triacylglycerols are converted to free fatty acids and glycerol under the influence of certain hormones. Hormones which control hydrolysis of the TAG are epinephrine, norepinephrine, and glucagon.

7. Mark the INCORRECT statement about the bile salt.
A. These are detergent substances
B. Stored in the gallbladder
C. It is hydrophobic in nature
D. It is made up of cholic acid

Answer: C
Clarification: The surface of bile salt molecule is both hydrophobic and hydrophilic in nature. Bile salts are made up of bile acids, synthesized in the liver and stored in the gallbladder. It facilitates the digestion of lipids.

8. Triacylglycerol packed with the apolipoprotein and cholesterol in lipoprotein aggregate is called_________
A. Chylomicrons
B. VLDL
C. HDL
D. LDL

Answer: A
Clarification: Triacylglycerol packed with cholesterol and apolipoprotein and forms chylomicron which moves through lymphatic system where lipoprotein lipase breaks it in fatty acids and glycerol. Finally, fatty acids absorbed as a fuel or stored.

9. What is the outcome of the accumulation of acetyl-CoA in the mitochondria of the liver?
A. It is used as an energy source
B. It has broken down in to free fatty acids
C. It gets converted to oxaloacetate
D. It forms ketone bodies

Answer: D
Clarification: Most of the acetyl-CoA has been used by citric acid cycle but during starvation acetyl-CoA accumulated in the mitochondria of liver and forms ketone bodies. Formation of ketone bodies by acetyl-CoA is known as ketogenesis.

10. Name the energy source of the brain during starvation?
A. Fat
B. Ketone bodies
C. Protein
D. Lipids

Answer: B
Clarification: In the absence of glucose or during prolonged starvation, the brain gets energy from ketone bodies by converting it to acetyl-CoA. This mechanism is absent in liver so, it cannot utilize ketone bodies as an energy source.

11. What is the biosynthetic source of all steroid hormones?
A. Cholesterol
B. Ketone bodies
C. Carbohydrate
D. Protein

Answer: A
Clarification: Pregnenolone is the precursor of all steroid hormones which is synthesized by cholesterol and catalyzed by desmolase enzyme. It involves the shortening of hydrocarbon chain of cholesterol and hydroxylation of steroid nucleus.

12. The cholesterol serves as the precursor for the following biosynthetic pathways, EXCEPT
a) Bile acid synthesis
b) Steroid hormone synthesis
c) Aldosterone synthesis
d) Thyroid hormone synthesis

13. Which of the following lipids act as lungs surfactants?
a) Phosphatidylcholine
b) Phosphatidylethanolamine
c) Ceramide
d) Phosphatidylinositol

14. Identify the simple lipid from the following?
a) Lecithin
b) Fatty acid
c) Triacylglycerol
d) Steroids

15. All of the following are complex lipids, Except?
a) Phosphatidic acid
b) Cerebroside
c) Cardiolipin
d) Cholesterol

16. Which of the following is an essential fatty acid?
a) Linolenic acid
b) Arachidonic acid
c) Oleic acid
d) Palmitic acid

17. Bile acid is derived from:
a) Cholesterol
b) Amino acids
c) Fatty acids
d) Bilirubin

18. Which of the following lipid is mostly present in mitochondrial membranes?
a) Lecithin
b) Cephalin
c) Cardiolipin
d) Ceramide

19. Insulin enhances the uptake of triacylglycerols in adipose tissues. Which of the following enzyme is activated that facilitates the uptake?
a) Hormone-sensitive lipase
b) Lipoprotein lipase
c) LCAT
d) Apo C-II

20. Familial hypercholesterolemia is a genetic disorder of cholesterol metabolism. The defect lies in the…………………………………………………………………
a) Transport of cholesterol from extrahepatic tissue to the liver
b) Impairment of cholesterol degradative pathway
c) Impairment of uptake of cholesterol by tissues
d) Impairment of HDL metabolism due to deficiency of Apo-A

