Introduction: This collection of Functions of cell MCQs With Answer is tailored for B.Pharm students preparing for exams and competitive tests. Covering core cell biology topics—organelles, membrane transport, signal transduction, cell cycle, apoptosis, and drug-target interactions—these MCQs emphasize clinical and pharmaceutical relevance. Questions explore mitochondrial energetics, lysosomal degradation, endocytosis, transporters like P-gp, receptor signaling and metabolic pathways important in drug action and toxicity. Clear answers and focused concepts help reinforce learning, improve recall, and aid exam preparation. The set is keyword-rich for easy reference: cell functions MCQs, cell biology MCQs, organelle functions, membrane transport, and pharmacological implications. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. Which organelle is primarily responsible for ATP production through oxidative phosphorylation?
- Mitochondrion
- Golgi apparatus
- Lysosome
- Ribosome
Correct Answer: Mitochondrion
Q2. What is the main function of lysosomes in a eukaryotic cell?
- Protein synthesis
- Intracellular digestion of macromolecules
- ATP generation
- Lipid synthesis
Correct Answer: Intracellular digestion of macromolecules
Q3. Which cellular structure is primarily involved in protein synthesis?
- Ribosome
- Peroxisome
- Endoplasmic reticulum (smooth)
- Mitochondrial matrix
Correct Answer: Ribosome
Q4. Smooth endoplasmic reticulum (SER) is especially important for which function relevant to pharmacology?
- Carbohydrate digestion
- Detoxification and lipid synthesis including drug metabolism (CYP enzymes)
- ATP synthesis
- Protein glycosylation
Correct Answer: Detoxification and lipid synthesis including drug metabolism (CYP enzymes)
Q5. Which process describes receptor-mediated uptake of specific molecules into the cell?
- Phagocytosis
- Pinocytosis
- Receptor-mediated endocytosis
- Exocytosis
Correct Answer: Receptor-mediated endocytosis
Q6. P-glycoprotein (P-gp) functions primarily as what in pharmacology?
- Drug-metabolizing enzyme
- Efflux transporter that pumps drugs out of cells
- Ion channel that allows drug entry
- Receptor for drug binding
Correct Answer: Efflux transporter that pumps drugs out of cells
Q7. Which cellular junction allows direct cytoplasmic exchange of ions and small molecules between adjacent cells?
- Tight junction
- Desmosome
- Gap junction
- Hemidesmosome
Correct Answer: Gap junction
Q8. The Na+/K+ ATPase maintains which of the following essential to cell function?
- Intracellular ATP synthesis
- Resting membrane potential and ionic gradients
- Protein folding in ER
- Lysosomal pH gradient
Correct Answer: Resting membrane potential and ionic gradients
Q9. Which organelle is central to synthesis and initial post-translational modification of secretory and membrane proteins?
- Golgi apparatus
- Rough endoplasmic reticulum (RER)
- Peroxisome
- Mitochondrion
Correct Answer: Rough endoplasmic reticulum (RER)
Q10. Which cellular process is primarily responsible for removal of damaged organelles and proteins via lysosomal degradation?
- Apoptosis
- Autophagy
- Nucleotide excision repair
- Exocytosis
Correct Answer: Autophagy
Q11. Which molecule acts as a common second messenger in G protein–coupled receptor signaling important for many drug actions?
- Dihydroxyacetone phosphate
- cAMP (cyclic adenosine monophosphate)
- Glutathione
- ATP synthase
Correct Answer: cAMP (cyclic adenosine monophosphate)
Q12. What is the primary function of peroxisomes in eukaryotic cells?
- Beta-oxidation of long-chain fatty acids and detoxification of hydrogen peroxide
- Synthesis of ribosomal RNA
- Energy production via oxidative phosphorylation
- Calcium storage
Correct Answer: Beta-oxidation of long-chain fatty acids and detoxification of hydrogen peroxide
Q13. In the context of drug delivery, which endocytic route is most selective and receptor-specific?
- Macropinocytosis
- Clathrin-mediated receptor-mediated endocytosis
- Bulk-phase pinocytosis
- Phagocytosis
Correct Answer: Clathrin-mediated receptor-mediated endocytosis
Q14. Which component of the cytoskeleton is primarily responsible for intracellular vesicle transport and motor proteins like kinesin and dynein?
- Microfilaments (actin)
- Intermediate filaments
- Microtubules
- Extracellular matrix
Correct Answer: Microtubules
Q15. Which organelle contains enzymes for steroid synthesis and is abundant in steroid-secreting cells?
- Rough ER
- Smooth ER
- Golgi apparatus
- Peroxisome
Correct Answer: Smooth ER
Q16. During apoptosis, which mitochondrial protein is released to activate caspases?
- Cytochrome c
- Bcl-2
- ATP synthase
- Ubiquitin
Correct Answer: Cytochrome c
Q17. What is the primary role of the Golgi apparatus in the secretory pathway?
