Dynamic Study Chapter 6
How does cholesterol affect membrane fluidity? It has no effect on membrane fluidity. At body temperature, it makes the membrane more fluid. At body temperature, it makes the membrane less fluid. It allows phospholipids to pack tightly together. At lower temperatures, it makes the membrane more fluid.
At body temperature, it makes the membrane less fluid.
Which of the following statements correctly describes cofactors and coenzymes? Both are nonprotein enzyme helpers; but most coenzymes are metal ions, and most cofactors are organic molecules. Cofactors that are metal ions activate enzymes, but coenzymes deactivate them. Both cofactors and coenzymes act as allosteric inhibitors to various enzymes. Both are nonprotein enzyme helpers; but most cofactors are metal ions, and coenzymes are organic molecules that are a specific type of cofactor. Neither cofactors nor coenzymes assist enzyme function.
Both are nonprotein enzyme helpers; but most coenzymes are metal ions, and most cofactors are organic molecules.
Which of the following statements correctly describes a common characteristic of a plant cell wall and an animal cell extracellular matrix? (Concept 6.7) SHOW HINT Both are permeable to water and small solutes. Both contain large amounts of collagen. Both are composed primarily of carbohydrates. Both are permeable to water and small solutes, and both contain large amounts of collagen. Both are permeable to water and small solutes, both contain large amounts of collagen, and both are composed primarily of carbohydrates.
Both are permeable to water and small solutes.
Which of the following is false in respect to cells' chromosomes? Chromosomes are present throughout a cell's reproductive cycle. Chromosomes exist even when cells are not actively synthesizing proteins. Chromosomes are only visible as a cell is about to divide. Chromosomes contain DNA and proteins.
Chromosomes are only visible as a cell is about to divide.
Which of the following pairs of pathways and their location in the cell is incorrectly matched? Citric acid cycle: cytosol Electron transport chain: mitochondrion Glycolysis: cytosol Oxidative phosphorylation: mitochondrion
Citric acid cycle: cytosol **This occurs in the mitochondione matrax
Which of the following correctly describes a general property of all electrogenic pumps? (Concept 7.4) SHOW HINT Electrogenic pumps create a voltage difference across the membrane. Electrogenic pumps result in a cell with a high internal concentration of protons. Electrogenic pumps result in a cell with an interior that is positively charged relative to the outside of the cell. Electrogenic pumps pump sodium out of the cell and potassium into the cell. Electrogenic pumps can pump a large variety of solutes across a membrane against their concentration gradient.
Electrogenic pumps create a voltage difference across the membrane.
In terms of cellular function, what is the most important difference between prokaryotic and eukaryotic cells? ukaryotic cells are much more successful than prokaryotic cells. Eukaryotic cells are larger than prokaryotic cells. Eukaryotic cells can synthesize proteins but prokaryotic cells cannot. Eukaryotic cells lack many of the organelles found in prokaryotes. Eukaryotic cells are compartmentalized, which allows for specialization.
Eukaryotic cells are compartmentalized, which allows for specialization.
Microtubules and microfilaments commonly work with which of the following to perform many of their functions? (Concept 6.6) SHOW HINT Golgi apparatus lysosomes RNA ribosomes None of the listed responses is correct
Golgi apparatus right answer feedback: Correct. Microtubules guide vesicles from the ER to the Golgi and from the Golgi to the plasma membrane.
Which of the following sequences represents the order in which a protein made in the rough endoplasmic reticulum might move through the endomembrane system? (Concept 6.4) SHOW HINT Golgi apparatus → mitochondria Golgi apparatus → lysosome plasma membrane → nuclear envelope lysosome → plasma membrane nuclear envelope → lysosome
Golgi apparatus → lysosome
Which of the following functions of membrane proteins is important in tissue formation during embryonic development in animals? (Concept 7.1) SHOW HINT Membrane proteins with short sugar chains form identification tags that are recognized by other cells. Membrane proteins attach the membrane to the cytoskeleton. Membrane proteins form channels, which move substances across the membrane. Membrane proteins possess enzymatic activity. All of the listed responses are correct.
Membrane proteins with short sugar chains form identification tags that are recognized by other cells.
Cilia and flagella move due to the interaction of the cytoskeleton with which of the following? Pseudopodia Actin Motor proteins Tubulin Mitochondria
Motor proteins
Which of the following environments or actions would NOT affect the rate of an enzyme reaction? (Concept 8.4) SHOW HINT substrate concentration heating the enzyme pH cooling the enzyme None of the listed responses is correct.
None of the listed responses is correct.
