closer the distance of the light, the higher it affects the photosynthesis.
Mount Royal University
Light as a source energy among organisms greatly affects the photosynthetic
activity. The change in the reaction using a plant (spinach extract) can be proved by
observing the color loss of the dye, DCPIP as well as the reading of the
spectrophotometer after exposed to light. Photosynthetic activity was determined in the
range of distance from the light using 0cm, 50 cm and 100cm. The greatest change occurs
on the closest distance at 0cm. Photosynthetic activity was less affected on the farthest
distance which is 100cm., concluding that the more distance the photosynthesis occurs
away from the light, the less it will affect the activity.
Photosynthesis is a process in which plants, some protist, bacterias as well as
other organisms uses light as a source of energy and converts it into chemical energy to
be used and made available in the world (Nickle, 2012). There are two process to
photosynthesis to occur, one of which is energy transduction reaction. It is a process that
requires the light as an energy, the chlorophyll molecules captures light and converts it to
chemical energy in the form of ATP and NADH (Bertoni, et. al., 2012). Chlorophyll as a
pigment is very important, the chloroplast extractshould have a specific pigment in order
to captures light photosynthesis to occur. Chlorophyll are the major photosynthetic
pigment in the plants, it is green in color, and the two most dominant types are
chlorophyll a and b, which are not that different (Russel, et.al., 2013). Spinach, as the
chosen leaf for experiment contains chlorophylls, as it mostly present in plants.
This experiment will investigare the effect of light intensity on the photosynthetic
activity, the rate of photosynthesis- of chloroplast extracted from spinach.The effect of
light to photosynthetic activity differs on how intense the light is. Lights have different
wavelengths capacities ranging from 380- 750nm (Russel, et.al., 2013). Changes in light
intensity and the quality affects the absorption of light which sometimes is too much or
too less for photosynthesis (Karpiński, et.al., 2013). The absorption of light by
chlorophylls determines the photosynthesis rate of reaction. This absorption is supported
by the action spectrum, it is a plot of effectiveness of light of particular wavelengths in a
one process (Bertoni, et.al., 2013). We hypothesize that as the chloroplast expose to more
and closer light, the change in photosynthesis activity increases.
A fresh spinach leaf was rinsed and cleaned with tap water. This was placed in a mortar and pestle containing a small pinch of sand and a small amount of acetone. It was grind gently until all the contents are distributed properly. The spinach extract was then removed from the mortar and pestle and was transferred in a centrifuge and was placed in a water bath with ice.
To ensure that the extract containing pigments can be used in the experiment,
especially for the light intensity, we test it using chromatography. A thin strip of filter
paper was cut and trimmed the bottom to exactly fit a test tube. We draw a line using a
pencil to the trim portion of the filter paper right about on the bottom and placed in a test
tube containing 2ml solvent (9 parts petroleum ether: 1 part acetone). After setting it
aside for 15minutes, we measure the bands of the color from the pencil line and the result
was 5cm, which is positive for the pigments to be used in the light intensity.
For the light intensity experiment, we decided to used 3 test tubes with the same
amount of chloroplast and a DCPIP dye for each distances at 0cm,…