Pathogenesis of cell injury – membrane damage MCQs With Answer

Pathogenesis of cell injury – membrane damage MCQs With Answer

The pathogenesis of cell injury centers on membrane damage, a critical concept for B. Pharm students studying cellular injury mechanisms, drug toxicity, and disease pathology. Membrane damage results from oxidative stress, lipid peroxidation, calcium influx, ATP depletion, phospholipase activation, and mitochondrial permeability transition, leading to necrosis, apoptosis, or regulated cell death forms like ferroptosis. Understanding biochemical markers (e.g., LDH, MDA), signaling cascades (caspases, calpains), and pharmacological interventions (antioxidants, calcium chelators, thiol donors) helps in designing safer drugs and protective therapies. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which process directly initiates membrane lipid peroxidation in cell injury?

• Excess intracellular calcium activating proteases
• Generation of reactive oxygen species (ROS)
• ATP-dependent ion pump failure
• Activation of caspases

Correct Answer: Generation of reactive oxygen species (ROS)

Q2. The primary biochemical consequence of lipid peroxidation on plasma membranes is:

• Cross-linking of DNA strands
• Loss of membrane fluidity and increased permeability
• Enhanced ATP synthesis
• Hyperactivation of Na+/K+ ATPase

Correct Answer: Loss of membrane fluidity and increased permeability

Q3. Which intracellular ion rise is most implicated in membrane damage and activation of degradative enzymes?

• Sodium (Na+)
• Potassium (K+)
• Calcium (Ca2+)
• Chloride (Cl-)

Correct Answer: Calcium (Ca2+)

Q4. Mitochondrial permeability transition (MPT) contributes to membrane damage primarily by:

• Increasing ATP production
• Causing mitochondrial swelling and outer membrane rupture
• Enhancing antioxidant capacity
• Stabilizing cardiolipin

Correct Answer: Causing mitochondrial swelling and outer membrane rupture

Q5. Which enzyme family is directly responsible for degrading membrane phospholipids during injury?

• Kinases
• Phospholipases
• Polymerases
• Dehydrogenases

Correct Answer: Phospholipases

Q6. A major lipid peroxidation product used as a biomarker of membrane damage is:

• Malondialdehyde (MDA)
• Urea
• Glutathione
• ATP

Correct Answer: Malondialdehyde (MDA)

Q7. During ischemia-reperfusion injury, which mechanism exacerbates membrane damage upon reperfusion?

• Decreased oxygen leading to reduced ROS
• Sudden burst of reactive oxygen species and calcium overload
• Activation of DNA repair enzymes
• Enhanced membrane lipid synthesis

Correct Answer: Sudden burst of reactive oxygen species and calcium overload

Q8. Which antioxidant directly reduces lipid hydroperoxides in membranes?

• Vitamin B12
• Vitamin E (alpha-tocopherol)
• Insulin
• Albumin

Correct Answer: Vitamin E (alpha-tocopherol)

Q9. Failure of Na+/K+ ATPase during membrane injury leads to which immediate cellular change?

• Cell shrinkage due to loss of water
• Cell swelling due to sodium and water influx
• Decreased intracellular sodium
• Hyperpolarization of membrane potential

Correct Answer: Cell swelling due to sodium and water influx

Q10. Lysosomal membrane permeabilization contributes to cell injury by releasing:

• ATP molecules
• Lysosomal hydrolytic enzymes (e.g., cathepsins)
• Phospholipid bilayers
• Ribosomal RNA

Correct Answer: Lysosomal hydrolytic enzymes (e.g., cathepsins)

Q11. Which regulated cell death is characterized by iron-dependent lipid peroxidation targeting membranes?

• Apoptosis
• Autophagy
• Ferroptosis
• Necroptosis

Correct Answer: Ferroptosis

Q12. Nitric oxide (NO) can cause membrane damage primarily when it reacts with superoxide to form:

• Hydrogen peroxide
• Peroxynitrite (ONOO-)
• Glutathione
• Uric acid

Correct Answer: Peroxynitrite (ONOO-)

Q13. Which membrane constituent’s alteration increases susceptibility to peroxidative damage?

• High saturated fatty acid content
• High polyunsaturated fatty acid content
• Increased cholesterol content only
• Increased transmembrane proteins

Correct Answer: High polyunsaturated fatty acid content

Q14. In drug-induced membrane injury, metabolic activation of a xenobiotic to a free radical intermediate commonly involves:

• CYP450 enzymes
• DNA polymerase
• Na+/K+ ATPase
• Lysosomal acid lipase

Correct Answer: CYP450 enzymes

Q15. Which assay is commonly used to estimate lipid peroxidation in tissues?

• ELISA for caspase-3
• TBARS (Thiobarbituric acid reactive substances)
• Western blot for Na+/K+ ATPase
• PCR for mitochondrial DNA

Correct Answer: TBARS (Thiobarbituric acid reactive substances)

Q16. Calcium-activated proteases that degrade cytoskeletal and membrane proteins are called:

• Kinases
• Calpains
• Reverse transcriptases
• Oxidases

Correct Answer: Calpains

Q17. Which of the following is an early ultrastructural feature of membrane injury visible by electron microscopy?

