Thus, three factors, namely light, carbon dioxide, andchlorophyll, are considered important in determining the rate ofphotosynthesis. We will study in this lab how each of these factorsinfluences the photosynthetic process.
A. Carbon Dioxide
Objective: To demonstrate that C02 is utilized in thephotosynthetic process.
Procedure:
1. Fill 2 test tubes 1/4 full with Bromthymol Blue.
a. TT#1 - add 1 drop of HCl; record the color change
b. TT#2 - add 1 drop of NaOH; record the color change
2. Place 100 ml Bromthymol Blue in a small beaker and blow into ituntil a color change appears. Divide this solution equally into 4test tubes and number the test tubes.
a. TT#1 - Blank.
b. TT#2 & #3 - Place 1 healthy green Elodea twig (of the samesize) in each.
c. TT#4 - Control.
d. Wrap TT#3 & #4 completely with aluminum foil (to cut offlight).
e. Place all 4 test tubes near a light source, equal distances away(but away from the light source to be used in Part B).
f. Remove the foil at the end of the lab period. Record the colorchanges and infer their significance.
Data:
Test Solution Color of Bromthymol Blue
HCl yellow
NaOH dark blue
CO2 (bubbled through)
Test Tube Color Before Color After
#1 yellow yellow
#2 yellow green blue
#3 yellow light green
#4 yellow yellow
Question 1. Which of the testtubes changed color? Why? (explain thecontrols)
Thus, three factors, namely light, carbon dioxide, andchlorophyll, are considered important in determining the rate ofphotosynthesis. We will study in this lab how each of these factorsinfluences the photosynthetic process.
A. Carbon Dioxide
Objective: To demonstrate that C02 is utilized in thephotosynthetic process.
Procedure:
1. Fill 2 test tubes 1/4 full with Bromthymol Blue.
a. TT#1 - add 1 drop of HCl; record the color change
b. TT#2 - add 1 drop of NaOH; record the color change
2. Place 100 ml Bromthymol Blue in a small beaker and blow into ituntil a color change appears. Divide this solution equally into 4test tubes and number the test tubes.
a. TT#1 - Blank.
b. TT#2 & #3 - Place 1 healthy green Elodea twig (of the samesize) in each.
c. TT#4 - Control.
d. Wrap TT#3 & #4 completely with aluminum foil (to cut offlight).
e. Place all 4 test tubes near a light source, equal distances away(but away from the light source to be used in Part B).
f. Remove the foil at the end of the lab period. Record the colorchanges and infer their significance.
Data:
Test Solution Color of Bromthymol Blue
HCl yellow
NaOH dark blue
CO2 (bubbled through)
Test Tube Color Before Color After
#1 yellow yellow
#2 yellow green blue
#3 yellow light green
#4 yellow yellow
Question 1. Which of the testtubes changed color? Why? (explain thecontrols)
