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The aim of this particular experiment is to investigate the real effects of different levels of carbon dioxide in the atmosphere on the growth of the tomato plants. It should be noted that carbon dioxide is utilized by the plants in the process of photosynthesis to make food. Therefore this means that carbon dioxide is vital towards the growth of vegetative plants hence different levels of carbon dioxide in the atmosphere dictate different levels of growth. Therefore it is very true to state that high levels of carbon dioxide in the atmosphere dictate high levels of growth that in turn translate to high amounts of dry weight of the tomato seedlings. Similarly when the levels of the carbon dioxide are low in the atmosphere, then growth is minimal meaning that dry weight of the tomato seedlings will be low since the plants were not able to make large amounts of food out of the photosynthesis process due to low levels of carbon dioxide (Dordrecht, 2001). Therefore in this experiment we are establishing to details the effects of the varying amount of carbon dioxide on the growth of the tomato plants.

The following are the results of the experiment.


Initial weight seedlings (g)

2Normal CO

Standard deviation


Figure: Graphs of the mean of the dry weights of tomato plants


Initial vs. Low

Low vs. Normal

Normal vs. High

Low vs. High

Table: The T test values

It is very evident that plants that grew in conditions with high levels of carbon dioxide had the highest amounts of dry weight. This is because they made much food due to high levels of photosynthesis promoted by high levels of carbon dioxide. Plants that grew in normal levels of carbon dioxide had greater amounts of dry weight than those that grew in low levels of carbon dioxide. Therefore we note that as the level of carbon dioxide increase, the rate of photosynthesis increases translating to greater growth hence the increase in dry weight.

Plants undergo both photosynthesis and respiration. During respiration, plants give out carbon dioxide and uses oxygen unlike the photosynthesis that uses the carbon dioxide (Spoehr & McGee, 1923). Light affects both processes, but it should be noted that plants respire all the time unlike photosynthesis that take place when there is light only (Hopkins, 2006). Therefore respiration has effect on the process of photosynthesis hence it affects the dry weight of the tomato plants.


(2001). Advances in photosynthesis and respiration. Dordrecht, Kluwer Academic.

HOPKINS, W. G. (2006). Photosynthesis and respiration. New York, Chelsea House.

SPOEHR, H. A., & MCGEE, J. M. (1923). Studies in plant respiration and photosynthesis. Washington, The Carnegie Institution of Washington.