• Chromatin fragmentation only late
• Plasma membrane blebbing and mitochondrial swelling
• Complete nuclear dissolution immediately
• Stable intact membranes with no change

Correct Answer: Plasma membrane blebbing and mitochondrial swelling

Q18. ATP depletion leads to membrane damage mainly by impairing which membrane process?

• Passive diffusion of gases
• Active ion transport (e.g., Na+/K+ ATPase)
• Spontaneous lipid synthesis
• Protein translation in ribosomes

Correct Answer: Active ion transport (e.g., Na+/K+ ATPase)

Q19. Which cellular antioxidant is critical for protecting membrane lipids from peroxidation?

• Reduced glutathione (GSH)
• Hemoglobin
• Fibrinogen
• Albumin esterases

Correct Answer: Reduced glutathione (GSH)

Q20. Which form of cell death typically shows early loss of plasma membrane integrity and inflammatory response?

• Apoptosis
• Necrosis
• Autophagy
• Programmed cell senescence

Correct Answer: Necrosis

Q21. Which membrane repair mechanism involves exocytosis of intracellular vesicles to patch the damaged plasma membrane?

• Endocytosis of membrane fragments
• Vesicle-mediated membrane resealing (patch repair)
• Proteasomal degradation of lipids
• Mitochondrial fusion only

Correct Answer: Vesicle-mediated membrane resealing (patch repair)

Q22. Which lipid class located in the inner mitochondrial membrane is critical for membrane integrity and is vulnerable in oxidative injury?

• Phosphatidylcholine
• Cardiolipin
• Cholesteryl ester
• Sphingosine-1-phosphate

Correct Answer: Cardiolipin

Q23. The release of intracellular enzymes (e.g., LDH) into extracellular fluid indicates:

• Enhanced protein synthesis
• Plasma membrane damage with loss of integrity
• Improved membrane repair
• Activation of mitochondrial biogenesis

Correct Answer: Plasma membrane damage with loss of integrity

Q24. Which reactive species is a primary initiator of lipid peroxidation chain reactions?

• Hydroxyl radical (•OH)
• Nitrogen gas
• Carbon dioxide
• Molecular hydrogen

Correct Answer: Hydroxyl radical (•OH)

Q25. In pharmacology, N-acetylcysteine protects membranes by replenishing:

• ATP stores
• Reduced glutathione (GSH)
• Calcium concentration
• Sodium gradients

Correct Answer: Reduced glutathione (GSH)

Q26. Which caspase family member directly executes apoptotic membrane blebbing and membrane changes?

• Caspase-8 initiator only
• Caspase-3 effector
• Caspase-1 inflammatory only
• Reverse transcriptase

Correct Answer: Caspase-3 effector

Q27. Phosphatidylserine externalization to the outer leaflet of the plasma membrane signals:

• Enhanced ATP production
• Apoptotic cell recognition by phagocytes
• Lipid synthesis activation
• Inhibition of caspases

Correct Answer: Apoptotic cell recognition by phagocytes

Q28. Which drug class can reduce calcium-mediated membrane damage during ischemia?

• Calcium channel blockers
• Beta-lactam antibiotics
• ACE inhibitors only
• Proton pump inhibitors

Correct Answer: Calcium channel blockers

Q29. Membrane lipid asymmetry loss during injury is primarily due to dysfunction of which type of enzyme?

• Flippases and translocases
• DNA ligases
• Glycogen phosphorylase
• RNA polymerase

Correct Answer: Flippases and translocases

Q30. Copper and iron catalyze membrane lipid peroxidation via the Fenton reaction producing which radical?

• Nitric oxide radical
• Hydroxyl radical (•OH)
• Peroxynitrite exclusively
• Superoxide dismutase

Correct Answer: Hydroxyl radical (•OH)

Q31. Which cellular compartment is a major source of ROS that damage membranes?

• Smooth endoplasmic reticulum
• Mitochondria (electron transport chain)
• Golgi lumen only
• Extracellular matrix

Correct Answer: Mitochondria (electron transport chain)

Q32. In experimental models, which chemical is used to induce lipid peroxidation and mimic membrane oxidative injury?

• Butylated hydroxytoluene (BHT) as antioxidant
• t-Butyl hydroperoxide (t-BHP)
• Glucose
• Sucrose

Correct Answer: t-Butyl hydroperoxide (t-BHP)

Q33. Which membrane transporter dysfunction contributes to intracellular calcium rise during injury?

