× Didn't find what you were looking for? Ask a question
Top Posters
Since Sunday
5
o
5
4
m
4
b
4
x
4
a
4
l
4
t
4
S
4
m
3
s
3
New Topic  
biolove biolove
wrote...
Donated
Trusted Member
Posts: 1745
13 years ago Edited: 13 years ago, biolove
Answers are attached
Enjoy Slight Smile

Biology, 8e (Campbell)
Chapter 7  

Membrane Structure and Function

Multiple-Choice Questions

1) Who was/were the first to propose that cell membranes are phospholipid bilayers?
A) H. Davson and J. Danielli
B) I. Langmuir
C) C. Overton
D) S. Singer and G. Nicolson
E) E. Gorter and F. Grendel

2) Who proposed that membranes are a phospholipid bilayer between two layers of hydrophilic proteins?
A) H. Davson and J. Danielli
B) I. Langmuir
C) C. Overton
D) S. Singer and G. Nicolson
E) E. Gorter and F. Grendel

3) Who proposed that the membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids?
A) H. Davson and J. Danielli
B) I. Langmuir
C) C. Overton
D) S. Singer and G. Nicolson
E) E. Gorter and F. Grendel

4) Which of the following types of molecules are the major structural components of the cell membrane?
A) phospholipids and cellulose
B) nucleic acids and proteins
C) phospholipids and proteins
D) proteins and cellulose
E) glycoproteins and cholesterol

For the following questions, match the labeled component of the cell membrane (Figure 7.1) with its description.

 

Figure 7.1
 
5) peripheral protein

6) cholesterol

7) fiber of the extracellular matrix

8) microfilament of the cytoskeleton

9) glycolipid

10) 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) hydrophilic interactions between the opposite membrane surfaces are destroyed on freezing.
D) the carbon-carbon bonds of the phospholipid tails are easily broken.
E) the hydrophobic interactions that hold the membrane together are weakest at this point.

11) The presence of cholesterol in the plasma membranes of some animals
A) enables the membrane to stay fluid more easily when cell temperature drops.
B) enables the animal to remove hydrogen atoms from saturated phospholipids.
C) enables the animal to add hydrogen atoms to unsaturated phospholipids.
D) makes the membrane less flexible, allowing it to sustain greater pressure from within the cell.
E) makes the animal more susceptible to circulatory disorders.

12) According to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids?
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 are free to depart from the membrane and dissolve in the surrounding solution.
E) They have hydrophilic tails in the interior of the membrane.

13) Which of the following is one of the ways that the membranes of winter wheat are able to remain fluid when it is extremely cold?
A) by increasing the percentage of unsaturated phospholipids in the membrane
B) by increasing the percentage of cholesterol molecules in the membrane
C) by decreasing the number of hydrophobic proteins in the membrane
D) by co-transport of glucose and hydrogen
E) by using active transport

14) In order for a protein to be an integral membrane protein it would have to be which of the following?
A) hydrophilic
B) hydrophobic
C) amphipathic
D) completely covered with phospholipids
E) exposed on only one surface of the membrane

15) When a membrane is freeze-fractured, the bilayer splits down the middle between the two layers of phospholipids. In an electron micrograph of a freeze-fractured membrane, the bumps seen on the fractured surface of the membrane are
A) peripheral proteins.
B) phospholipids.
C) carbohydrates.
D) integral proteins.
E) cholesterol molecules.

16) Which of the following is a reasonable explanation for why unsaturated fatty acids help keep any membrane more fluid at lower temperatures?
A) The double bonds form kinks in the fatty acid tails, forcing adjacent lipids to be further apart.
B) Unsaturated fatty acids have a higher cholesterol content and therefore more cholesterol in membranes.
C) Unsaturated fatty acids permit more water in the interior of the membrane.
D) The double bonds block interaction among the hydrophilic head groups of the lipids.
E) The double bonds result in shorter fatty acid tails and thinner membranes.

17) Which of the following is true of integral membrane proteins?
A) They lack tertiary structure.
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.
E) They serve only a structural role in membranes.

18) Of the following functions, which is most important for the glycoproteins and glycolipids of animal cell membranes?
A) facilitated diffusion of molecules down their concentration gradients
B) active transport of molecules against their concentration gradients
C) maintaining the integrity of a fluid mosaic membrane
D) maintaining membrane fluidity at low temperatures
E) a cell's ability to distinguish one type of neighboring cell from another

19) An animal cell lacking oligosaccharides on the external surface of its plasma membrane would likely be impaired in which function?
A) transporting ions against an electrochemical gradient
B) cell-cell recognition
C) maintaining fluidity of the phospholipid bilayer
D) attaching to the cytoskeleton
E) establishing the diffusion barrier to charged molecules

20) In the years since the proposal of the fluid mosaic model of the cell membrane, which of the following observations has been added to the model?
A) The membrane is only fluid across a very narrow temperature range.
B) Proteins rarely move, even though they possibly can do so.
C) Unsaturated lipids are excluded from the membranes.
D) The concentration of protein molecules is now known to be much higher.
E) The proteins are known to be made of only acidic amino acids.

