Biology 101 study guide (ch 6-7)
In which of the following environments would there be the greatest need for osmoregulation? -a plant being grown hydroponically in a watery mixture of designated nutrients -an animal connective tissue cell bathed in isotonic body fluid -a red blood cell surrounded by plasma -a salmon moving from a river into an ocean
-a salmon moving from a river into an ocean
Three lab groups carried out an experiment to identify the concentration of sucrose in six solutions. Each unknown contained one of the following sucrose concentrations: 0.0 M, 0.2 M, 0.4 M, 0.6 M, 0.8 M, and 1.0 M. Cubes of sweet potato (1 cm3) were soaked for 24 hours in each solution and weighed to determine the change in mass. Each data entry represents the average of three sample replicates expressed as percent change in mass following a 24-hour soak in the unknown solutions. Unknown Percent change in mass Percent change in mass Percent change in mass Group 1 Group 2 Group 3 A 6.6 7.8 7.5 B 3.1 3.7 2.9 C -2.7 -3.5 -2.5 D 0.7 0.5 1.1 E -11.6 -12.3 -12.6 F -5.2 -6.2 -4.9 Based on the data provided, the intracellular molarity of dissolved solutes in sweet potato cells is approximately ________. 0.2 M 0.8 M 0.6 M 0.4 M
0.4 M
Which of the following will have the greatest ratio of surface area to volume? A box that is 1×1×2. A box that is 2×2×1. A box that is 2×2×2. A box that is 1×1×1.
A box that is 1×1×1.
Which of the following statements is most likely true of a protein that cotransports glucose and sodium ions into the intestinal cells of an animal? -A substance that blocks sodium ions from binding to the cotransport protein will also block the transport of glucose. -Sodium and glucose compete for the same binding site in the cotransporter. -Sodium ions can move down their electrochemical gradient through the cotransporter whether or not glucose is present outside the cell. -Glucose entering the cell down its concentration gradient provides energy for uptake of sodium ions against the electrochemical gradient.
A substance that blocks sodium ions from binding to the cotransport protein will also block the transport of glucose.
The diameter of a typical eukaryotic cell is approximately ten times the diameter of a typical prokaryote. What is the ratio of the volume of typical eukaryotic:prokaryotic cells? 10:1 1000:1 100:1
1000:1
Active and passive transport of solutes across a membrane typically differ in which of the following ways? -Active transport is always faster than passive transport. -Active transport uses protein carriers, whereas passive transport uses carbohydrate carriers. -Active transport is used for ions, passive transport is used for uncharged solutes. -Active transport is usually down the concentration gradient of the solute, whereas passive transport is always against the concentration gradient of the solute. -Active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy.
Active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy.
Both the volume and the surface area for three different cells were measured. These values are listed in the following table: Volume Surface Area Cell 1 9.3 μm3 26.5 μm2 Cell 2 12.2 μm3 37.1 μm2 Cell 3 17.6 μm3 40.6 μm2 Using data from the table above, select the best explanation for why that cell will be able to eliminate waste most efficiently? -Cell 3, because it is big enough to allow wastes to easily diffuse through the plasma membrane. -Cell 1, since it has the smallest volume and will not produce as much waste as the other cells. -Cell 3, since it has the largest surface area, which will enable it to eliminate all of its wastes efficiently. -Cell 2, since it has the highest ratio of surface area to volume, which facilitates the exchange of materials between a cell and its environment.
Cell 2, since it has the highest ratio of surface area to volume, which facilitates the exchange of materials between a cell and its environment.
A cell has formed a food vacuole as it ingested a food particle. Which of the following events is associated with the breakdown of that food particle? -Proteins for digestion of the food particle were initially processed in mitochondria. -Proteins for digestion of the food are made by ribosomes in the Golgi apparatus. -Enzymes for the breakdown of the food are delivered to the food vacuole from the cytosol. -The membrane of the food vacuole is derived from the cell wall. -Digestion of the food particle occurs in a vesicle enclosed by a membrane that separates the digestion from the cytoplasm.
Digestion of the food particle occurs in a vesicle enclosed by a membrane that separates the digestion from the cytoplasm.
Which of the following is a major difference between prokaryotic cells and eukaryotic cells? -Eukaryotic cells have flagella, while prokaryotic cells do not. -Eukaryotic cells have membrane-bound organelles, while prokaryotic cells do not. -Prokaryotic cells have cell walls, while eukaryotic cells do not. -Prokaryotic cells are generally larger than eukaryotic cells.
Eukaryotic cells have membrane-bound organelles, while prokaryotic cells do not.
Which of the following correctly describes some aspect of exocytosis or endocytosis? -Both processes provide a mechanism for exchanging membrane-impermeable molecules between the organelles and the cytosol. -The inner surface of a transport vesicle that fuses with or buds from the plasma membrane is most closely related to the inner surface of the plasma membrane. -These two processes require the participation of mitochondria. -Exocytosis and endocytosis temporarily change the surface area of the plasma membrane. -Endocytosis and exocytosis involve passive transport.
Exocytosis and endocytosis temporarily change the surface area of the plasma membrane.
Which of the following organelles produces and modifies polysaccharides that will be secreted? peroxisome lysosome Golgi apparatus mitochondrion
Golgi apparatus
A mutation that disrupts the ability of an animal cell to add polysaccharide modifications to proteins would most likely cause defects in which of the following organelles or structures? -mitochondria and Golgi apparatus -nuclear pores and secretory vesicles -nuclear matrix and extracellular matrix -Golgi apparatus and extracellular matrix
Golgi apparatus and extracellular matrix
Which of the following statements correctly describes osmosis? -In osmosis, solutes move across a membrane from areas of lower water concentration to areas of higher water concentration. -Osmosis only takes place in red blood cells. -Osmosis is an energy-demanding or "active" process. -In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration.
In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration.
Which statement about extracellular structures (plant cell walls and the extracellular matrix of animal cells) is correct? -Extracellular structures store energy in the form of -polysaccharides for subsequent metabolism by the cell. -All extracellular structures form barriers to separate adjacent cells. -Information can be transmitted from these extracellular structures to the cytoplasm. -Proteins and lipids are common components of extracellular structures. -Extracellular structures regulate the passage of water molecules across the cell membrane.
Information can be transmitted from these extracellular structures to the cytoplasm.
Which statement about extracellular structures (plant cell walls and the extracellular matrix of animal cells) is correct? -All extracellular structures form barriers to separate adjacent cells. -Proteins and lipids are common components of extracellular structures. -Extracellular structures store energy in the form of polysaccharides for subsequent metabolism by the cell. -Information can be transmitted from these extracellular structures to the cytoplasm. -Extracellular structures regulate the passage of water molecules across the cell membrane.
Information can be transmitted from these extracellular structures to the cytoplasm.
Which of the following statements describes a characteristic feature of a carrier protein in a plasma membrane? -It requires the expenditure of cellular energy to function. -It works against diffusion. -It has no hydrophobic regions. -It exhibits specificity for a particular type of molecule.
