Minggu, 23 September 2012

making wet preparation


LEARNING MATERIAL
MAKING WET PREPARATION

The object to be observed has to be prepared in a specific way in order to get the best result. Usually, the object to be observed is very small in size or a thin slice of a living organism. The method to prepare the object to be observed is as follows:
1.      Put the object on a clean glass slide and place one or two drops of distilled water on the object. Then put the cover glass (coverslip) to cover the object using a long needle.
2.      Place one or two drops of coloring liquid into the edge of cover glass.
3.      By using absorbing paper, dry the excessive water and coloring liquid around the cover glass, and then observe the specimen through the microscope.

















Preparing Plant Specimen
We need a slice of plant in order to observe the structure of plant tissue. To get a slice (section) of a plant, we can make a transverse or longitudinal section. The section depends on the part of the plant that we want to observe.
1.      Transverse section (cross section)
The steps to make a transverse section of a plant stem as the specimen to be observed :
a.       Choose a green and medium size stem (diameter + 0.2 – 0.5 cm).
b.      Slice the stem as thin as possible in a transverse section using a sharp razorblade or cutter.
c.       Put the slice onto the glass slide and place one drop of water on it.
d.      Cover it with a cover glass.
e.       Place one or two drops of coloring liquid.
f.       Dry the excessive water and coloring liquid around the cover glass with absorbing paper.
g.      Observe the specimen through the microscope.
In order to make a transverse section of a leaf specimen, you can use a carrot or a cork. Cut the carrot or cork in half sufficient enough to insert a leaf into it. After inserting the leaf, slice the carrot or cork in a transverse position as thin as possible. The next step is similar to the steps above.
Another way to make a transverse section of a leaf is by using a cutting method with two razorblades. In this method we put the two blades together and use them to make a slice of a stem or leaf in a transverse section.
2.      Longitudinal section
Use the following instructions in order to make a longitudinal section of a leaf:
a.       Take one leaf and peel the bottom surface with your nail.
b.      Put the transparent part of the peeled-off leaf onto the glass slide.
c.       Place one or two drops of distilled water and cover it with the cover glass.
d.      In order to make the specimen more visible under the microscope, place one or two drops of coloring liquid.
e.       Dry the excessive water and coloring liquid around the cover glass with absorbing paper.
f.       Observe the specimen through the microscope.










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