- Transcription of mRNA
- Sorting, modification (glycosylation), and packaging of proteins for secretion or delivery
- ATP generation
- DNA replication
Correct Answer: Sorting, modification (glycosylation), and packaging of proteins for secretion or delivery
Q18. Which transport mechanism requires energy and moves substances against their concentration gradient?
- Simple diffusion
- Facilitated diffusion
- Active transport
- Osmosis
Correct Answer: Active transport
Q19. Which cellular structure forms the barrier controlling paracellular passage between epithelial cells?
- Gap junctions
- Tight junctions (zonula occludens)
- Desmosomes
- Basal lamina
Correct Answer: Tight junctions (zonula occludens)
Q20. Which process describes the synthesis of glucose from non-carbohydrate precursors and is regulated within cells?
- Glycolysis
- Gluconeogenesis
- Glycogenolysis
- Beta-oxidation
Correct Answer: Gluconeogenesis
Q21. Which protein complex tags proteins for proteasomal degradation in the ubiquitin–proteasome pathway?
- Clathrin coat
- Ubiquitin conjugation system
- SNARE complex
- Ribosomal subunit
Correct Answer: Ubiquitin conjugation system
Q22. Which ion channel activity is directly responsible for the rapid depolarization phase of neuronal action potentials?
- Voltage-gated potassium channels
- Ligand-gated chloride channels
- Voltage-gated sodium channels
- Sodium–calcium exchanger
Correct Answer: Voltage-gated sodium channels
Q23. Endoplasmic reticulum stress and unfolded protein response (UPR) primarily affect which cellular function relevant to drug toxicity?
- Membrane potential maintenance
- Protein folding and secretory pathway integrity
- Nucleotide synthesis
- Golgi-mediated lipid secretion
Correct Answer: Protein folding and secretory pathway integrity
Q24. Which cellular location houses cytochrome P450 enzymes important for Phase I drug metabolism?
- Inner mitochondrial membrane
- Smooth endoplasmic reticulum (microsomes)
- Lysosomal lumen
- Golgi cisternae
Correct Answer: Smooth endoplasmic reticulum (microsomes)
Q25. Which molecule primarily drives secondary active transport by providing an electrochemical gradient?
- ATP directly
- Sodium ion gradient established by Na+/K+ ATPase
- cAMP concentration
- Calcium stored in ER
Correct Answer: Sodium ion gradient established by Na+/K+ ATPase
Q26. Which cytoskeletal element provides structural support and tensile strength in epithelial cells?
- Microtubules
- Actin microfilaments
- Intermediate filaments (e.g., keratin)
- Centrioles
Correct Answer: Intermediate filaments (e.g., keratin)
Q27. Which cell organelle contributes to cellular calcium storage and release, important for signal transduction?
- Golgi apparatus
- Endoplasmic reticulum
- Lysosome
- Peroxisome
Correct Answer: Endoplasmic reticulum
Q28. Which phase of the cell cycle is DNA synthesized and replicated?
- G1 phase
- S phase
- G2 phase
- M phase (mitosis)
Correct Answer: S phase
Q29. Which cellular mechanism allows a drug to be released from secretory vesicles into the extracellular space?
- Endocytosis
- Exocytosis
- Transcytosis
- Autophagy
Correct Answer: Exocytosis
Q30. Which protein family regulates mitochondrial outer membrane permeabilization during apoptosis?
- SNARE proteins
- Bcl-2 family proteins
- Clathrin heavy chains
- Heat shock proteins
Correct Answer: Bcl-2 family proteins
Q31. The blood–brain barrier restricts drug entry primarily due to which cellular feature of brain capillary endothelial cells?
- Abundant fenestrations
- Tight junctions and efflux transporters
- High pinocytotic activity
- Loose basement membrane
Correct Answer: Tight junctions and efflux transporters
Q32. Which mitochondrial function, if impaired, is most likely to cause lactic acidosis due to increased anaerobic glycolysis?
- Beta-oxidation only
- Oxidative phosphorylation and electron transport chain
- Protein glycosylation
- Peroxisomal oxidation
Correct Answer: Oxidative phosphorylation and electron transport chain
Q33. Which enzyme present in lysosomes is crucial for degrading glycosaminoglycans and whose deficiency causes storage diseases?
- Cytochrome P450
- Lysosomal hydrolases (e.g., iduronidase)
- ATP synthase
- DNA polymerase
Correct Answer: Lysosomal hydrolases (e.g., iduronidase)
Q34. Which mechanism best explains how ionotropic receptors differ from metabotropic receptors?
- Ionotropic receptors are G-protein coupled; metabotropic are ligand-gated ion channels
- Ionotropic receptors are ligand-gated ion channels causing rapid responses; metabotropic receptors activate second messenger cascades causing slower, modulatory responses
- Both are identical in mechanism
- Metabotropic receptors directly allow ion flow without intermediates
Correct Answer: Ionotropic receptors are ligand-gated ion channels causing rapid responses; metabotropic receptors activate second messenger cascades causing slower, modulatory responses
Q35. Which cellular feature facilitates rapid cell-to-cell electrical coupling in cardiac tissue?
