Bio 1406 ch 5

3) Which object in Figure 5.1 represents a component of the extracellular matrix? A) A B) B C) C D) D E) E

A) A

48) In what way would the lack of receptors for local paracrine signal molecules affect animal cells? A) The cells would not respond to growth factors from nearby cells. B) The cells would not respond to hormone signals delivered through the bloodstream. C) The cells would bind locally secreted growth factors, but signal transduction to alter gene expression would not occur. D) The cells would grow and divide normally.

A) The cells would not respond to growth factors from nearby cells.

10) How do unsaturated fatty acids help keep any membrane more fluid at lower temperatures? A) The double bonds form kinks in the fatty acid tails that prevent adjacent lipids from packing tightly together. B) Unsaturated fatty acids have a higher cholesterol content that prevents adjacent lipids from packing tightly together. C) Unsaturated fatty acids are more polar than saturated fatty acids. D) The double bonds result in shorter fatty acid tails and therefore thinner membranes.

A) The double bonds form kinks in the fatty acid tails that prevent adjacent lipids from packing tightly together.

6) Based on the fluid mosaic model of cell membranes, which of the following statements about membrane phospholipids is true? A) They can move laterally along the plane of the membrane. B) They frequently flip-flop from one side of the membrane to the other. C) They occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane. D) They frequently leave the bilayer and dissolve in the surrounding solution.

A) They can move laterally along the plane of the membrane.

26) Mammalian blood contains the equivalent of 0.15 M NaCl. Seawater contains the equivalent of 0.45 M NaCl. What will happen if red blood cells are transferred to seawater? A) Water will leave the cells, causing them to shrivel and collapse. B) NaCl will be exported from the red blood cells by facilitated diffusion. C) The blood cells will take up water, swell, and eventually burst. D) NaCl will passively diffuse into the red blood cells.

A) Water will leave the cells, causing them to shrivel and collapse.

13) A protein that spans the phospholipid bilayer one or more times is A) a transmembrane protein. B) a glycoprotein. C) a peripheral protein. D) an extracellular matrix protein.

A) a transmembrane protein.

55) Immediately following binding of a growth factor, an activated receptor would most likely stimulate A) activation of a protein kinase. B) activation of adenylyl cyclase. C) activation of a calcium-binding protein. D) activation of a protein phosphatase.

A) activation of a protein kinase.

52) The mechanism by which testosterone alters cell function is by A) binding to a receptor protein that enters the nucleus and activates specific genes. B) binding to a transmembrane signal receptor that activates cell-signaling pathways. C) acting as a steroid signal receptor that activates ion channel proteins. D) serving as a second messenger that activates cell-signaling pathways.

A) binding to a receptor protein that enters the nucleus and activates specific genes.

39) Proteins that allow the diffusion of ions across membranes in the direction of their concentration gradients are most likely A) channel proteins. B) carrier proteins. C) aquaporins. D) active transport pumps.

A) channel proteins.

66) Binding of the signaling molecule epinephrine to its receptor results in A) increased concentrations of cyclic AMP in the cytoplasm. B) lower blood glucose levels. C) activation of a steroid hormone receptor inside muscle cells. D) inactivation of the enzyme glycogen phosphorylase.

A) increased concentrations of cyclic AMP in the cytoplasm.

58) Which of the following enzymes adds a phosphate group to target proteins? A) kinase B) phosphatase C) G protein-coupled receptor D) adenylyl cyclase

A) kinase

5) At human body temperature (37°C), cholesterol in membranes functions to A) make the membrane less fluid by restricting the movement of phospholipids. B) make the membrane more fluid by stimulating the movement of phospholipids. C) facilitate cell-cell interactions by binding to receptors on neighboring cells. D) make the membrane more fluid by crowding integral membrane proteins into restricted areas.

A) make the membrane less fluid by restricting the movement of phospholipids.

59) The primary function of G proteins in signal transduction is A) transmitting the signal from an activated receptor to the next protein in the pathway. B) binding extracellular signal molecules to activate the pathway. C) converting ATP to cATP to amplify the signal. D) phosphorylating relay molecules in the pathway.

