Chapter 7

Last update by Babara on 09/08/2014
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What is the voltage across a membrane called?

A) water potential

B) chemical gradient

C) membrane potential

D) osmotic potential

E) electrochemical gradient



Answer:

C) membrane potential



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  • feldman2009
    Answered in Chapter 7

    In most cells, there are electrochemical gradients of many ions across the plasma membraneeven though there are usually only one or two electrogenic pumps present in the membrane. Thegradients of the other ions are most likely accounted for by

    A) cotransport proteins.

    B) ion channels.

    C) carrier proteins.

    D) B and C only

    E) A, B, and C



    A) cotransport proteins.



  • feldman2009
    Answered in Chapter 7

    The sodium-potassium pump is called an electrogenic pump because it

    A) pumps equal quantities of Na+ and K+ across the membrane.

    B) pumps hydrogen ions out of the cell.

    C) contributes to the membrane potential.

    D) ionizes sodium and potassium atoms.

    E) is used to drive the transport of other molecules against a concentration gradient.



    C) contributes to the membrane potential.



  • feldman2009
    Answered in Chapter 7

    If a membrane protein in an animal cell is involved inthe cotransport of glucose and sodiumions into the cell, which of the following is most likely true?

    A) The sodium ions are moving down their electrochemical gradient while glucose is moving up.

    B) Glucose is entering the cell along its concentration gradient.

    C) Sodium ions can move down their electrochemical gradient through the cotransporter whetheror not glucose is present outside the cell.

    D) Potassium ions move across the same gradient as sodium ions.

    E) A substance that blocked sodium ions from binding to the cotransport protein would alsoblock the transport of glucose.



    E) A substance that blocked sodium ions from binding to the cotransport protein would alsoblock the transport of glucose.



  • feldman2009
    Answered in Chapter 7

    The movement of potassium into an animal cell requires

    A) low cellular concentrations of sodium.

    B) highcellular concentrations of potassium.

    C) an energy source such as ATP or a proton gradient.

    D) a cotransport protein.

    E) a gradient of protons across the plasma membrane.

    C) an energy source such as ATP or a proton gradient.



  • feldman2009
    Answered in Chapter 7

    Ions diffuse across membranes down their

    A) chemical gradients.

    B) concentration gradients.

    C) electrical gradients.

    D) electrochemical gradients.

    E) A and B are correct.



    D) electrochemical gradients.



  • feldman2009
    Answered in Chapter 7

    What mechanisms do plants use to load sucrose produced by photosynthesis into specializedcells in the veins of leaves?

    A) an electrogenic pump

    B) a proton pump

    C) a contransport protein

    D) A and C only

    E) A, B, and C

    E) A, B, and C
  • feldman2009
    Answered in Chapter 7

    The sodium-potassium pump in animal cells requires cytoplasmic ATP to pump ions acrossthe plasma membrane. When the proteins of the pump are first synthesized in the rough ER, whatside of the ER membrane will the ATP binding site be on?

    A) It will be on the cytoplasmic side of the ER.

    B) It will be on the side facing the interior of the ER.

    C) It could be facing in either direction because the orientation of proteins is scrambled in the

    Golgi apparatus.

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    A) It will be on the cytoplasmic side of the ER.



  • feldman2009
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    Proton pumps are used in various ways by members of every kingdom of organisms. Whatdoes this most probably mean?

    A) Proton pumps must have evolved before any living organisms were present on the earth.

    B) Proton pumps are fundamental to all cell types.

    C) The high concentration of protons in the ancient atmosphere must have necessitated a pumpmechanism.

    D) Cells with proton pumps were maintained in each Kingdom by natural selection.

    E) Proton pumps are necessary to all cell membranes.



    D) Cells with proton pumps were maintained in each Kingdom by natural selection.



  • feldman2009
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    Several seriously epidemic viral diseases of earlier centuries were then incurable becausethey resulted in severe dehydration due to vomiting and diarrhea. Today they are usually not fatalbecause we have developed which of the following?

    A) antiviral medications that are efficient and work well with all viruses

    B) antibiotics against the viruses in question

    C) intravenous feeding techniques

    D) medication to prevent blood loss

    E) hydrating drinks that include high concentrations of salts and glucose



    E) hydrating drinks that include high concentrations of salts and glucose



  • feldman2009
    Answered in Chapter 7

    An organism with a cell wall would have the most difficulty doing which process?

    A) diffusion

    B) osmosis

    C) active transport

    D) phagocytosis

    E) facilitated diffusion

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  • feldman2009
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    White blood cells engulf bacteria through what process?

    A) exocytosis

    B) phagocytosis

    C) pinocytosis

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    B) phagocytosis