C The animal cell is in a hypertonic solution, and the plant cell is in an isotonic solution. Celery stalks that are immersed in fresh water for several hours become stiff and hard. What color should she use to reduce overall light energy, but still maximize plant growth? Which of the following best describes the general structure of a cell membrane? D It is an active process in which molecules move from a region of lower concentration to one of higher concentration. Why are lipids and proteins free to move laterally in membranes? A Chloride ions will move out of the cell, and water will move into the cell. They are completely insoluble in water. Glucose diffuses slowly through artificial phospholipid bilayers. B Unsaturated fatty acids have a higher cholesterol content and therefore more cholesterol in membranes.
Using this information, which transport mechanism is most probably functioning in the intestinal cells? Assuming that glucose is not actively transported into the cell, which of the following terms describes the tonicity of the external solution relative to the cytoplasm of the cell? E Molecules such as cellulose can pull them in various directions. D a decrease in the concentration of NaCl and a decrease in the water level. B It functions as a testable hypothesis. It requires integral proteins of the cell membrane. Water enters the sucrose solution because the sucrose molecule is a disaccharide and thus larger than the monosaccharide glucose. One hypothesis is that the volume of this airway surface liquid is regulated osmotically by transport of sodium and chloride ions across the epithelial cell membrane. Active transport involves transport proteins and facilitated diffusion does not.
D the carbon-carbon bonds of the phospholipid tails are easily broken. A cessation of cellular protein synthesis B localization of enzymes into specific organelles or membranes C exporting enzymes out of the cell D connecting enzymes into large aggregates E hydrophobic interactions For the enzyme-catalyzed reaction shown in the figure, which of these treatments will cause the greatest increase in the rate of the reaction, if the initial reactant concentration is 1. C no net change in the system. A patient has had a serious accident and lost a lot of blood. Why are phospholipids well suited to be the main structural components of membranes? E They have hydrophilic tails in the interior of the membrane. C Bacteria congregated in these areas because these areas had the most oxygen being released.
Which of the following is the most likely explanation? D There are only weak hydrophobic interactions in the interior of the membrane. What will be the most probable result of this transfusion? Which of the following would you expect to be a problem for someone with nonfunctional chloride channeling? One hypothesis is that the volume of this airway surface liquid is regulated osmotically by transport of sodium and chloride ions across the epithelial cell membrane. E free to depart from the fluid membrane and dissolve in the surrounding solution. D Only certain membranes are constructed from amphipathic molecules. Facilitated diffusion can move solutes against a concentration gradient and active transport cannot. Active transport requires a protein carrier. According to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids? D pinocytosis requires cellular energy, but receptor-mediated endocytosis does not.
C The blood cells will take up water, swell, and eventually burst. Mammalian blood contains the equivalent of 0. D All components of membranes evolve in response to natural selection. D Enzyme-catalyzed reactions require energy to activate the enzyme. E membranes consist of a mosaic of polysaccharides and proteins. D It serves as a data point among results.
Phosphate import depends on a pH gradient across the membrane—more acidic outside the cell than inside the cell. C The two sides of a cell membrane face different environments and carry out different functions. At 10-minute intervals, the bags were massed weighed and the percent change in mass of each bag was graphed. D The double bonds block interaction among the hydrophilic head groups of the lipids. B Lipids and proteins repulse each other in the membrane.
Which of the following statements is true? A The molarity of sucrose and glucose are equal on both sides. C membranes are a single layer of phospholipids and proteins. C Only certain membranes of the cell are selectively permeable. Which of the following factors would tend to increase membrane fluidity? Singer and Nicolsonʹs fluid mosaic model of the membrane proposed that A membranes are a phospholipid bilayer. E membranes consist of a mosaic of polysaccharides and proteins. A It will have no unfavorable effect as long as the water is free of viruses and bacteria.
C The reaction nears equilibrium at high reactant concentrations. C membranes are a single layer of phospholipids and proteins. E Sodium ion transport will be unaffected; lack of chloride transport still reduces osmotic potential and decreases the airway surface liquid volume. A Feedback inhibition by product occurs at high reactant concentrations. Facilitated diffusion of solutes occurs through protein pores in the membrane. E by ribosomes bound to the inner surface of the plasma membrane. E The proteins are known to be made of only acidic amino acids.
C embedded in a lipid bilayer. E makes the animal more susceptible to circulatory disorders. E The active site creates a microenvironment ideal for the reaction. Phosphate import depends on a pH gradient across the membrane—more acidic outside the cell than inside the cell. D may affect the physicochemical properties of the enzyme such as its optimal temperature and pH.
E It requires integral proteins in the cell membrane. Where in the membrane would cholesterol most likely be found? D Sodium ion transport will decrease; lower osmotic potential will increase the airway surface liquid volume. Membrane proteins provide receptors for chemical messengers. How would the lack of a functional chloride channel in cystic fibrosis patients affect sodium ion transport and the volume of the airway surface liquid? What does this most probably mean? A Proton pumps must have evolved before any living organisms were present on Earth. C The two sides of a cell membrane face different environments and carry out different functions.