Biological significance of cholesterol MCQs With Answer

The biological significance of cholesterol MCQs With Answer focuses on cholesterol’s central roles in cell membranes, steroid hormone synthesis, bile acid formation, and lipoprotein metabolism — essential topics for B. Pharm students. This concise, SEO-friendly introduction highlights cholesterol metabolism, regulation of HMG‑CoA reductase, LDL/HDL functions, reverse cholesterol transport, and clinical links to atherosclerosis and statin therapy. Understanding enzymatic steps, transport proteins (LDL receptor, NPC1L1, CETP), and genetic disorders (familial hypercholesterolemia, PCSK9 mutations) prepares pharmacy students for therapeutics and lab interpretation. These targeted MCQs with answers reinforce biochemical mechanisms, pharmacologic interventions, and clinical relevance for exam success. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which enzyme catalyzes the rate-limiting step in cholesterol biosynthesis?

• HMG-CoA synthase
• HMG-CoA reductase
• Mevalonate kinase
• Squalene synthase

Correct Answer: HMG-CoA reductase

Q2. Cholesterol is an essential component of cell membranes primarily because it:

• Increases membrane permeability to ions
• Acts as a primary energy source
• Modulates membrane fluidity and stability
• Serves as a membrane protein

Correct Answer: Modulates membrane fluidity and stability

Q3. Which transcription factor increases LDL receptor and HMG‑CoA reductase gene expression when cellular cholesterol is low?

• LXRα (Liver X receptor alpha)
• PPARγ
• SREBP2 (Sterol regulatory element-binding protein 2)
• NF-κB

Correct Answer: SREBP2 (Sterol regulatory element-binding protein 2)

Q4. The immediate precursor of cholesterol in the mevalonate pathway is:

• Lanosterol
• Mevalonate
• Squalene
• Farnesyl pyrophosphate

Correct Answer: Lanosterol

Q5. Which protein mediates intestinal absorption of dietary cholesterol?

• ABCA1 transporter
• NPC1L1 (Niemann-Pick C1-Like 1)
• CETP (cholesteryl ester transfer protein)
• LDL receptor

Correct Answer: NPC1L1 (Niemann-Pick C1-Like 1)

Q6. Statins lower plasma LDL cholesterol primarily by:

• Inhibiting intestinal cholesterol absorption
• Upregulating hepatic LDL receptors through HMG‑CoA reductase inhibition
• Activating CETP to transfer cholesterol to HDL
• Directly degrading plasma LDL particles

Correct Answer: Upregulating hepatic LDL receptors through HMG‑CoA reductase inhibition

Q7. Which enzyme converts free cholesterol to cholesteryl esters in plasma HDL particles?

• ACAT (acyl-CoA:cholesterol acyltransferase)
• LCAT (lecithin–cholesterol acyltransferase)
• HMG-CoA reductase
• Cholesterol oxidase

Correct Answer: LCAT (lecithin–cholesterol acyltransferase)

Q8. Familial hypercholesterolemia is most commonly caused by mutations in which gene?

• APOE
• PCSK9
• LDLR (LDL receptor)
• ABCA1

Correct Answer: LDLR (LDL receptor)

Q9. Which of the following is a primary function of HDL in cholesterol metabolism?

• Delivering triglycerides to peripheral tissues
• Facilitating reverse cholesterol transport to the liver
• Carrying dietary cholesterol from intestine to liver
• Activating HMG-CoA reductase

Correct Answer: Facilitating reverse cholesterol transport to the liver

Q10. Conversion of cholesterol into bile acids begins with which enzyme in the liver?

• CYP7A1 (cholesterol 7α-hydroxylase)
• 7β-hydroxylase
• Sterol 12α-hydroxylase
• Bile salt hydrolase

Correct Answer: CYP7A1 (cholesterol 7α-hydroxylase)

Q11. Which of the following drugs blocks intestinal cholesterol absorption by inhibiting NPC1L1?

• Ezetimibe
• Cholestyramine
• Atorvastatin
• Niacin

Correct Answer: Ezetimibe

Q12. ACAT (acyl-CoA:cholesterol acyltransferase) is responsible for:

• Hydrolyzing cholesteryl esters in lysosomes
• Esterifying cholesterol for intracellular storage
• Exporting cholesterol to HDL
• Converting cholesterol into bile acids

Correct Answer: Esterifying cholesterol for intracellular storage

Q13. Elevated oxidized LDL in the arterial wall primarily contributes to:

• Increased HDL production
• Formation of foam cells and atherosclerotic plaques
• Enhanced bile acid synthesis
• Improved endothelial function

Correct Answer: Formation of foam cells and atherosclerotic plaques

Q14. Which lipoprotein class carries the highest proportion of triglycerides in fasting plasma?

• LDL
• HDL
• VLDL
• Chylomicrons

Correct Answer: VLDL

Q15. Mevalonate-derived isoprenoids (farnesyl pyrophosphate, geranylgeranyl pyrophosphate) are important for:

• Lipid digestion in intestine
• Protein prenylation and cell signaling
• Direct cholesterol esterification
• Bile salt reabsorption

Correct Answer: Protein prenylation and cell signaling

Q16. Which enzyme in macrophages hydrolyzes internalized cholesteryl esters to free cholesterol for efflux?

