Identifying Starch Using Iodine as a Reagent

Identifying Starch Using Iodine as a Reagent

INTRODUCTION

Starch is a carbohydrate (polysaccharide) which is made from thousands of α glucose units, joined together by glycosidic linkages.  It is the main compound that all green plants use to store their food energy. Starch is insoluble in water. The purpose of this experiment is to demonstrate that using an iodine solution, starch is present in potato.

 MATERIALS AND METHOD

• We used a scalpel and cut a small piece of onions and then smeared the juice from the onions into the microscopic slide.

• We added a drop of iodine on the same microscopic slide and covered it with a cover slip.

• We also ensured that there was no bubble trapped on the slide.

• We proceeded to observe the slide under a light microscope using the scanning power objective lens and recorded the results.

• After washing the slide properly we conducted the same procedure for the potato.

• We used a scalpel and cut a small piece of potato and smeared the juice from the potato into the microscopic slide.

• We Added a drop of iodine on the same microscopic slide and covered it with a cover slip.

• We observed the slide under a light microscope, using the scanning power objective lens and recorded the results.

• RESULTS

We observed that when we used the microscope to see the slide containing the mixture of iodine solution and onion juice the plate was clear, which indicated the lack  levels of starch then when we used the microscope to see the slide containing the mixture of iodine and potato juice,which contained black dots and a dark blue color. The potato cells were packed together which showed the presence of starch. The experiment showed that starch was present.