Chapter 5 Mastery Quiz

Why doesn't the antibiotic penicillin harm humans? Select one: a. Human cells do not have cell walls. b. The dosage given to kill bacteria is too low to harm humans. c. Penicillin attacks the nervous system. d. Penicillin attacks plasma membranes. e. Penicillin inhibits the action of acetylcholinesterase.

a. Human cells do not have cell walls.

The eukaryotic cell has multiple membrane-enclosed compartments. This evolutionary innovation provides what advantage to the cell? Select one: a. The different membrane-enclosed spaces allow different parts of the cell to perform specific functions. b. The membrane-enclosed spaces allow for eukaryotic cells to be larger. c. The membrane-enclosed spaces lead to the evolution of many different cell types when they are extruded to form daughter cells with novel functions. d. The mebrane-enclosed spaces have allowed eukaryotes to evolve forms of metabolism that no longer require the intake of any molecules from outside the cell.

a. The different membrane-enclosed spaces allow different parts of the cell to perform specific functions.

Table sugar, or sucrose, is quite stable, and left on its own at room or even human body temperature, breakdown occurs very slowly. The breakdown of sucrose into the simple sugars fructose and glucose is an exergonic reaction. Sucrase, an enzyme, can increase the reaction rate at least one-million-fold. How does the net amount of energy released during the breakdown of sucrose compare between a spontaneous reaction and one catalyzed by sucrase? Select one: a. The sucrase-catalyzed reaction releases about one-millionth the energy of the spontaneous reaction. b. The sucrase-catalyzed reaction releases the same amount of energy as the spontaneous reaction. c. The sucrase-catalyzed reaction releases roughly two to three times more energy than the spontaneous reaction. d. The sucrase-catalyzed reaction releases one million times more energy than the spontaneous reaction.

b. The sucrase-catalyzed reaction releases the same amount of energy as the spontaneous reaction.

Utah's Great Salt Lake has an average salinity seven times higher than that of the oceans. Very few multicellular organisms live in this harsh environment. An example is the brine shrimp, which must devote a large portion of its metabolic energy to osmoregulation. These brine shrimp must _____. Select one: a. synthesize membranes that are impermeable to substances that upset osmotic balance Incorrect b. actively pump water back into their cells to counter its loss due to osmosis c. actively pump water back out of their cells to counter its inflow due to osmosis d. actively pump salt back out of their cells to counter its inflow due to osmosis

b. actively pump water back into their cells to counter its loss due to osmosis

Cellular respiration is an example of _____. Select one: a. an endergonic reaction b. an exergonic reaction c. bioenergetics d. thermodynamics e. entropy

b. an exergonic reaction

Endocytosis moves materials _____ a cell via _____. Select one: a. into ... facilitated diffusion b. into ... membranous vesicles c. into ... a transport protein d. out of ... diffusion e. out of ... membranous vesicles Feedback

b. into ... membranous vesicles

The mechanism of enzyme action is to _____. Select one: a. create an energy barrier between substrates b. lower the energy of the activation of a reaction c. change the direction of thermodynamic equilibrium d. change endergonic into exergonic reactions e. allow substrates to move more freely in solution

b. lower the energy of the activation of a reaction

The diffusion of water across a selectively permeable membrane is called _____. Select one: a. active transport b. osmosis c. exocytosis d. passive transport e. facilitated diffusion

b. osmosis

Seawater is dangerous to drink because _____. Select one: a. one cup of seawater contains enough sodium to poison you b. sea water is hypertonic to your body tissues and drinking it will cause you to lose water by osmosis c. seawater is isotonic to your body fluids and you will absorb too much water, causing your cells to burst d. the salt causes hypertension and you will promptly die of a stroke e. it contains toxic levels of iodine

b. sea water is hypertonic to your body tissues and drinking it will cause you to lose water by osmosis

In plant cells, carbon dioxide and water are joined to form carbohydrates. Plant cells can also break down carbohydrates such as glucose, releasing carbon dioxide, water, and energy. No one has ever observed such reactions between water and carbon dioxide outside of living cells. What allows simple molecules to assemble into more complex molecules, and also disassemble, in cells but not in other, nonbiological environments? Select one: a. Cells possess properties not seen in nonliving things that allow them to run physical processes in reverse. b. Cells are subject to only the first law, not the second law, of thermodynamics. c. Cells couple energy-releasing reactions to energy-requiring reactions. d. Cells are far more efficient in energy transactions than nonliving substances.

c. Cells couple energy-releasing reactions to energy-requiring reactions.

Macrophages are white blood cells that roam the body searching for invading microbes. Inside macrophage vacuoles these invaders are destroyed. How do the microbes get inside the macrophages? Select one: a. The invaders cross the membranes via facilitated transport through specific transport proteins. b. The invaders cross the membranes via active transport through specific transport proteins. c. Microbes are engulfed into the macrophage via phagocytosis. d. They are taken in by the form of exocytosis known as pinocytosis.

c. Microbes are engulfed into the macrophage via phagocytosis.

The energy for an endergonic reaction comes from _____ reaction. Select one: a. the ADP + P --> ATP b. the glucose + glucose --> maltose c. an anabolic d. an exergonic e. a synthesis

d. an exergonic

You're on the pilot episode of a new reality show called "The Transport Factor." The host hands you three different amino acids, four different sugars, and two different ions. Then the host shouts, "How many different proteins does the cell need to move these molecules across the plasma membrane using facilitated transport?" Quickly, you correctly respond: _____. Select one: a. one b. three c. five d. nine

d. nine

Enzymes work by _____. Select one: a. adding a phosphate group to a reactant b. decreasing the potential energy difference between reactant and product c. adding energy to a reaction d. increasing the potential energy difference between reactant and product e. reducing EA

e. reducing EA