• Cholesteryl ester hydrolase (CEH)
• LCAT
• ACAT
• HMG-CoA reductase

Correct Answer: Cholesteryl ester hydrolase (CEH)

Q17. Which apolipoprotein is the primary ligand for LDL receptor-mediated uptake?

• ApoA-I
• ApoC-II
• ApoB-100
• ApoE

Correct Answer: ApoB-100

Q18. Bile acid sequestrants reduce LDL cholesterol mainly by:

• Inhibiting HMG-CoA reductase directly
• Binding bile acids in the intestine and increasing hepatic bile acid synthesis from cholesterol
• Blocking intestinal absorption of triglycerides
• Increasing HDL synthesis

Correct Answer: Binding bile acids in the intestine and increasing hepatic bile acid synthesis from cholesterol

Q19. Which genetic defect causes increased PCSK9 activity leading to higher LDL levels?

• Gain-of-function mutation in PCSK9
• Loss-of-function mutation in LDLR
• Overexpression of ApoA-I
• Mutation in LCAT

Correct Answer: Gain-of-function mutation in PCSK9

Q20. Cholesterol is the precursor for all the following EXCEPT:

• Glucocorticoids
• Vitamin D
• Bile acids
• Insulin

Correct Answer: Insulin

Q21. Which organ is the major site of cholesterol synthesis in humans?

• Heart
• Liver
• Brain
• Adipose tissue

Correct Answer: Liver

Q22. Which plasma lipoprotein is formed in the intestine and transports dietary lipids?

• VLDL
• Chylomicrons
• LDL
• IDL

Correct Answer: Chylomicrons

Q23. Phosphorylation of HMG‑CoA reductase by AMP-activated protein kinase (AMPK) results in:

• Activation of HMG‑CoA reductase
• Increased cholesterol synthesis
• Inhibition of HMG‑CoA reductase activity
• Ubiquitination of LDL receptor

Correct Answer: Inhibition of HMG‑CoA reductase activity

Q24. CETP (cholesteryl ester transfer protein) facilitates exchange between:

• HDL and LDL/VLDL, transferring cholesteryl esters for triglycerides
• LDL and chylomicrons, transferring phospholipids
• Hepatocytes and enterocytes for bile salts
• ABCA1 and SR-BI receptors

Correct Answer: HDL and LDL/VLDL, transferring cholesteryl esters for triglycerides

Q25. Which lab parameter defines hypercholesterolemia when elevated and is most associated with atherosclerotic risk?

• High HDL cholesterol
• Low triglycerides
• High LDL cholesterol
• High albumin

Correct Answer: High LDL cholesterol

Q26. The drug class that increases LDL receptor recycling and markedly lowers LDL-C by inhibiting PCSK9 is:

• Statins
• PCSK9 monoclonal antibodies
• Bile acid sequestrants
• Fibrates

Correct Answer: PCSK9 monoclonal antibodies

Q27. Which transport protein mediates cholesterol efflux from macrophages to lipid-poor apoA-I?

• NPC1L1
• SR-BI
• ABCA1
• ACAT

Correct Answer: ABCA1

Q28. Which statement about esterified vs free cholesterol is correct?

• Esterified cholesterol is more polar than free cholesterol
• Free cholesterol cannot be transported in lipoproteins
• Esterified cholesterol is the storage/transport form and is more hydrophobic
• Free cholesterol is only found in bile

Correct Answer: Esterified cholesterol is the storage/transport form and is more hydrophobic

Q29. In the context of cholesterol metabolism, SREBP cleavage and activation is triggered by:

• High cellular cholesterol
• Low cellular cholesterol
• High HDL levels
• High bile acid concentration

Correct Answer: Low cellular cholesterol

Q30. Which lipid-lowering agent primarily activates PPARα to lower triglycerides?

• Fibrate (e.g., fenofibrate)
• Statin (e.g., simvastatin)
• Ezetimibe
• Niacin

Correct Answer: Fibrate (e.g., fenofibrate)

Q31. Which cellular organelle houses the early steps of cholesterol biosynthesis?

• Mitochondria
• Endoplasmic reticulum
• Golgi apparatus
• Lysosome

Correct Answer: Endoplasmic reticulum

Q32. Which of the following decreases cholesterol synthesis by promoting HMG-CoA reductase degradation?

• SREBP activation
• Insulin signaling
• High intracellular cholesterol and ubiquitin-mediated proteasomal degradation
• Thyroid hormone deficiency

Correct Answer: High intracellular cholesterol and ubiquitin-mediated proteasomal degradation

Q33. Sitosterolemia, a rare inherited condition of increased plant sterols, results from defects in which transporters?

• NPC1L1
• ABCG5/ABCG8
• LDLR
• SR-BI

Correct Answer: ABCG5/ABCG8

Q34. Which of these is NOT a direct product of the mevalonate pathway?

