Life: The Science of Biology, Ninth Edition Sadava • Hillis • Heller • Berenbaum CH 6 Cell Membranes

Cell Membranes TEST FILE QUESTIONS AND ANSWERS (By Catherine Ueckert) Multiple Choice 1. The compounds in biological membranes that form a barrier to the movement of hydrophilic materials across the membrane are a. integral membrane proteins. b. carbohydrates. c. lipids. d. nucleic acids. e. peripheral membrane proteins. Answer: c Textbook Reference: 6.1 What Is the Structure of a Biological Membrane? Page: 106 Bloom’s Category: 1. Remembering 2. The plasma membrane of animals contains carbohydrates a. on the inner side of the membrane, facing the cytosol. b. on the outer side of the membrane, protruding into the environment. c. on both sides of the membrane. d. on neither side of the membrane. e. within the membrane. Answer: b Textbook Reference: 6.1 What Is the Structure of a Biological Membrane? Page: 106 Bloom’s Category: 1. Remembering 3. Biological membranes are composed of a. nucleotides and nucleosides. b. enzymes, electron acceptors, and electron donors. c. fatty acids. d. monosaccharides. e. lipids, proteins, and carbohydrates. Answer: e Textbook Reference: 6.1 What Is the Structure of a Biological Membrane? Page: 107 Bloom’s Category: 1. Remembering 4. In biological membranes, the phospholipids are arranged in a , with the . a. bilayer; fatty acids pointing toward each other b. bilayer; fatty acids facing outward c. single layer; fatty acids facing the interior of the cell d. single layer; phosphorus-containing region facing the interior of the cell e. bilayer; phosphorus groups in the interior of the membrane Answer: a Textbook Reference: 6.1 What Is the Structure of a Biological Membrane? Page: 107 Bloom’s Category: 1. Remembering 5. Which of the following statements about the proteins of the plasma membrane and the proteins of the inner mitochondrial membrane is true? a. Both membranes have only peripheral proteins. b. Only the mitochondrial membrane has integral proteins. c. Only the mitochondrial membrane has peripheral proteins. d. All of the proteins from both membranes are hydrophilic. e. The two membranes differ in their lipid composition. Answer: e Textbook Reference: 6.1 What Is the Structure of a Biological Membrane? Page: 108 Bloom’s Category: 2. Understanding 6. Which of the following statements about cholesterol molecules is true? a. They help hold a membrane together. b. They transport ions across membranes. c. They attach to carbohydrates. d. They disrupt membrane function. e. They alter the fluidity of the membrane. Answer: e Textbook Reference: 6.1 What Is the Structure of a Biological Membrane? Page: 108 Bloom’s Category: 2. Understanding 7. Which of the following statements about peripheral membrane proteins is true? a. They have hydrophobic regions within the lipid portion of the bilayer. b. They have hydrophilic regions that protrude in aqueous environments on either side of the membrane. c. They move laterally but not vertically within the bilayer. d. They control the rate of diffusion. e. Their polar regions interact with similar regions of integral membrane proteins. Answer: e Textbook Reference: 6.1 What Is the Structure of a Biological Membrane? Page: 108 Bloom’s Category: 1. Remembering 8. Houseplants adapted to indoor temperatures may die if they are left outdoors, because in a cold environment their a. DNA cannot function. b. membranes lack adequate fluidity. c. photosynthesis is impaired. d. chloroplasts malfunction. e. membranes need more cholesterol. Answer: b Textbook Reference: 6.1 What Is the Structure of a Biological Membrane? Page: 108 Bloom’s Category: 4. Analyzing 9. A characteristic of plasma membranes that helps them fuse during vesicle formation and phagocytosis is the a. ratio of one protein molecule for every 25 phospholipid molecules. b. capacity of lipids to associate and maintain a bilayer organization. c. constant fatty acid chain length and degree of saturation. d. ability of phospholipid molecules to flip over and trade places with other phospholipid molecules. e. asymmetrical distribution of membrane proteins. Answer: b Textbook Reference: 6.1 What Is the Structure of a Biological Membrane? Page: 108 Bloom’s Category: 2. Understanding 10. The plasma membranes of winter wheat are able to remain fluid when it is extremely cold by a. increasing the number of cholesterol molecules present. b. closing protein channels. c. decreasing the number of hydrophobic proteins present. d. replacing saturated fatty acids with unsaturated fatty acids. e. using fatty acids with longer tails. Answer: d Textbook Reference: 6.1 What Is the Structure of a Biological Membrane? Page: 108 Bloom’s Category: 3. Applying