File:55. Прости скробни зрна од грав (Phaseolus vulgaris).ogg

English: Simple starch grains of common bean seeds (Phaseolus vulgaris) under microscope

During the process of photosynthesis in plants, sugars are created in the form of starch. Those sugars are stored in the leucoplasts in the cells and form starch grains. We use flour from ground wheat grains to prepare this slide. Two drops of water are placed on the object glass, one central larger and one peripheral smaller. With the back of the tweezers, pick up the powder mass and pour a small amount onto the middle drop of water. The excess of the powdered mass is returned back to the container. A cover glass is placed on it, which is lowered next to the peripheral drop of water and at an angle of 45° it moves towards the middle of the object glass until the moment when the two drops of water merge, during which it is lowered. This procedure needs to be performed precisely because otherwise air bubbles will form which will count during microscopy. We add water under the cover glass in order to push out the trapped air. In this way, the native microscopic slide is prepared and it is ready for microscopy. The simple starch grains in bean are of the concentric type, because the hilus is placed in the middle of the starch grain. They are characterized by a central crack.

Prepared and performed by Sara Cvetanoska, Institute of Biology, FNSM, Ss. Cyril and Methodius University, Skopje, Macedonia.