It exhibits specificity for a particular type of molecule.
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. -It is an active process in which molecules move from a region of lower concentration to a region of higher concentration. -It requires an expenditure of energy by the cell. -It is very rapid over long distances.
It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.
What is the function of the nuclear pore complex found in eukaryotes? -It regulates the movement of proteins and RNAs into and out of the nucleus. -It synthesizes the proteins required to copy DNA and make mRNA. -It synthesizes secreted proteins. -It assembles ribosomes from raw materials that are synthesized in the nucleus.
It regulates the movement of proteins and RNAs into and out of the nucleus.
Which of the following functions is NOT associated with the cytoskeleton in eukaryotic cells? -determining the shape of animal cells -the beating of cilia or flagella -the contraction of muscle cells in animals -maintaining the position of the nucleus in the cell -Movement of RNA molecules from the nucleus to the cytoplasm
Movement of RNA molecules from the nucleus to the cytoplasm
Which of the following functions is NOT associated with the cytoskeleton in eukaryotic cells? -the contraction of muscle cells in animals -the beating of cilia or flagella -determining the shape of animal cells -maintaining the position of the nucleus in the cell -Movement of RNA molecules from the nucleus to the cytoplasm
Movement of RNA molecules from the nucleus to the cytoplasm
Which of the following statements about the cytoskeleton is true? -Chemicals that block the assembly of the cytoskeleton would have little effect on a cell's response to external stimuli. -The cytoskeleton of eukaryotes is a static structure most resembling scaffolding used at construction sites. -Although microtubules are common within a cell, actin filaments are rarely found outside of the nucleus. -Movement of cilia and flagella is the result of motor proteins causing microtubules to move relative to each other.
Movement of cilia and flagella is the result of motor proteins causing microtubules to move relative to each other.
Which of the following would likely diffuse through the lipid bilayer of a plasma membrane most rapidly? an amino acid sucrose Na+ O2
O2
Select the correct statement about osmosis. -Osmosis is the diffusion of water molecules across a selectively permeable membrane. -If a dead cell is placed in a solution hypotonic to the cell contents, osmosis will not occur. -Osmotic equilibrium cannot be reached unless solute concentrations equalize across the membrane.
Osmosis is the diffusion of water molecules across a selectively permeable membrane.
Three lab groups carried out an experiment to identify the concentration of sucrose in six solutions. Each unknown contained one of the following sucrose concentrations: 0.0 M, 0.2 M, 0.4 M, 0.6 M, 0.8 M, and -1.0 M. Cubes of sweet potato (1 cm3) were soaked for 24 hours in each solution and weighed to determine the change in mass. Each data entry represents the average of three sample replicates expressed as percent change in mass following a 24-hour soak in the unknown solutions. From the data given, which statement most accurately describes what is occurring in response to a particular unknown solution? Unknown Percent change in mass Percent change in mass Percent change in mass Group 1 Group 2 Group 3 A 6.6 7.8 7.5 B 3.1 3.7 2.9 C -2.7 -3.5 -2.5 D 0.7 0.5 1.1 E -11.6 -12.3 -12.6 F -5.2 -6.2 -4.9 -Passive transport of sucrose out of the potato cells explains the change in mass observed for unknown solution F. -Unknown solution C represents a sucrose concentration slightly higher than the molarity of sweet potato cells, thus water is transported out of the cells. -Unknown solution E contains the highest concentration of sucrose, and the change in mass is due to the active transport of sucrose out of the cell. -Osmosis of water molecules from unknown solution B likely caused the increase in mass observed.
Osmosis of water molecules from unknown solution B likely caused the increase in mass observed.
A phospholipid bilayer with equal amounts of saturated and unsaturated fatty acids displays a specific permeability to glucose. What effect will increasing the proportion of unsaturated fatty acids in the bilayer have on the membrane's permeability to glucose? -Permeability to glucose will increase. -Permeability will decrease initially then increase as the bilayer fills with glucose. -Permeability to glucose will decrease. -Permeability to glucose will stay the same.
Permeability to glucose will increase.
Select the correct statement describing cellular structure or function. -Mitochondria and chloroplasts are part of the endomembrane system of the eukaryotic cell. -Only plant cells contain chloroplasts, and only animal cells contain mitochondria. -Plant and animal cells both carry out cellular respiration, producing ATP.
Plant and animal cells both carry out cellular respiration, producing ATP.
Select the correct statement describing cellular structure or function. -Plant and animal cells both carry out cellular respiration, producing ATP. -Only plant cells contain chloroplasts, and only animal cells contain mitochondria. -Mitochondria and chloroplasts are part of the endomembrane system of the eukaryotic cell.
Plant and animal cells both carry out cellular respiration, producing ATP.
Which statement correctly describes an endomembrane function? -The lumen of the endoplasmic reticulum (ER) is continuous with the cell nucleus. -Products of the ER are usually modified during their transit from the cis to the trans region of the Golgi apparatus. -Secretory proteins in transit from one part of the cell to another are carried in lysosomes.
Products of the ER are usually modified during their transit from the cis to the trans region of the Golgi apparatus.
Which of the following statements correctly describes some aspect of protein secretion from prokaryotic cells? -Prokaryotes cannot secrete proteins because they lack an endomembrane system. -The mechanism of protein secretion in prokaryotes is probably the same as that in eukaryotes. -Prokaryotes cannot secrete proteins because they lack rough endoplasmic reticulum. -Proteins secreted by prokaryotes are likely synthesized on ribosomes bound to the cytoplasmic surface of the plasma membrane.
Proteins secreted by prokaryotes are likely synthesized on ribosomes bound to the cytoplasmic surface of the plasma membrane.
Which one of the following statements about the endomembrane system is correct? -Most of the phospholipids of the endomembrane system are synthesized in the mitochondria. -The endoplasmic reticulum is continuous with the plasma membrane. -Mitochondria function in the modification and sorting of lipids and proteins. -Proteins that will be secreted from the cell are likely to be found in closed spaces bounded by membranes of the endomembrane system. -Ribosomes move lipids and proteins among the different organelles of the endomembrane system.
Proteins that will be secreted from the cell are likely to be found in closed spaces bounded by membranes of the endomembrane system.
Proton pumps are used in various ways by members of every domain of organisms: Bacteria, Archaea, and Eukarya. What does this fact most probably mean? -The high concentration of protons in the ancient atmosphere must have necessitated a pump mechanism. -Proton pumps are necessary to all cell membranes. -Cells of each domain evolved proton pumps independently when oceans became more acidic. -Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life.
Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life.
Choose the best description of the cell cytoskeleton. -The cell cytoskeleton is similar to an animal skeleton in providing rigid internal support and structure to the cell. -The cell cytoskeleton is a dynamic network of fibers that can be quickly dismantled and reassembled to change cell shape and the position of cell components. -The cell cytoskeleton serves as permanent scaffolding to anchor cell components into position within the cell cytoplasm.