A) transmitting the signal from an activated receptor to the next protein in the pathway.

27) Thinking about the environments where plant and animal cells typically exist, which of the following statements is correct? A) Animal cells are generally in a hypotonic solution, and plant cells are generally in an isotonic solution. B) Animal cells are generally in an isotonic solution, and plant cells are generally in a hypotonic solution. C) Animal cells are generally in an isotonic solution, and plant cells are generally in a hypertonic solution. D) Animal cell are generally in a hypertonic solution, and plant cells are generally in an isotonic solution. E) Animal cells are generally in a hypertonic solution, and plant cells are generally in a hypotonic solution.

B) Animal cells are generally in an isotonic solution, and plant cells are generally in a hypotonic solution.

5) Which component in Figure 5.1 is a glycolipid? A) A B) B C) C D) D E) E

B) B

7) Which component in Figure 5.1 plays an important role in cell-cell recognition? A) A B) B C) C D) D E) E

B) B

56) Following activation of a receptor, which sequence below represents the correct order in which components will be involved in a signaling pathway that utilizes the second messenger cAMP? A) G protein → cAMP → adenyl cyclase → protein kinase B) G protein → adenyl cyclase → cAMP → protein kinase C) adenyl cyclase → cAMP → G protein → protein kinase D) cAMP → adenyl cyclase → protein kinase → G protein E) protein kinase → G protein → adenyl cyclase → cAMP

B) G protein → adenyl cyclase → cAMP → protein kinase

20) Which of the following is a characteristic feature of a carrier protein in a plasma membrane? A) It is a peripheral membrane protein. B) It exhibits a specificity for a particular type of molecule. C) It requires the expenditure of cellular energy to function. D) It works against a concentration gradient.

B) It exhibits a specificity for a particular type of molecule.

10) The solutions in the two arms of the U-tube shown in Figure 5.2 are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is half-filled with a solution of 2 M sucrose and 1 M glucose. Side B is half-filled with 1 M sucrose and 2 M glucose. Initially, the liquid levels are equal. After the system depicted in the figure reaches equilibrium, what changes are observed with respect to the concentrations of sugars? A) The concentration of sucrose is equal in sides A and B, and the concentrations of glucose are unchanged. B) The concentrations of glucose and sucrose are equal in sides A and B. C) The concentration of glucose is equal in sides A and B, and the concentrations of sucrose are unchanged. D) The water levels change, but the concentrations of glucose and sucrose in sides A and B are unchanged.

B) The concentrations of glucose and sucrose are equal in sides A and B.

17) Several species of bacteria and archaea live in hot springs and deep sea thermal vents where the water temperature exceeds 90°C (194°F). Which of the following evolutionary adaptations would you expect to find in the cell membranes of these thermophilic organisms? A) a high percentage of very long chain saturated fatty acids B) a high percentage of cholesterol C) a high percentage of unsaturated fatty acids D) a high percentage of carbohydrates on membrane lipids

B) a high percentage of cholesterol

1) The fluid mosaic model of membrane structure suggests that membranes A) are composed of a fluid bilayer of fatty acids with proteins associated on the outer and inner surfaces. B) are composed of protein molecules embedded in a fluid bilayer of phospholipids. C) are composed of a single fluid layer of phospholipids and proteins. D) are composed of a fluid phospholipid bilayer sandwiched between two layers of hydrophilic proteins.

B) are composed of protein molecules embedded in a fluid bilayer of phospholipids.

Based on the figure below, which of these experimental treatments would increase the rate of sucrose transport into a plant cell?

B) decreasing extracellular pH

60) Phosphatase enzymes in signal transduction pathways function primarily to A) transfer a phosphate group from a kinase to the next relay molecule in a series. B) inactivate protein kinases to turn off signal transduction pathways. C) amplify signal transduction so it activates multiple relay molecules. D) amplify the second messenger cAMP.

B) inactivate protein kinases to turn off signal transduction pathways.

