Chapt 5 Cell Membrane Test

Chapt 5 Cell membrane-Key 1. The lipid layer that forms the foundation of cell membranes is primarily composed of molecules called __________. A. phospholipids B. fats C. proteins D. carbohydrates 2. What is the net movement of substances to regions of lower concentration called? A. Osmosis B. Active transport C. Facilitation D. Diffusion 3. Osmosis is the diffusion of water across a membrane in response to the concentration of one or more of the ______. A. solutes B. membranes C. compartments D. cells 4. Which type of proteins is embedded in the cell membrane in both active transport and facilitated transport? A. carrier B. cytoskeletal C. structural D. targeted 5. The plasma membrane is a thin sheet of lipid embedded with A. proteins. B. carbohydrates. C. polymers. D. nucleotides. E. sodium and and potassium ions. 6. Membrane proteins are not very soluble in water, because they possess long stretches of non-polar amino acids that are A. too long to interact with the water molecules. B. hydrophobic. C. are transmembranal. D. hydrophilic. E. used as as transport channels. 7. If a cell has the same concentration of dissolved molecules as its outside environment, the cell's condition is referred to as being B. hypertonic. C. hypotonic. A. isotonic. D. hydrophobic. E. hydrophilic. 8. A type of transport of a solute across a membrane, up its concentration gradient, using protein carriers driven by the expenditure of chemical energy is known as A. osmosis. B. diffusion. C. facilitated transport. D. active transport. E. exocytosis. 9. How are the tails and heads of membrane phospholipids oriented in their environment? A. The hydrophobic heads are oriented towards each other and the hydrophillic tails are oriented towards the extracellular fluid and the intracellular fluid. B. The hydrophillic tails are oriented towards each other and the hydrophobic heads are oriented towards towards the extracellular fluid and the intracellular fluid. C. The hydrophobic tails are oriented towards each other and the hydrophillic heads are oriented towards the extracellular fluid and the intracellular fluid. D. The hydrophillic heads are oriented towards each each other and the hydrophobic tails are oriented towards the extracellular fluid and the intracellular fluid.

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2 10. On the outer surface of the plasma membrane there are marker molecules that identify the cell type. Often these molecules are A. ATP. B. amino acids. C. nucleotides. D. carbohydrate chains. E. inorganic ions. 11. The part of a membrane protein that extends through the phospholipid bilayer is primarily composed of amino acids that are A. highly polar. B. negatively charged. C. non-polar. D. positively charged. E. water soluble. 12. . The movement of substances to regions of lower concentration is called A. active transport. B. diffusion. C. pinocytosis. D. pumping. E. exocytosis. 13. If two solutions have unequal concentrations of a solute, the solution with the lower concentration is called A. isotonic. B. hypertonic. C. hypotonic. D. osmosis. 14. The process often referred to as "cellular eating" is A. osmosis. B. pinocytosis. C. phagocytosis. D. diffusion. E. active transport. 15. Carrier-mediated transport is also called A. facilitated diffusion. B. active transport. C. exocytosis. D. endocytosis. E. phagocytosis. 16. Osmosis can only occur if water travels through the A. cell wall. B. semi-permeable membrane. C. vacuole. D. ER. E. cytoskeleton. 17. The type of movement that is specific and requires carrier molecules and energy is C. active transport. A. exocytosis. B. facilitated diffusion. D. endocytosis. E. osmosis.



3 19. The fluid mosaic model proposed by Singer and Nicolson in 1972 explained that A. the cell membrane was composed of lipids and and proteins. B. the cell membrane was composed of a phospholipid bilayer between two layers of globular globular proteins. C. the cell membrane was composed of a phospholipid bilayer with globular proteins actually inserted into the bilayer. D. the cell membrane was composed of a phospholipid bilayer but the polar ends of the phospholipid molecules were reversed. 20. When the solute concentration of solution A is lower than the solute concentration of solution B, solution A is considered A. hypertonic. B. hypotonic. C. isotonic. 21. A scientist performs an experiment in which they create an artificial cell with a selectively permeable membrane through which only water can pass. They inject a 5M solution of glucose into the cell and then place the cell into a beaker of water. After an hour, what effect do you expect to observe? A. Water moves out out of the cell B. Glucose moves out of the cell C. No net change change in cell weight D. Water moves into the cell E. Glucose moves moves into the cell 22. If you were a very thirsty cell, which process would you use to take in some nutrients secreted by one of your neighbors? A. Phagocytosis B. Pinocytosis C. Receptor-mediated endocytosis D. Exocytosis 24. Facilitated diffusion is an important method for cells in obtaining necessary molecules and removing other ones. Requirements for facilitated diffusion include A. The carrier molecule must be specific to the molecule that is transported. The direction of movement is always with the concentration gradient, never against the gradient. B. The carrier molecule is nonspecific to the molecule that is transported. transported. The direction of movement is always with the concentration gradient, never against the gradient. C. The carrier molecule is nonspecific to the molecule that is transported. transported. The direction of movement is always against the concentration gradient, never with the gradient. D. The carrier molecule must be specific to the molecule molecule that is transported and an ATP molecule must be attached to the specific carrier. The direction of movement is always against the concentration gradient, never with the gradient. 25. Who was/were the first to propose that cell membranes are phospholipid bilayers? A) H. Davson and J. Danielli B) I. Langmuir C) C. Overton D) S. Singer and G. Nicolson E) E. Gorter and F . Grendel

26. Who proposed that the membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids? A) H. Davson and J. Danielli B) I. Langmuir C) C. Overton D) S. Singer and G. Nicolson E) E. Gorter and F. Grendel



4 28. Which of these often serve as receptors or cell recognition molecules on cell surfaces? A) transmembrane proteins B) integral proteins C) peripheral proteins D) integrins E) glycoproteins 29. What kinds of molecules pass through a cell membrane most easily? A) large and hydrophobic B) small and hydrophobic C) large polar D) ionic

30. Which of the following is a characteristic feature of a carrier protein in a plasmamembrane? A) It is a peripheral membrane protein. B) It exhibits specificity for a particular type of molecule. C) It requires the expenditure of cellular energy to function. D) It works against diffusion. E) It has few, if any, hydrophobic amino acids.

31. Which of the following would likely move through he lipid bilayer of a plasma membrane most rapidly? A) CO2 B) an amino acid C) glucose D) K+ E) starch 32. The movement of potassium into an animal cell requires A) Low cellular concentrations of sodium. B) High cellular concentrations of potassium. C) An energy source such as ATP or a proton gradient . D) A cotransport protein. E) A gradient f protons across the plasma membrane. 33. White blood cells engulf bacteria through what process? A) exocytosis B) phagocytosis C) pinocytosis D) osmosis

Chapt 5 Cell Membrane Test

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