Name: ________________________________________________
Homeostasis and Cell Transport Webquest Equilibrium Unit
Period: _____ Date: __________
Objectives: Understand the structure and function of the cell membrane. Understand how cells and single–celled
organisms maintain homeostasis using cell transport mechanisms.
Part I: The Cell Membrane
http://telstar.ote.cmu.edu/biology/MembranePage/index2.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). Please explain your answer:____________
_____________________________________________________________________________________________
10. Facilitated diffusion requires the use of special membrane proteins. (True or False). Please explain your answer:
_____________________________________________________________________________________________
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? __________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
c. 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.microscopy-uk.org.uk/mag/artjun99/vidjun99.html
Once at the above site 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?)
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
from: http://mysite.cherokee.k12.ga.us/personal/michelle_snead/site/Assignments/1/Cell%20Transport%20Webquest.pdf