Biology H-Mr. Willets
Pg 95 (start at the very top)
1) How do cell membranes help maintain homeostasis (stable internal environment)? _______________
______________________________________________
2) If substances cross the cell membrane without the cell using energy, it is called __________________
transport.
3) Define diffusion______________________________________________________________
4) The difference in concentration is called the concentration _________________________
5) Molecules (like the sugar in the example) move because they have ________________energy are in __________________ motion.
6) As molecules move and bounce off objects they spread out moving from areas of _______________ concentration to areas of ________________________________________.
7) When the molecules have spread out completely and are evenly spaced, they have reached a state called
____________________________________
Pg. 96
8) Even when they reach equilibrium, the molecules keep ________________.
7) If a molecule can pass through a membrane, it will diffuse from an area of ________________
____________________________ to an area of ___________________________________
8) Molecules that can dissolve in _________________ can pass easily through the membrane (because it is made of ______________) Molecules that are small can pass through the ____________ formed by the proteins in the membrane.
9) Define Osmosis- ____________________________________________________________
10) Water diffusing in and out of a cell can be described three ways-
a) Cells in hypotonic solution- water diffuses _______________ the cell until equilibrium.
b) Cells in hypertonic solution- water diffuses ______________the cell until equilibrium is reached
c) Cells in ________________ solution- water diffuses in and out of the cell ____________________
Pg. 97
11) Which type of osmotic situation (see #10 above) does not pose a problem to cells? _______________
12) In hypotonic situations, water ________________ the cell. It is often removed by an organelle called the _____________________ vacuole. This is common in unicellular organisms that live in _________________________. The contractile vacuole requires that the cell use _____________ to get rid of the water.
Pg 98
13)What prevents plant cells from bursting when water enters? _______________________ The pressure that builds up in cells when water enters is called _____________________________
14) In hypertonic situations, water __________________ the cell. This cause loss of ____________
pressure and the cell shrinks- this is called ______________________
15) Red blood cells have to live in an _____________________ solution. If they are in hypertonic solution, the cells will __________________. If they are in hypotonic solution, the cells will _________________ which is called _________________________. (What does this word literally mean?)
pg 99
16) __________________________ diffusion is when molecules that cannot normally get through a membrane are assisted through by _____________________ in the membrane. These proteins are called __________________ proteins. The cell does not have to supply energy for this to happen, so it is _____________________ transport. This is still diffusion, so the molecules still move from _______________ to _________________ concentration.
pg 100
17) Another kind of passive transport helps move ions (molecules with charges on them) through the membrane. The proteins that do this are known as ion _________________. Some of these are always open while others have ______________ that open or close in response to stimuli.
Pg 101
18) If a cell moves substances from lower to higher concentration, it is called _________________ transport. This requires that the cell use _______________
19) Proteins in the cell membrane that help active transport are called membrane _______________
One example of this is the _________________-____________________ pump.
Pg 102
20) Endocytosis- process by which cells ingest (take in) external fluid, ____________________ or large ____________________
21) There are two types of endocytosis: ______________________ which takes in fluids and ________________________ which takes in large particles (or even whole cells)
22) What is the name of the process that is the opposite of endocytosis? ________________________