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Biology Quiz 4
| Question | Answer |
|---|---|
| active transport | method of transporting material that requires energy |
| uniporter | transporter that carries one specific ion or molecule |
| transporter | specific carrier proteins or pumps that facilitate movement |
| amphiphilic | molecule possessing a polar or charged area and a nonpolar or uncharged area capable of interacting with both hydrophilic and hydrophobic environments |
| transport protein | membrane protein that facilitates a substance's passage across a membrane by binding it |
| tonicity | amount of solute in a solution |
| antiporter | transporter that carries two ions or small molecules in different directions |
| symporter | transporter that carries two different ions or small molecules, both in the same direction |
| solute | substance dissolved in a liquid to form a solution |
| aquaporin | channel protein that allows water through the membrane at a very high rate |
| selectively permeable | membrane characteristic that allows some substances through |
| carrier protein | membrane protein that moves a substance across the plasma membrane by changing its own shape |
| secondary active transport | movement of material that results from primary active transport to the electrochemical gradient |
| receptor-mediated endocytosis | variation of endocytosis that involves using specific binding proteins in the plasma membrane for specific molecules or particles, and clathrin-coated pits that become clathrin-coated vesicles |
| channel protein | membrane protein that allows a substance to pass through its hollow core across the plasma membrane |
| pump | active transport mechanism that works against electrochemical gradients |
| primary active transport | active transport that moves ions or small molecules across a membrane and may create a difference in charge across that membrane |
| concentration gradient | area of high concentration adjacent to an area of low concentration |
| plasmolysis | detaching the cell membrane from the cell wall and constricting the cell membrane when a plant cell is in a hypertonic solution |
| pinocytosis | a variation of endocytosis that imports macromolecules that the cell needs from the extracellular fluid |
| diffusion | passive transport process of low-molecular weight material according to its concentration gradient |
| peripheral protein | protein at the plasma membrane's surface either on its exterior or interior side |
| passive transport | method of transporting material through a membrane that does not require energy |
| electrochemical gradient | a combined electrical and chemical force that produces a gradient |
| osmosis | transport of water through a semipermeable membrane according to the water's concentration gradient across the membrane that results from the presence of solute that cannot pass through the membrane |
| osmolarity | total amount of substances dissolved in a specific amount of solution |
| electrogenic pump | pump that creates a charge imbalance |
| isotonic | situation in which the extracellular fluid has the same osmolarity as the fluid inside the cell, resulting in no net water movement into or out of the cell |
| integral protein | protein integrated into the membrane structure that interacts extensively with the membrane lipids' hydrocarbon chains and often spans the membrane |
| endocytosis | type of active transport that moves substances, including fluids and particles, into a cell |
| hypotonic | situation in which extracellular fluid has a lower osmolarity than the fluid inside the cell, resulting in water moving into the cell |
| hypertonic | situation in which extracellular fluid has a higher osmolarity than the fluid inside the cell, resulting in water moving out of the cell |
| exocytosis | process of passing bulk material out of a cell |
| hydrophobic | molecule that does not have the ability to bond with water; "water-hating" |
| hydrophilic | molecule with the ability to bond with water; "water-loving" |
| facilitated transport | process by which material moves down a concentration gradient (from high to low concentration) using integral membrane proteins |
| fluid mosaic model | describes the plasma membrane's structure as a mosaic of components including phospholipids, cholesterol, proteins, glycoproteins, and glycolipids (sugar chains attached to proteins or lipids, respectively), resulting in a fluid character (fluidity) |
| glycolipid | combination of carbohydrates and lipids |
| glycoprotein | combination of carbohydrates and proteins |
| Which of the following is an accurate description of the plasma membrane? | Two layers of phospholipids with a number of proteins embedded within |
| What is a phospholipid? | A special kind of lipid with a water-loving head and 2 water-fearing tails |
| How many layers of phospholipids make up the plasma membrane? | 2 |
| Which of the following molecules dramatically increases the rate of diffusion of water across cell membranes? | aquaporins |
| According to the fluid mosaic model, a membrane ________. | is composed of a fluid bilayer of phospholipids with embedded amphipathic proteins |
| What will happen to a red blood cell (RBC), which has an internal ion content of about 0.9%, if it is placed into a beaker of pure water? | The cell would swell because the water in the beaker is hypotonic relative to the cytoplasm of the RBC. |
| Celery stalks that are immersed in fresh water for several hours become stiff. Similar stalks left in a 0.15 M salt solution become limp. From this we can deduce that the fresh water ________. | is hypotonic and the salt solution is hypertonic to the cells of the celery stalks |
| Which would most likely pass unaided through a plasma membrane? | Something small and nonpolar, such as nitrogen gas |
| According to the fluid mosaic model of cell membranes, phospholipids ________. | can move laterally along the plane of the membrane |
| Which of the following statements about diffusion is true? | it is a passive process in which molecules move from a region of higher concentration to a region of lower concentration. |
| When a cell is in equilibrium with its environment, which of the following processes occurs for substances that can diffuse through the plasma membrane? | There is random movement of substances into and out of the cell. |
| What is the main role of membrane proteins? | Regulate the passage of materials in and out of the cell |
| Which of the following statements is a reasonable explanation for why unsaturated fatty acids help keep a membrane more fluid at lower temperatures? | The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly. |
| The passive transport of water is specifically called ________. | osmosis |
| Cell membranes have distinct inside and outside faces. Which of the following statements is the most likely explanation for the membrane's asymmetrical nature? | The two sides of a cell membrane face different environments and carry out different functions. |
| The sodium-potassium pump is called an electrogenic pump because it ________. | is used to drive the transport of glucose against a concentration gradient |
| Which form of transport requires the expenditure of energy? | Active transport |
| The voltage across a membrane is called the ________. | membrane potential |
| What is the definition of endocytosis? | It is the transport of large molecules into the cell. |
| Diffusion of ions across membranes through specific ion channels is driven by ________. | ion electrochemical gradients |
| For a protein to be an integral membrane protein, it would have to be ________. | amphipathic, with at least one hydrophobic region |
| Which of the following statements correctly describes osmosis? | In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration. |
| What might happen to your red blood cells if you were suddenly unable to regulate the solute concentration of your blood and it began to rise? | Your blood cells would shrivel because water would move out of the cells via osmosis. |
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fratbrotori