Structure of cell MCQs With Answer

Structure of cell MCQs With Answer is a focused resource for B.Pharm students to master cell structure and function through targeted practice. This collection covers organelles, plasma membrane architecture, membrane transport, cytoskeleton, nucleus, endomembrane system, mitochondria, lysosomes, peroxisomes, and cell junctions. Each MCQ emphasizes mechanisms relevant to pharmacology—drug transporters, ER-based metabolism, autophagy, and cytoskeletal drug targets—helping you connect cell biology to drug action and delivery. The questions include clear options and correct answers to reinforce learning and prepare you for exams. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which organelle is the primary site of ATP production in eukaryotic cells?

• Mitochondria
• Golgi apparatus
• Ribosome
• Peroxisome

Correct Answer: Mitochondria

Q2. The fluid mosaic model of the plasma membrane describes which key features?

• Static lipid bilayer with fixed proteins
• Lipid bilayer with mobile proteins and dynamic lateral diffusion
• Protein-only layer without lipids
• Crystalline arrangement of lipids

Correct Answer: Lipid bilayer with mobile proteins and dynamic lateral diffusion

Q3. Which of the following is a transmembrane protein involved in ATP-dependent drug efflux relevant to multidrug resistance?

• Glucose transporter (GLUT)
• P-glycoprotein (P-gp/ABCB1)
• Clathrin
• Actin

Correct Answer: P-glycoprotein (P-gp/ABCB1)

Q4. Which organelle is primarily responsible for protein glycosylation and sorting for secretion?

• Rough endoplasmic reticulum
• Golgi apparatus
• Lysosome
• Mitochondrion

Correct Answer: Golgi apparatus

Q5. Ribosomes attached to the rough ER synthesize proteins destined for which locations?

• Peripheral cytosolic enzymes only
• Secretory pathway, plasma membrane, or lysosomes
• Mitochondrial matrix exclusively
• Nucleus exclusively

Correct Answer: Secretory pathway, plasma membrane, or lysosomes

Q6. Which sequence directs a newly synthesized protein to the endoplasmic reticulum?

• Mitochondrial targeting sequence rich in arginine
• Signal peptide with a hydrophobic core at the N-terminus
• Peroxisomal SKL tripeptide at the C-terminus
• Ubiquitin tag

Correct Answer: Signal peptide with a hydrophobic core at the N-terminus

Q7. Which cytoskeletal element is composed of tubulin and is the main component of microtubules?

• Actin filaments (microfilaments)
• Intermediate filaments
• Microtubules composed of alpha- and beta-tubulin dimers
• Collagen fibrils

Correct Answer: Microtubules composed of alpha- and beta-tubulin dimers

Q8. Which organelle contains hydrolytic enzymes and functions in intracellular digestion?

• Peroxisome
• Lysosome
• Golgi apparatus
• Endosome

Correct Answer: Lysosome

Q9. The rough endoplasmic reticulum is characterized by which feature?

• High concentration of cholesterol and smooth surface
• Ribosomes bound to cytosolic side synthesizing membrane/secretory proteins
• Main site of beta-oxidation of fatty acids
• Primary location for DNA replication

Correct Answer: Ribosomes bound to cytosolic side synthesizing membrane/secretory proteins

Q10. Which process transports molecules into the cell via clathrin-coated pits?

• Phagocytosis
• Pinocytosis
• Clathrin-mediated endocytosis
• Passive diffusion

Correct Answer: Clathrin-mediated endocytosis

Q11. Peroxisomes are primarily involved in which metabolic activity?

• Synthesis of ATP via oxidative phosphorylation
• Detoxification of hydrogen peroxide and beta-oxidation of very long-chain fatty acids
• Protein glycosylation
• DNA transcription

Correct Answer: Detoxification of hydrogen peroxide and beta-oxidation of very long-chain fatty acids

Q12. Which structure forms the spindle apparatus during mitosis?

• Actin filaments
• Intermediate filaments
• Microtubules originating from centrosomes
• Endoplasmic reticulum

Correct Answer: Microtubules originating from centrosomes

Q13. Which protein complex degrades ubiquitinated proteins in the cytosol?

• Lysosome
• Proteasome (26S)
• Ribosome
• Peroxisome

Correct Answer: Proteasome (26S)

Q14. Which membrane lipid contributes most to membrane fluidity at physiological temperatures?

• Saturated phospholipids with long acyl chains
• Cholesterol exclusively increases fluidity at all temps
• Unsaturated phospholipids with cis double bonds
• Glycosphingolipids only

Correct Answer: Unsaturated phospholipids with cis double bonds

Q15. The nuclear pore complex primarily facilitates which function?

• Replication of DNA
• Selective transport of RNA and proteins between nucleus and cytoplasm
• Protein synthesis
• ATP synthesis

Correct Answer: Selective transport of RNA and proteins between nucleus and cytoplasm

Q16. Which organelle is the major site of cytochrome P450 enzymes involved in drug metabolism?

