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Quantitative Results

Distance from light source to Spinacia oleracea


Water Level (mm)


Water Level (mm)

Change in

Water Level (mm)





10 cm




20 cm




30 cm




40 cm




50 cm




Graph showing therelationship between light intensity and photosynthesis


The experimentwas designed to identify the effect of light intensity on the rate oftranspiration in plants. The shorter the distance from the lightsource the higher the intensity of light. This means that ifdistances are significantly far away from the light source, thenature of light intensity is substantially diminished (Clayton,1980). For this reason, 10 centimeters away from the light is thelevel at which the light intensity is higher compared to 50 cm. Thewater level changes from 0 to 1290 which is an equivalent of 1290millimeters.

When the sourceof light is placed an additional 20 cm from the experiment, the levelof water rises from 150 to 750. This is an indication of a finalchange of 600 mm in the water levels which is much lower than 1290that was posted when the source of light was 10 centimeters away. Thesame trend is witnessed when the source of light is placed 30 cmaway. In this case, the water levels change from 610 to 890. Thistranslates to a change of water levels by 280 mm, which isconsiderably lower than the values posted when the spinacia oleraceais 10 cm and 20 cm away respectively.

The experimentthen proceeds to the light source now 40 cm away from the experiment.In this case, the study notes that the water levels changes by 110from 620 to 720. As is the common trend, the value obtained is lesserthan that obtained from the experiment with the light source 10 cm,20 cm, and 30 cm away from the spinacia oleracea. Finally, with thelight source 50 cm away, the results indicate that the water levelschange by a modest 90 cm from 1020 cm to 1110 cm. This value issignificantly lower than 1290 mm, 600 mm, 290 mm, and 110 mm thatwere obtained when the light sources were 10 cm, 20 cm, 30 cm, and 40cm respectively.


Various factorsaffect the rate of transpiration among the plants. As such, the aboveresults indicate that light is one such that factor. The lightintensity to the amount of a plant exposed determines the rate ofphotosynthesis (Hall &amp Rao, 1999). Light intensity plays asignificant role in stimulation of the stomata to open as more lightintensity will result in an increased rate of photosynthesis. For theabove process to occur there must be gaseous exchange. Stomataprovide the avenue where such process takes place. It is the poreswhich facilitate the gaseous exchange that is required forphotosynthesis to take place (Kalman, 2005).

Therefore, withthe rate of photosynthesis increasing it means that the there hasbeen a corresponding rise in the stomata opening which has led toincreased gaseous exchange. Evaporation is a process that occurs onthe surface of the leaves of the plants and as such the stomata is animportant element for the process to occur (Raghavendra, 2000).Therefore, when the light intensity is increased, there will be anincreased rate of transpiration which will have been facilitated as aresult of the elevation of stomata opening.

The stomata areopen during the day whereby it allows the plant to take in carbondioxide (CO2) and release Oxygen (O2) (Silverstein, Silverstein &ampNunn, 2008). In the same way, the opening of the stomata enableswater to escape in the form of water vapor through a process known asstomatal transpiration. With the major exception of CAM, the stomatain plants close at darkness. acts by reducing thelevel of concentration of carbon dioxide in the intercellular cellswithin the leaves. Such occurrence leads to the opening of thestomata (Silverstein, Silverstein &amp Nunn, 2008).





The use of a dropper to add water into the rubber tuber to the initial level

At times, the student may accidently add water above the initial level thereby compromising the final conclusions.

A container that measures a specific amount of water can be used to ensure that the experiment is not compromised.

The use of 60W light instead of actual sunlight

The lights might have mechanical problems and as such will not provide the desired outcomes

The lamps can be taken for testing to ensure that they meet the expected standards. Moreover, by using the same lamp, related readings can be made


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Clayton, R. K. (1980).&nbsp.Cambridge [Eng.: Cambridge University Press.

Hall, D. O., &amp Rao, K. K. (1999).&nbsp.Cambridge, England: Cambridge University Press.

Kalman, B. (2005).&nbsp:Changing sunlight into food. NewYork, NY: Crabtree Pub. Co.

Raghavendra, A. S. (2000).&nbsp:A comprehensive treatise. Cambridge:Cambridge University Press.

Silverstein, A., Silverstein, V. B., &ampNunn, L. S. (2008).&nbsp.Minneapolis: Twenty-First Century Books.

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