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Which of the following factors does not affect membrane permeability? The amount of cholesterol in the membrane The saturation of hydrocarbon tails in membrane phospholipids Temperature The polarity of membrane phospholipids |
The polarity of membrane phospholipids |
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How can a lipid be distinguished from a sugar? A lipid is made up of only hydrocarbons. Lipids are mostly saturated. Lipids are mostly nonpolar. A lipid dissolves in water. |
Lipids are mostly nonpolar. |
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True or false? Osmosis is a type of diffusion. True |
True |
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What property of dishwashing liquid (detergent) makes it useful to wash grease from pans? Hydrophobic nature Solubility in water Amphipathic nature Permeability |
Amphipathic nature |
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Which of the following particles could diffuse easily through a cell membrane? Oxygen (O2) Hydrogen ion (H+) Sodium ion (Na+) Glucose |
Oxygen (O2) |
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True or false? The water-soluble portion of a phospholipid is the polar head, which generally consists of a glycerol molecule linked to a phosphate group. True False |
True |
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If a red blood cell is placed in a salt solution and bursts, what is the tonicity of the solution relative to the interior of the cell? Hypertonic Hypotonic Osmotic Isotonic |
Hypotonic |
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What distinguishes facilitated diffusion from simple diffusion? Membrane proteins help move molecules across the membrane. No energy is used to move molecules across the membrane. Molecules move from a region of higher concentration to a region of lower concentration. Molecules move from a region of lower concentration to a region of higher concentration. |
Membrane proteins help move molecules across the membrane. |
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Which of the following transporters does not use passive transport to move molecules across a membrane? GLUT-1 glucose transporter Sodium-potassium pump Gramicidin ion channel Valinomycin |
Sodium-potassium pump |
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True or false? Active transport differs from passive transport in that active transport does not require an input of energy. True False |
False |
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Which membrane protein would be used to move glucose across a membrane from a region of higher concentration to a region of lower concentration? Pump Transporter Ion channel No protein is necessary. |
Transporter |
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Which of the following statements is true about the net movement of an ion across a membrane by passive diffusion through a membrane channel? There is a higher concentration of ions on the side of the membrane toward which the ion diffuses. For every ion that diffuses through the membrane, a different ion diffuses in the opposite direction. The charge on the other side of the membrane is generally the opposite of the ion’s charge. The cell expends energy as the ion passes through the membrane. |
The charge on the other side of the membrane is generally the opposite of the ion’s charge. |
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True or false? During active transport through the sodium-potassium pump, ATP hydrolysis provides the energy to pump three sodium ions into the cell for every two potassium ions pumped out of the cell. True False |
False |
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Lactose transport by membrane proteins occurs under conditions in which the concentration of lactose inside the cell is higher than the concentration outside the cell. What type of transport is used to move lactose into the cell? Facilitated diffusion Simple diffusion Osmosis Active transport |
Active transport |
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Which of the following types of molecules are the major structural components of the cell membrane? proteins and cellulose glycoproteins and cholesterol phospholipids and proteins phospholipids and cellulose nucleic acids and proteins |
phospholipids and proteins |
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The presence of cholesterol in the plasma membranes of some animals enables the animal to add hydrogen atoms to unsaturated phospholipids enables the membrane to stay fluid more easily when cell temperature drops. makes the membrane less flexible, allowing it to sustain greater pressure from within the cell. makes the animal more susceptible to circulatory disorders. |
enables the membrane to stay fluid more easily when cell temperature drops. |
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In order for a protein to be an integral membrane protein it would have to be hydrophobic. hydrophilic. amphipathic, with at least one hydrophobic region. exposed on only one surface of the membrane. completely covered with phospholipids. |
amphipathic, with at least one hydrophobic region. |
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Which of the following is true of integral membrane proteins? They serve only a structural role in membranes. They are not mobile within the bilayer. They are loosely bound to the surface of the bilayer. They are usually transmembrane proteins. They lack tertiary structure. |
They are usually transmembrane proteins. |
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Which of these are not embedded in the hydrophobic portion of the lipid bilayer at all? glycoproteins integrins integral proteins transmembrane proteins peripheral proteins |
peripheral proteins |
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Which of the following statements correctly describes the normal tonicity conditions for typical plant and animal cells? The animal cell is in an isotonic solution, and the plant cell is in a hypertonic solution. The animal cell is in a hypertonic solution, and the plant cell is in a hypotonic solution. The animal cell is in a hypertonic solution, and the plant cell is in an isotonic solution. The animal cell is in a hypotonic solution, and the plant cell is in an isotonic solution. The animal cell is in an isotonic solution, and the plant cell is in a hypotonic solution. |
The animal cell is in an isotonic solution, and the plant cell is in a hypotonic solution. |
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White blood cells engulf bacteria through what process? osmosis phagocytosis exocytosis receptor-mediated exocytosis pinocytosis |
phagocytosis |
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The difference between pinocytosis and receptor-mediated endocytosis is that pinocytosis can concentrate substances from the extracellular fluid, but receptor-mediated endocytosis cannot. pinocytosis increases the surface area of the plasma membrane whereas receptor-mediated endocytosis decreases the plasma membrane surface area. pinocytosis requires cellular energy, but receptor-mediated endocytosis does not. pinocytosis brings only water molecules into the cell, but receptor-mediated endocytosis brings in other molecules as well. pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis offers more selectivity. |
pinocytosis brings only water molecules into the cell, but receptor-mediated endocytosis brings in other molecules as well. |
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The membranes of winter wheat are able to remain fluid when it is extremely cold by _____. cotransport of glucose and hydrogen increasing the percentage of unsaturated phospholipids in the membrane decreasing the number of hydrophobic proteins in the membrane increasing the percentage of cholesterol molecules in the membrane |
increasing the percentage of unsaturated phospholipids in the membrane |
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Which of the following is a characteristic feature of a carrier protein in a plasma membrane? It works against diffusion. It requires the expenditure of cellular energy to function. It exhibits a specificity for a particular type of molecule. It has no hydrophobic regions. |
It exhibits a specificity for a particular type of molecule. |
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When a cell is in equilibrium with its environment, which of the following occurs for substances that can diffuse through the cell? All movement of molecules is directed by active transport. There is random movement of substances into and out of the cell. There is no movement of substances into and out of the cell. There is directed movement of substances into and out of the cell. |
There is random movement of substances into and out of the cell. |
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Which of the following is true of osmosis? Osmosis is an energy-demanding or "active" process. In osmosis, solutes move across a membrane from areas of lower water concentration to areas of higher water concentration. In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration. Osmosis only takes place in red blood cells. |
In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration. |
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When a plant cell, such as one from a rose stem, is submerged in a very hypotonic solution, what is likely to occur? The cell will become flaccid. The cell will become turgid. Plasmolysis will shrink the interior. The cell will burst. |
The cell will become turgid. |
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Ions diffuse across membranes through specific ion channels down _____. their concentration gradients their electrochemical gradients the electrical gradients their chemical gradients |
their electrochemical gradients |
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