• Smooth endoplasmic reticulum
• Peroxisome
• Rough endoplasmic reticulum
• Golgi apparatus

Correct Answer: Smooth endoplasmic reticulum

Q17. Which junctional complex allows direct cytoplasmic communication between adjacent animal cells?

• Desmosome
• Tight junction
• Gap junction composed of connexins
• Hemidesmosome

Correct Answer: Gap junction composed of connexins

Q18. What is the typical microtubule arrangement in eukaryotic motile cilia and flagella?

• 9+2 arrangement of microtubule doublets
• 7+1 arrangement
• Random actin bundles
• Microfilament core only

Correct Answer: 9+2 arrangement of microtubule doublets

Q19. Which of the following best describes the role of the Golgi in protein processing?

• Protein translation from mRNA
• Post-translational modifications like glycosylation, sulfation, and sorting
• Replication of genetic material
• ATP production via substrate-level phosphorylation

Correct Answer: Post-translational modifications like glycosylation, sulfation, and sorting

Q20. Autophagy is a cellular process primarily involved in:

• Exporting proteins from the cell
• Selective degradation and recycling of intracellular components via autophagosomes
• Protein synthesis on ribosomes
• Generation of membrane potentials

Correct Answer: Selective degradation and recycling of intracellular components via autophagosomes

Q21. Which of these is a characteristic of prokaryotic cells compared to eukaryotic cells?

• Membrane-bound nucleus present
• Organelles like mitochondria present
• 70S ribosomes and absence of membrane-bound nucleus
• Endoplasmic reticulum prominent

Correct Answer: 70S ribosomes and absence of membrane-bound nucleus

Q22. Which ion pump is electrogenic and helps maintain resting membrane potential?

• Glucose transporter
• Na+/K+ ATPase pumping 3 Na+ out and 2 K+ in
• H+/K+ ATPase pumping equal charges
• Passive K+ channel only

Correct Answer: Na+/K+ ATPase pumping 3 Na+ out and 2 K+ in

Q23. Which organelle contains catalase as a major enzyme?

• Lysosome
• Peroxisome
• Golgi apparatus
• Nucleus

Correct Answer: Peroxisome

Q24. Which of the following targets are microtubule-disrupting anticancer drugs acting upon?

• Actin filaments
• Tubulin polymerization dynamics in microtubules
• DNA topoisomerase II only
• Phospholipid bilayer composition

Correct Answer: Tubulin polymerization dynamics in microtubules

Q25. The nucleolus is the site of:

• Ribosomal RNA transcription and ribosome subunit assembly
• mRNA splicing only
• DNA replication origins
• Lipid synthesis

Correct Answer: Ribosomal RNA transcription and ribosome subunit assembly

Q26. Which mechanism describes passive movement of solutes down their concentration gradient through a channel?

• Primary active transport
• Secondary active transport
• Facilitated diffusion via channel proteins
• Endocytosis

Correct Answer: Facilitated diffusion via channel proteins

Q27. TOM and TIM translocases are involved in targeting proteins to which organelle?

• Nucleus
• Endoplasmic reticulum
• Mitochondria
• Golgi apparatus

Correct Answer: Mitochondria

Q28. Which of the following best explains membrane asymmetry?

• Both leaflets have identical lipid and protein composition
• Inner and outer leaflets have different lipid and protein distributions maintained by flippases/floppases
• Asymmetry is due to random lipid movement across bilayer
• Only cholesterol creates asymmetry

Correct Answer: Inner and outer leaflets have different lipid and protein distributions maintained by flippases/floppases

Q29. Which structure anchors cells to the extracellular matrix and involves integrins?

• Gap junction
• Tight junction
• Focal adhesion
• Desmosome only

Correct Answer: Focal adhesion

Q30. Which molecule is a common peripheral membrane protein association mechanism?

• Transmembrane alpha-helix spanning the bilayer
• Hydrophobic lipid anchor or electrostatic interactions with membrane phospholipids
• DNA binding motif
• Integral beta-barrel insertion

Correct Answer: Hydrophobic lipid anchor or electrostatic interactions with membrane phospholipids

Q31. Which organelle plays a central role in apoptosis through cytochrome c release?

• Nucleus
• Mitochondria
• Endoplasmic reticulum only
• Golgi apparatus

Correct Answer: Mitochondria

Q32. Which of these is NOT a function of the smooth endoplasmic reticulum?

• Detoxification and drug metabolism
• Synthesis of steroid hormones and lipids
• Processing of secretory proteins by ribosomes
• Storage of calcium in muscle (sarcoplasmic reticulum)

Correct Answer: Processing of secretory proteins by ribosomes

Q33. Which cytoskeletal component provides tensile strength and is composed of proteins like keratin and vimentin?

• Microtubules
• Actin filaments
• Intermediate filaments
• Myosin thick filaments

Correct Answer: Intermediate filaments

Q34. Which process requires ATP directly to move solutes against their concentration gradient?

