The effect of light intensity on the amount of chlorophyll in Cicer a

The effect of light intensity on the amount of chlorophyll in Cicer a.
The effect of light intensity on the amount of chlorophyll in Cicer arietinum Extended Essay

The effect of light intensity on the amount of chlorophyll in Cicer

Word count: 4 413 words


Abstract 2
Introduction .. 3
Hypothesis 3
Description .... 8
Results .. 10
Discussion .... 14
Conclusion .... 14
Evaluation of the method .. 15
Bibliography . 16
Plants, growing on the shaded area has less concentrated green color
and are much longer and thinner than plants growing on the sun areas as
they are dark green, short and thick. Research question was: How does the
amount of chlorophyll-a and chlorophyll-b, gram per gram of plant, depends
on the light intensity in which plants are placed?
Hypothesis suggests that there are several inner and outer factors
that affect the amount of chlorophylls a and b in plants and that with the
increase of light intensity the amount of chlorophyll will also increase
until light intensity exceeds the value when the amount of destructed
chlorophylls is greater than formatted thus decreasing the total amount of
chlorophylls in a plant.
The seeds of Cicer arietinum were divided into seven groups and
placed into various places with different values of light intensities.
Light intensities were measured with digital colorimeter. After three weeks
length was measured. Then plants were cut and quickly dried. Their biomass
was also measured. Three plants from each group were grinded and the
ethanol extract of pigments was prepared. The amount of chlorophylls was
measured using method of titration and different formulas.
The investigation showed that plants growing on the lowest light
intensity equal 0 lux contained no chlorophyll and had the longest length.
The amount of chlorophyll quickly increased and length decreased with the
increase of light intensity from 0 lux to 1200 lux. The amount of
chlorophyll in plants unpredictably decreased during light intensity equal
to 142 lux and than continued increasing and didnt start decreasing
reaching very high value (1200 lux).
The sudden decrease happened due to mighty existence of some inner
genetical damages of seeds which prevented them from normal chlorophyll
synthesis and predicted decrease didnt decrease because extremely high
light intensity was not exceeded.
Word count: 300 words

I. Introduction.
This theme seemed to be attractive for me because I could see that
results of my investigation could find application in real life.
While walking in the forest in summer I saw lots of plants of
different shades of green color: some of them were dark green, some were
light green and some even very-very light green with yellow shades, hence I
became very interested in this situation and wanted to know why it happens
to be so. I also saw that those plants that were growing on sunny parts of
forest, where trees were not very high, had dark green color and those,
that were growing in shady parts of the same forest had very light green
color. They also had difference in their length and thickness those, that
were growing on light were very short, but thick and strong, and those,
growing in shady regions were very thin and fragile.
Hence I became very interested in finding scientifical description of
my observations.
The aim of my project is to find out how does the changes in light
intensity affect balance of chlorophyll in Cicer arietinum.

II. Hypothesis.

There are several factors that affect the development of chlorophyll
in plants.[1]
Inner factors. The most important one is genetical potential o
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