Here are MCQs on Cell Physiology (no answers included, as for exam practice): 🧬 Cell Physiology MCQs The basic unit of life is: A. Tissue B. Organ C. Cell D. System The cell membrane is primarily composed of: A. Carbohydrates and proteins B. Lipids and proteins C. Nucleic acids and lipids D. Water and salts Which organelle is responsible for energy production? A. Ribosome B. Nucleus C. Mitochondrion D. Golgi apparatus Diffusion is defined as: A. Movement of water across a membrane B. Movement of solute against gradient C. Movement of particles from high to low concentration D. Active transport of ions Osmosis involves movement of: A. Solutes only B. Water molecules C. Proteins D. Lipids Active transport requires: A. Oxygen only B. ATP energy C. Enzymes only D. Passive movement The nucleus controls: A. Protein synthesis only B. Cell activities C. Energy production D. Waste removal Which structure modifies and packages proteins? A. Lysosome B. Golgi apparatus C. Ribosome D. Cytoplasm Ribosomes are the site of: A. Lipid synthesis B. Protein synthesis C. DNA replication D. Waste digestion The fluid inside the cell is called: A. Plasma B. Cytoplasm C. Serum D. Interstitium 🧪 Intermediate Questions Facilitated diffusion differs from simple diffusion because it: A. Requires ATP B. Uses carrier proteins C. Moves against gradient D. Uses vesicles The sodium-potassium pump moves: A. Na⁺ in and K⁺ out B. Na⁺ out and K⁺ in C. Both into the cell D. Both out of the cell Which organelle contains digestive enzymes? A. Mitochondria B. Lysosome C. Ribosome D. Centriole The resting membrane potential is mainly due to: A. Equal ion distribution B. Ion pumps and channels C. Water movement D. Protein synthesis Endocytosis is: A. Release of substances out B. Uptake of substances into cell C. Passive diffusion D. Ion exchange Exocytosis is important for: A. Intake of nutrients B. Waste removal and secretion C. Oxygen transport D. DNA synthesis Which ion is highest inside the cell? A. Sodium (Na⁺) B. Potassium (K⁺) C. Chloride (Cl⁻) D. Calcium (Ca²⁺) The cell membrane is: A. Rigid B. Fluid mosaic C. Solid structure D. Non-selective Which transport does NOT require energy? A. Active transport B. Endocytosis C. Diffusion D. Exocytosis The cytoskeleton helps in: A. Energy production B. Cell shape and movement C. DNA storage D. Protein digestion 🧠 Advanced Which process maintains cell volume? A. Diffusion B. Osmosis C. Active transport D. Filtration Membrane permeability depends on: A. Size and charge of molecules B. Color of molecules C. Temperature only D. Pressure only The main function of smooth endoplasmic reticulum is: A. Protein synthesis B. Lipid synthesis C. DNA storage D. ATP production Rough ER differs from smooth ER because it: A. Contains DNA B. Has ribosomes attached C. Produces energy D. Stores ions Calcium ions are important for: A. Protein digestion B. Muscle contraction C. Oxygen transport D. Cell division only Which process is vesicular transport? A. Diffusion B. Osmosis C. Endocytosis D. Facilitated diffusion The lipid bilayer allows easy passage of: A. Ions B. Large proteins C. Lipid-soluble substances D. Glucose Which organelle detoxifies drugs? A. Rough ER B. Smooth ER C. Golgi apparatus D. Nucleus The electrochemical gradient combines: A. Pressure and temperature B. Concentration and electrical forces C. Size and shape D. Energy and enzymes Which best describes homeostasis at cellular level? A. Constant external environment B. Stable internal environment C. No movement of substances D. Continuous cell division.

Welcome back Lawrence — been a while! Let's pick up where you left off. 1. C. The cell is the fundamental structural and functional unit of all known organisms. 2. B. The cell membrane is primarily composed of a lipid bilayer with embedded proteins. 3. C. Mitochondria are often called the "powerhouses" of the cell because they generate most of the cell's supply of adenosine triphosphate (ATP), used as a source of chemical energy. 4. C. Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration. 5. B. Osmosis is the specific diffusion of water molecules across a selectively permeable membrane. 6. B. Active transport moves substances against their concentration gradient, which requires energy, typically in the form of ATP. 7. B. The nucleus contains the cell's genetic material (DNA) and controls all cell activities, including growth, metabolism, and reproduction. 8. B. The Golgi apparatus (or Golgi complex) modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles. 9. B. Ribosomes are cellular organelles responsible for protein synthesis, translating messenger RNA into polypeptide chains. 10. B. The cytoplasm is the jelly-like substance that fills the cell, enclosing the organelles. 11. B. Facilitated diffusion uses carrier proteins or channel proteins to help substances cross the membrane, but it does not require ATP and moves down the concentration gradient. 12. B. The sodium-potassium pump actively transports three Na⁺ ions out of the cell and two K⁺ ions into the cell, maintaining electrochemical gradients. 13. B. Lysosomes are membrane-bound organelles that contain digestive enzymes to break down waste materials and cellular debris. 14. B. The resting membrane potential is primarily established and maintained by the differential distribution of ions (especially K⁺, Na⁺, and Cl⁻) across the membrane, largely due to the action of ion pumps and channels. 15. B. Endocytosis is the process by which cells take in substances from outside by engulfing them in a vesicle. 16. B. Exocytosis is the process by which cells release substances (like waste products or hormones) from the cell by fusing vesicles with the plasma membrane. 17. B. Potassium (K⁺) ions are typically found in the highest concentration inside the cell, while sodium (Na⁺) is highest outside. 18. B. The cell membrane is described by the fluid mosaic model, indicating it is a dynamic structure composed of a lipid bilayer with embedded proteins that can move laterally. 19. C. Diffusion (including simple and facilitated diffusion) is a form of passive transport and does not require energy (ATP). 20. B. The cytoskeleton is a network of protein filaments and tubules in the cytoplasm of many living cells, giving them shape and coherence, and enabling movement. 21. B. Osmosis is the movement of water across a semipermeable membrane and is crucial for maintaining cell volume and turgor. 22. A. Membrane permeability is influenced by the size and charge of molecules, as well as their lipid solubility. Small, uncharged, lipid-soluble molecules pass more easily. 23. B. The main function of the smooth endoplasmic reticulum (SER) includes lipid synthesis, detoxification of drugs and poisons, and storage of calcium ions. 24. B. Rough ER is distinguished from smooth ER by the presence of ribosomes attached to its surface, which are involved in protein synthesis and modification. 25. B. Calcium ions (Ca²⁺) play a critical role in many cellular processes, including muscle contraction, nerve impulse transmission, and cell signaling. 26. C. Endocytosis (and exocytosis) are forms of vesicular transport, where substances are moved into or out of the cell within membrane-bound vesicles. 27. C. The lipid bilayer is selectively permeable, allowing easy passage of lipid-soluble substances (like oxygen, carbon dioxide, and steroid hormones) due to their ability to dissolve in the lipid core. 28. B. The smooth ER is a primary site for the detoxification of drugs and harmful metabolic byproducts, particularly in liver cells. 29. B. The electrochemical gradient is a gradient of electrochemical potential, usually for an ion that can move across a membrane. It combines the concentration gradient (chemical force) and the electrical potential difference (electrical force). 30. B. Homeostasis at the cellular level refers to the cell's ability to maintain a stable internal environment despite changes in the external conditions. Drop the next question 📸