• Cholesterol
• Ubiquinone (CoQ)
• Dolichol
• Glucose

Correct Answer: Glucose

Q35. HDL scavenger receptor that mediates selective uptake of cholesteryl esters into liver is:

• LDL receptor
• SR-BI (scavenger receptor class B type I)
• ABCA1
• CETP

Correct Answer: SR-BI (scavenger receptor class B type I)

Q36. Which vitamin is synthesized from a cholesterol derivative in the skin under UV light?

• Vitamin A
• Vitamin D
• Vitamin E
• Vitamin K

Correct Answer: Vitamin D

Q37. Cholesterol measurement in routine lipid profile typically reports total cholesterol, HDL, triglycerides; LDL is often estimated using:

• Direct ultracentrifugation method only
• Friedewald formula
• Western blotting
• ELISA for LDL receptor

Correct Answer: Friedewald formula

Q38. Which of the following increases biliary cholesterol secretion and may promote cholesterol gallstone formation?

• Elevated hepatic cholesterol and decreased bile acid synthesis
• Increased bile acid synthesis
• Enhanced intestinal bile acid reabsorption causing low hepatic cholesterol
• Inhibition of HMG-CoA reductase

Correct Answer: Elevated hepatic cholesterol and decreased bile acid synthesis

Q39. Foam cells in atherosclerotic plaques are mainly derived from:

• Smooth muscle cells that lost cholesterol
• Macrophages that have ingested modified LDL and accumulated cholesteryl esters
• Endothelial cells secreting HDL
• Lymphocytes producing antibodies to LDL

Correct Answer: Macrophages that have ingested modified LDL and accumulated cholesteryl esters

Q40. Which adverse effect is most commonly associated with high-dose statin therapy?

• Severe hypoglycemia
• Hepatotoxicity and myopathy (elevated transaminases and muscle enzymes)
• Renal stones
• Hyperthyroidism

Correct Answer: Hepatotoxicity and myopathy (elevated transaminases and muscle enzymes)

Q41. Which apolipoprotein activates lipoprotein lipase to hydrolyze triglycerides?

• ApoA-I
• ApoB-100
• ApoC-II
• ApoE

Correct Answer: ApoC-II

Q42. The primary role of bile acids in digestion is to:

• Hydrolyze triglycerides enzymatically
• Emulsify dietary fats to aid lipase action and micelle formation for lipid absorption
• Transport cholesterol to peripheral tissues
• Inhibit pancreatic enzymes

Correct Answer: Emulsify dietary fats to aid lipase action and micelle formation for lipid absorption

Q43. Which laboratory finding suggests impaired reverse cholesterol transport?

• Elevated HDL cholesterol
• Low HDL cholesterol and dysfunctional ApoA-I
• Low LDL cholesterol
• Normal triglycerides

Correct Answer: Low HDL cholesterol and dysfunctional ApoA-I

Q44. Squalene synthase catalyzes which conversion in cholesterol biosynthesis?

• Acetyl-CoA to HMG-CoA
• Two molecules of farnesyl pyrophosphate to squalene
• Lanosterol to cholesterol
• Mevalonate to isopentenyl pyrophosphate

Correct Answer: Two molecules of farnesyl pyrophosphate to squalene

Q45. Which therapeutic strategy increases HDL-mediated cholesterol efflux from macrophages?

• Inhibition of LCAT
• Upregulation of ABCA1 and ApoA-I mimetics
• Blocking SR-BI function in the liver
• Inhibiting bile acid synthesis

Correct Answer: Upregulation of ABCA1 and ApoA-I mimetics

Q46. The predominant sterol in animal cell membranes is:

• Ergosterol
• Cholesterol
• Campesterol
• Beta-sitosterol

Correct Answer: Cholesterol

Q47. Lipoprotein X (abnormal bile-derived lipoprotein) appears in which clinical condition?

• Familial hypercholesterolemia
• Cholestatic liver disease with obstructive jaundice
• Nephrotic syndrome exclusively
• Hyperthyroidism

Correct Answer: Cholestatic liver disease with obstructive jaundice

Q48. Which molecule provides the two-carbon units (acetyl groups) that start cholesterol synthesis?

• Acetoacetate
• Acetyl-CoA
• Pyruvate carboxylate
• Malonyl-CoA

Correct Answer: Acetyl-CoA

Q49. Which condition is specifically associated with decreased HDL and increased risk of premature coronary artery disease?

• Tangier disease (ABCA1 deficiency)
• Smith-Lemli-Opitz syndrome
• Familial combined hyperlipidemia with high HDL
• Hypobetalipoproteinemia

Correct Answer: Tangier disease (ABCA1 deficiency)

Q50. The clinical benefit of statins beyond LDL lowering (pleiotropic effects) may include:

• Increased platelet aggregation
• Improved endothelial function and reduced vascular inflammation
• Raised CRP levels
• Enhanced hepatic cholesterol synthesis

Correct Answer: Improved endothelial function and reduced vascular inflammation

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

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