BSOSF

Hi, I'm taking Biology right now and I'm having trouble with 2 questions. Any help would do.

Questions:

2.What process produces CO2?
5.In this lab, how will you introduce CO2 to Bromothymol Blue?

Information on the Lab:

Purpose: To determine if plants soak up carbon dioxide by observing changes in the color indicator Bromothymol Blue

Procedure:
1.Measure 50mL of Bromothymol Blue into beaker.
2.Using a drinking straw, blow bubbles gently into the Bromothymol Blue solution until the color turns light-green/yellow.
3.Label the test tubes 1, 2, & 3. Place 10mL of Bromothymol Blue into each test tube.
4.Record the initial color of each test tube in Data Table 1.
5.In test tube #1: add a 2 inch piece of Anacharis plant. Make sure the plant is pushed down to the bottom of the test tube (submerged in the solution). Seal the test tube with a rubber stopper.
6.In test tube #2: Seal the test tube with a rubber stopper as in step 5. NO PLANT.
7.In test tube #3: add a 2 inch piece of Anacharis plant. Make sure the plant is submerged. Wrap the entire test tube in aluminum foil to make the environment dark. Cap the test tube with a rubber stopper.
8.Place all test tubes into the test tube rack and expose them to lamplight.
9.After 24 hours, uncover the foil test tube and hold all 3 test tubes up to a white background in order to compare the shades of color. Record your observations in Data Table 1

1. Cellular respiration.
2. You are using YOUR own carbon dioxide to make the CO2 for the experiment. You put it into the bromothymol blue by blowing bubbles into it via your drinking straw.