• Facilitated diffusion
• Primary active transport
• Simple diffusion
• Osmosis

Correct Answer: Primary active transport

Q35. The signal recognition particle (SRP) is essential for:

• Import of proteins into nucleus through nuclear pores
• Targeting ribosome-nascent chain complexes to the ER membrane
• Inserting proteins into mitochondrial inner membrane
• Export of mRNA from nucleus

Correct Answer: Targeting ribosome-nascent chain complexes to the ER membrane

Q36. Which of the following best describes endosomes?

• Primary site of protein synthesis
• Membrane-bound compartments involved in sorting internalized material to recycling or degradative pathways
• Sites of ATP generation
• Extracellular matrix components

Correct Answer: Membrane-bound compartments involved in sorting internalized material to recycling or degradative pathways

Q37. Which cellular structure is the main site of ribosomal assembly and is visible as dense nucleolar regions?

• Nuclear envelope
• Nucleolus
• Chromatin euchromatin
• Golgi cisternae

Correct Answer: Nucleolus

Q38. Which lipid modification commonly anchors proteins to the inner leaflet of the plasma membrane?

• N-linked glycosylation
• GPI anchor to outer leaflet only
• Myristoylation or palmitoylation (acylation)
• Phosphorylation of serine residues

Correct Answer: Myristoylation or palmitoylation (acylation)

Q39. Tight junctions between epithelial cells primarily function to:

• Allow free diffusion of solutes between cells
• Create a selective barrier preventing paracellular flow and maintain cell polarity
• Provide mechanical anchoring between cells
• Facilitate electrical coupling

Correct Answer: Create a selective barrier preventing paracellular flow and maintain cell polarity

Q40. Which organelle is involved in the initial folding and quality control of newly synthesized secretory proteins?

• Rough endoplasmic reticulum
• Golgi apparatus only
• Peroxisome
• Mitochondria

Correct Answer: Rough endoplasmic reticulum

Q41. Which transporter mediates secondary active transport by using an ion gradient established by primary active transport?

• ATP-binding cassette (ABC) directly hydrolyzing ATP
• Symporter or antiporter like Na+/glucose cotransporter using Na+ gradient
• Simple diffusion channel
• Proteasome

Correct Answer: Symporter or antiporter like Na+/glucose cotransporter using Na+ gradient

Q42. Which of the following best characterizes chromatin in its transcriptionally active form?

• Highly condensed heterochromatin
• Euchromatin with less condensed structure and active transcription
• Completely DNA-free regions
• Organized into nucleoli only

Correct Answer: Euchromatin with less condensed structure and active transcription

Q43. Which event occurs during the unfolded protein response (UPR) in the ER?

• Decrease in chaperone expression
• Upregulation of chaperones and attenuation of overall protein synthesis to restore folding homeostasis
• Immediate apoptosis without signaling
• Export of misfolded proteins to extracellular space

Correct Answer: Upregulation of chaperones and attenuation of overall protein synthesis to restore folding homeostasis

Q44. Which molecule is commonly used as a marker for lysosomal pH-dependent enzyme activity?

• Cytochrome c
• Acid hydrolases such as cathepsins
• ATP synthase
• Ribosomal RNA

Correct Answer: Acid hydrolases such as cathepsins

Q45. Caveolae are specialized plasma membrane invaginations rich in which protein?

• Clathrin
• Caveolin
• Connexin
• Integrin

Correct Answer: Caveolin

Q46. Which component of the electron transport chain accepts electrons from NADH?

• Complex IV (cytochrome c oxidase)
• Complex I (NADH:ubiquinone oxidoreductase)
• ATP synthase
• Cytochrome c only

Correct Answer: Complex I (NADH:ubiquinone oxidoreductase)

Q47. What is the primary role of the extracellular matrix (ECM) in tissues?

• Site of ATP production
• Provides structural support, signaling cues, and influences cell behavior
• Protein synthesis and folding
• Genetic material storage

Correct Answer: Provides structural support, signaling cues, and influences cell behavior

Q48. Which of the following is a feature of mitochondrial DNA (mtDNA)?

• Linear chromosomes packaged with histones
• Circular genome inherited maternally and encoding components of oxidative phosphorylation
• Encoded in the nucleus only
• Contains exclusively noncoding RNA

Correct Answer: Circular genome inherited maternally and encoding components of oxidative phosphorylation

Q49. Which pathway targets proteins for degradation by linking ubiquitin to lysine residues on substrate proteins?

• Autophagy only
• Ubiquitin-proteasome system targeting proteins for proteasomal degradation
• Lysosomal secretion pathway
• Signal peptide cleavage in ER

Correct Answer: Ubiquitin-proteasome system targeting proteins for proteasomal degradation

Q50. Which process describes receptor-mediated endocytosis leading to lysosomal degradation of internalized ligand-receptor complexes?

• Constitutive exocytosis only
• Clathrin-mediated endocytosis followed by endosome-lysosome pathway
• Direct transport through nuclear pores
• Passive diffusion across membrane

Correct Answer: Clathrin-mediated endocytosis followed by endosome-lysosome pathway

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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