- Tight junctions
- Gap junctions composed of connexins
- Desmosomes only
- Hemidesmosomes
Correct Answer: Gap junctions composed of connexins
Q36. Which process is primarily responsible for transmembrane movement of water across cell membranes?
- Diffusion through ion channels
- Active transport by pumps
- Osmosis via aquaporins or lipid bilayer
- Endocytosis
Correct Answer: Osmosis via aquaporins or lipid bilayer
Q37. Which cellular organelle synthesizes most transmembrane and secreted proteins and presents them into the ER lumen?
- Free cytosolic ribosomes
- Ribosomes bound to rough endoplasmic reticulum
- Mitochondrial ribosomes
- Peroxisomal ribosomes
Correct Answer: Ribosomes bound to rough endoplasmic reticulum
Q38. In drug-induced mitochondrial toxicity, inhibition of which complex in the electron transport chain commonly reduces ATP production?
- Complex II (succinate dehydrogenase) only
- Complex I, III, or IV leading to impaired electron transport
- Complex V increases ATP production
- Complexes are not involved in ATP production
Correct Answer: Complex I, III, or IV leading to impaired electron transport
Q39. Which intracellular signaling lipid is produced by phospholipase C and leads to Ca2+ release from ER?
- cGMP
- Diacylglycerol (DAG) and inositol trisphosphate (IP3), with IP3 releasing Ca2+
- Adenosine
- Phosphatidylcholine only
Correct Answer: Diacylglycerol (DAG) and inositol trisphosphate (IP3), with IP3 releasing Ca2+
Q40. Which membrane lipid component contributes most to membrane fluidity and is a target for certain lipophilic drugs?
- Sphingomyelin only
- Cholesterol and phospholipid fatty acyl chain composition
- DNA within the membrane
- Glycosaminoglycans
Correct Answer: Cholesterol and phospholipid fatty acyl chain composition
Q41. Which transport process across the cell membrane does not require protein carriers or energy and depends on concentration gradient?
- Facilitated diffusion
- Simple diffusion through lipid bilayer
- Primary active transport
- Endocytosis
Correct Answer: Simple diffusion through lipid bilayer
Q42. Which cellular organelle is involved in packaging and trafficking of proteins to lysosomes, plasma membrane, or secretion?
- Mitochondrion
- Golgi apparatus
- Peroxisome
- Ribosome
Correct Answer: Golgi apparatus
Q43. Which enzyme family localized in the endoplasmic reticulum is crucial for oxidative protein folding and formation of disulfide bonds?
- Protein disulfide isomerases (PDI)
- DNA ligases
- ATPases
- Lipases
Correct Answer: Protein disulfide isomerases (PDI)
Q44. Which cell cycle checkpoint prevents cells with damaged DNA from entering mitosis?
- G1/S checkpoint and G2/M checkpoint, with G2/M specifically preventing mitosis entry
- S-phase checkpoint only
- M-phase checkpoint only
- No checkpoints exist
Correct Answer: G1/S checkpoint and G2/M checkpoint, with G2/M specifically preventing mitosis entry
Q45. Which membrane transporter class is commonly implicated in multi-drug resistance by exporting chemotherapeutic agents out of cancer cells?
- Solute carrier (SLC) uptake transporters only
- ATP-binding cassette (ABC) transporters such as P-gp (ABCB1)
- Ligand-gated ion channels
- Voltage-gated calcium channels
Correct Answer: ATP-binding cassette (ABC) transporters such as P-gp (ABCB1)
Q46. Which cellular event is a hallmark of necrosis but not apoptosis?
- Programmed DNA laddering
- Uncontrolled cell swelling and plasma membrane rupture leading to inflammation
- Orderly cell shrinkage
- Phagocytic clearance without inflammation
Correct Answer: Uncontrolled cell swelling and plasma membrane rupture leading to inflammation
Q47. Which cellular organelle contains cardiolipin and is central to intrinsic apoptosis and energy metabolism?
- Endoplasmic reticulum
- Mitochondrion
- Golgi apparatus
- Peroxisome
Correct Answer: Mitochondrion
Q48. Which mechanism best explains how tight junctions influence drug absorption across intestinal epithelium?
- Tight junctions increase paracellular permeability to large proteins
- Tight junctions restrict paracellular passage, limiting passive drug diffusion between cells
- Tight junctions actively pump drugs into blood
- Tight junctions convert drugs to metabolites
Correct Answer: Tight junctions restrict paracellular passage, limiting passive drug diffusion between cells
Q49. Which cellular enzyme defends against oxidative stress by reducing hydrogen peroxide to water in peroxisomes?
- Catalase
- Ligase
- Dehydrogenase in mitochondria
- RNA polymerase
Correct Answer: Catalase
Q50. Which signaling pathway involves receptor tyrosine kinases and is frequently targeted by anticancer drugs due to its role in cell growth and proliferation?
- Wnt/beta-catenin only
- Receptor tyrosine kinase → Ras → MAPK (ERK) pathway
- cGMP–PKG pathway only
- Glycolysis pathway
Correct Answer: Receptor tyrosine kinase → Ras → MAPK (ERK) pathway
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