The Perspective

General Biology 153L

Exercise 12

Lab Section 10

TITLE:

The Affects of Light on a Geranium Leaf's Starch Accumulation

INTRODUCTION:

In order for all life forms to survive the circle has to continue, and photosynthesis has to occur to convert sunlight into chemical energy which allows all other organisms to breath in oxygen (Vodopich and Moore, 2005).

The objective of this laboratory exercise was to compare starch accumulation and or consumption in a Geranium leaf cells exposed to light and dark conditions.

MATERIALS AND METHODS:

First a Geranium leaf was half covered with a piece of cardboard and was left for four days in the dark. Then the cardboard and staples were removed. The Geranium leaf was boiled in water for one min. After that the leaf was boiled in methanol of 5 min. The leaf then was placed in a Petri dish containing a small amount of water and five drops of iodine. Then the color change was observed where the cardboard was and where the leaf absorbed radiant energy (Vodopich and Moore, 2005).

RESULTS:

Where the Geranium leaf was not covered the leaf changed to a purplish blue color. Where the leaf was covered with cardboard the color of the leaf stayed the same white color; maybe a tint of yellow was represented from the iodine. When the iodine test for starch was administered the covered part of the Geranium leaf had no starch and the part that was not covered had starch. In figure one the Geranium leaf was represented and the part of the leaf that was covered in the light colored spot in the middle of the leaf.

...