29) Submerging a red blood cell in distilled water will result in A) plasmolysis of the cell. B) lysis of the cell. C) the cell becoming turgid. D) the cell becoming flacid.

B) lysis of the cell.

42) A bacterium engulfed by a white blood cell through phagocytosis will be digested by enzymes contained in A) peroxisomes. B) lysosomes. C) Golgi vesicles. D) vacuoles. E) secretory vesicles.

B) lysosomes.

45) In receptor-mediated endocytosis, where are the receptors that bind specific molecules located immediately following endocytosis? A) on the cytoplasmic surface of the cell membrane B) on the interior surface of a cytoplasmic vesicle C) on the exterior surface of a cytoplasmic vesicle D) on the interior surface of the Golgi apparatus E) on the interior surface of a lysosome membrane

B) on the interior surface of a cytoplasmic vesicle

57) A proper relationship between an enzyme and its function is illustrated by which of the following? A) kinase: addition of a tyrosine B) phosphatase: removal of a phosphate group C) glycogen phosphorylase: synthesis of glycogen D) adenylyl cyclase: conversion of cAMP to AMP

B) phosphatase: removal of a phosphate group

3) The primary structural components of the cell membrane are A) phospholipids and cellulose. B) phospholipids and proteins. C) cholesterol and proteins. D) proteins and cellulose. E) glycoproteins and cholesterol.

B) phospholipids and proteins.

12) The sugars associated with glycoproteins and glycolipids of animal cell membranes A) serve as an energy source for the cell. B) serve as markers that distinguish one cell from another. C) decrease membrane fluidity at high temperatures. D) maintain membrane fluidity at low temperatures.

B) serve as markers that distinguish one cell from another.

18) What kinds of molecules pass through a cell membrane most easily? A) large hydrophobic B) small hydrophobic C) large polar D) small ionic E) large and hydrophilic

B) small hydrophobic

11) Five dialysis bags, constructed from a semipermeable membrane that is impermeable to sucrose, were filled with various concentrations of sucrose and then placed in separate beakers containing an initial concentration of 0.6 M sucrose solution. At 10-minute intervals, the bags were massed (weighed), and the percent change in mass of each bag was graphed. Figure 5.4 illustrates the change in the mass of the bags over time. Which line in the graph represents the bag that contained a 0.6 M solution at the beginning of the experiment? A) A B) B C) C D) D E) E

C) C

4) In Figure 5.1, a microfilament of the cytoskeleton is represented by A) A. B) B. C) C. D) D. E) E.

C) C.

67) Which of the following is the greatest advantage of having multiple steps in a transduction pathway? A) Each step can be used in multiple pathways. B) Having multiple steps in a pathway requires the least amount of ATP. C) Having multiple steps provides for greater possible amplification of a signal. D) Each step can be activated by several G proteins simultaneously.

C) Having multiple steps provides for greater possible amplification of a signal.

23) Which of the following statements about diffusion is correct? A) It is very rapid over long distances. B) It requires an expenditure of energy by the cell. C) It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration. D) It is an active process in which molecules move from a region of lower concentration to one of higher concentration. E) It is a passive process in which molecules move from a region of lower concentration to a region of higher concentration.

C) It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.

21) Which of the following molecules would you expect to diffuse through the lipid bilayer of a plasma membrane most rapidly? A) glucose B) starch C) O2 D) Na+ E) an amino acid

C) O2

41) Proton pumps are used in various ways by members of every domain of organisms: Bacteria, Archaea, and Eukarya. What does this most probably mean? A) Proton pumps must have evolved before any living organisms were present on Earth. B) Proton pumps are an essential feature of all cell membranes. C) Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life. D) Cells of each domain evolved proton pumps independently when oceans became more acidic.

C) Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life.

46) Immediately after a membrane receptor protein binds to its ligand, which of the following processes occurs? A) Cytoplasmic enzymes are activated by phosphorylation. B) An intracellular G protein is activated. C) The membrane receptor protein undergoes a conformational change. D) The receptor/ligand complex enters the cytoplasm by endocytosis.