The cell cytoskeleton is a dynamic network of fibers that can be quickly dismantled and reassembled to change cell shape and the position of cell components.
Choose the best description of the cell cytoskeleton. -The cell cytoskeleton serves as permanent scaffolding to anchor cell components into position within the cell cytoplasm. -The cell cytoskeleton is a dynamic network of fibers that can be quickly dismantled and reassembled to change cell shape and the position of cell components. -The cell cytoskeleton is similar to an animal skeleton in providing rigid internal support and structure to the cell.
The cell cytoskeleton is a dynamic network of fibers that can be quickly dismantled and reassembled to change cell shape and the position of cell components.
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. -The cell would shrink because the water in the beaker is hypotonic relative to the cytoplasm of the RBC. -The cell would shrink because the water in the beaker is hypertonic relative to the cytoplasm of the RBC. -The cell will remain the same size because the solution outside the cell is isotonic.
The cell would swell because the water in the beaker is hypotonic relative to the cytoplasm of the RBC.
Which statement is correct? -The contents of a red blood cell are hyperosmotic to distilled water. -A solution of seawater is hypertonic. -A solution of distilled water is hypotonic.
The contents of a red blood cell are hyperosmotic to distilled water.
Which of the following statements is a reasonable explanation for why unsaturated fatty acids help keep a membrane more fluid at lower temperatures? -Unsaturated fatty acids are more nonpolar than saturated fatty acids. -Unsaturated fatty acids have a higher cholesterol content, which prevents adjacent lipids from packing tightly. -The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly. -The double bonds block interaction among the hydrophilic head groups of the lipids.
The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.
Gaucher disease is the most common of lipid storage diseases in humans. It is caused by a deficiency of an enzyme necessary for the breakdown of lipids. This leads to the accumulation of fatty material in organs of the body including the spleen, liver, kidneys, lungs, brain, and bone marrow. Using your knowledge of the structure of eukaryotic cells, identify the statement below that best explains how internal membranes and the organelles of cells may be involved in Gaucher disease. -The rough endoplasmic reticulum contains too many ribosomes, which results in an overproduction of the enzyme involved in lipid breakdown. -The Golgi apparatus produces vesicles with faulty membranes, which fail to be transported to the plasma membrane for secretion. -The mitochondria are most likely defective and do not produce adequate amounts of ATP needed for cellular energy. -The lysosomes lack sufficient amounts of enzymes necessary for the metabolism of lipids.
The lysosomes lack sufficient amounts of enzymes necessary for the metabolism of lipids.
H. V. Wilson worked with sponges to gain some insight into exactly what was responsible for holding adjacent cells together. He exposed two species of differently pigmented sponges to a chemical that disrupted intercellular junctions, and the cells of the sponges dissociated. Wilson then mixed the cells of the two species and removed the chemical that caused the cells to dissociate. Wilson found that the sponges reassembled into two separate species. The cells from one species did not interact or form associations with the cells of the other species. How do you explain the results of Wilson's experiments? -The two species of sponge had different enzymes that functioned in the reassembly process. -The molecules responsible for cell-cell adhesion (cell junctions) differed between the two species of sponge. -The molecules responsible for cell-cell adhesion (cell junctions) were irreversibly destroyed during the experiment. -One cell functioned as an organizer for each organism, thereby attracting only cells of the same species.
The molecules responsible for cell-cell adhesion (cell junctions) differed between the two species of sponge.
Which statement correctly describes the nuclear envelope of a eukaryotic cell? -The nuclear envelope is a single membrane, consisting of a phospholipid bilayer. -Plasmadesmosomes in the nuclear envelope permit the exchange of macromolecules between the nucleus and the cytoplasm. -All of the proteins of the cell are synthesized on ribosomes bound on the nuclear envelope. -The nuclear envelope is continuous with the endoplasmic reticulum. -The outer layer of the nuclear envelope is coated with laminin.
The nuclear envelope is continuous with the endoplasmic reticulum.
Which statement correctly describes the nuclear envelope of a eukaryotic cell? -The nuclear envelope is a single membrane, consisting of a phospholipid bilayer. -Plasmadesmosomes in the nuclear envelope permit the exchange of macromolecules between the nucleus and the cytoplasm. -All of the proteins of the cell are synthesized on ribosomes bound on the nuclear envelope. -The nuclear envelope is continuous with the endoplasmic reticulum. -The outer layer of the nuclear envelope is coated with laminin.
The nuclear envelope is continuous with the endoplasmic reticulum.
Identify the correct statement about differences between rough and smooth endoplasmic reticulum (ER). -The outer surface of smooth ER lacks ribosomes, whereas the outer surface of rough ER has ribosomes. -Rough ER consists of a network of membranous tubules and sacs called cisternae, whereas smooth ER is less complex. -Smooth ER is part of the endomembrane system of the eukaryotic cell, and rough ER is not.
The outer surface of smooth ER lacks ribosomes, whereas the outer surface of rough ER has ribosomes.
A patient was involved in a serious accident and lost a large quantity of blood. In an attempt to replenish body fluids, distilled water equal to the volume of blood lost is added to the blood directly via one of his veins. What will be the most probable result of this transfusion? -The patient's red blood cells will shrivel up because the blood has become hypotonic compared to the cells. -The patient's red blood cells will shrivel up because the blood has become hypertonic compared to the cells. -The patient's red blood cells will swell and possibly burst because the blood has become hypotonic compared to the cells. -The patient's red blood cells will burst because the blood has become hypertonic compared to the cells.
The patient's red blood cells will swell and possibly burst because the blood has become hypotonic compared to the cells.
Which of the following statements about osmosis is correct? -If a cell is placed in an isotonic solution, more water will enter the cell than leaves the cell. -The presence of aquaporins (proteins that form water channels in the membrane) should speed up the process of osmosis. -Osmotic movement of water into a cell would likely occur if the cell accumulates water from its environment. -If a solution outside the cell is hypertonic compared to the cytoplasm, water will move into the cell by osmosis. -Osmosis is the diffusion of water from a region of lower water concentration to a region of higher water concentration.
The presence of aquaporins (proteins that form water channels in the membrane) should speed up the process of osmosis.
Which of the following statements about osmosis is correct? -Osmotic movement of water into a cell would likely occur if the cell accumulates water from its environment. -Osmosis is the diffusion of water from a region of lower water concentration to a region of higher water concentration. -If a solution outside the cell is hypertonic compared to the cytoplasm, water will move into the cell by osmosis. -If a cell is placed in an isotonic solution, more water will enter the cell than leaves the cell. -The presence of aquaporins (proteins that form water channels in the membrane) should speed up the process of osmosis.
The presence of aquaporins (proteins that form water channels in the membrane) should speed up the process of osmosis.
