EFFECT OF COLOURED LIGHT ON THE GERANIUM LEAF (LIGHT-DEPENDENT REACTION OF PHOTOSYNTHESIS)
Section number: 15
Tuesday November 11th, 2014
TA: Brian Hanna
"Photosynthesis is an endergonic suite of reactions that reduces carbon dioxide to glucose or other sugars," as it says on p. 189, Freeman, Harrington & Sharp (2014). This lab report discusses the experiment of effect of coloured light on the light-dependent reaction of photosynthesis. The purpose of this lab is to examine what wavelengths of light the geranium leaf, needs to undergo photosynthesis to produce energy. So, to determine the effect of different colored light o photosynthesis, we put three filters on three sides of the geranium leaf and the other parts of the leaf was exposed.
Fig. 1. Before the experiment, the coloured filters were put on three sides of the geranium leaf.
Then the leaf was put into the ethanol bath, (250 mL beaker consisting of ethanol and 400 mL beaker with water).
The purpose of bathing the leaf in the boiling alcohol bath was to get the green chlorophyll pigment to be extracted from the leaf, turning the colour of the leaf to be white. Next we put the geranium leaf from the ethanol bath to a petri dish and pour iodine over it.
In this experiment I hypothesized that the red filter will have the most starch in it rather than green, or blue. My hypotheses can only be supported if the red filter turns out to be black compared to the other coloured filters. I chose the red filter because, as the textbook shows the details of an experiment that, "chlorophyll a and chlorophyll b absorb strongly in the blue and red regions of the visible spectrum. The presence of chlorophylls make plants look green...