Chapter 4: Cell Membrane Structure and Function

1.	The fluid mosaic model describes membranes as fluid because ___________. [Hint]
2.	Which of the following types of molecules must pass through membranes via the aqueous pores formed by membrane proteins? [Hint]
3.	Diffusion is the movement of molecules from __________. [Hint]
4.	In osmosis, water diffuses from the side of the membrane with a higher concentration of water to the side with a lower concentration of water. What determines the concentration of water in a solution? [Hint]
5.	Which of the following processes does a cell use to take up molecules against their concentration gradient? [Hint]
6.	What is the difference between active transport and passive transport? [Hint]
7.	Of the following list of substances that can enter a cell, match the order with the correct mechanism by which they would enter cells: oxygen, water, sodium ions, potassium ions, bacterium. (Note that sodium ions are more concentrated outside cells than inside; potassium ions are more concentrated inside cells than outside.) [Hint]
8.	Imagine that you are studying cell structure in various organisms in your biology lab. Your instructor gives you a microscope slide showing two types of cells that have been suspended in pure water. One type of cell swells up until it bursts. The other cell maintains its shape throughout the experiment. Suggest an explanation for these observations; assume that both cells were alive at the start of the experiment. Assume also that the concentration of water inside both types of cells is similar. [Hint]
9.	The concentration of sodium ions is lower in the cytoplasm of a heart muscle cell than it is in the extracellular fluid. By what mechanism does the cell maintain this difference? [Hint]
10.	When placed in a certain sucrose solution, the volume of a cell decreases; therefore, the sucrose solution is __________ to the cell contents. [Hint]
11.	Choose the substance that will diffuse most rapidly across the plasma membrane. [Hint]
12.	Facilitated diffusion requires __________. [Hint]
13.	During endocytosis, the contents of the endocytic vesicle __________. [Hint]
14.	Which of the following transport processes require(s) energy? [Hint]
15.	Membrane fluidity within a phospholipid bilayer is based upon __________. [Hint]
16.	Recognition proteins function to __________. [Hint]
17.	The point at which a substance is evenly dispersed within a fluid __________. [Hint]
18.	Substances are able to cross the lipid bilayer of a cell at different rates that are unique for each substance. Which of the following characteristics would favor the simple diffusion of a substance across a cell membrane? [Hint]
19.	The term tonicity describes the solute concentration of the extracellular fluid relative to the solute concentration of the aqueous solution known as cytoplasm. In which direction would water flow according to the principles of osmosis if a cell were placed in a hypertonic solution? [Hint]
20.	Certain microorganisms have a high percentage of unsaturated fatty acids in their membrane. Because of this, these organisms __________. [Hint]
21.	A hormone circulating in the bloodstream would most likely bind to __________. [Hint]
22.	Many metabolic poisons work by inhibiting ATP production. Which type of transport would be most affected? [Hint]
23.	The antifungal drug nystatin combines with sterols in the plasma membrane of the fungal cell to disrupt the membrane and kill the cell. What other cell types might also be affected by nystatin? [Hint]
24.	When a drop of food coloring is placed in a glass of water, the spreading out of the molecules of food dye is caused by __________. [Hint]
25.	Two types of connections between cells called "gap junctions" and "plasmodesmata" are specialized to __________. [Hint]
26.	All cells are surrounded by a thin . [Hint]
27.	The consists of all of the internal contents of a cell, except the nucleus in eukaryotic cells. [Hint]
28.	The membrane components that spontaneously form a bilayer are . [Hint]
29.	Substances move from high to low concentration by a process called . [Hint]
30.	During , energy is used to move substances against their concentration gradient. [Hint]
31.	If a cell is placed in a solution, there will be net water movement out of the cell. [Hint]
32.	The type of cell connection that makes the adjacent cells leakproof is a . [Hint]
33.	Label the indicated parts of the cell membrane. [Hint] For each item below, use the pull-down menu to select the letter that labels the correct part of the image. Choice A Choice B Choice C Choice D Choice E cholesterol Choice A Choice B Choice C Choice D Choice E phospholipid bilayer Choice A Choice B Choice C Choice D Choice E glycoprotein Choice A Choice B Choice C Choice D Choice E protein filaments Choice A Choice B Choice C Choice D Choice E carbohydrate
34.	This is a diagram of one phospholipid from the cell membrane. Label the individual parts. [Hint] For each item below, use the pull-down menu to select the letter that labels the correct part of the image. Choice A Choice B hydrophilic head Choice A Choice B hydrophobic tail
35.	Match the steps in the process of diffusion with the sequence of images below: [Hint] For each item below, use the pull-down menu to select the letter that labels the correct part of the image. Choice A Choice B Choice C A drop of dye is placed in water. Choice A Choice B Choice C Both dye molecules and water molecules are evenly dispersed. Choice A Choice B Choice C Dye molecules diffuse into the water, and water molecules diffuse into the dye.
36.	Blood cells are used to demonstrate osmosis, since they show obvious shape changes in various solutions. Label the solution to which each of the following blood cells is reacting. [Hint] For each item below, use the pull-down menu to select the letter that labels the correct part of the image. Choice A Choice B Choice C hypotonic solution Choice A Choice B Choice C hypertonic solution Choice A Choice B Choice C isotonic solution
37.	Identify the structures of a typical plant cell as seen in the image below. [Hint] For each item below, use the pull-down menu to select the letter that labels the correct part of the image. Choice A Choice B Choice C Choice D Choice E cytoplasm Choice A Choice B Choice C Choice D Choice E secondary cell wall Choice A Choice B Choice C Choice D Choice E middle lamella Choice A Choice B Choice C Choice D Choice E cell membrane Choice A Choice B Choice C Choice D Choice E primary cell wall
38.	Active transport through the plasma membrane occurs through the action of:
39.	The following is a characteristic of a plasma membrane:
40.	If an animal cell is placed into a solution whose concentration of dissolved substances is higher than that inside the cell,
41.	Small, nonpolar hydrophobic molecules such as fatty acids
42.	Which of the following would be least likely to diffuse through a lipid bilayer?
43.	Which of the following processes causes substances to move across membranes without the expenditure of cellular energy?
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