C) The membrane receptor protein undergoes a conformational change.

9) The solutions in the two arms of the U-tube shown in Figure 5.2 are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is half-filled with a solution of 2 M sucrose and 1 M glucose. Side B is half-filled with 1 M sucrose and 2 M glucose. Initially, the liquid levels are equal. After the system depicted in the figure reaches equilibrium, what changes are observed? A) The concentrations of glucose and sucrose are unchanged. B) The water level is higher in side A than in side B. C) The water level is unchanged. D) The water level is higher in side B than in side A.

C) The water level is unchanged.

11) Which of the following is true of integral membrane proteins? A) They serve only a structural role in membranes. B) They are loosely bound to the surface of the bilayer. C) They are usually transmembrane proteins. D) They are not mobile within the bilayer.

C) They are usually transmembrane proteins.

63) A drug designed to inhibit the response of cells to the steroid hormone aldosterone would almost certainly result in which of the following? A) lower cytoplasmic levels of cAMP B) an increase in receptor tyrosine kinase activity C) a decrease in transcriptional activity of certain genes D) a decrease in G protein activity

C) a decrease in transcriptional activity of certain genes

14) Which of the following evolutionary adaptations would you expect to find in the cell membranes of Antarctic icefish? A) a high percentage of very long chain saturated fatty acids B) no cholesterol C) a high percentage of unsaturated fatty acids D) a high percentage of carbohydrates on membrane lipids

C) a high percentage of unsaturated fatty acids

40) The electrochemical gradient across a membrane would generally be increased by which of the following membrane proteins? A) a calcium ion channel B) a sucrose-proton cotransporter C) a hydrogen ion pump D) a sodium ion channel

C) a hydrogen ion pump

8) An integral membrane protein would have to be A) hydrophilic. B) composed primarily of alpha helix structural domains. C) amphipathic, with at least one hydrophobic and one hydrophilic region. D) exposed to water on only one surface of the membrane.

C) amphipathic, with at least one hydrophobic and one hydrophilic region.

54) Signal transduction pathways that include a phosphorylation cascade A) are generally initiated by a phosphorylase enzyme. B) are propagated by steroid hormone receptors. C) cause a structural change in each phosphorylated protein. D) are generally inactivated by a kinase enzyme.

C) cause a structural change in each phosphorylated protein.

65) Research on aging suggests that as cells age, their rate of cell division decreases until they ultimately no longer divide. Which of the following would provide evidence that the decreased rate of cell division is related to cell signaling? A) decreased ATP production in aged cells B) decreased hormone production in aged cells C) decreased affinity of growth factor receptors for their respective ligands D) decreased numbers of cytoplasmic ribosomes

C) decreased affinity of growth factor receptors for their respective ligands

19) The movement of the hydrophobic gas nitrous oxide (N2O) (laughing gas) into a cell is an example of A) active transport across the lipid bilayer. B) facilitated diffusion through the lipid bilayer. C) diffusion through the lipid bilayer. D) osmosis through the lipid bilayer. E) cotransport across the lipid bilayer.

C) diffusion through the lipid bilayer

62) Theoretically, how might researchers disrupt signal transduction pathways as possible treatments for cancer? A) alter G protein-coupled receptors involved in cell cycle regulation to be active in the absence of their normal signaling molecules B) inactivate epinephrine receptors on cancer cells C) disrupt the function of protein kinases involved in cell cycle regulation D) stimulate production of cAMP in cancer cells

C) disrupt the function of protein kinases involved in cell cycle regulation

53) Transcription factors play a major role in regulating which of the following processes? A) the conversion of ATP into cAMP B) DNA replication C) gene expression D) transmission of signals from steroid hormone receptors to intracellular G proteins

C) gene expression

36) Which of the following is a primary function of an electrogenic pump in cell membranes, such as the sodium-potassium pump? A) transporting electrons across the plasma membrane B) transporting hydrogen ions out of the cell C) generating the membrane potential D) ionizing sodium and potassium atoms

C) generating the membrane potential

8) The solutions in the two arms of the U-tube shown in Figure 5.2 are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is half-filled with a solution of 2 M sucrose and 1 M glucose. Side B is half-filled with 1 M sucrose and 2 M glucose. Initially, the liquid levels are equal, and the solution in side A is A) hypotonic to the solution in side B. B) hypertonic to the solution in side B. C) isotonic to the solution in side B.

