# The Effect of the Presence of Light on the Amount of CO2 Produced by a Plant

Essay by picklepieCollege, UndergraduateA, April 2006

Hypothesis

If a plant is placed in the dark then the amount of CO2 produced will be higher, versus, if a plant is placed in the light, then the amount of CO2 produced will be lower. This is because all organisms, even plants, carry out the operation of aerobic cellular respiration, with the following equation:

C6H12O6 + 6O2 6CO2 + 6H2O + ATP + Heat

Carbon dioxide is a product that is then used to fuel photosynthesis, which occurs in all plants. The equation for photosynthesis is as follows:

6CO2 + 12H2O C6H12O6 + 6H2O + 6O2

light

Therefore, the plant that is placed in the dark will undergo aerobic cellular respiration, producing CO2, but because there is no light available to it, it cannot undergo photosynthesis. Subsequently, there will be an excess of CO2 because it is not used in photosynthesis. Conversely, the plant that is placed in light will undergo photosynthesis, due to the presence of light , and will use CO2.

Consequently the light plants will have less CO2 then the dark plants.

Results

Beaker Amount of CO2 Present (ÃÂµM of CO2/g/hr)

4 - Light 185.0

5 - Light 93.8

6 - Light 31.9

7 - Dark 98.0

8 - Dark 23.6

9 - Dark -44.0

The Effect of the Presence of Light on the Amount of CO2 Produced by a Plant

The average value of HCl used in the titrations for the control beakers (those that contained no plant) was calculated:

11.39 mL + 12.36 mL + 11.11 mL = 11.62 mL of HCl used

3

This average was then used in calculations used to find the amount of CO2 present in beakers 4 - 9. The following formula was used:

ÃÂµM of CO2/g/hr =

Beaker #4:

M of CO2/g/hr = [11.39 mL- 9.4...