21) Which of the following span the phospholipids bilayer, usually a number of times?
A) transmembrane proteins
B) integral proteins
C) peripheral proteins
D) integrins
E) glycoproteins

22) Which of these are not embedded in the lipid bilayer at all?
A) transmembrane proteins
B) integral proteins
C) peripheral proteins
D) integrins
E) glycoproteins

23) Which of these are attached to the extracellular matrix?
A) transmembrane proteins
B) integral proteins
C) peripheral proteins
D) integrins
E) glycoproteins

24) Which of these often serve as receptors or cell recognition molecules on cell surfaces?
A) transmembrane proteins
B) integral proteins
C) peripheral proteins
D) integrins
E) glycoproteins

25) The formulation of a model for a structure or for a process serves which of the following purposes?
A) It asks a scientific question.
B) It functions as a testable hypothesis.
C) It records observations.
D) It serves as a data point among results.
E) It can only be arrived at after years of experimentation.

26) Cell membranes are asymmetrical. Which of the following is a most likely explanation?
A) The cell membrane forms a border between one cell and another in tightly packed tissues such as epithelium.
B) Cell membranes communicate signals from one organism to another.
C) Cell membrane proteins are determined as the membrane is being packaged in the ER and Golgi.
D) The "innerness" and "outerness" of membrane surfaces are predetermined by genes.
E) Proteins can only span cell membranes if they are hydrophobic.

27) Which of the following is true of the evolution of cell membranes?
A) Cell membranes have stopped evolving now that they are fluid mosaics.
B) Cell membranes cannot evolve if proteins do not.
C) The evolution of cell membranes is driven by the evolution of glycoproteins and glycolipids.
D) As populations of organisms evolve, different properties of their cell membranes are selected for or against.
E) An individual organism selects its preferred type of cell membrane for particular functions.

28) Why are lipids and proteins free to move laterally in membranes?
A) The interior of the membrane is filled with liquid water.
B) There are no covalent bonds between lipid and protein in the membrane.
C) Hydrophilic portions of the lipids are in the interior of the membrane.
D) There are only weak hydrophobic interactions in the interior of the membrane.
E) Molecules such as cellulose can pull them in various directions.

29) What kinds of molecules pass through a cell membrane most easily?
A) large and hydrophobic
B) small and hydrophobic
C) large polar
D) ionic
E) monosaccharides such as glucose

30) 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 diffusion.
E) It has few, if any, hydrophobic amino acids.

31) After a membrane freezes and then thaws, it often becomes leaky to solutes. The most reasonable explanation for this is that
A) transport proteins become nonfunctional during freezing.
B) the lipid bilayer loses its fluidity when it freezes.
C) aquaporins can no longer function after freezing.
D) the integrity of the lipid bilayer is broken when the membrane freezes.
E) the solubility of most solutes in the cytoplasm decreases on freezing.

32) Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly?
A) CO2
B) an amino acid
C) glucose
D) K+
E) starch

33) Which of the following statements is correct about diffusion?
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 requires integral proteins in the cell membrane.

34) Water passes quickly through cell membranes 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, polar, charged molecule.
E) it moves through aquaporins in the membrane.

The following information should be used to answer the following questions.

Cystic fibrosis is a genetic disease in humans in which chloride ion channels in cell membranes are missing or nonfunctional.
 
35) Chloride ion channels are membrane structures that include which of the following?
A) gap junctions
B) aquaporins
C) hydrophilic proteins
D) carbohydrates
E) sodium ions

36) Which of the following would you expect to be a problem for someone with nonfunctional chloride channeling?
A) inadequate secretion of mucus
B) buildup of excessive secretions in organs such as lungs
C) buildup of excessive secretions in glands such as the pancreas
D) sweat that includes no NaCl
E) mental retardation due to low salt levels in brain tissue

37) If a young male child has cystic fibrosis, which of the following would affect his fertility?
A) inability to make sperm
B) incomplete maturation of the testes
C) failure to form genital structures appropriately
D) incorrect concentrations of ions in semen
E) abnormal pH in seminal fluid

Use the diagram of the U-tube in Figure 7.2 to answer the questions that follow.