C) isotonic to the solution in side B.

38) The sodium-potassium pump generates the following concentration gradients across the plasma membrane: A) high [Na+] and [K+] inside the cell and low [Na+] and [K+] outside. B) low [Na+] and [K+] inside the cell and high [Na+] and [K+] outside. C) low [Na+] and high [K+] inside the cell and high [Na+] and low [K+] outside. D) high [Na+] and low [K+] inside the cell and low [Na+] and high [K+] outside.

C) low [Na+] and high [K+] inside the cell and high [Na+] and low [K+] outside.

35) The cytoplasmic side of a cell membrane is negative in charge relative to the extracellular side. What is the voltage across a cell membrane called? A) water potential B) chemical gradient C) membrane potential D) osmotic potential E) electrochemical gradient

C) membrane potential

32) Which of the following membrane activities requires energy from ATP hydrolysis? A) facilitated diffusion of chloride ions across the membrane through a chloride channel B) movement of water into a cell through aquaporins C) movement of sodium ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid D) movement of glucose molecules into a bacterial cell from a medium containing a higher concentration of glucose than inside the cell E) movement of carbon dioxide out of a paramecium

C) movement of sodium ions from a lower concentration in a mammalian cell to a higher

15) In Figure 5.5, the dots in the space between the two structures represent which of the following types of molecules? A) receptor molecules B) signal transducers C) neurotransmitters D) hormones

C) neurotransmitters

9) Which of the following membrane proteins tend to lack hydrophobic regions on their surfaces? A) transmembrane proteins B) integral membrane proteins C) peripheral membrane proteins D) integrins

C) peripheral membrane proteins

2) Which of the following molecules are localized on the exterior of a phospholipid bilayer? A) saturated fatty acids B) unsaturated fatty acids C) phosphate groups D) cholesterol

C) phosphate groups

44) The difference between pinocytosis and receptor-mediated endocytosis is that A) pinocytosis brings only water molecules into the cell, whereas receptor-mediated endocytosis brings in other molecules as well. B) pinocytosis increases the surface area of the plasma membrane, whereas receptor-mediated endocytosis decreases the plasma membrane surface area. C) pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis is highly selective. D) pinocytosis requires cellular energy, but receptor-mediated endocytosis does not. E) pinocytosis generally concentrates substances from the extracellular fluid, but receptor-mediated endocytosis does not.

C) pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis is highly selective.

51) When a neuron responds to a particular neurotransmitter by opening gated ion channels, the neurotransmitter is serving as which part of the signal pathway? A) receptor B) relay molecule C) signal molecule D) transducer E) molecule protein

C) signal molecule

4) When biological membranes are frozen and then fractured, they tend to break along the middle of the bilayer. The best explanation for this is that A) the integral membrane proteins are not strong enough to hold the bilayer together. B) water that is present in the middle of the bilayer freezes and is easily fractured. C) the hydrophobic interactions between ends of the fatty acid tails of the two phospholipid monolayers are the weakest interactions in the membrane. D) the carbon-carbon bonds of the phospholipid tails are easily broken.

C) the hydrophobic interactions between ends of the fatty acid tails of the two phospholipid

An accident victim has lost a lot of blood due to a serious injury. Replacement of the lost body fluids with distilled water would have which of the following results?

C) the patient's red blood cells will swell and lyse because the blood fluid has become hypotonic compared to the cells

50) How is the plant hormone ethylene delivered to target cells? A) through intracellular steroid hormone receptors B) through the plant vascular system C) through the air D) through plasmodesmata from adjacent cells

C) through the air

1) 1) In Figure 5.1, a peripheral membrane protein is represented by A) A. B) B. C) C. D) D. E) E.

