Solubility as a Physical Property

Krizza Angela S. Balanquit                                                                                      January 31, 2019

Section JK                

1. Introduction

Viewing specimens under a microscope accurately would not be possible without having a wet mount first. A wet mount is a common type of preparation for microscope work that is used to view parts of living organisms and liquid substances. For specimens that need to be kept moist, the preparation of wet mount is also done. The wet mount is done by putting a fluid, usually water, to a slide, suspending the specimen in the liquid, and then covering it with a cover slide. In this way, it would be easier to view the specimen because it has been flattened. This would also increase the translucency of the specimen.

The liquid refractive index serves as a support to the specimen and also improves its image quality. It is also termed “temporary mount” for the reason that it cannot be stored over extend time period as the water will evaporate. However, there are special cases where it is possible to store wet mounts over extended time periods.

1. Objectives

At the end of the exercise, the student was able to learn how to make a wet mount slide and accurately sketch and identify the different organelles and other cellular components of the cells examined. The similarities and differences in terms of the structure of the plant cells observed was also described.

1. Methodology

Wet Mount of Hydrilla Water Plant

        First a tip of the Hydrilla water plant was obtained and set aside. Then a drop of water was placed in the center of a dry and clean glass slide using a dropper. The tip of the Hydrilla water plant was then placed in the drop of water that was in the glass slide. The coverslip was then positioned just above the water and the specimen and was carefully lowered into place. There was no air bubble observed after the preparation of the wet mounted Hydrilla Water Plant. Finally, the prepared wet mount of the Hydrilla water plant was observed using a microscope. The specimen was observed under the Scanner objective, LPO, and HPO. To observe cytoplasmic streaming the slide was left under the microscope for at least 20 minutes.

Wet Mount of Potato

        First, an extremely thin piece of potato was sliced and set aside. Then a drop of water was placed in the center of a dry and clean glass slide using a dropper. The extremely thin piece of potato was then placed in the drop of water that was in the glass slide. The coverslip was then positioned just above the water and the specimen and was carefully lowered into place. The coverslip did not wobble indicating that the piece of potato obtained was not to thick. As much as possible, only a thin slice of potato should be obtained to avoid obstruction of the view of the specimen. Then, iodine solution was placed just on the right side of the glass slide and was left to be drawn under the coverslip slowly. This is to avoid bubbles and to clearly see the specimen under the microscope. Finally, the prepared wet mount of the potato was observed using a microscope. The specimen was observed under the Scanner objective, LPO, and HPO.

Wet Mount of onion  

        First, a very thin membrane from the onion layer was obtained by taking a single layer of onion and bending the onion towards its shiny side and pulling the transparent layer of skin. The thin layer was set aside. Then a drop of water was placed in the center of a dry and clean glass slide using a dropper. The onion layer was then placed in the drop of water that was in the glass slide. Then, an iodine solution was dropped on the onion layer The coverslip was then positioned just above the water and the specimen and was carefully lowered into place. To drain excess iodine and water solution, a blotting paper was used. Finally, the prepared wet mount of the potato was observed using a microscope. The specimen was observed under the Scanner objective, LPO, and HPO.

1. Results and Discussion

To be able to study specimens under a microscope, one should know how to prepare the specimens to be observed. One common type of preparation of specimen is the method of wet mounts. Wet mount is commonly used in Biology to observed organisms. To develop such skill in preparing a wet mount, it should be practiced a lot and the precise instructions should be followed. Before preparing a wet mount slide, it should be assured first that the microscope to be used should be clean specially the lenses and its eye piece. A dirty lenses and eye piece might end up obstructing the view of the specimen. Drop a water first on the center of the glass slide using a dropper and place the specimen in the water. Then the coverslip should be carefully placed on top of the specimen and water. for any excess of water, a blotting paper should be used. Lastly, the prepared wet mount slide should be placed on the stage of the microscope to start observing it.

[pic 1]

[pic 2]

                    Plant Cell (Hydrilla)                                               Plant Cell (Hydrilla)

                               400x                                                                             400x

The magnified view of a Hydrilla water plant shows a living photosynthetic cell. A large portion of the cell, a central vacuole is observed because most of the cell is water – filled. The chloroplasts are placed around the periphery of the cell just inside the cell wall. However the chloroplast is not part of the central vacuole rather, it is placed just outside of it. Also, it was observed that the chloroplast in the Hydrilla water plant is moving around the cell. Most of them are on edges. This ability of a leaf ell to “move into the shade”  of other chloroplasts is called photorelocation. This usually happens when a leaf cell is under a bright sunlight to maximize photosynthesis and minimize photo – damage in plants under fluctuating light conditions. (Takagi, 2003).

[pic 3][pic 4]

                     Plant Cell (Potato)                                                    Plant Cell (Potato)

                                 100x                                                                           100x

Upon observation of the extremely thin piece of potato, a membrane-bond starch-storage organelles, amyloplasts was observed. Others refer to it as “starch grains.” The iodine stain was helpful in viewing the amyloplasts more clear since it turned the starch into purplish – black. Also, If a potato to be observed under a microscope is too thick, there will be an obstruction of the view and no starch would be observed.