Which factors affect the rate of osmotic movement of water? -Hydrostatic pressure applied to a hypertonic solution separated from a hypotonic solution by a selectively permeable membrane increases osmotic movement across the membrane. -No factors have an effect; the rate of osmosis is constant. -The rate of osmosis increases with increasing differences in solute concentrations between two solutions separated by a selectively permeable membrane.
The rate of osmosis increases with increasing differences in solute concentrations between two solutions separated by a selectively permeable membrane.
Which factors affect the rate of osmotic movement of water? -Hydrostatic pressure applied to a hypertonic solution separated from a hypotonic solution by a selectively permeable membrane increases osmotic movement across the membrane. -The rate of osmosis increases with increasing differences in solute concentrations between two solutions separated by a selectively permeable membrane. -No factors have an effect; the rate of osmosis is constant.
The rate of osmosis increases with increasing differences in solute concentrations between two solutions separated by a selectively permeable membrane.
What would be observed by live-cell fluorescence microscopy immediately after HIV entry if HIV is endocytosed first, and then later fuses with the endocytotic vesicle membrane? -A spot of red fluorescence will diffuse in the infected cell's cytoplasm. -A spot of red fluorescence will remain outside the cell after delivering the viral capsid. -The red fluorescent dye-labeled lipids will appear in the infected cell's interior. -A spot of red fluorescence will be visible on the infected cell's plasma membrane, marking the site of membrane fusion and HIV entry.
The red fluorescent dye-labeled lipids will appear in the infected cell's interior.
Cell membranes have distinct inside and outside faces. Which of the following statements is the most likely explanation for the membrane's asymmetrical nature? -Since cell membranes communicate signals from one organism to another, the cell membranes must be asymmetrical. -Since the cell membrane forms a border between one cell and another in tightly packed tissues such as epithelium, the membrane must be asymmetrical. -Proteins only function on the cytoplasmic side of the cell membrane, which results in the membrane's asymmetrical nature. -The two sides of a cell membrane face different environments and carry out different functions.
The two sides of a cell membrane face different environments and carry out different functions.
Which of the following statements about a typical plasma membrane is correct? -The hydrophilic interior of the membrane is composed primarily of the fatty acid tails of the phospholipids. -Carbohydrates on the membrane surface are important in determining the overall bilayer structure. -Phospholipids are the primary component that determines which solutes can cross the plasma membrane. -The plasma membrane is a covalently linked network of phospholipids and proteins that controls the movement of solutes into and out of a cell. -The two sides of the plasma membrane have different lipid and protein composition.
The two sides of the plasma membrane have different lipid and protein composition.
Which of the following statements about a typical plasma membrane is correct? -The plasma membrane is a covalently linked network of phospholipids and proteins that controls the movement of solutes into and out of a cell. -Carbohydrates on the membrane surface are important in determining the overall bilayer structure. -The hydrophilic interior of the membrane is composed primarily of the fatty acid tails of the phospholipids. -The two sides of the plasma membrane have different lipid and protein composition. -Phospholipids are the primary component that determines which solutes can cross the plasma membrane.
The two sides of the plasma membrane have different lipid and protein composition.
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 directed movement of substances into and out of the cell. -There is no movement of substances into or out of the cell. -There is random movement of substances into and out of the cell. -All movement of molecules across the plasma membrane occurs by active transport.
There is random movement of substances into and out of the cell.
The cell walls of bacteria, fungi, and plant cells, and the extracellular matrix of animal cells are all external to the plasma membrane. Which of the following characteristics are common to all of these extracellular structures? -They are constructed of materials that are synthesized in the cytoplasm and then transported out of the cell for assembly. -They are composed of a mixture of lipids and nucleotides. -They must block water and small molecules to regulate the exchange of matter and energy with their environment. -They must provide a rigid structure that maintains an appropriate ratio of cell surface area to volume.
They are constructed of materials that are synthesized in the cytoplasm and then transported out of the cell for assembly.
In facilitated diffusion, what is the role of the transport protein? -Transport proteins provide a hydrophilic route for the solute to cross the membrane. -Transport proteins organize the phospholipids to allow the solute to cross the membrane. -Transport proteins provide a low-resistance channel for water molecules to cross the membrane. -Transport proteins provide the energy for diffusion of the solute. -Transport proteins provide a protein site for ATP hydrolysis, which facilitates the movement of a solute across a membrane.
Transport proteins provide a hydrophilic route for the solute to cross the membrane.
In facilitated diffusion, what is the role of the transport protein? -Transport proteins provide a protein site for ATP hydrolysis, which facilitates the movement of a solute across a membrane. -Transport proteins provide a low-resistance channel for water molecules to cross the membrane. -Transport proteins provide the energy for diffusion of the solute. -Transport proteins organize the phospholipids to allow the solute to cross the membrane. -Transport proteins provide a hydrophilic route for the solute to cross the membrane.
Transport proteins provide a hydrophilic route for the solute to cross the membrane.
The figure shows two U-like tubes with a selectively permeable membrane separating each of the tubes in two equal parts. All tubes contain 6 green spheres in the left half and 13 green spheres in the right half. Green spheres represent a sugar molecule. The first tube has the same level of solution on both sides with the left half of the tube having lower concentration of solute and the right half of the tube having higher concentration of solute. The second tube has the same concentration of solute on both sides, but the level of the solution is higher in the right half and lower in the left one. What happens when two solutions separated by a selectively permeable membrane reach osmotic equilibrium? -Water molecules continue to move from the hypotonic solution to the hypertonic solution. -Water molecules move between the two solutions, but there is no net movement of water across the membrane. -Water molecules no longer move between the solutions.
Water molecules move between the two solutions, but there is no net movement of water across the membrane.
What happens when two solutions separated by a selectively permeable membrane reach osmotic equilibrium? -Water molecules move between the two solutions, but there is no net movement of water across the membrane. -Water molecules continue to move from the hypotonic solution to the hypertonic solution. -Water molecules no longer move between the solutions.
Water molecules move between the two solutions, but there is no net movement of water across the membrane.
