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50 Cards in this Set
- Front
- Back
What does it mean if the plasma membrane exhibits selective permeability?
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some substances can cross the membrane more easily than other substances.
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Which of the following is the main structural component of plasma membranes?
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phospholipids
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Which of the following describes a phospholipid molecule?
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polar head, hydrophobic tail
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In an aqueous environment, phospholipids tend to organize into a bilayer because the formation of a bilayer:
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shields the hydrophobic tails from water
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What type of molecuels pass most easily through plasma membranes?
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nonpolar molecules because they are soluble in lipids
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Which of the following has the greatest effect on the ability of polar molecules to pass through membranes?
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the protein carriers that are present in the membrane
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Which of the following best describes the plasma membrane?
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fluid mosaic
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How do proteins in the plasma membrane help hold the membrane in place?
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A and B only- they many be linked to the cytoskeleton inside the cell-they may be linked to the extracellular matrix outside the cell
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What type of organism has cholesterrol in it's membranes?
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animals
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What is the role of cholesterol molecules that are embedded in the membranes of some living things?
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only B and C- help stabilize the phospholipids at body temperature-keep the membrane fluid at lower temperatures
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Which of the following function as cell indentification tags that can be recognized by other cells?
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glycoproteins and glycolipids
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Which of the following are functions of membrane proteins?
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All of the Above- Aome proteins are involved in attaching the membrane to the cytoskeleton and external fibers-some proteins help in providing identification tags-some proteins help form junctions between adjacent cells
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Which of the folowing are functions of membrane proteins?
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All of the Above- some proteins are enzymes involved in catalytic reactions-some proteins function as receptors for chemical messengers from other cells-some proteins receptors involved in signal transduction-some proteins are involved in transport, and help move substances across the membrane
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The movement of molecules from higher concentration to lower concentration is called:
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diffusion
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Which of the following requires the use of energy in the form of ATP?
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active transport
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Which of the following can move across membranes by passive transport?
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All of the Above-oxygen-carbon dioxide-water
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Which of the following can move across membranes by diffusion?
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All of the Above-Oxygen-Carbon Dioxide-Water
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Which of the following is the difusion of water molecules across a selectively permeable membrane?
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osmosis
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If the solution outside of a cell h as a greater concentration of solutes than the solution inside the cell, the solution outside the cell is ___ in relation to the cell
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hypertonic
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If the solution outside of a cell has a lower concentration of solutes than the solution inside the cell, the solution outside the cell is ____ in relation to the cell.
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hypotonic
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If the solutions both inside and outside of a cell have an equal concentration of solutes, the solution outside the cell is ___ in relation to the cell.
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isotonic
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If the salt concentration insdie a cell is 0.9%, and the salt concentration outside a cell is 9%, in whcih direction will there be a net movement of water by diffustioin?
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out of the cell
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If the salt concentration inside a cell is 0.9%, and the salt concentration outside a cell is 9%, in which direction will there be a net movement of salt by diffusion?
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there will be no movement since salt cannot cross the membrane by diffusion
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If a cell is in equilibrium with its environment
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the environment is probably isotonic to the cell
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Which of the following will happen to an animal cell if placed in a hypotonic environment?
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the cell will become larger, and may burst
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What is osmoregulation?
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the control of water balance
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In a hypertonic environment, a plant cell will:
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shrivel, and the cell membrane will pull away from the cell wayy
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In a bypotonic enviroment, a plant cell will become:
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turgid
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In a plant cell, if there is a net inflow of water keeping pressure exerted against the inside of the cell wall, the cell must be in ____ environment.
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a hypotonic
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Which of the following cells have contractile vaculoes for osmoregulation?
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Paramecium
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If the contractile vacuoles in a single-celled organism are actively contracting, the organism is likely to be in ____ environment.
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a hypotonic
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A plant cell is placed into a solution whose solute concentration is twice as great as the concentration of the cell cytoplasm. The cell membrane is selectively permeable, allowing water but not all the solutes to pass through. What will happen to the cell?
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the cell will shrivel because of osmosis
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Red blood cells shrivel when placed in a 10% sucrose solution. When first placed in the solution, the solute concentration of the cells is ____ the concentration of the sucrose solution. After the cells shrivel, their solute concentration is ____ the concentration of the sucrose solution.
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less than.... equal to
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In facilitated diffusion, a molecule cannot cross a biologcial membrane unless ___ is present.
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a transport protein
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Which of the following requires specific transport proteins?
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only B and C- facilitated diffusion, active transport
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Which of the following moves molecules against their concentration gradient?
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active transport
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Which of the following is an endergonic process?
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active transport
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Which of the following is a difference between active transport and facilitated diffusion?
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active transport requires energy from ATP and facilitated diffusion does not
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The export of macromolecules out of the cell by means of a membrane enclosed vesicle moving to the plasma membrane is called:
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exocytosis
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The import of macromolecules into the cell using a vesicle is called:
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endocytosis
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If a hormone is produced inside a cell, it can be released out into the environment by:
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exocytosis
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"cellular eating" is called:
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phagocytosis
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"cellular drinking" is called:
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pinocytosis
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In which of the following does the product of protein synthesis never have to cross a membrane?
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exocytosis
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A white blood cell is capable of producing and releasing thousands of antibody molecules every second. Antibodies are large, complex protein molecules. How would you expect them to leave the cell?
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exocytosis
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If a person has an excessive cholesterol level in the blood even without producing more cholesterol than other people, that person probably:
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lacks sufficient LDL receptors in plasma membranes
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Sodium ions require energy to move across a plasma membrane. The movement of sodium ions across a membrane:
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only A and B- is by active transport-requires a transport protein
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Which best describes the general structure of a cell membrane?
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proteins embedded in two layers of phospolipid
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The total solute concentration in a red blood cell is about 2%. Sucrose cannot pass through the membrane, but water and urea can. Osmosis would cause such a cell to shrink the most when immersed in which of the following?
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a hypertonic sucrose solution
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The calcium concentration in a cell is 0.3%; the concentration in the surrounding fluid is 0.1%. How could the cell obtain more calcium?
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Any of the above-passive transport-diffusion-active transport-osmosis
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