Chapter 4 ­ Reading Guide                     Name ____________________

1.  One way cells maintain homeostasis is by controlling the movement of substances across the [ cell membrane / cytoplasm ].

2.  Movement across the cell membrane that does not require energy is called [ active / passive ] transport.

3.  The difference in the concentration of a substance across a space is called a concentration [ equilibrium / gradient ].

4.  If there is a concentration gradient, substances will move from an area of high concentration to an area of [ equal / low ] concentration.

5.  The cell membrane is [ selectively permeable / impermeable ].

6.  [ Equilibrium / Diffusion ] is the simplest type of passive transport.

7.  The diffusion of water through a selectively permeable membrane is called [ osmosis / diffusion ].

8.  The direction of water movement across the cell membrane depends on the concentration of free water [ molecules / solutions ].

9. A solution that causes a cell to swell is called a [ hypertonic / hypotonic ] solution.

10.  Organelles that collect excess water inside the cell and force water out are called [ diffusion organelles / contractile vacuoles ]

11.  Transport proteins provide passageways for molecules to move across the [ vacuole / cell membrane ]

12.  In some ion channels, pores can be closed by an ion channel
[ gate / membrane ]

13.  The rate of movement of a substance across the cell membrane is determined by the [ speed of the molecules / concentration gradient ]

14.  [ Carrier / Facilitated ] proteins are used to transport specific substances across the cell membrane.

15.  Facilitated diffusion moves substances down their concentration gradient [ with / without ] using the cell’s energy.