Organisms are described as thermodynamically open systems. Which of the following statements is consistent with this description? (Concept 8.1) SHOW HINT Because energy must be conserved, organisms constantly recycle energy and thus need no input of energy. Heat produced by the organism is conserved in the organism and not lost to the environment. The metabolism of an organism is isolated from its surroundings. Organisms acquire energy from, and lose energy to, their surroundings. All of the listed responses are correct.
Organisms acquire energy from, and lose energy to, their surroundings.
Which of the following is a correct description of the events of cellular respiration and the sequence of events in cellular respiration? Oxidation of glucose to pyruvate; oxidation of pyruvate; oxidation of acetyl-coA; oxidative phosphorylation Oxidation of glucose to pyruvate; reduction of pyruvate; TCA cycle; oxidative phosphorylation Oxidation of pyruvate; TCA cycle; oxidation of glucose to pyruvate; oxidative phosphorylation Glycolysis; reduction of pyruvate; TCA cycle; oxidative phosphorylation Glycolysis; oxidative phosphorylation; TCA cycle; oxidation of pyruvate
Oxidation of glucose to pyruvate; oxidation of pyruvate; oxidation of acetyl-coA; oxidative phosphorylation
Which of the following structural arrangements of the components in biological membranes facilitates the cell membrane's property of selective permeability? A layer of protein coating a layer of phospholipid Proteins sandwiched between two layers of phospholipids A phospholipid bilayer with proteins scattered on the surfaces of the membranes Proteins embedded in two layers of phospholipids Phospholipids sandwiched between two layers of protein
Proteins embedded in two layers of phospholipids
In preparing pyruvate to enter the citric acid cycle, which of the following steps occurs? ANSWER INCORRECT Pyruvate is oxidized and decarboxylated, and the resulting electrons are donated to NADH to produce NAD+. Pyruvate is ionized directly to acetyl-coA. Pyruvate is oxidized and decarboxylated, and the removed electrons are used to reduce an NAD+ to an NADH. Pyruvate is reduced and decarboxylated, and the resulting electrons oxidize an NAD+ to an NADH. Pyruvate is reduced to acetyl-coA, which involves the reduction of pyruvate, the addition of a carbon dioxide from the environment, and its reduction by NADH.
Pyruvate is oxidized and decarboxylated, and the removed electrons are used to reduce an NAD+ to an NADH.
Which of the following groups is primarily involved in synthesizing molecules needed by the cell? Lysosome, vacuole, and ribosomes Smooth endoplasmic reticulum, ribosomes, and vacuole Rough endoplasmic reticulum, lysosome, and vacuole Vacuole, rough endoplasmic reticulum, and smooth endoplasmic reticulum Ribosomes, rough endoplasmic reticulum, and smooth endoplasmic reticulum
Ribosomes, rough endoplasmic reticulum, and smooth endoplasmic reticulum
What is the functional connection between the nucleolus, nuclear pores, and the nuclear membrane? ANSWER INCORRECT The nuclear pores are connections between the nuclear membrane and the endoplasmic reticulum that permit ribosomes to assemble on the surface of the ER. Subunits of ribosomes are assembled in the nucleolus and pass through the nuclear membrane via the nuclear pores. The nucleolus contains messenger RNA (mRNA), which crosses the nuclear envelope through the nuclear pores. Endoplasmic reticulum membrane is produced in the nucleolus and leaves the nucleus through the nuclear pores.
Subunits of ribosomes are assembled in the nucleolus and pass through the nuclear membrane via the nuclear pores.
Which of the following is an example of the second law of thermodynamics as it applies to biological reactions? (Concept 8.1) SHOW HINT The aerobic respiration of one molecule of glucose produces six molecules each of carbon dioxide and water. All types of cellular respiration produce ATP. Cellular respiration releases some energy as heat. The first and second choices are correct. The first, second, and third choices are correct.
The aerobic respiration of one molecule of glucose produces six molecules each of carbon dioxide and water. right answer feedback: Correct. The second law of thermodynamics states that every energy transformation makes the universe more disordered—carbon dioxide and water are more disordered than glucose.
Which part of the catabolism of glucose by cellular respiration requires molecular oxygen (O2) and produces CO2? The combination of the citric acid cycle and electron transport The combination of glycolysis and the citric acid cycle The citric acid cycle Glycolysis The electron transport chain
The combination of the citric acid cycle and electron transport
What is meant by the "induced fit" of an enzyme? (Concept 8.4) SHOW HINT The enzyme structure is altered so that it can be induced to fit many different types of substrate. The shape of the active site is nearly perfect for specifically binding the enzyme's substrate or substrates. The substrate can be altered so that it is induced to fit into the enzyme's active site. The presence of the substrate in solution induces the enzyme to slightly change its structure. The enzyme changes its shape slightly as the substrate binds to it.
