Chapter 7

Last update by Babara on 09/08/2014
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Which of the following is true of the evolution of cell membranes?

A) Cellmembranes 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 selectedfor or against.

E) An individual organism selects its preferred type of cell membrane for particular functions.

Answer:

D) As populations of organisms evolve,different properties of their cell membranes are selectedfor or against.



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Related Quiz Content
  • feldman2009
    Answered in Chapter 7

    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.



    C) Hydrophilic portions of the lipids are in the interior of the membrane.

    Feldman, I think "C" is wrong.. "D" makes more sense to me (someone correct me if I'm wrong).. The phospholipid-bilayer of membranes consists of hydrophilic heads on each exterior side and hydrophobic tails facing each other on the interior.. Therefore "D" would make more sense to me.


    yes i agree with you. D is the only answer that makes sense
  • feldman2009
    Answered in Chapter 7

    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

    B) small and hydrophobic



  • feldman2009
    Answered in Chapter 7

    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.



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



  • feldman2009
    Answered in Chapter 7

    After a membrane freezes and then thaws, it often becomes leaky to solutes. The mostreasonable 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) thesolubility of most solutes in the cytoplasm decreases on freezing.



    D) the integrity of the lipid bilayer is broken when the membrane freezes.



  • feldman2009
    Answered in Chapter 7

    Which of the following would likely move through the lipid bilayer of a plasma membranemost rapidly?

    A) CO2

    B) an amino acid

    C) glucose

    D) K+

    E) starch



    A) CO2



  • feldman2009
    Answered in Chapter 7

    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.



    E) it moves through aquaporins in the membrane.



  • feldman2009
    Answered in Chapter 7

    Cystic fibrosis is a genetic disease in humans in which chloride ion channels in cell membranesare missing or nonfunctional.

    Chloride ion channels are membrane structures that include which of the following?

    A) gap junctions

    B) aquaporins

    C) hydrophilic proteins

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    C) hydrophilic proteins



  • feldman2009
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    Which of the following would you expect to be a problem for someone with nonfunctionalchloride 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



    B) buildup of excessive secretions in organs such as lungs



  • feldman2009
    Answered in Chapter 7

    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

    D) incorrect concentrations of ions in semen



  • feldman2009
    Answered in Chapter 7

    A patient has had a serious accident andlost a lot of blood. In an attempt to replenish bodyfluids, distilled water, equal to the volume of blood lost, is transferred directly into one of hisveins. 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 tothe cells.

    C) The patient's red blood cells will swell because the blood fluid is hypotonic comparedto thecells.

    D) The patient's red blood cells will shrivel up because the blood fluid is hypertonic compared tothe cells.

    E) The patient's red blood cells will burst because the blood fluid is hypertonic compared to thecells.

    C) The patient's red blood cells will swell because the blood fluid is hypotonic comparedto thecells.



  • feldman2009
    Answered in Chapter 7

    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.


    C) hypertonic to fresh water but hypotonic (lesser concentration) to the salt solution.