Biology Chapter 3B Answers

Chapter 3B A primary active transport process is one in which __________. - molecules move through transport proteins that have been activated by ATP Some transport processes use transport proteins in the plasma membrane, but do not require ATP. This type of transport is known as _____. - facilitated diffusion The majority of water molecules moving across plasma membranes by osmosis do so via a process that is most similar to ____. - facilitated diffusion The sodium-potassium pump uses ATP to move sodium and potassium ions across the plasma membrane. This statement describes _____. - primary active transport A vesicle fuses with the plasma membrane and releases its contents to the extracellular fluid. This statement describes _____. - exocytosis What is the difference between active and passive transport across the plasma membrane? - Active transport is ATP dependent, whereas passive transport uses only the kinetic energy of the particles for movement across the plasma membrane. Which of the following is a difference between primary and secondary active transport? - In primary active transport, the transport protein gets phosphorylated; in secondary active transport, the transport protein is not phosphorylated. T/F Channel-mediated diffusion is a form of active transport. - FALSE Phosphorylation Changes Pump Conformation Na+ Release--During this step, the pump releases Na+ into the extracellular fluid. Na+ has now been transported from the cytoplasm to the extracellular fluid. Which of the following best describes why Na+ isn't also transported in the opposite direction—from the extracellular fluid to the cytoplasm? - In this pump conformation, Na+ can no longer bind Change in Conformation - dephosphorylation of the pump This figure illustrates which of the following descriptions? - the use of a sodium concentration gradient to power the pumping of glucose into the cell What is the purpose of the energy extracted from ATP in this figure? - to generate a sodium concentration gradient Why is it necessary for glucose to be pumped into the cell rather than diffusing in? Glucose may have to be moved against a concentration gradient If active transport establishes a concentration gradient with the use of ATP, then the concentration gradient can be looked at as ________. - potential energy that can be harnessed when molecules passively diffuse down the concentration gradient A cell engulfing a relatively large particle will likely utilize ________. - phagocytosis If a cell is non-selectively engulfing samples of extracellular fluid, for example to absorb nutrients, it will likely utilize ________. - pinocytosis Which transport process is the main mechanism for the movement of most macromolecules by body cells? - receptor-mediated endocytosis Which vesicular transport process occurs primarily in some white blood cells and macrophages? - phagocytosis Some hormones enter cells via ________. - receptor-mediated endocytosis T/F During exocytosis, substances from inside the cell are moved outside. - TRUE FALSE STATEMENTS - Exocytosis involves infolding of the plasma membrane. Unlike endocytosis, exocytosis does not rely on protein interactions with the plasma membranes. Endocytosis and exocytosis are passive transport mechanisms. What is a membrane potential? - a voltage or electrical charge across the plasma membrane T/F A resting membrane potential is a sign of a depolarized membrane. - FALSE T/F In their resting state, all body cells exhibit a resting membrane potential; therefore, all cells are polarized. - TRUE Which of the following is FALSE regarding the membrane potential? - The resting membrane potential is maintained solely by passive transport processes. Which of the following is TRUE regarding the membrane potential? - The resting membrane potential occurs due to active transport of ions across the membrane due to the sodium-potassium pump. The resting membrane potential is determined mainly by the concentration gradients and differential permeability of the plasma membrane to K+ and Na+ ions. In their resting state, all body cells exhibit a resting membrane potential. Which of the following would not be restricted (limited) by low levels of ATP? - osmosis T/F Concentration differences cause ionic imbalances that polarize the cell membrane. TRUE Which of the following is NOT a factor that binds cells together? - glycolipids in the glycocalyx Which of the following IS a factor that binds cells together? - wavy contours of the membranes of adjacent cells, special membrane junctions, glycoproteins in the glycocalyx Which of the following statements is most correct regarding the intracellular chemical signals known as "second messengers"? - Cyclic AMP and calcium may be second messengers