Structure and functions of the cell MCQs With Answer

Understanding the structure and functions of the cell is essential for B.Pharm students, linking cell biology with pharmacology and drug action. This concise overview emphasizes organelles — nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes — and core concepts such as cell membrane composition, membrane transport, signal transduction, cytoskeleton, and cell cycle. Mastery of cellular ultrastructure and mechanisms like ATP production, receptor-mediated endocytosis, ion channels, and intracellular trafficking supports drug targeting, pharmacokinetics, and toxicology. These MCQs probe functional details and clinical relevance to strengthen exam readiness and practical understanding in drug development and therapeutic interventions. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which component of the plasma membrane primarily determines membrane fluidity at physiological temperature?

• Cholesterol content
• Integral membrane proteins
• Carbohydrate side chains
• Peripheral proteins

Correct Answer: Cholesterol content

Q2. Which organelle is the main site of ATP production through oxidative phosphorylation?

• Mitochondrion
• Golgi apparatus
• Rough endoplasmic reticulum
• Lysosome

Correct Answer: Mitochondrion

Q3. Which structure is involved in protein synthesis and is abundant on the rough endoplasmic reticulum?

• Ribosomes
• Peroxisomes
• Clathrin-coated pits
• Proteasomes

Correct Answer: Ribosomes

Q4. Clathrin-coated vesicles are primarily associated with which cellular process?

• Receptor-mediated endocytosis
• Autophagy
• Constitutive exocytosis
• Proteasomal degradation

Correct Answer: Receptor-mediated endocytosis

Q5. Which pump is directly responsible for maintaining the resting membrane potential in most animal cells?

• Na+/K+ ATPase
• Ca2+ ATPase
• H+/K+ ATPase
• Glucose transporter (GLUT)

Correct Answer: Na+/K+ ATPase

Q6. Which cytoskeletal element is the main track for kinesin- and dynein-mediated vesicle transport?

• Microtubules
• Actin microfilaments
• Intermediate filaments
• Extracellular matrix fibers

Correct Answer: Microtubules

Q7. Which organelle contains hydrolytic enzymes and functions in intracellular digestion and autophagy?

• Lysosome
• Peroxisome
• Endosome
• Golgi apparatus

Correct Answer: Lysosome

Q8. The Golgi apparatus modifies and sorts proteins destined for secretion. Which modification commonly occurs in the Golgi?

• Glycosylation of proteins
• Translation of proteins from mRNA
• ATP synthesis
• Lipid beta-oxidation

Correct Answer: Glycosylation of proteins

Q9. Which membrane transport process requires specific carrier proteins but no direct energy input?

• Facilitated diffusion
• Primary active transport
• Endocytosis
• Exocytosis

Correct Answer: Facilitated diffusion

Q10. Which nuclear substructure is the site of ribosomal RNA (rRNA) transcription and ribosome assembly?

• Nucleolus
• Nuclear lamina
• Nuclear pore complex
• Chromatin

Correct Answer: Nucleolus

Q11. Which process is a major mechanism for regulated secretion of peptide hormones and neurotransmitters?

• Calcium-dependent exocytosis of secretory vesicles
• Autophagy-mediated release
• Passive diffusion through channels
• Proteasomal export

Correct Answer: Calcium-dependent exocytosis of secretory vesicles

Q12. Which organelle is primarily involved in detoxification of hydrogen peroxide and fatty acid oxidation?

• Peroxisome
• Mitochondrion
• Lysosome
• Smooth endoplasmic reticulum

Correct Answer: Peroxisome

Q13. Which type of cell junction allows direct cytoplasmic exchange of small molecules and ions between adjacent cells?

• Gap junctions
• Tight junctions
• Desmosomes
• Hemi-desmosomes

Correct Answer: Gap junctions

Q14. Which enzyme complex on the inner mitochondrial membrane creates a proton gradient used for ATP synthesis?

• Electron transport chain (ETC)
• Fatty acid synthase
• DNA polymerase
• Ribulose bisphosphate carboxylase

Correct Answer: Electron transport chain (ETC)

Q15. Ubiquitin-proteasome pathway targets proteins for degradation mainly by tagging them with:

• Ubiquitin molecules
• Glycosyl residues
• Phosphate groups
• Lipid anchors

Correct Answer: Ubiquitin molecules

Q16. Which receptor class commonly signals via heterotrimeric G proteins and influences second messengers like cAMP?

