Use of our material:
 All original materials links are created by Kelly Riedell for students in Honors Biology/AP BIOLOGY/Zoology classes at Brookings High School  and are licensed under a Creative Commons Atribution-NonCommercial-ShareAlike 4.0 International License.

We have worked very hard on activities, Powerpoints/games/worksheets, etc to make this a resource for our students. If you are using our materials, please give us credit for our efforts by listing us as a source with links to our site. DO NOT USE these materials for commercial purposes.  PLEASE DO NOT POST ANSWER KEYS FOR OUR MATERIALS TO OTHER WEBSITES!
Any questions, comments, or corrections can be directed to Kelly Riedell at

COUNTER CURRENT FLOW ACT IT OUT      Counter current flow Handout

   

Photocopy the oxygen and/or carbon dioxide cards
I run the activity with oxygen cards alone first. You can add CO2 later if you want. 

SET UP:
Give half of the students 12 oxygen cards. Divide class in half and have students line up in two parallel lines. I push lab tables together to make a row between students.

SIMPLE DIFFUSION

"Which line represents the water outside the fish?"
"Which line represents the blood inside the gills?"
"What does the table represent?" (cell membranes... blood and water don't physically touch)
Review diffusion. " How do molecules move?"  [High to low] 

 

ACT IT OUT
Have both lines of students move along the tables IN THE SAME DIRECTION taking one step at a time. 

After each step, stop and trade cards. Students opposite each other check the number of cards they have. If there is a difference in numbers, the student with the greater number of cards passes one card to the student with fewer cards directly across from him/her. If students have the same number of cards, no cards are exchanged.

 

 

Take one more step and repeat

Take one more step and repeat

 

Continue until students "reach equilibrium".


WHAT HAPPENED?
Have them count up their cards and see how many each side has.
They should see that once the oxygen concentration is equal on both sides of the membrane, no more net oxygen will be transferred even if they continue to more along side each other.

 

NOW TRY IT WITH COUNTER CURRENT FLOW
Repeat set up with two lines of students and only one side having 12 cards. 
This time the beginning of each line should meet in the middle and lines will move in opposite directions past each other. 

Have students move along the tables one step at a time. Repeat directions for trading cards above.



Repeat

 

Repeat . . . . .

 

 

Continue until you reach points where some students have 6 tickets.
Remind them what happened the first time at this point.

Have students continue moving and passing cards

 

 

 

 

Depending on how many tickets you start with and how many students you have in your class, you may get more or less total oxygen passed.

 

WHAT HAPPENED?
Have them count up their cards and see how many each side has.
They should see the two sides are NOT equal this time. The "water side" was able to pass more oxygen cards to the "fish side". Because two sides move in opposite directions, the "water side" is always encountering "new" blood that has a lower concentration of oxygen even if some of the oxygen has already been passed.  Counter current flow keeps generating a concentration gradient, so more transport can happen. 

 

APBIOteacher help      Riedell Science Home      Bioteacher help    APBIO other units        Zoology other units       Biology other units

 

Back to