The solutions in the two arms of this U-tube 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 on both sides are equal.

 

Figure 7.2
 
38) Initially, in terms of tonicity, the solution in side A with respect to that in side B is
A) hypotonic.
B) plasmolyzed.
C) isotonic.
D) saturated.
E) hypertonic.

39) After the system reaches equilibrium, what changes are observed?
A) The molarity of sucrose and glucose are equal on both sides.
B) The molarity of glucose is higher in side A than in side B.
C) The water level is higher in side A than in side B.
D) The water level is unchanged.
E) The water level is higher in side B than in side A.

40) A patient has had a serious accident and lost a lot of blood. In an attempt to replenish body fluids, distilled water, equal to the volume of blood lost, is transferred directly into one of his veins. What will be the most probable result of this transfusion?
A) It will have no unfavorable effect as long as the water is free of viruses and bacteria.
B) The patient's red blood cells will shrivel up because the blood fluid is hypotonic compared to the cells.
C) The patient's red blood cells will swell because the blood fluid is hypotonic compared to the cells.
D) The patient's red blood cells will shrivel up because the blood fluid is hypertonic compared to the cells.
E) The patient's red blood cells will burst because the blood fluid is hypertonic compared to the cells.

41) Celery stalks that are immersed in fresh water for several hours become stiff and hard. Similar stalks left in a salt solution become limp and soft. From this we can deduce that the cells of the celery stalks are
A) hypotonic to both fresh water and the salt solution.
B) hypertonic to both fresh water and the salt solution.
C) hypertonic to fresh water but hypotonic to the salt solution.
D) hypotonic to fresh water but hypertonic to the salt solution.
E) isotonic with fresh water but hypotonic to the salt solution.

42) A cell whose cytoplasm has a concentration of 0.02 molar glucose is placed in a test tube of water containing 0.02 molar glucose. Assuming that glucose is not actively transported into the cell, which of the following terms describes the tonicity of the external solution relative to the cytoplasm of the cell?
A) turgid
B) hypertonic
C) hypotonic
D) flaccid
E) isotonic

Refer to Figure 7.3 to answer the following questions.

The solutions in the arms of a U-tube are separated at the bottom of the tube by a selectively permeable membrane. The membrane is permeable to sodium chloride but not to glucose. Side A is filled with a solution of 0.4 M glucose and 0.5 M sodium chloride (NaCl), and side B is filled with a solution containing 0.8 M glucose and 0.4 M sodium chloride. Initially, the volume in both arms is the same.

 

Figure 7.3
 
43) At the beginning of the experiment,
A) side A is hypertonic to side B.
B) side A is hypotonic to side B.
C) side A is isotonic to side B.
D) side A is hypertonic to side B with respect to glucose.
E) side A is hypotonic to side B with respect to sodium chloride.

44) If you examine side A after 3 days, you should find
A) a decrease in the concentration of NaCl and glucose and an increase in the water level.
B) a decrease in the concentration of NaCl, an increase in water level, and no change in the concentration of glucose.
C) no net change in the system.
D) a decrease in the concentration of NaCl and a decrease in the water level.
E) no change in the concentration of NaCl and glucose and an increase in the water level.

45) Which of the following statements correctly describes the normal tonicity conditions for typical plant and animal cells?
A) The animal cell is in a hypotonic solution, and the plant cell is in an isotonic solution.
B) The animal cell is in an isotonic solution, and the plant cell is in a hypertonic solution.
C) The animal cell is in a hypertonic solution, and the plant cell is in an isotonic solution.
D) The animal cell is in an isotonic solution, and the plant cell is in a hypotonic solution.
E) The animal cell is in a hypertonic solution, and the plant cell is in a hypotonic solution.

Read the following information and refer to Figure 7.4 to answer the following questions.

Five dialysis bags, constructed from a semi-permeable 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 7.4
 
46) Which line represents the bag that contained a solution isotonic to the 0.6 molar solution at the beginning of the experiment?

47) Which line represents the bag with the highest initial concentration of sucrose?

48) Which line or lines represent(s) bags that contain a solution that is hypertonic at the end of 60 minutes?
A) A and B
B) B
C) C
D) D
E) D and E
 Attached file 
You must login or register to gain access to this attachment.
Read 41684 times

Related Topics

New Topic      
Explore
Post your homework questions and get free online help from our incredible volunteers
  1132 People Browsing
Related Images
  
 764
  
 1445
  
 216
Your Opinion
What's your favorite math subject?
Votes: 293

Previous poll results: Where do you get your textbooks?