Ch4 Test Review
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As a result of diffusion, the concentration of many types of substances eventually becomes balanced on both sides of a membrane
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Diffusion is the movement of a substance from an area of high concentration to an area of low concentration
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The dispersal of ink in a beaker of water is an example of diffusion
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The diffusion of water into or out of a cell is called osmosis
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Osmosis is a type of passive transport
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A cell will well when it is placed in a(n) hypotonic solution
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The interior portion of a cell membrane forms a nonpolar zone that prevents ions and most large molecules from passing through the membrane
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Ions move through ion channels by passive transport
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Ion channel gates close the pores of some ion channels in response to stretching of the cell membrane, a change in electrical charge, and the binding of specific molecules to the channel
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Proteins that act like selective passageways in the cell membrane are known as channel proteins
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Transport proteins that allow ions to pass through the cell membrane are called ion channels
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Sugar molecules cross the cell membrane by facilitated diffusion
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Proteins involved in facilitated diffusion are carrier proteins
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Sugar molecules can enter cells through the process of facilitated diffusion
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Diffusion does not require energy
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Both active transport and facilitated diffusion involve carrier proteins
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Sodium-potassium pump is a form of active transport
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The sodium-potassium pump is a carrier protein
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The sodium-potassium pump usually pumps potassium ions into the cell
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The sodium-potassium pump decreases the concentration of sodium ions inside a cell, and increases the concentration of potassium ions inside a cell
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Proteins and polysaccharides that are too large to move into a cell through diffusion or active transport move in by endocytosis
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Molecules that are too large to be moved through the membrane can be transported into the cell by endocytosis
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Molecules that are too large to be moved across a cell membrane can be removed from the cell by exocytosis
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Ridding the cell of materials by discharging the materials in vesicles is called exocytosis
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Signal molecules bind to receptor proteins
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When a signal molecule binds to a receptor protein, the receptor protein, the receptor protein may change the permeability of the membrane, cause the formation of a second messenger molecule, and catalyze certain chemical reactions in the cell
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Receptor proteins transmit information into a cell by binding to signal molecules
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The random motion of particles of a substance that causes the substances to move from an area of high concentration to an area of lower concentration is called diffusion

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The diffusion of water through cell membranes is called osmosis
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Substances always flow from an area of high concentration to an area of low concentration
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When the concentration of free water molecules is higher outside a cell than inside a cell, water will diffuse into the cell
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Is a cell is placed in a(n) hypertonic solution, water will flow out of the cell
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If a cell is placed in hypertonic solution, water will flow into the cell
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If a cell is placed in a(n) isotonic solution, water flows into the cell at a rate that is equal to the rate at which water flows out of the cell
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Diffusion of ions through ion channels is a form of passive transport
If the interior of a typical cell is negatively charged, positively charged ions will not require energy to diffuse into the cell using an ion channel
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In facilitated diffusion, carrier proteins are used to transport substances down their concentration gradient
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In facilitated diffusion, carrier proteins do not require energy to transport amino acids into a cell
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Carrier proteins change shape to transport sugars to the interior of cells
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A cell does not expend energy when diffusion takes place
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Active transport requires the use of ATP or energy by a cell
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The sodium-potassium pump transports ions against their concentration gradients
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The sodium-potassium pump uses energy supplied by ATP
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The sodium-potassium pump prevents the accumulation of sodium ions inside the cell
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The movement of a substance into a cell by a vesicle is called endocytosis