Homeostasis and Transport Webquest
Name
Objectives: Understand the structure and function of the cell membrane. Understand how cells and
single – celled organisms maintain homeostasis through transport mechanisms.
Part I: The Cell Membrane
http://telstar.ote.cmu.edu/biology/downloads/membranes/index.html
Scroll down to the animation titled “Membranes are not static sheets of molecules locked rigidly
in place”. View the animation.
1. Write a statement that summarizes the structural properties of the cell membrane
Scroll down to the picture of the cell membrane
2. What is the function of the carbohydrates on the membrane’s outer surface?
3. How are the functions of the proteins on the outer and inner sides of the membrane different?
4. List the two general types of proteins found in the cell membrane and their function.
a.
b.
Part II: Passive Transport
Use the links for the appropriate sets of questions.
http://physioweb.med.uvm.edu/diffusion/ Watch the Diffusion and Osmosis Segments (tabs on right
side of screen)
1. Draw an outline of a cell. Show internal and external concentrations of water on the inside and
outside of the cell that would cause a concentration gradient.
2. Define the term diffusion:
http://programs.northlandcollege.edu/biology/Biology1111/animations/transport1.html
3. The movement of substances across a cell membrane without any energy expenditure by the cell
is ______________ _______________.
4. What are the three types of passive transport?
a.
b.
c.
5. What is the function of an integral protein?
6. _____________ molecules do NOT pass through the cell membrane easily, while
_____________ molecules pass through the membrane easily.
7. Define the term concentration gradient:
8. List four factors that affect the rate of diffusion
a.
b.
c.
d.
9. Facilitated diffusion would be used on large molecules (True or False).
10. Facilitated diffusion requires the use of special membrane proteins. (True or False).
11. Define osmosis:
12. Draw a cell.
a. Label the interior of the cell as 90% H2O and 10% solute. Label the exterior of the cell as
100% H2O. Does a concentration gradient exist? (Y/N) _________
b. Label the exterior and interior of the cell using the terms hypertonic and hypotonic.
c. According to osmosis, which way would water move in this cell’s environment?
Part III: Active Transport
1. The movement of substances across a cell membrane requiring energy expenditure by the cell is
______________ _______________.
2. In an ion pump, what kind of concentration gradient is established? _______________________
3. In an ion pump, what molecule is used to supply the energy required to move molecules (such as
the H+ ions shown) up the concentration gradient?
4. Some cells are able to infold their cell membranes to literally engulf substances. This general
process is called _______________ and (does/does not) ____________ require energy.
5. List the three types of endocytosis
a.
b.
c.
6. Name two organisms that would use phagocytosis.
a.
b.
http://home.earthlink.net/~shalpine/anim/Life/endo.htm
7. Refer to the weblink above.
a. What is the role of the receptor proteins on the surface of the cell membrane?
b. What eventually happens to the receptor proteins?
What is the role of the lysosome in this animation/process?
RED BLOOD CELLS IN:
Click on the links below
Isotonic Solution
Hypertonic Solution
Hypotonic Solution
8.
a. Draw a red blood cell in an isotonic solution. Use 90% water and 10% solute as the
concentration inside the cell. Label the external environment of the cell appropriately.
b. Draw a red blood cell in a hypertonic solution. Use 90% water and 10% solute as the
concentration inside the cell. Label the external environment of the cell appropriately.
c. Draw a red blood cell in a hypotonic solution. Use 90% water and 10% solute as the
concentration inside the cell. Label the external environment of the cell appropriately.
http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopyuk.org.uk/mag/artjun99/vidjun99.html
Make sure to click on the “green” CLICK HERE prompt to view the videos!!
Look at the movie at the above weblink.
9. The organism in the movie is a protozoan called a paramecium. Read the captions along
with the movie clips.
a. What is the role of the specialized cell structure cilia for this organism?
b. What is the role of the contractile vacuole?
c. Do you believe the paramecium lives in a fresh water or saltwater environment?
____________ Explain: (clue – what is the function of the contractile vacuole and
which direction (into or out – of) is the water being pumped?)
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