Do plants use CO 2

Investigative Question  Will the aquatic plant (Elodea) fix the carbon from carbon dioxide in the water it is placed in?

Indicator  The indicator for carbon dioxide we will be using is Bromothymol Blue.  BTB turns green to yellow in the presence of Carbon Dioxide (CO 2 ).  Green = small amount of carbon dioxide  Yellow means a lot of carbon dioxide  It is also an indicator for pH. Yellow= more acidic

PS Lab  Hypothesis  Write your hypothesis here using the if then because format. If Elodea is placed in a solution of water and Carbon Dioxide along with BTB

PS Lab  Hypothesis  If we place a water plant (Elodea) in a solution containing CO 2, will see a color change from yellow toward blue because plants fix carbon from CO 2 in the process of photosynthesis.

PS Lab  II Materials  2 test tubes with stoppers  straw  100ml beaker  BTB  Elodea  Tape  Pen/pencil  Safety goggles  Classroom Control (Test tube #1, tap water + BTB)  Grow lights  Ringstands

Experimental Design (sketch in your journal)  Test tube # 1  Test tube # 2  Test tube # 3 Water and BTB Negative control Water, BTB and CO2 Water, BTB, CO2 and Elodea Plant Positive control

PS LAB  III Procedure  1. Label one test tube as #2 and fill halfway with tap water.  2. Label the other tube as #3 and fill halfway with tap water  3. Place 9 drops of BTB in both test tubes  4. Put on safety goggles and pour the contents of test tube #2 into the 100ml beaker.  5. With goggles on, take the straw and gently blow into the solution in the beaker. Continue until the solution turns yellow and then quickly pour back into test tube #2, place stopper in the tube.  6. Repeat steps 4 and 5 for test tube #3 but add Elodea before stopper.  7. Place under light for 24 hours  8. Record color of the solutions in tubes 1,2,3.

Data Table Test Tube #Day1Color Day 2 Color ChangeYes/no 1.neg. control 2.Positive control 3. Experimental setup

Photosynthesis Rap  KSSH4

Gather your data (Results)  Record results in class data table on board.  What do your test tubes look like?  What happened in your tube with no elodea?  What happened in the tube with elodea?

Clean up  Drain test tubes into sinks.  Dispose of Elodea into garbage can (Not in sinks)  Rinse test tubes and clean using one drop of soap and the test tube brush.  Rinse again and place back in test tube holder.  Rinse stopper and place in bin at front of class.

Analysis  What does the data say happened?  Did the elodea plant use up the CO 2 in the test tube?  How did you know?  Did anyone’s data differ in the class?

Conclusion  Answer the investigative question?  Does the data support or refute the hypothesis.  State the data and how it supports this.  What could you do differently or what could you test differently?

Reading  Getting Energy and Matter into Living Systems. Page  Tape in and answer questions on quarter sheet of paper.