The nuclear lamina is an array of intermediate filaments that line the inner side of the nuclear membrane. If a chemical treatment caused the lamina to disassemble, what would you expect to be the most likely immediate consequence? -a change in the shape of the nucleus -closing of nuclear pores -a loss of genetic information from chromosomes -the inability of the nucleus to divide during cell division
a change in the shape of the nucleus
The force driving simple diffusion is ________, while the energy source for active transport is ________. -transmembrane pumps; an electrochemical gradient -a concentration gradient; ATP hydrolysis -a concentration gradient; ADP -phosphorylated carrier proteins; ATP
a concentration gradient; ATP hydrolysis
Which of the following factors would tend to increase membrane fluidity? -a greater proportion of saturated phospholipids -a greater proportion of relatively large glycolipids compared with lipids having smaller molecular masses -a relatively high protein content in the membrane -a lower temperature -a greater proportion of unsaturated phospholipids
a greater portion of unsaturated phospholipids
Which of the following factors would tend to increase membrane fluidity? -a greater proportion of relatively large glycolipids compared with lipids having smaller molecular masses -a greater proportion of saturated phospholipids -a greater proportion of unsaturated phospholipids -a relatively high protein content in the membrane -a lower temperature
a greater proportion of unsaturated phospholipids
A newly discovered unicellular organism isolated from acidic mine drainage is found to contain a cell wall, a plasma membrane, two flagella, and peroxisomes. Based just on this information, the organism is most likely ________. a motile eukaryote a nonmotile eukaryote a motile archaea a motile bacterium a nonmotile prokaryote
a motile eukaryote
Cilia and flagella bend because of ________. -a motor protein called dynein -contraction by myosin -a motor protein called radial spokes -conformational changes in ATP that thrust microtubules laterally
a motor protein called dynein
Which of the following structures would decrease the electrochemical gradient across a membrane? a proton pump a potassium channel an aquaporin both a proton pump and a sodium channel
a potassium channel
Spherocytosis is a human blood disorder associated with a defective cytoskeletal protein in the red blood cells (RBCs). What do you suspect is the consequence of such a defect? -an insufficient supply of oxygen-transporting proteins in the RBCs -adherence of RBCs to blood vessel walls, causing plaque formation -abnormally shaped RBCs -an insufficient supply of ATP in the RBCs
abnormally shaped RBCs
If the concentration of phosphate in the cytosol is 2.0 mM and the concentration of phosphate in the surrounding fluid is 0.1 mM, how could the cell increase the concentration of phosphate in the cytosol? passive transport diffusion active transport osmosis facilitated diffusion
active transport
Motor proteins provide for molecular motion in cells by interacting with what types of cellular structures? -free ribosomes and ribosomes attached to the ER -cellulose fibers in the cell wall -components of the cytoskeleton -membrane proteins of the inner nuclear envelope
components of the cytoskeleton
If the concentration of phosphate in the cytosol is 2.0 mM and the concentration of phosphate in the surrounding fluid is 0.1 mM, how could the cell increase the concentration of phosphate in the cytosol? -passive transport -diffusion -active transport -osmosis -facilitated diffusion
active transport For the cell to accumulate phosphate, it must move calcium against the concentration gradient. This process requires energy.
For a protein to be an integral membrane protein, it would have to be _____. -exposed on only one surface of the membrane -amphipathic, with at least one hydrophobic region -hydrophobic -hydrophilic
amphipathic, with at least one hydrophobic region
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 hypotonic solution -a hypotonic solution, and the plant cell is in an isotonic solution -a hypertonic solution, and the plant cell is in an isotonic solution -an isotonic solution, and the plant cell is in a hypertonic solution
an isotonic solution, and the plant cell is in a hypotonic solution
Which of the following molecules dramatically increases the rate of diffusion of water across cell membranes? ATP aquaporins gated ion channels the sodium-potassium pump
aquaporins
Which domains of life are classified as prokaryotes? Bacteria and Archaea Bacteria and Protista Bacteria and Eukarya Archaea and Fungi
bacteria and archaea
Which of the following are common traits of chloroplasts and mitochondria? -Both are surrounded by a single membrane. -Both reproduce by meiosis. -Both have their own DNA. -Both are found in plant and animal cells. -Proteins for both are synthesized on ribosomes in the rough ER.
both have their own DNA
In an HIV-infected cell producing HIV virus particles, the viral glycoprotein is expressed on the plasma membrane. How do the viral glycoproteins get to the plasma membrane? They are synthesized ________. -on ribosomes on the plasma membrane -on free cytoplasmic ribosomes and then inserted into the plasma membrane -by ribosomes in the rough ER, secreted from the cell, and inserted into the plasma membrane from the outside -by ribosomes in the rough ER and arrive at the plasma membrane in the membrane of secretory vesicles
by ribosomes in the rough ER and arrive at the plasma membrane in the membrane of secretory vesicles
According to the fluid mosaic model of cell membranes, phospholipids _____. -have hydrophilic tails in the interior of the membrane -can move laterally along the plane of the membrane -occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane -frequently flip-flop from one side of the membrane to the other
can move laterally along the plane of the membrane
An animal cell lacking carbohydrates on the external surface of its plasma membrane would likely be impaired in which function? -establishing a diffusion barrier to charged molecules -transporting ions against an electrochemical gradient -cell-cell recognition -attaching the plasma membrane to the cytoskeleton
cell-cell recognition
Which organelle often takes up much of the volume of a plant cell? lysosome Golgi apparatus central vacuole chloroplast
central vacuole
Which of the following correctly matches an organelle with its function? -lysosome ... movement -mitochondrion ... photosynthesis -nucleus ... cellular respiration -central vacuole ... storage -ribosome ... manufacture of lipids
central vacuole ... storage
In what way do membranes vary among eukaryotic cells? -Certain proteins are unique to each membrane. -Some membranes have hydrophobic surfaces exposed to the cytoplasm, while others have -hydrophilic surfaces facing the cytoplasm. -Phospholipids are found only in certain membranes. -Only certain membranes are constructed from amphipathic molecules. -Only certain membranes of the cell are selectively permeable.