• G protein-coupled receptors (GPCRs)
• Ligand-gated ion channels
• Intracellular nuclear receptors
• Tyrosine kinase receptors

Correct Answer: G protein-coupled receptors (GPCRs)

Q17. Which of the following best describes receptor-mediated endocytosis specificity?

• Ligand binds to a specific cell-surface receptor triggering internalization
• Random engulfment of extracellular fluid
• Direct diffusion of large proteins through the membrane
• Secretion of ligands into extracellular space

Correct Answer: Ligand binds to a specific cell-surface receptor triggering internalization

Q18. Which organelle network synthesizes lipids, detoxifies drugs, and stores calcium?

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

Correct Answer: Smooth endoplasmic reticulum

Q19. Which ion movement primarily sets the membrane potential according to the Goldman equation besides Na+ and K+?

• Cl- (chloride)
• Ca2+ (calcium)
• Mg2+ (magnesium)
• Glucose

Correct Answer: Cl- (chloride)

Q20. During mitosis, which structure ensures correct chromosome segregation by attaching to kinetochores?

• Mitotic spindle microtubules
• Actin filaments
• Intermediate filaments
• Centrosomal membranes

Correct Answer: Mitotic spindle microtubules

Q21. Which cellular process is primarily responsible for programmed cell death and has pharmacological relevance in cancer therapy?

• Apoptosis
• Necrosis
• Autophagy
• Necroptosis

Correct Answer: Apoptosis

Q22. Which membrane lipid commonly faces the extracellular side and participates in cell recognition and signaling?

• Glycolipids
• Cardiolipin
• Phosphatidylserine (inner leaflet)
• Sphingosine in inner leaflet

Correct Answer: Glycolipids

Q23. Which transporter family often contributes to multidrug resistance by exporting drugs out of cells?

• ATP-binding cassette (ABC) transporters
• Solute carrier (SLC) family only
• Gap junction proteins
• Cytoskeletal motor proteins

Correct Answer: ATP-binding cassette (ABC) transporters

Q24. Which signaling molecule mobilizes intracellular Ca2+ by acting on IP3 receptors on the endoplasmic reticulum?

• Inositol 1,4,5-trisphosphate (IP3)
• cAMP
• Diacylglycerol (DAG)
• Nitric oxide (NO)

Correct Answer: Inositol 1,4,5-trisphosphate (IP3)

Q25. Which protein structure motif often directs proteins to mitochondria via an N-terminal targeting sequence?

• Amphipathic alpha-helix
• Poly-lysine transmembrane segment
• C-terminal KDEL sequence
• Nuclear localization signal rich in arginine

Correct Answer: Amphipathic alpha-helix

Q26. Which mechanism explains how aquaporins increase water permeability across the plasma membrane?

• Forming selective water channels
• Acting as lipid carriers for water
• Creating pores for ions
• Digesting membrane lipids

Correct Answer: Forming selective water channels

Q27. Which process describes the movement of solute and solvent such that water flows toward higher solute concentration across a semipermeable membrane?

• Osmosis
• Active transport
• Facilitated diffusion
• Phagocytosis

Correct Answer: Osmosis

Q28. Which intracellular compartment receives newly synthesized membrane proteins from the ER for further processing and sorting?

• Golgi apparatus (cis face)
• Mitochondrial matrix
• Nucleoplasm
• Lysosomal lumen

Correct Answer: Golgi apparatus (cis face)

Q29. Which enzyme complex in the cytosol is responsible for degrading misfolded proteins tagged with ubiquitin?

• Proteasome (26S)
• Ribosome
• Lipase complexes
• Peroxisomal oxidases

Correct Answer: Proteasome (26S)

Q30. Which cell-surface receptor type typically undergoes dimerization and autophosphorylation to activate downstream signaling pathways important in growth and cancer?

• Receptor tyrosine kinases (RTKs)
• Ionotropic neurotransmitter receptors
• GPCRs without kinase activity
• Scavenger receptors

Correct Answer: Receptor tyrosine kinases (RTKs)

Download