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The Effect of Temperature on Production of Oxygen During Photosynthesis in Elodea

Jamie has a degree in molecular biology and has worked in Histology Labs for over ten years.

A graphic illustration of Blackman's experiment.

A graphic illustration of Blackman's experiment.


This experiment is a continuation of the experiment "Oxygen Production in Elodea in Direct Light, Distant Light, and Darkness."

Temperatures under 15C will not affect oxygen production in photosynthesis yet temperature over 40C will greatly increase oxygen production.

In 1905 F.F. Blackmen, an English plant physiologist, found that there was one set of light dependent reactions which were also temperature independent.

He also found that when the temperature was increased over 30C, the rate of photosynthesis increased dramatically.

He concluded that temperature had an effect on the carbon fixation reactions of photosynthesis.

This increase in the carbon fixation reactions requires more ATP and NADPH2 from the breaking down of water molecules in the light dependent stages. Therefore, an increase in temperature will also produce an increase in oxygen production.

In some plants carbon dioxide is converted to "ribulose-1,5-diphosphate" a five carbon sugar with two phosphates. It then splits into a three carbon compound called PGA (Phosphoglyceric acid), which with the addition of hydrogen, becomes starch. Plants that use the PGA pathway are called C-3 plants.

Some plants convert their carbon dioxide into Oxaloacetic acid instead of PGA. This is called the C-4 or the Hatch and Slack pathway.

The optimum temperature for plant photosynthesis depends on the environment that the plant is used to living in on a daily basis. C-4 plants normally exist in desert environments and have adjusted to higher temperatures, while C-3 plants have adapted to lower temperatures.

Increased temperatures will stimulate photosynthetic rates until the plant's stomates close or until the plant's enzymes denature. If the temperature increases too much, it will cause an imbalance in the O2:CO2 ratio, which cases a loss of CO2, thus causing CO2 fixation to stop production.

The optimum range for photosynthesis in C-3 plants is 15C-30C. The optimum range in C-4 plants is 30C-40C.



Materials and Methods

Using three different Elodeas submerged in a 0.05% dilution of potassium bicarbonate, the amount of oxygen produced at 14C, at 30C, and at 40C will be read in a YUS-190-M Photosynthesis device.

The amount of light from the beaker containing the Elodea will remain constant, from a flourescent light source located a meters distance.

The amount of oxygen produced by the Elodea at 30C (lab temperature) in one minute will be logged.

Three separate Elodea will be placed into a beaker containing a new diluted potassium bicarbonate solution and placed on wet ice until the temperature of the solution has reached 15C. The oxygen produced will then be read using the Photosynthesis apparatus and will be logged.

Three new Elodea will be placed in three separate beakers containing a new diltued potassium bicarbonate colution placed on a heating device until the temperature of solution has reached 40C. The oxygen produced will then be read and logged.

The previous step will be repeated until the solution reaches 65C and the oxygen produced will be read and logged.

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The t test will be used to determine whether the results from each temperature are statistically significant, using meand and standard deviations to find a 95% Confidence Interval for the population.


The oxygen produced from the Elodea at 30C with a fixed light source reached optimal oxygen production.

The oxygen produced from Elodea at 40C with a fixed light source was dramatically increased due to an increase in carbon fixation requiring a greater number of water molecules to be broken down.

The oxygen production at 65C began to decrease dramatically due to the unbalanced O2:CO2 ratio, and enzyme denaturation.


A Very Brief Discussion

A study of the decidous forests of the Northern Hemisphere observed that climate changes created a change in carbon dioxide exchange by one gigaton of carbon annually.

With increasing variance in seasonal temperatures around the world, it is important to know the effect of these temperature shifts on the local flora, since the local flora is essential in the ecology of the air we breath.

Please read for more information on similar Photosynthesis experiments:


Jamie Lee Hamann (author) from Reno NV on January 18, 2013:

Thank you unknown spy. Jamie

DragonBallSuper on January 18, 2013:

glad to read something that adds knowledge on my brain :) thanks jamie

Jamie Lee Hamann (author) from Reno NV on November 19, 2012:

Back to sonnets. Jamie

Martin Kloess from San Francisco on November 16, 2012:

This is a far cry from the world of sonnets. But thanks for a fascinating hub.

Jamie Lee Hamann (author) from Reno NV on November 16, 2012:

Sorry Gus I missed the second part of the question, this is interesting, I believe that this effect observed by Blackman could very well describe how photosynthesis is occurring in the various oceanic organisms that encounter various ocean temperatures. This is a fun question and I will do some research, maybe write a hub about it. Thank you. Jamie

Jamie Lee Hamann (author) from Reno NV on November 16, 2012:

GusTheRedneck-Elodea is a freshwater plant that would not be found in aggregate enough to effect change in any measurable amount. Elodea was the plant used by Blackman in his original experiment back in 1905. So this experiment is not a breakthrough but very educational and has been used to explain the chemistry of photosynthesis since he published his results. To answer your other questions, whether plants are located in water or air the chemistry of photosynthesis remains the same and the cycles that occur in plant cells remain similar even though the physiology may differ. So the question would be is there enough of an aggregate of plant life on the planet that is effected by temperature, not necessarily Elodea. Jamie

Gustave Kilthau from USA on November 16, 2012:

Howdy jhamann - Several things here. The first is a question. Because the rates of temperature change vary so very little in what folks are now calling "climate change" what might be the micro-changes in actuality for oxygen production in photosynthesis in elodea (and other plants in aggregate within measured geographical areas - say in square kilometers of some measure? The second is also a question. Is elodea's photosynthetic performance analogous to that of oceanic organisms that undergo photosynthesis at various ocean temperatures?

Thank you,

Gus :-)))

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