D) D.

64) At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogens and other steroid hormones. How can one hormone, such as estrogen, mediate so many effects? A) Estrogen is produced in high concentrations by a large number of different cell types. B) Estrogen binds to common receptors inside several cell types, and each cell responds in the same way to its binding. C) Estrogen does not affect cells that lack estrogen receptors in the cell membrane. D) Estrogen binds to specific receptors inside many kinds of cells, each of which has different responses to its binding.

D) Estrogen binds to specific receptors inside many kinds of cells, each of which has different responses to its binding.

16) The protein, lipid, and carbohydrate compositions of the cytoplasmic and extracellular sides of membranes are different from one another. Why is this the case? A) Proteins only function on the cytoplasmic side of the cell membrane, which results in asymmetry across the membrane. B) Some membrane components are synthesized outside of the cell, while others are synthesized in the cytosol. C) The molecular composition of the inner and outer layers of the cell membrane is determined by genes. D) The two sides of a cell membrane face different environments and carry out different functions.

D) The two sides of a cell membrane face different environments and carry out different functions.

33) Which of the following is most likely true of a protein that cotransports glucose and sodium ions into the intestinal cells of an animal? A) Sodium and glucose bind to the same site on the cotransporter. B) Transport of glucose against its concentration gradient provides energy for uptake of sodium ions against the electrochemical gradient. C) Following transport of sodium ions into the cell, the cotransporter can also transport potassium ions out of the cell. D) Transport of sodium ions down their electrochemical gradient facilitates the transport of glucose against its concentration gradient.

D) Transport of sodium ions down their electrochemical gradient facilitates the transport of glucose against its concentration gradient.

15) Why are lipids and proteins free to move laterally in membranes? A) The interior of the membrane is filled with liquid water. B) Lipids and proteins repulse each other in the membrane. C) Phospholipids form hydrogen bonds with water at the membrane surface, which moves the lipids as water moves. D) Weak hydrophobic interactions in the interior of the membrane are easily disrupted.

D) Weak hydrophobic interactions in the interior of the membrane are easily disrupted.

61) The primary function of kinases in signal transduction is to A) inactivate relay molecule to turn off signal transduction. B) regulate gene expression by serving as a transcription factor. C) inactivate second messengers such as cAMP. D) activate protein kinases or other relay molecules in a series.

D) activate protein kinases or other relay molecules in a series.

34) The phosphate transport system in bacteria imports phosphate into the cell against the phosphate concentration gradient. The energy for phosphate import is provided by a pH gradient across the membrane (lower pH outside the cell than inside the cell), rather than by ATP hydrolysis. The bacterial phosphate transport system is an example of A) passive diffusion. B) facilitated diffusion. C) active transport. D) cotransport. E) receptor-mediated endocytosis.

D) cotransport.

31) The rate of diffusion of glucose through artificial phospholipid bilayers is exceptionally low. By contrast, the cells lining the small intestine rapidly transport large quantities of glucose from glucose-rich food into their glucose-poor cytoplasm. Based on this information, which transport mechanism is most likely responsible for glucose transport in the intestinal cells? A) simple diffusion B) phagocytosis C) active transport pumps D) facilitated diffusion

D) facilitated diffusion

7) Cell membranes in plants that thrive in extreme cold are able to remain fluid by A) increasing the average length of the fatty acid tails in the membrane. B) decreasing the percentage of cholesterol molecules in the membrane. C) decreasing the number of hydrophobic proteins in the membrane. D) increasing the percentage of unsaturated phospholipids in the membrane.

D) increasing the percentage of unsaturated phospholipids in the membrane.

43) Familial hypercholesterolemia results in extremely high levels of cholesterol in the blood. The underlying cause of this disease is A) defective cell membranes that cannot incorporate cholesterol. B) poor attachment of cholesterol to the extracellular matrix of cells. C) inhibition of the cholesterol active transport system in red blood cells. D) nonfunctional or missing LDL receptors on cell membranes.

