Chloroplasts extract exposed in light results in decrease of photosynthesis, the

closer the distance of the light, the higher it affects the photosynthesis.

Khrisffer Gialen

Mount Royal University

Abstract

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.

Method
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,