certain proteins are unique to each membrane
Which of the following types of molecules lack hydrophilic domains? -peripheral membrane proteins -transmembrane proteins -cholesterol -integral membrane proteins
chloresterol
Which structure below is independent of the endomembrane system? nuclear envelope chloroplast plasma membrane Golgi apparatus
chloroplast
Which structure is not part of the endomembrane system? -plasma membrane -chloroplast -Golgi apparatus -ER -nuclear envelope
chloroplast
Which structure is not part of the endomembrane system? plasma membrane nuclear envelope Golgi apparatus ER chloroplast
chloroplast
Thylakoids, DNA, and ribosomes are all components found in _____. mitochondria lysosomes nuclei chloroplasts
chloroplasts
The movement of glucose into a cell against a concentration gradient is most likely to be accomplished by which of the following? -receptor-mediated endocytosis -facilitated diffusion of the glucose using a carrier protein -movement of glucose into the cell through a glucose channel -co transport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis -passive diffusion of the glucose through the lipid bilayer
co transport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis
In a liver cell detoxifying alcohol and some other poisons, the enzymes of the peroxisome remove hydrogen from these molecules and ________. -combine the hydrogen with water molecules to generate hydrogen peroxide -combine the hydrogen with hydrogen peroxide to generate oxygen -combine the hydrogen with oxygen molecules to generate hydrogen peroxide -combine the hydrogen with hydrogen peroxide to generate oxygen and water
combine the hydrogen with oxygen molecules to generate hydrogen peroxide(h2o2)
The phosphate transport system in bacteria imports phosphate into the cell even when the concentration of phosphate outside the cell is much lower than the cytoplasmic phosphate concentration. Phosphate import depends on a pH gradient across the membrane more acidic outside the cell than inside the cell. In this bacterial cell, phosphate transport is an example of ________. passive diffusion active transport cotransport facilitated diffusion
cotransport
The movement of glucose into a cell against a concentration gradient is most likely to be accomplished by which of the following? -movement of glucose into the cell through a glucose channel -passive diffusion of the glucose through the lipid bilayer -receptor-mediated endocytosis -facilitated diffusion of the glucose using a carrier protein -cotransport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis
cotransport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis
In some cells, there are many ion electrochemical gradients across the plasma membrane even though there are usually only one or two proton pumps present in the membrane. The gradients of the other ions are most likely accounted for by _____. cotransport proteins ion channels passive diffusion across the plasma membrane pores in the plasma membrane
cotransport proteins
Which of the following is least likely to be important in holding the components of a biological membrane together? -hydrophobic interactions between the phospholipid tails and the surface of integral membrane proteins buried in the membrane -hydrophobic interactions among the fatty acid tails of phospholipids on the same side of the membrane -hydrophobic interactions among the fatty acid tails of phospholipids on opposite sides of the membrane -polar interactions among the phospholipid head groups on the same surface of the membrane -covalent interactions between the phospholipid and protein components of the membrane
covalent interactions between the phospholipid and protein components of the membrane
Which of the following is least likely to be important in holding the components of a biological membrane together? -polar interactions among the phospholipid head groups on the same surface of the membrane -hydrophobic interactions among the fatty acid tails of phospholipids on the same side of the membrane -hydrophobic interactions among the fatty acid tails of phospholipids on opposite sides of the membrane -hydrophobic interactions between the phospholipid tails and the surface of integral membrane proteins buried in the membrane -covalent interactions between the phospholipid and protein components of the membrane
covalent interactions between the phospholipid and protein components of the membrane
Based on Figure 7.18 in your textbook, which of these experimental treatments would increase the rate of sucrose transport into the cell? -adding a substance that makes the membrane more permeable to hydrogen ions -adding an inhibitor that blocks the regeneration of ATP -decreasing cytoplasmic pH -decreasing extracellular sucrose concentration -decreasing extracellular pH
decreasing extracellular pH
Based on Figure 7.18 in your textbook, which of these experimental treatments would increase the rate of sucrose transport into the cell? -adding an inhibitor that blocks the regeneration of ATP -adding a substance that makes the membrane more permeable to hydrogen ions -decreasing cytoplasmic pH -decreasing extracellular pH -decreasing extracellular sucrose concentration
decreasing extracellular pH
Familial hypercholesterolemia is characterized by _____. -poor attachment of the cholesterol to the extracellular matrix of cells -a poorly formed lipid bilayer that cannot incorporate cholesterol into cell membranes -defective LDL receptors on the cell membranes -inhibition of the cholesterol active transport system in red blood cells
defective LDL receptors on the cell membranes
A defect in which of the following intercellular junctions would allow partially digested material to leak passively between the cells of the small intestine into the abdominal cavity? tight junctions plasmodesmata desmosomes gap junctions
desmosomes
According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly -confined to the hydrophobic interior of the membrane. -spread in a continuous layer over the inner and outer surfaces of the membrane. -randomly oriented in the membrane, with no fixed inside-outside polarity. -free to depart from the fluid membrane and dissolve in the surrounding solution. -embedded in a lipid bilayer.
embedded in a lipid bilayer
According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly -spread in a continuous layer over the inner and outer surfaces of the membrane. -embedded in a lipid bilayer. -confined to the hydrophobic interior of the membrane. -randomly oriented in the membrane, with no fixed inside-outside polarity. -free to depart from the fluid membrane and dissolve in the surrounding solution.
embedded in a lipid bilayer
The evolution of eukaryotic cells most likely involved ________. -endosymbiosis of an oxygen-using bacterium in a larger bacterial host cell-the endosymbiont evolved into mitochondria -endosymbiosis of an oxygen-using bacterium in a larger bacterial host cell-the endosymbiont evolved into chloroplasts -evolution of an endomembrane system and subsequent evolution of mitochondria from a portion of the smooth endoplasmic reticulum -endosymbiosis of a photosynthetic archaeal cell in a larger bacterial host cell to escape toxic oxygenthe anaerobic archaea evolved into chloroplasts
endosymbiosis of an oxygen-using bacterium in a larger bacterial host cell-the endosymbiont evolved into mitochondria
A characteristic 9 + 2 arrangement of microtubules, consisting of nine doublets of microtubules surrounding a pair of single microtubules is associated with ________. centrioles and basal bodies eukaryotic flagella, motile cilia, and nonmotile cilia bacterial flagella eukaryotic flagella and motile cilia
eukaryotic flagella and motile cilia
Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through _____. desmosomes gap junctions plasmodesmata tight junctions
gap junctions
The sodium-potassium pump is called an electrogenic pump because it ________. -pumps equal quantities of Na+ and K+ across the membrane in opposite directions -decreases the voltage difference across the membrane -generates voltage across the membrane -is used to drive the transport of glucose against a concentration gradient
generates voltage across the membrane
In plant cells, the middle lamella ________. -connects the cytoplasm of adjacent cells -prevents excessive uptake of water by plant cells -glues adjacent cells together -prevents dehydration of adjacent cells
glues adjacent cells together
Amoebae move by crawling over a surface (cell crawling), which involves ________. -localized contractions driven by myosin and microtubules -reinforcement of the pseudopod with intermediate filaments -assembly of microtubule extensions that vesicles can follow in the direction of movement -growth of actin filaments to form bulges in the plasma membrane
growth of actin filaments to form bulges in the plasma membrane
Several epidemic microbial diseases of earlier centuries incurred high death rates because they resulted in severe dehydration due to vomiting and diarrhea. Today they are usually not fatal because we have developed which of the following types of treatments? -medications to slow blood loss -intravenous feeding techniques -hydrating drinks with high concentrations of salt and glucose -antiviral medications that are efficient and work well with most viruses
hydrating drinks with high concentrations of salt and glucose
Where are proteins produced other than on ribosomes free in the cytosol or ribosomes attached to the endoplasmic reticulum? in lysosomes in the nucleolus in the Golgi apparatus in mitochondria
in mitochondria
If plant cells are grown on media containing radioactively labeled thymine for one generation, radioactively labeled macromolecules will be detected in which of the following? -only in the nucleus and chloroplasts -only in the nucleus and mitochondria -only in the nucleus -in the nucleus, mitochondria, and chloroplasts
in the nucleus, mitochondria, and chloroplasts
The membranes of winter wheat are able to remain fluid when it is extremely cold by ________. -decreasing the number of hydrophobic proteins in the membrane -increasing the proportion of unsaturated phospholipids in the membrane -increasing the proportion of glycolipids in the membrane -decreasing the percentage of cholesterol molecules in the membrane
increasing the proportion of unsaturated phospholipids in the membrane
Diffusion of ions across membranes through specific ion channels is driven by ________. ion electrochemical gradients ion concentration gradients only active transport pumps electrical gradients only
ion electrochemical gradients
According to the fluid mosaic model, a membrane ________. -is composed of a mosaic of fluid polysaccharides and amphipathic proteins -is composed of a fluid bilayer of phospholipids between two layers of hydrophilic proteins -is composed of a fluid bilayer of phospholipids with embedded amphipathic proteins -is composed of a single layer of fluid phospholipids between two layers of hydrophilic proteins
is composed of a fluid bilayer of phospholipids with embedded amphipathic proteins
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_____. -and the salt solution are both hypertonic to the cells of the celery stalks -is hypertonic and the salt solution is hypotonic to the cells of the celery stalks -is isotonic and the salt solution is hypertonic to the cells of the celery stalks -is hypotonic and the salt solution is hypertonic to the cells of the celery stalks
is hypotonic and the salt solution is hypertonic to the cells of the celery stalks
A bacterium engulfed by a white blood cell through phagocytosis will be digested by enzymes contained in _____. secretory vesicles Golgi vesicles lysosomes vacuoles
lysosomes
Asbestos is a material that was once used extensively in construction. One risk from working in a building that contains asbestos is the development of asbestosis caused by the inhalation of asbestos fibers. Cells will take up asbestos by phagocytosis, but are not able to degrade it. As a result, asbestos fibers accumulate in ________. lysosomes the Golgi apparatus peroxisomes nuclei
lysosomes
Which of the following macromolecules leaves the nucleus of a eukaryotic cell through pores in the nuclear membrane? amino acids DNA phospholipids mRNA
mRNA
The voltage across a membrane is called the _____. chemical gradient osmotic potential membrane potential electrochemical gradient
membrane potential
Cyanide binds to at least one molecule involved in producing ATP. If a cell is exposed to cyanide, most of the cyanide will be found within the -peroxisomes. -endoplasmic reticulum. -ribosomes. -lysosomes. -mitochondria.