The enzyme changes its shape slightly as the substrate binds to it.
The energy from the electrons in NADH and FADH2 fuel what process in the electron transport chain? ANSWER INCORRECT The electrons in NADH and FADH2 are not involved in the electron transport chain. Chemiosmosis The movement of H+ through ATP synthase The oxidation of oxygen The pumping of H+ across the cristae of the mitochondrion
The pumping of H+ across the cristae of the mitochondrion
Active transport requires an input of energy and can also generate voltages across membranes. Based on this information, which of the following statements is true? (Concept 7.4) SHOW HINT Active transport can use ATP as its energy source and ensures that there is no voltage across the cell membrane. Active transport moves solutes down their concentration gradients and always uses ATP as the source of energy to do this. Active transport uses channel proteins and ensures that the interior of the cell is always positive compared to the exterior of the cell. The source of energy for active transport of a solute up its gradient can be ATP or a concentration gradient of a second solute. This second gradient of solutes maintains no net difference in voltage across the membrane. The sodium-potassium pump hydrolyzes ATP and results in a net positive change outside the cell membrane.
The sodium-potassium pump hydrolyzes ATP and results in a net positive change outside the cell membrane.
Consider the growth of a farmer's crop over a season. Which of the following correctly states a limitation imposed by the first or second law of thermodynamics? (Concept 8.1) SHOW HINT The process of photosynthesis produces energy that the plant uses to grow. To obey the first law, the crops must represent an open system. The entropy of the universe must decrease to account for the increased entropy associated with plant growth. Growth of the crops must occur spontaneously. All of the listed responses are correct.
To obey the first law, the crops must represent an open system.
A particular cell has a nucleus and chloroplasts in addition to the fundamental structures required by all cells. Based on this information, this cell could be __________. (Concept 6.2) SHOW HINT a bacterium a photosynthetic protist cell or a plant cell a yeast (fungus) cell a cell from a pine tree a cell from the intestinal lining of a cow
a photosynthetic protist cell or a plant cell
Glucose is the primary fuel for cellular respiration. Which of the following molecules can also be used by cellular respiration to generate ATP? Amino acids Glycerol Fatty acids
all
Which of the following is/are likely to limit the maximum size of a cell? (Concept 6.2) SHOW HINT the cell's surface-to-volume ratio the shape of the cell the time it takes a molecule to diffuse across a cell All of the choices are correct. None of the choices is correct.
all
Consider two cells with the same volume but with very different surface areas due to differences in their shapes. The cell with the larger surface area is likely to __________. (Concept 6.2) SHOW HINT be involved in the rapid uptake of compounds from the cell's environment be buried deep in the interior of an organism have a very high metabolic rate be a prokaryotic cell be nearly spherical in shape r
be involved in the rapid uptake of compounds from the cell's environment right answer feedback: Correct. The high surface area is likely to be associated with high transport rates of compounds across the plasma membrane. The greater the surface area, the greater the potential for transport.
How do enzymes lower activation energy? (Concept 8.4) SHOW HINT by increasing reactivity of products by locally concentrating the reactants by harnessing heat energy to drive the breakage of bonds between atoms The first two responses are correct. The second and third choices are correct.
by locally concentrating the reactant
A cell has a membrane potential of -100 mV (more negative inside than outside) and has 1,000 times more calcium ions outside the cell than inside. Which of the following best describes a mechanism by which Ca2+ enters the cell? (Concept 7.4) SHOW HINT movement of Ca2+ into the cell through an ion channel down its concentration gradient movement of Ca2+ into the cell through a carrier protein down its electrical gradient facilitated diffusion of Ca2+ into the cell down its electrochemical gradient passive diffusion of Ca2+ into the cell down its electrochemical gradient cotransport of Ca2+ into the cell with Cl-
facilitated diffusion of Ca2+ into the cell down its electrochemical gradient
During the energy investment phase of glycolysis, __________. glucose is phosphorylated before it is split into two three-carbon molecules carbon dioxide is produced NADH is produced ATP is produced glucose is phosphorylated after it is split into two three-carbon molecules
glucose is phosphorylated before it is split into two three-carbon molecules
Observing a fluorescent micrograph cell with intermediate filaments would help you identify the cell as a __________. fungal cell plant cell prokaryotic cell human skin cell eukaryotic cell
human skin cell
Consider the currently accepted fluid mosaic model of the plasma membrane. Where in the plasma membrane would cholesterol most likely be found? (Concept 7.1) SHOW HINT on the outside (external) surface of the membrane in the interior and on the inside surface, but not on the outside surface on the inside (cytoplasmic) surface in the interior of the membrane on either surface of the membrane, but not in the interior of the membrane
in the interior of the membrane right answer feedback: Correct. The steroid cholesterol, wedged between phospholipid molecules in the plasma membranes of animals, helps stabilize the membrane
A protein that ultimately functions in the plasma membrane of a cell is most likely to have been synthesized __________. (Concept 6.4) SHOW HINT in the rough endoplasmic reticulum in the ribosomes of the mitochondria in the plasma membrane in the smooth endoplasmic reticulum on free cytoplasmic ribosomes
in the rough endoplasmic reticulum right answer feedback: Correct. All of the membrane proteins of the endomembrane systems are made in the rough ER.
