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Measuring Photosynthetic Activity In Plants

Photosynthesis is a process in which crops obtain food by switching light energy into blood sugar. Photosynthesis occurs in all plants and is essential to humans since it creates an Oxygen rich atmosphere. As Frank Adam states, in his publication Photosynthesis in Plants that even the modern developments are still heavily determined by plants that go through photosynthesis. Things such as medicine, clothes, Furniture etc all result from plants so that's why I believe, plants are fundamental players in transforming us from the rock age to the present day 20th century and the reason why they still are being used for Modern development( Frank 1)

Photosynthesis doesn't only take place in day light but, it also happens during the night. As Anne Helmenstine suggests that in Photosynthesis there are two types of response: the reactions that require light are called light dependant reactions. In this particular response light is captured from the suns rays to produce a molecules called ATP. Alternatively there are those reactions which do not require light to function these reactions are called the dark reactions(Calvin pattern). They take place at nights- time and their role is by using the used ATP that was made during the light response and convert into glucose. (Helmenstine 4)

One way to evaluate Photosynthetic activity in plant life is the fact you can measure the starch creation. Darrell Vodopich states in his publication Biology Lab Manuel that the Sugars(Sugar) which is the finish product created by the photosynthesis effect are often stored as starch. Therefore we can evidently observe that the starch production found in the leaves indirectly measures photosynthetic activity in plant life. "(Vodopich 143)

My hypothesis predicated on my lab test on Photosynthesis : From the geranium leaf, variegated or purple coleus leaf; the crops retained in dark will exhibit a reduced amount of starch production then the plants which were exposed to light as a result of photosynthesis.

I used the Lugol's test for my hypothesis and test its validity the iodine test in essence uses iodine to point the presence of starches by producing a bluish dark color (Vodopich 58).

Materials and Methods

Procedure 13. 6

In this Procedure the main goal was to qualitatively observe the starch creation of the Geranium leaf. We first had taken the Geranium leaf and dipped it in the boiling drinking water for a minute. Then we took the same leaf and again boiled it but this time it was with methanol and we allow leaf sit for approximately 3-5 minutes. From then on we put the leaf onto the Petri dish and stained the leaf with iodine to disclose the indicator of the starch development (Vodopich 144). THE COLOUR of the leaf was inexperienced when it was boiled with water alone, then following the leaf transformed to a pale white color stripped of its inexperienced pigment. Directly after we stained the leaf with Iodine we saw a yellowish/white color along with crimson where the veins were located.

Procedure 13. 7

In this process the main objective was to find the condition of light for the photosynthesis process. In this procedure of the geranium leaf was covered completely with a foil or newspaper for 3-4 times before being run upon in the lab. Then we placed the leaf into the boiling drinking water and allow it sit down there for a minute before placing it into another boiler comprising methanol for about 3-5 minutes. After that we put the leaf onto the Petri dish and stained the leaf showing the starch production (Vodopich 146). Just like 13. 6 the color of the leaf was inexperienced when it arrived of the boiling drinking water and after wards when the leaf from taken off the boiling methanol its renewable pigmentation was stripped giving a pale white color behind. Then after we stained the leaf with the iodine we observed more purple places on the side which was subjected to light then your other darker of the leaf which comprised little to no dots of purple which suggested the starches development.

Procedure 13. 8

In this process the main objective was the find the requirements essential for chlorophyll for the photosynthesis process. First we'd to secure a variegated coleus leaf and a crimson coleus leaf; both were kept in areas subjected to light before the start of experiment, unlike process 13. 7. Then we draw out the pigments in the leaves by first putting both the leaf in the boiling water for a minute. Then we placed the two leaves in another boiler containing methanol for approximately 3-5 minutes. After that we place both the leaves onto a Petri dish and we stain them with iodine. (Vodopich 146). We saw both leaves exhibited different properties after going through the methanol boiling period. The variegated leaf possessed a renewable color with white places and the purple leaf had inexperienced color and regions of brown. From then on when the 2 2 leaves were stained with iodine we observed that the variegated leaf had white corners and a purple sections in the middle of the leaf whereas in the crimson leaf there have been several dark purple big places on the leaf rather than a unique isolated area where in fact the starch production occurs.

One of the tendencies found in this table is that during the beginning stage when the leaves are boiled in drinking water alone they keep their color pigmentation but during the second period when the same leaves are boiled in methanol their inexperienced pigment is almost entirely stripped leaving behind a fine pale white/ greenish color. Another craze which is also found from the desk is that the geranium leaf held in conditions with light has more Staining Intensity( Starch Creation) as opposed to the Geranium leaf stored in the dark.


The craze that the Starches production is higher in leaves that were already acquired pre existing condition of being subjected to light where when compared with leaf being half exposed to light environment and the spouse covered or in dark environment. Plants who face light are more likely to produce starch therefore of photosynthesis alternatively than plants that are kept at night. As Vodopich mentions in his Biology Manuel that the finish product (blood sugar) of the photosynthesis process is stored as substances called starches. So there fore the starch production can be an indirect measure of photosynthesis and vice versa. Also in photosynthesis we are in need of some type of a source of light then we can forecast that if a host does not have any light it'll halt the photosynthesis creation and if that occurs then we will not be able to makes sugars in the form of starch and get a lack of starch production (Vodopich 143).

Some of the items I expected was for the leaf to keep its renewable color throughout the experiment and I expected the uncovered/ unexposed leaf showing a distinct style in starch creation but instead the results exhibited no such clear differentiation in the leaf as well as the renewable color also didn't previous after the leaves travelled under the procedure to be boiled in methanol.

For future analysis I recommend doing an experiment with more types of leaves for a better correctness in results. I'd also suggest locating the wave length spectrum of t he leaves and how much their absorbance's are to see if if the absorbance spectrums of the leaves correlate with the amount of image synthesis thus indirectly calculating starch creation. Also I'd try going outside the house in the morning and during the night and do the task pointed out in 13. 6 - 13. 8 to see is there is any difference in starch creation. Also I'd try experimenting the leaves under different light rather than the standard light from the sun and compare the amount of starch production between the two different wavelengths of light.

Source Citations

Brooker, Robert, Eric Widmaier, Linda Graham, and Peter Stiling. "Biology". Eighth Model.

New York, NY: McGraw-Hills Companies Inc, 2008. 0-1299. Print

Franck, Adam and Loomis, W. Earl. (1949). Photosynthesis in plant life. Ames: Iowa Point out College Press.

Helmenstine, Anne Marie, and Ph. D. . "Photosynthesis Research Guide. " Chemistry - Periodic

Table, Chemistry Jobs, and Chemistry Home work Help. The New York Times

Company, n. d. Web. 23 Mar. 2010.

Vodopich, Darrell, Randy Moore, and. "Biology Lab Manuel". Eighth Release. New

York, NY: McGraw Hills Companies Inc, 2008. 0-567. Print out.

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