Experiment for Starch

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  • Topic: Microscope, Microscopy, Eyepiece
  • Pages : 4 (930 words )
  • Download(s) : 125
  • Published : October 20, 2011
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Experiment 1: Preparation of biological material for microscopic examination Introduction:
Microscopes are instruments used for observing and/or imaging cells. A simple light microscope [used in bright field microscopy] consists of a light source, microscope stage, coarse adjuster, fine adjuster, objective lens, and last but not least eyepiece lenses. A magnified image of a cell which is examined by a microscope is observed directly by looking into the eyepiece lens. Coarse and fine adjusters permit up-and-down movement of the microscope stage. This facilitates precise focus. Objective lenses produce an image from the light rays that are transmitted from the light source and through the microscope stage which holds the sample under examination. The visibility of objects in a sample can be enhanced by staining. In this experiment three different samples of biological material are observed and examined by a microscope. Their images are recorded before and after staining, after observation under 10× and 40× power. Experiment Objection:

I. Observation of starch grains under microscope (before and after staining) II. Observation of onion cells under microscope (before and after staining) III. Observation of cheek cells under microscope (before and after staining)

* iodine,
* methylene blue
* a small piece of potato,
* an onion
* water
* A light microscope
* 3 slides
* 3 cover slips
* filter paper
* forceps
* several toothpicks
I. Observation of starch grains:
1. A small piece of potato was cut and placed on a slide. Enough pressure was applied to the potato to force its juice out. The potato was discarded afterwards. 2. A drop of water was added to the slide and then it was covered by a cover slip. 3. The slide was put on the microscope stage and the sample was examined under low power (10×) and high power (40×). Magnified images of the sample were drawn....
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