The walls of plant cells are largely composed of polysaccharides and proteins that are synthesized __________. in the smooth endoplasmic reticulum in the rough endoplasmic reticulum externally to the plasma membrane in the rough endoplasmic reticulum and in the Golgi apparatus
in the rough endoplasmic reticulum and in the Golgi apparatus
The network of fibers that organizes structures and activities in a cell __________. are intermediate filaments are microfilaments is the cytoskeleton are microtubules are centrioles
is the cytoskeleton
A researcher wants to film the movement of chromosomes during cell division. Which type of microscope should she choose and why is it the best choice? (Concept 6.1) SHOW HINT light microscope, because the specimen is alive transmission electron microscope, because of its high magnifying power light microscope, because of its high resolving power transmission electron microscope, because of its high resolving power scanning electron microscope, because of its ability to visualize the surface of subcellular
light microscope, because the specimen is alive
Which of the following five membranes is most likely to have a lipid composition that is distinct from those of the other four? (Concept 6.5) SHOW HINT lysosome membrane plasma membrane mitochondrial outer membrane Golgi apparatus endoplasmic reticulum
mitochondrial outer membrane
Which of the following pairs correctly matches a membrane transport process to its primary function? (Concept 7.5) SHOW HINT pinocytosis: the uptake of water and small solutes into the cell by formation of vesicles at the plasma membrane phagocytosis: secretion of large particles from the cell by fusion of vesicles with the plasma membrane osmosis: passive diffusion of water and small solutes across a membrane exocytosis: the movement of water and solutes out of the cell by vesicle fusion with the plasma membrane None of the listed responses is correct.
pinocytosis: the uptake of water and small solutes into the cell by formation of vesicles at the plasma membrane
A plot of reaction rate (velocity) against temperature for an enzyme indicates little activity at 10°C and 45°C, with peak activity at 35°C. The most reasonable explanation for the low velocity at 10°C is that __________. (Concept 8.4) SHOW HINT the substrate becomes a competitive inhibitor at lower temperature the cofactors required by the enzyme system lack the thermal energy required to activate the enzyme there is too little activation energy available the enzyme was denatured the hydrogen bonds that define the structure of the enzyme's active site are unstable right answer feedback: Correct. The environment usually supplies activation energy in the form of heat. The lower the temperature, the less energy that is available to overcome the activation energy barrier.
right answer feedback: Correct. The environment usually supplies activation energy in the form of heat. The lower the temperature, the less energy that is available to overcome the activation energy barrier. there is too little activation energy available
A dish of animal cells was grown in the presence of radioactive phosphorous. The phosphorous largely ended up in nucleotides inside the actively growing animal cells. In which cellular structure or structures would you predict the majority of the radioactive phosphorous to accumulate? (Concept 6.3) SHOW HINT rough endoplasmic reticulum the Golgi apparatus the nucleus rough endoplasmic reticulum and Golgi apparatus the Golgi apparatus and the nucleus
the nucleus
A chemical reaction is designated as exergonic rather than endergonic when __________. (Concept 8.2) and (Concept 8.4) SHOW HINT activation energy exceeds net energy release activation energy is required the potential energy of the products is less than the potential energy of the reactants the products are less complex than the reactants**This measures entropy it absorbs more energy
the potential energy of the products is less than the potential energy of the reactants
Cell motility, which includes changes both in cell location and in the movement of cell parts, requires interactions of the cytoskeleton without ATP with glycosomes with the endoplasmic reticulum with motor proteins with "feet" to "walk"
with motor proteins