• Sodium-calcium exchanger (NCX) failure
• Glutamate transporter overactivity
• Facilitated diffusion of oxygen
• Mitochondrial ribosome activation

Correct Answer: Sodium-calcium exchanger (NCX) failure

Q34. Phospholipase A2 (PLA2) activation during membrane injury leads to release of:

• Glycogen
• Arachidonic acid and lysophospholipids
• Cholesterol esters
• DNA fragments

Correct Answer: Arachidonic acid and lysophospholipids

Q35. Which lipid oxidation end-product can form adducts with proteins, altering membrane protein function?

• Malondialdehyde (MDA)
• Water
• Oxygen gas
• Sodium chloride

Correct Answer: Malondialdehyde (MDA)

Q36. Ferroptosis inhibitors protect membranes by:

• Promoting mitochondrial fission
• Inhibiting lipid peroxidation and iron-dependent ROS
• Activating caspase cascade
• Increasing lysosomal rupture

Correct Answer: Inhibiting lipid peroxidation and iron-dependent ROS

Q37. Which protein acts as a key antioxidant enzyme reducing hydrogen peroxide and indirectly protecting membranes?

• Catalase
• RNA polymerase II
• Phosphofructokinase
• DNA helicase

Correct Answer: Catalase

Q38. Which membrane phenomenon is characteristic of early reversible cell injury?

• Nuclear fragmentation
• Cellular swelling and plasma membrane blebs
• Complete cell lysis
• Dense calcification

Correct Answer: Cellular swelling and plasma membrane blebs

Q39. Reactive aldehydes from lipid peroxidation can impair membrane enzymes by:

• Serving as substrates for ATPases
• Cross-linking and carbonylating membrane proteins
• Increasing membrane cholesterol biosynthesis
• Promoting ribosomal assembly

Correct Answer: Cross-linking and carbonylating membrane proteins

Q40. Which oxidative enzyme in neutrophils contributes to extracellular and membrane-targeted ROS generation?

• NADPH oxidase (NOX)
• Pepsin
• RNAse
• Hexokinase

Correct Answer: NADPH oxidase (NOX)

Q41. Which membrane lipoprotein alteration increases membrane rigidity and affects drug interactions?

• Decrease in cholesterol
• Increase in cholesterol-to-phospholipid ratio
• Complete loss of proteins only
• Increased water content only

Correct Answer: Increase in cholesterol-to-phospholipid ratio

Q42. Which intracellular process can amplify membrane damage by producing more ROS during protein folding stress?

• Endoplasmic reticulum (ER) stress and unfolded protein response
• Glycolysis enhancement only
• Ribosomal RNA degradation
• Exocytosis of vesicles

Correct Answer: Endoplasmic reticulum (ER) stress and unfolded protein response

Q43. Which pharmacological agent is used experimentally to chelate iron and reduce membrane lipid peroxidation?

• Deferoxamine
• Amoxicillin
• Cholesterol
• Propranolol

Correct Answer: Deferoxamine

Q44. Membrane rupture and release of intracellular damage-associated molecular patterns (DAMPs) triggers:

• Immunosuppression exclusively
• Innate immune activation and inflammation
• Complete tissue regeneration without inflammation
• Exclusive activation of adaptive immunity only

Correct Answer: Innate immune activation and inflammation

Q45. Which lipid-modifying enzyme generates lysophosphatidylcholine, a detergent-like molecule that perturbs membranes?

• Phospholipase A2 (PLA2)
• Lipase in adipose tissue only
• Lactate dehydrogenase
• ATP synthase

Correct Answer: Phospholipase A2 (PLA2)

Q46. In membrane injury, protein oxidation often leads to:

• Increased enzymatic activity uniformly
• Loss of function and increased proteolytic degradation
• Immediate protein synthesis upregulation
• Formation of new functional membrane channels

Correct Answer: Loss of function and increased proteolytic degradation

Q47. Which imaging technique can best reveal early membrane integrity loss and cell swelling in tissues?

• Light microscopy only for gross changes
• Transmission electron microscopy (TEM)
• X-ray plain film
• Ultrasound for intracellular membranes

Correct Answer: Transmission electron microscopy (TEM)

Q48. The term “oxidative burst” in phagocytes describes a rapid increase in ROS meant to:

• Promote membrane repair in phagocytes
• Kill engulfed microbes but potentially damage host membranes
• Synthesize new phospholipids
• Stimulate ATP production

Correct Answer: Kill engulfed microbes but potentially damage host membranes

Q49. Which change in membrane carbohydrate components can impair cell recognition and clearance of injured cells?

• Losing sialic acid residues exposing galactose residues
• Complete loss of phospholipids only
• Increased ATP in glycoproteins
• Removal of all membrane proteins

Correct Answer: Losing sialic acid residues exposing galactose residues

Q50. A drug that preserves membrane integrity during oxidative stress would likely have which properties?

• Pro-oxidant and iron-releasing
• Antioxidant, radical-scavenging, and membrane-stabilizing
• Only DNA intercalating activity
• Selective lysosomal destabilization

Correct Answer: Antioxidant, radical-scavenging, and membrane-stabilizing

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.

Mail- Sachin@pharmacyfreak.com