As oxygen is consumed during
respiration, it is normally replaced by CO2 gas at a ratio of one molecule of CO2 for each
molecule of O2. Thus, one would expect no change in gas volume to result from this
experiment. However, the CO2 produced is removed by potassium hydroxide (KOH),
which reacts with CO2 to form solid potassium carbonate (K2CO3) through the following
reaction:
CO2 + 2KOH → K2CO3 + H2O
This doesn’t
happen, does it?
We have learned that plants carry out photosynthesis by using carbon dioxide, water, and
sunlight to create sugar and oxygen.
(http://funbiologyclass.blogspot.com/)
We have also learned that organisms carry out cellular respiration by converting sugar
and oxygen into carbon dioxide and water.
(http://enclosedcanopy.com/media/aerobic-cellular-respiration-formula.html)
So plants carry out photosynthesis and animals carry out cellular respiration. On the
other hand, animals don’t carry out photosynthesis and plants don’t carry out cellular
respiration, right? Wait a second, IS that right?
We will now conduct an investigation into whether or not plants carry out cellular
respiration as well as photosynthesis.
Let’s think about the purpose of photosynthesis. What is it?
What is the purpose of cellular respiration?
Knowing what you do about the purpose of both processes, do you think that plants also
need to carry out cellular respiration?
To get started with your investigation, take a look at the overall formula for
photosynthesis and cellular respiration.
Consider the reactants and the products in the formula. How could you set up an
investigation that would help to determine if plants carry out cellular respiration as well
as photosynthesis?
You will prepare your investigation with as many classmates as you wish, but must be
ready to share some of the equipment, such as Vernier monitors.
Written Requirements
You must:
1. Prepare a purpose
2. Create a table of observations
3. Make a conclusion based on your results