mitochondria
Cyanide binds with at least one molecule involved in producing ATP. If a cell is exposed to cyanide, most of the bound cyanide is likely to be localized within the ________. smooth endoplasmic reticulum peroxisomes lysosomes mitochondria
mitochondria
Suppose a young boy is always tired and fatigued, suffering from a metabolic disease. Which of the following organelles is most likely malfunctioning in this disease? Golgi apparatus mitochondria lysosomes smooth endoplasmic reticulum
mitochondria
Which organelle is the primary site of ATP synthesis in eukaryotic cells? peroxisome mitochondrion Golgi apparatus lysosome
mitochondrion
Which structure is common to plant and animal cells? -chloroplast -central vacuole -mitochondrion -centriole -wall made of cellulose
mitochondrion
Which structure is common to plant and animal cells? -mitochondrion -chloroplast -central vacuole -centriole
mitochondrion
Researchers investigating the mechanism of vesicular transport assembled a cell-free system that included microtubule tracks, vesicles, and ATP. However, they observed no movement of transport of vesicles in this system. What were they missing? an axon motor proteins contractile microfilaments intermediate filaments
motor proteins
Cytochalasin D is a drug that prevents actin polymerization. A cell treated with cytochalasin D will still be able to carry out which of the following processes? divide in two move vesicles within a cell contract muscle fibers extend pseudopodia
move vesicles within a cell
Which of the following membrane activities requires energy from ATP hydrolysis? -movement of carbon dioxide out of a paramecium -movement of Na+ ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid -facilitated diffusion of chloride ions across the membrane through a chloride channel -movement of glucose molecules into a bacterial cell from a medium containing a higher concentration of glucose than inside the cell
movement of Na+ ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid
A sodium-potassium pump ________. -move three sodium ions out of a cell and two potassium ions into a cell and generates an ATP in each cycle -moves three potassium ions out of a cell and two sodium ions into a cell using energy from ATP hydrolysis -moves three sodium ions out of a cell and two potassium ions into a cell using energy from ATP hydrolysis -moves three potassium ions out of a cell and two sodium ions into a cell while producing ATP for each cycle
moves three sodium ions out of a cell and two potassium ions into a cell using energy from ATP hydrolysis
Suppose a cell has the following molecules and structures: enzymes, DNA, ribosomes, plasma membrane, and mitochondria. It could be a cell from ________. -a plant, but not an animal -an animal, but not a plant -nearly any eukaryotic organism -a bacterium, but not a eukaryote
nearly any eukaryotic organism
In receptor-mediated endocytosis, receptor molecules initially project to the outside of the cell. Where do they end up after endocytosis? -on the inside surface of the vesicle -on the outside of vesicles -on the inside surface of the cell membrane -on the outer surface of the nucleus
on the inside surface of the vesicle
Which of the following processes includes all of the others? osmosis transport of an ion down its electrochemical gradient passive transport facilitated diffusion
passive transport
Which of the following processes includes all others? -transport of an ion down its electrochemical gradient -osmosis -facilitated diffusion -diffusion of a solute across a membrane -passive transport
passive transport
Which of the following types of molecules are hydrophilic and therefore excluded from the hydrophobic portion of the phospholipid bilayer? cholesterol integral membrane proteins peripheral membrane proteins transmembrane proteins
peripheral membrane proteins
Which cell would be best for studying lysosomes? -nerve cell -muscle cell -bacterial cell -phagocytic white blood cell
phagocytic white blood cell
An organism with a cell wall would most likely be unable to take in materials through _____. phagocytosis osmosis facilitated diffusion active transport
phagocytosis
White blood cells engulf bacteria using _____. phagocytosis osmosis receptor-mediated exocytosis pinocytosis
phagocytosis
The difference between pinocytosis and receptor-mediated endocytosis is that _____. -pinocytosis increases the surface area of the plasma membrane, whereas receptor-mediated endocytosis decreases the plasma membrane surface area. -pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis offers more selectivity. -pinocytosis can concentrate substances from the extracellular fluid, but receptor-mediated endocytosis cannot. -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.
