The movement of a substance from an area of high concentration to an area of less concentration is called
A. endocytosis.
B. osmosis.
C. diffusion.
D. facilitated diffusion.
E. active transport.
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Question 2) Salt was added to a beaker of distilled water (the water was not stirred). A sample taken from the bottom of the beaker was found to be 20 salt.
At the same time, a sample taken from the top of the beaker was found to be 2 salt. After 24 hours
A. the difference in the percentage of salt between the top and bottom samples would increase.
B. the percentage of salt in top and bottom samples would be approximately equal.
C. the samples would still be 2 and 20 respectively.
D. the salt would float to the top.
E. None of these choices are correct.
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Question 3) The movement of oxygen from the alveoli of the lungs into the bloodstream is an example of
A. osmosis.
B. active transport.
C. bulk transport.
D. facilitated diffusion.
E. diffusion.
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Question 4) A group of cells was treated with a proteolytic (protein-digesting) enzyme. Which of the following processes would be least affected by this treatment?
A. use of carrier molecules in facilitated diffusion
B. sodium-potassium exchange pump
C. secondary active transport
D. diffusion of lipid-soluble molecules through the plasma membrane
E. diffusion of sodium through sodium membrane channels
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Question 5) In the process of diffusion, net movement of substances is always from a region
A. outside the cell to a region inside the cell.
B. inside the cell to a region outside the cell.
C. of lower concentration to a region of higher concentration.
D. of higher concentration to a region of lower concentration.
E. None of these choices are correct.
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Question 6) The aroma of cookies baking in the kitchen reaches you in the living room. The distribution of this odor throughout the house is an example of
A. osmosis.
B. filtration.
C. diffusion.
D. dialysis.
E. active transport.
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Question 7) Which of the following statements concerning membrane transport across the plasma membrane is true?
A. All molecules are moved across by active transport.
B. Water cannot move through the membrane.
C. Lipid-soluble substances pass through the membrane by dissolving in the lipid bilayer.
D. Generally, cations pass through the membrane more easily than anions.
E. Polar molecules are transported more easily than nonpolar molecules.
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Question 8) The plasma membrane is selectively permeable. This means
A. substances need permission to pass through it.
B. ATP is always needed to move molecules across the plasma membrane.
C. substances need carrier molecules to pass through it.
D. only gases and water can pass through it.
E. only certain substances can pass through it.
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Question 9) In general, water-soluble molecules diffuse through the ______ ______; and lipid-soluble molecules diffuse through the ______ ______.
A. membrane channels; membrane channels
B. membrane channels; lipid bilayer
C. lipid bilayer; membrane channels
D. lipid bilayer; lipid bilayer
E. None of these choices is correct.
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Question 10) A symporter will transport _____ across the cell membrane.
A. two different ions or molecules in opposite directions
B. two of the same ions or molecules in the same direction
C. two different ions or molecules in the same direction
D. two of the same ions or molecules in opposite directions
E. one specific ion or molecule
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