University of Santo TomasFaculty of Pharmacy

1AMT Group 2 Members: Kristiana Calupitan, Koleen Chavez, Valerie Co

Carlson David, Eleonor Dolorfino, Princess EstimoExercise 9: Starch as Indirect Evidence of Photosynthesis

I. Introduction

Glucose, the immediate sugar produced in photosynthesis is used by the plant in respiration. The excess of it, however, is polymerized and stored as starch in amyloplasts. To produce both carbohydrates products, the plant has an absolute need for light as energy source and the photosynthetic pigments chlorophyll.

II. Objectives

1. To determine the presence of starch as an indirect end-product of photosynthesis2. To determine the necessity of light and chlorophyll pigments in photosynthetic process3. To determine the relationship between the rate of photosynthesis and the detection of starch in plant organs

III. Materials

Dark and light Mayana leaves Beaker Petri dish Water Ethanol Iodine solution

IV. Methodology/ Procedure

V. Results and Explanation

Fresh Specimen

(Column A)

Boiling Water(Column B)

Boiling Alcohol

(Column C)

Iodine Solution(Column D)

“Dark Leaf”

Color of Water: Yellow

Color of Alcohol: Green

Color of Leaf: Brown

“Light Leaf” Color of

Water: Yellow

Color of Alcohol: Green

Color of Leaf: Blue-black

One indication of photosynthetic activity in plants is the detection of starch in plant organs. The presence of starch may be detected in actively photosynthesizing green parts of the leaves. Xanthophyll was extracted from the leaves in Column A making the water yellow in color. In Column B, the chlorophyll from the leaves was extracted making the boiling alcohol green in color. The presence of starch was determined through the iodine solution. It has produced more starch in the “light leaf” since it is exposed in light and light is a valuable component of photosynthesis.

VI. Conclusion

Sunlight supplies the energy for photosynthesis. That light energy is absorbed by the chlorophyll and is used to make two energy-enriched compounds: ATP and NADPH. One of the end products of photosynthesis is glucose and its excess is stored as starch.

Starch was present in the uncovered leaf whereas little to no starch could be found on the leaf that was not exposed to sunlight. The uncovered leaf underwent photosynthesis and was able to produce glucose and was stored as starch. On the other hand sunlight could not penetrate the covered leaf preventing photosynthesis therefore it barely contained any starch.

VII. References

http://www.biology4kids.com/files/plants_photosynthesis.htmlhttp://biology.clc.uc.edu/courses/bio104/photosyn.ht

mhttp://www.mcwdn.org/Plants/Photosynthsis.htmlMauseth, J. (1998) Botany: An Introduction to Plant Biology 2nd edition, Jones and Bartlett Publishers: Canada, p286