1. Photosynthesis & Respiration Lab
What is the relationship between photosynthesis and respiration?

2. Part 1
Investigative Question: What will happen to a carbon dioxide solution of CO2 and water if a water plant is added?
Write your hypothesis:
“If _______________ then__________ because__________________________.”
*Get signed off by your teacher

3. Materials Test tubes x 4 Stoppers x4 Test tube rack Foil Elodea (2cm)
Bromothymol Blue
Lamp

4. The Acid-Base Scale & Bromthymol Blue
CO2 in water
No CO2 in water,
Regular tap water
Water
Distilled water
Most least least most
Acidic Neutral Basic

5. Protocol
Label your test tubes with your names and the letters A, B, C, and D.
Fill each 1/2 full with distilled water.
Add 1 dropper of acid/base indicator (bromothymol blue)
A B C D
Per5 Per5 Per5 Per5
Name Name Name Name

6. Place a straw into Test Tube A.
Gently blow into the solution until it starts to turn yellow- STOP IMMEDIATELY when you see a change in color!!!
STOP! A A

7. Repeat Steps 4 & 5 for all test tubes& place 1 sprig of elodea into test tubes A & C.
A B C D
Per5 Per5 Per5 Per5
Name Name Name Name

8. 7. Then place stoppers on all test tubes.
A B C D
Per5 Per5 Per5 Per5
Name Name Name Name

9. 8. Wrap Test Tubes C & D with foil so that no light can get in.
A B C D
Per5 Per5 Per5 Per5
Name Name Name Name

10. 9. Place all test tubes on a test tube rack or holder and place in the tray that will go under a light.
A B C D
Per5 Per5 Per5 Per5
Name Name Name Name

11. Predictions: Test Tube Color after 24 hours pH = ?
Why do you think this? A B C D

12. Original Data Table Test Tube Color start (pH = 6-, 7, 8+)
Color after 24 hours A B C D

13. Class Results: Color (pH) changes for Day 1
Group
Tube A
Tube B
Tube C
Tube D 1 2 3 4 5 6 7
Mode:

14. Part 1- Data Collection Observe the results after 24-48 hrs.
Record data on data table.

15. Part 2
Investigative question: What is the role of light in photosynthesis? What might happen if the tinfoil was switched to test tubes A & B?
Write your hypothesis:
“If _______________ then__________ because__________________________.”
*Get signed off by your teacher

16. Identify the following in this inquiry:
The manipulated variable _____________
Responding variable_________________
Controlled variables _________________
____________________
Experimental control _________________
Purpose of the experimental control _____ __________________________________
*Get teacher signature

17. 10. Wrap Test Tubes A & B with the foil so that no light can get in.
C D A B
Per5 Per5 Per5 Per5
Name Name Name Name

18. 11. Place all test tubes on a test tube rack or holder and place in the tray that will go into the greenhouse.
C D A B
Per5 Per5 Per5 Per5
Name Name Name Name

19. Part 2 Data Table: pH after light/dark conditions reversed
Test Tube
Color after hours
pH = ?
Why? A B C D

20. Part 2 – Data Collection
Record your results in your data table.

21. Analysis Questions Part 1:
Explain what happened to the pH of the solution for Test tube A. Why did you get these results?
How were these results different than test tube B? Why?
How were they different than C? Why?
And D? Why?

22. Analysis Questions Part 2 & 3:
What results changed as a result of switching the foil on the test tubes?
Why do you think this happened?
What is the role of light in photosynthesis?
Can plants do respiration? What evidence supports this?
What changes would you make to improve this lab and why?