D) nonfunctional or missing LDL receptors on cell membranes.

49) The secretion of a signal molecule by a cell into the local environment, followed by a response by a number of cells in the immediate vicinity, is an example of A) hormonal signaling. B) synaptic signaling. C) endocrine signaling. D) paracrine signaling.

D) paracrine signaling.

30) Submerging a red blood cell in a hypertonic solution will result in A) plasmolysis of the cell. B) lysis of the cell. C) the cell becoming turgid. D) shriveling of the cell.

D) shriveling of the cell.

47) Steroid hormone receptors in animals tend to be A) glycolipids rather than protein. B) transmembrane proteins with an extracellular steroid binding domain. C) transmembrane proteins with an intracellular steroid binding domain. D) soluble proteins in the cytoplasm.

D) soluble proteins in the cytoplasm.

14) Which of the following types of signaling is represented in Figure 5.5? A) autocrine B) paracrine C) hormonal D) synaptic

D) synaptic

28) Submerging a plant cell in distilled water will result in A) plasmolysis of the cell. B) lysis of the cell membrane. C) bursting of the cell. D) the cell becoming turgid. E) the cell becoming flaccid.

D) the cell becoming turgid.

25) Carrot slices placed in a 0.2 M salt solution for several hours become flaccid (limp). Carrot slices placed in fresh water for several hours become turgid (stiff). From this we can deduce that A) the fresh water and the salt solution are both hypertonic to the cells of the carrot slices. B) the fresh water and the salt solution are both hypotonic to the cells of the carrot slices. C) the fresh water is hypertonic and the salt solution is hypotonic to the cells of the carrot slices. D) the fresh water is hypotonic and the salt solution is hypertonic to the cells of the carrot slices. E) the fresh water is isotonic and the salt solution is hypertonic to the cells of the carrot slices.

D) the fresh water is hypotonic and the salt solution is hypertonic to the cells of the carrot slices.

13) Five dialysis bags, constructed from a semipermeable membrane that is impermeable to sucrose, were filled with various concentrations of sucrose and then placed in separate beakers containing an initial concentration of 0.6 M sucrose solution. At 10-minute intervals, the bags were massed (weighed), and the percent change in mass of each bag was graphed. Figure 5.4 illustrates the change in the mass of the bags over time. Which line or lines in the graph in the figure represent(s) bags that contain a solution that is hypertonic at 50 minutes? A) A and B B) B C) C D) D E) D and E

E) D and E

12) Five dialysis bags, constructed from a semipermeable membrane that is impermeable to sucrose, were filled with various concentrations of sucrose and then placed in separate beakers containing an initial concentration of 0.6 M sucrose solution. At 10-minute intervals, the bags were massed (weighed), and the percent change in mass of each bag was graphed. Figure 5.4 illustrates the change in the mass of the bags over time. Which line in the graph represents the bag with the highest initial concentration of sucrose? A) A B) B C) C D) D E) E

E) E

2) Which component in Figure 5.1 is cholesterol? A) A B) B C) C D) D E) E

E) E

6) Which component in Figure 5.1 helps membranes resist changes in fluidity at high and low temperatures? A) A B) B C) C D) D E) E

E) E

37) Which of the following is required for the sodium-potassium pump to transport potassium ions into an animal cell? A) low intracellular concentrations of sodium B) high intracellular concentrations of sodium C) high intracellular concentrations of potassium D) low intracellular concentrations of potassium E) energy from ATP

E) energy from ATP

24) Water can move quickly through the plasma membrane of some cells because A) the bilayer is hydrophilic. B) it moves through hydrophobic channels. C) water movement is tied to ATP hydrolysis. D) it is a small, nonpolar molecule. E) it moves through aquaporin channel proteins.

E) it moves through aquaporin channel proteins.

22) Which of the following molecules would you expect to diffuse through the lipid bilayer of a plasma membrane most slowly, if at all? A) CH4 B) an amino acid C) O2 D) CO2 E) water

E) water