1. Homeostasis Lab: A Balancing Act
15 points

2. Underneath your Definitions, create this chart:
CAUSE
EFFECT
Ex. The temperature in the room drops
Ex. You shiver

3. Instructions:
In groups of 3-4 students, travel to each of the three stations. You will have five minutes at each station. At the end of the five minutes, you must move on, even if you are not finished.
At each station, follow the directions.
After completing each set of directions, record the cause and effect seen at that station.
When fifteen minutes are up, return to your seat to begin the discussion questions. If you needed more time at a station, it is okay to return and finish at this time, however you will still be responsible for completing the discussion questions by the end of class.

4. Discussion Questions: Write Under Cause and effect Chart
How did Station 1 (Balancing) illustrate homeostasis?
What was the negative feedback at Station 1?
How did Station 2(Pulse Rate) illustrate homeostasis?
What was the negative feedback at Station 2?
How did Station 3 (Pupil Response) illustrate homeostasis?
What was the negative feedback at Station 3?
Describe one additional cause and effect relationship not seen in our text or in the lab. Identify the negative feedback.
Why do you think homeostasis is considered one of the four unifying themes of biology?
Each of the three other unifying themes played a role in this lab as well. Name each of the three themes and give an example from the lab of each.
Did we follow the scientific method for this lab? Explain your answer.

5. Station 1: Balancing
Stand only on your right leg. Try not to look down.
While standing on one leg, begin talking to the other people in your lab group. Look at each person and tell them what their eye color is, then what their hair color is, and if they are taller or shorter than you. All partners should take turns talking.
Now, try raising your arms above your head and closing your eyes. Count how long you can keep balance.
4) Lastly, try to touch the toes of the foot that is still on the floor with your eyes open, then with your eyes closed.
5) Write down the cause and effect you experienced at this station on your chart.
6) Discuss with your partners: Is this an example of homeostasis? Why or why not?

6. Station 2: Pulse Rate
Have one group member volunteer to be “it” for this one.
Take the volunteer’s pulse rate by pressing either their wrist or their neck at the base of their jaw lightly. Record how many times you feel a pulse within 15 seconds. (have your third group member keep time on the stopwatch)
Then use the calculator to multiply that number by 4 to get their “base” heart beats per minute. Write that number down on the notecard so you don’t forget.
Have the volunteer do jumping jacks for one minute. Time them using the stopwatch.
Take their pulse for 15 seconds immediately after they have stopped doing jumping jacks. Multiply that number by 4 to get their heart beats per minute. Compare your new heart rate to the one you had previously written down.
6) Write down the cause and effect you experienced at this station on your chart.
7) Discuss with your partners: Is this an example of homeostasis? Why or why not?
***Optional: If you have extra time, try having another group member volunteer. Whose heart rate will be greater after the jumping jacks?

7. Station 3: Pupil Response
Assign yourselves in either role A, B, or C (if there are four of you, you can take turns being person A). Read all directions before beginning.
Person A should stare straight ahead towards the board.
Person B will take the flashlight and slowly pass it across Person A’s face from left to right, into and then out of their line of sight.
As Person B passes the flashlight, Person C will use the stopwatch to record how long it takes for Person A’s pupils (dark spot in the center of your eye) to return to their normal size.
Retry this experiment two more times, gradually decreasing the speed at which the flashlight passes over Person A’s face (in other words, shine the light towards their eyes a little longer each time – 5 seconds should be the absolute maximum) and it should never be directly into their eyes.
6) Write down the cause and effect you experienced at this station on your chart.
7) Discuss with your partners: Is this an example of homeostasis? Why or why not?
***Optional: If you have extra time, try having another group member volunteer. Whose eyes will be take longer to return to normal? Does wearing glasses or contacts have an effect on pupil response time?