Cellular Biophysics – MCQs 50 Score: 0 Attempted: 0/50 Subscribe 1. The basic functional unit of life is: (A) Nucleus (B) Cell (C) Organelle (D) Chromosome 2. The plasma membrane is primarily composed of: (A) DNA and RNA (B) Lipids and proteins (C) Sugars only (D) Peptide bonds 3. The fluid mosaic model describes: (A) Cytoskeleton arrangement (B) Structure of the plasma membrane (C) DNA replication (D) Protein folding 4. The main driving force for passive transport is: (A) ATP hydrolysis (B) Concentration gradient (C) Protein phosphorylation (D) Vesicle formation 5. Which organelle is known as the “powerhouse of the cell”? (A) Nucleus (B) Lysosome (C) Mitochondrion (D) Endoplasmic reticulum 6. ATP synthesis in mitochondria occurs at: (A) Inner mitochondrial membrane (B) Outer mitochondrial membrane (C) Matrix (D) Cytoplasm 7. Osmosis is the movement of: (A) Proteins across a membrane (B) Water across a selectively permeable membrane (C) Lipids into vesicles (D) DNA across pores 8. The cytoskeleton does NOT include: (A) Microtubules (B) Actin filaments (C) Intermediate filaments (D) Mitochondria 9. Ion channels in membranes allow transport by: (A) Facilitated diffusion (B) Active transport (C) Endocytosis (D) Exocytosis 10. Sodium-potassium ATPase transports ions in which ratio? (A) 2 Na⁺ in, 3 K⁺ out (B) 3 Na⁺ out, 2 K⁺ in (C) 1 Na⁺ in, 1 K⁺ out (D) 2 Na⁺ out, 3 K⁺ in 11. Endocytosis involves: (A) Export of substances (B) Uptake of substances into the cell (C) DNA replication (D) Protein synthesis 12. The nucleolus is the site of: (A) DNA replication (B) RNA and ribosome synthesis (C) Protein degradation (D) Lipid metabolism 13. Gap junctions are important for: (A) Energy storage (B) Cell-to-cell communication (C) Protein folding (D) Vesicle transport 14. Which organelle contains hydrolytic enzymes? (A) Lysosome (B) Golgi apparatus (C) Endoplasmic reticulum (D) Nucleus 15. The resting membrane potential of most animal cells is approximately: (A) +70 mV (B) –70 mV (C) 0 mV (D) –120 mV 16. Which biophysical technique is used to study ion channels? (A) Patch-clamp (B) SDS-PAGE (C) Western blot (D) ELISA 17. Microtubules are made of: (A) Actin (B) Tubulin (C) Keratin (D) Collagen 18. The main role of the Golgi apparatus is: (A) DNA transcription (B) Protein modification and sorting (C) ATP production (D) Lipid degradation 19. Which type of transport requires energy input? (A) Passive diffusion (B) Active transport (C) Osmosis (D) Facilitated diffusion 20. Mitochondria and chloroplasts both contain: (A) Ribosomes and DNA (B) Lysosomes (C) Peroxisomes (D) Centrioles 21. The lipid bilayer is stabilized by: (A) Hydrogen bonds (B) Hydrophobic interactions (C) Disulfide bonds (D) Ionic interactions only 22. The process of programmed cell death is called: (A) Necrosis (B) Apoptosis (C) Autophagy (D) Exocytosis 23. Cell membranes are selectively permeable due to: (A) DNA structure (B) Protein and lipid composition (C) Ribosome activity (D) ATP concentration 24. Chloroplasts perform photosynthesis in which part? (A) Stroma (B) Thylakoid membrane (C) Cytoplasm (D) Outer membrane 25. Which cytoskeletal structure is involved in cell division spindle formation? (A) Microtubules (B) Actin filaments (C) Intermediate filaments (D) Myosin 26. Aquaporins are membrane proteins that facilitate movement of: (A) Sodium (B) Proteins (C) Water (D) Lipids 27. The mitochondrial matrix contains enzymes for: (A) Glycolysis (B) Krebs cycle (C) Oxidative phosphorylation (D) DNA replication 28. The nuclear envelope is continuous with: (A) Golgi apparatus (B) Endoplasmic reticulum (C) Plasma membrane (D) Lysosome membrane 29. Exocytosis is the process of: (A) Import of molecules (B) Export of molecules (C) DNA replication (D) Protein folding 30. In facilitated diffusion, carrier proteins: (A) Use ATP (B) Transport molecules down their concentration gradient (C) Transport against the gradient (D) Break covalent bonds 31. The mitochondrial electron transport chain generates: (A) Proton gradient (B) Oxygen gas (C) ATP directly (D) DNA 32. The main function of peroxisomes is: (A) ATP production (B) Breakdown of fatty acids and toxins (C) DNA replication (D) Protein folding 33. Clathrin is associated with: (A) DNA replication (B) Endocytosis and vesicle formation (C) Transcription (D) Exocytosis only 34. The cytoplasm is best described as: (A) Static gel (B) Dynamic fluid medium (C) Pure water (D) DNA storehouse 35. The main structural component of the plant cell wall is: (A) Chitin (B) Cellulose (C) Peptidoglycan (D) Lignin 36. Tight junctions function to: (A) Anchor cells to ECM (B) Prevent leakage between cells (C) Facilitate ion transport (D) Store proteins 37. The rough endoplasmic reticulum is distinguished by: (A) Lack of ribosomes (B) Ribosomes attached to its surface (C) ATP synthesis (D) DNA replication 38. Actin filaments are essential for: (A) Muscle contraction and cell motility (B) ATP synthesis (C) DNA storage (D) Lysosome digestion 39. The pH inside lysosomes is approximately: (A) 2 (B) 4.5–5.0 (C) 7 (D) 9 40. The mitochondrial ATP synthase uses: (A) Proton motive force (B) Electron movement (C) Sodium transport (D) ATP hydrolysis 41. The cytoskeleton helps in: (A) DNA replication (B) Maintaining cell shape and motility (C) Protein synthesis (D) ATP production 42. Which organelle detoxifies harmful compounds in liver cells? (A) Nucleus (B) Peroxisome (C) Lysosome (D) Mitochondrion 43. Cell signaling pathways often use: (A) Second messengers (B) DNA bases (C) Lipid bilayer only (D) Protein denaturation 44. Which ion is most important for generating resting potential in neurons? (A) Calcium (B) Sodium (C) Potassium (D) Chloride 45. The major difference between prokaryotic and eukaryotic cells is: (A) Presence of ribosomes (B) Presence of nucleus and organelles in eukaryotes (C) Presence of DNA (D) Plasma membrane composition 46. The endoplasmic reticulum responsible for lipid synthesis is: (A) Rough ER (B) Smooth ER (C) Nuclear envelope (D) Golgi body 47. The Na⁺/Ca²⁺ exchanger in cells works by: (A) Active transport using ATP (B) Antiport mechanism (C) Uniport mechanism (D) Symport mechanism 48. Vesicle trafficking between organelles is mediated by: (A) SNARE proteins (B) Tubulin (C) Actin only (D) Histones 49. The main function of centrioles is: (A) DNA replication (B) Formation of spindle fibers during cell division (C) Protein synthesis (D) RNA transcription 50. 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