21. Which of the following inhibits acetyl CoA carboxylase- a rate-limiting enzyme of fatty metabolism?
a) Citrate
b) ATP
c) Malonyl CoA
d) Acyl CoA

22. Acetyl CoA serves as the precursor for the synthesis of cholesterol, and the biosynthesis of cholesterol is tightly regulated.
Which of the following step is a regulatory step of cholesterol biosynthesis?
a) Formation 3-hydroxy-3-methylglutaryl COA
b) Formation of Mevalonate
c) Formation of Isoprenoid Unit
d) Formation of Lansterol

23. The enzyme that regulates the biosynthesis of cholesterol also serves as the druggable target for the reduction of hypercholesterolemia (increase blood cholesterol). Identify the regulatory enzyme from the following options:
a) HMG-CoA synthase
b) HMG- CoA reductase
c) Lansterol oxidase
d) Cholesterol synthase

24. Which of the following hormone increases the synthesis of cholesterol by regulating the enzyme HMG CoA reductase?
a) Insulin
b) Glucagon
c) Glucocorticoids
d) All of the above

25. Sterol Regulatory Binding Protein binds to DNA at the sterol regulatory element to increase the expression of HMG CoA reductase, and synthesis of cholesterol.
What happens when there is the presence of a high cellular concentration of cholesterol?
a) Increases the proteolytic cleavage, release, and shuttling of SREBP into the nucleus
b) Decreases the proteolytic cleavage and release of SREBP from ER
c) Activates SREBP by inducing the conformational change
d) Inhibit SREBP by competitively binding to DNA binding site of SREBP

26. Hormones such as insulin & glucagon regulate HMG CoA reductase by a phosphorylation and dephosphorylation process.
Phosphorylation of HMG CoA reductase results in decreased enzyme activity.
Identify the correct statement from the following:
a) Insulin inhibits kinase that phosphorylates HMG CoA reductase
c) Insulin activates kinase that phosphorylates HMG CoA reductase
c) Insulin activates the phosphatase that removes a phosphate group from HMG CoA reductase
d) Insulin inhibits kinase that phosphorylates HMG CoA reductase

27. Hypercholesterolemia refers to a condition with high cholesterol with a serum cholesterol level of………………………………………
a) >160 mg/dL
b) >200 mg/dL
c) >240 mg/dL
d) >280 mg/dL

28. Which of the following enzyme is responsible for the conversion of cholesterol to cholesterol ester inside the cells?
a) Lecithin Cholesterol Acyl Transferase
b) Acyl CoA Cholesterol Acyl Transferase
c) Cholesterol Esterase
d) None of the Above

29. Which of the following glycolytic intermediates serves as the precursor for the backbone for the synthesis of Triglycerides, Phosphatidylcholine, Phosphatidylethanolamine?
a) Glyceraldehyde-3-phosphate
b) Pyruvate
c) 1-3 Bisphosphoglycerate
d) 3-Phosphoglycerate

30. Ceramide is synthesized in the endoplasmic reticulum from the amino acid serine.
Ceramide is an important signaling molecule (second messenger) that regulates the pathways including which of the following process?
a) apoptosis
b) cell senescence
c) cell differentiation
d) All of the above

31. Identify the phospholipid that possesses a surfactant activity and is synthesized shortly before parturition in full-term infants, and its deficiency in the lungs can cause respiratory distress syndrome.
a) Dipalmitoylphosphatidyletholamine
b) Ceramide
c) Dipalmitoylphosphatidylcholine
d) All of the above

32. A child is was brought to the hospital with the clinical presentation of mental retardation, blindness, and muscular weakness. The biochemical examination showed the accumulation of GM2 gangliosides in the tissues.
What is the possible cause of the disease?
a) Tay Sachs Disease caused by Hexosaminidase A deficiency
b) Fabry Disease caused by Alpha-Galactosidase deficiency
c) Krabbe Disease caused by Beta-Galactosidase deficiency
d) Gaucher Disease caused by Beta-Glucosidase deficiency