Mitochondria are found in _____. -all cells -animal cells only -plant and animal cells -animal cells and prokaryotic cells, but not plant cells -plant cells only
plant and animal cells
Which of the following are found in plant, animal, and bacterial cells? chloroplasts mitochondria endoplasmic reticulum ribosomes
ribosomes
Which of the following is present in a prokaryotic cell? ER nuclear envelope ribosomes chloroplast mitochondrion
ribosomes
Which of the following structures form cytoplasmic channels that connect adjacent plant cells through the cell walls? plasmodesmata tight junctions desmosomes gap junctions
plasmodesmata
When a plant cell, such as one from a tulip leaf, is submerged in a hypertonic solution, what is likely to occur? The cell will burst. Plasmolysis will shrink the interior of the cell. The cell will become flaccid. The cell will become turgid.
plasmolysis will shrink the interior of the cell
A cell with a predominance of rough endoplasmic reticulum is most likely ________. -producing large quantities of proteins in the cytosol -producing large quantities of carbohydrates to assemble an extensive cell wall matrix -producing large quantities of proteins for secretion -producing large quantities of carbohydrates for storage in the vacuole
producing large quantities of proteins for secretion
Examination of a cell by transmission electron microscopy reveals a high density of ribosomes in the cytoplasm. This observation suggests that this cell is actively producing large amounts of which of the following molecules? lipids polysaccharides proteins nucleic acids
proteins
Which of the following frequently imposes a limit on cell size? -the number of mitochondria in the cytoplasm -the volume of the endomembrane system -the absence of a nucleus -ratios of surface area to volume
ratios of surface area to volume
Which of the following macromolecules enter the nucleus of a eukaryotic cell through pores in the nuclear membrane? mRNA phospholipids rRNA ribosomal proteins
ribosomal proteins
Which of the following is present in a prokaryotic cell? -chloroplast -mitochondrion -nuclear envelope -ER -ribosome
ribosome
Which of the following is the most common pathway taken by a newly synthesized protein that will be secreted by a cell? -rough ER → lysosome → transport vesicle → plasma membrane -rough ER → Golgi → transport vesicle → nucleus -rough ER → Golgi → transport vesicle → plasma membrane -Golgi → rough ER → lysosome → transport vesicle → plasma membrane
rough ER → Golgi → transport vesicle → plasma membrane
You have a cube of modeling clay in your hands. Which of the following changes to the shape of this cube of clay will decrease its surface area relative to its volume? -Pinch the edges of the cube into small folds. -Round the clay up into a sphere. -Stretch the cube into a long, shoe box shape. -Flatten the cube into a pancake shape.
round the clay up into a sphere
Vinblastine, a drug that inhibits microtubule polymerization, is used to treat some forms of cancer. Cancer cells given vinblastine would be unable to _____. -form cleavage furrows during cell division -separate chromosomes during cell division -maintain the shape of the nucleus -migrate by amoeboid movement
separate chromosomes during cell division
A research team is working on the design of a new drug for the treatment of lung cancer. To be most effective, this drug must specifically enter the cytoplasm of lung cells while not entering the cells of other tissues. Which of the following characteristics would likely enhance the specificity of this drug? -the relative hydrophobicity of the drug molecule -similarity of the drug molecule to other molecules normally transported lung cells -phospholipid composition of lung cell plasma membranes -specificity of the drug molecule for binding to the extracellular matrix of lung cells
similarity of the drug molecule to other molecules normally transported lung cells
What kinds of molecules pass through a cell membrane most easily? small and hydrophobic small and ionic large and hydrophobic large polar
small and hydrophobic
Which of the following are least likely to diffuse through the phospholipid bilayer of a cell membrane? small ions carbon dioxide small hydrophobic molecules large hydrophobic molecules
small ions
The liver is involved in detoxification of many poisons and drugs. Which of the following structures is primarily involved in this process and, therefore, abundant in liver cells? Golgi apparatus nuclear envelope smooth endoplasmic reticulum rough endoplasmic reticulum
smooth endoplasmic reticulum
A cell with a predominance of smooth endoplasmic reticulum is likely specialized to ________. -synthesize large quantities of lipids -store large quantities of water -import and export large quantities of protein -actively secrete large quantities of protein
synthesize large quantities of lipids
Tay-Sachs disease is a human genetic abnormality that results in cells accumulating and becoming clogged with very large, complex, undigested lipids. Which cellular organelle is most likely defective in this condition? -the rough endoplasmic reticulum -the smooth endoplasmic reticulum -the lysosome -the Golgi apparatus
the lysosome
In bacteria, DNA will be found in ________. a membrane-enclosed nucleus the nucleoid ribosomes mitochondria
the nucleoid
The permeability of a biological membrane to a specific polar solute depends primarily on which of the following? -the amount of cholesterol in the membrane -the types of transport proteins in the membrane -the phospholipid composition of the membrane -the presence of unsaturated fatty acids in the membrane -the types of polysaccharides present in the membrane
the types of transport proteins in the membrane
Why are lipids and proteins free to move laterally in membranes? -The interior of the membrane is filled with liquid water. -Lipids and proteins repulse each other in the membrane. -Hydrophilic portions of the lipids are in the interior of the membrane. -There are only weak hydrophobic interactions in the interior of the membrane.
there are only weak hydrophobic interactions in the interior of the membrane.
What is a primary function of integrins? -linking the primary and secondary cell walls in plants -connecting intermediate filaments to microtubules involved in vesicular transport -transmitting signals from the extracellular matrix to the cytoskeleton -transmitting chemical signals from the Golgi apparatus to the plasma membrane
transmitting signals from the extracellular matrix to the cytoskeleton
Cells require which of the following to form cilia or flagella? intermediate filaments laminin actin tubulin
tubulin
Which of the following best describes the structure of a biological membrane? -a mixture of covalently linked phospholipids and proteins that determines which solutes can cross the membrane and which cannot -two layers of phospholipids (with opposite orientations of the phospholipids in each layer) with each layer covered on the outside with proteins -two layers of phospholipids with proteins embedded between the two layers -two layers of phospholipids with proteins either crossing the layers or on the surface of the layers -a fluid structure in which phospholipids and proteins move freely between sides of the membrane
two layers of phospholipids with proteins either crossing the layers or on the surface of the layers
Which of the following best describes the structure of a biological membrane? -two layers of phospholipids with proteins embedded between the two layers -a fluid structure in which phospholipids and proteins move freely between sides of the membrane -two layers of phospholipids with proteins either crossing the layers or on the surface of the layers -two layers of phospholipids (with opposite orientations of the phospholipids in each layer) with each layer covered on the outside with proteins -a mixture of covalently linked phospholipids and proteins that determines which solutes can cross the membrane and which cannot
two layers of phospholipids with proteins either crossing the layers or on the surface of the layers
Which of the following molecular movements is due to diffusion or osmosis? -The sodium-potassium pump pumps three sodium ions out of a neuron for every two potassium ions it pumps in. -Cells of the pancreas secrete insulin into the bloodstream. -When a plant cell is placed in concentrated salt water, water moves out of the cell.
when a plant cell is placed in concentrated salt water, water moves out of the cell
Which of the following clues would tell you if a cell is prokaryotic or eukaryotic? -the presence or absence of a rigid cell wall -the presence or absence of ribosomes -whether or not the cell carries out cellular metabolism -whether or not the cell contains DNA -whether or not the cell is partitioned by internal membranes
whether or not the cell is partitioned by internal membranes
Which of the following clues would tell you if a cell is prokaryotic or eukaryotic? -whether or not the cell is partitioned by internal membranes -whether or not the cell carries out cellular metabolism -whether or not the cell contains DNA -the presence or absence of ribosomes -the presence or absence of a rigid cell wall
whether or not the cell is partitioned by internal membranes