1. experimental purpose: 1. Make temporary transfer sheets of plant cells and learn the basic methods of making temporary transfer sheets.
2. Understand the basic structure of plant cells.
3. Practice drawing cell structure map.
Second, teaching focus: making temporary films and summarizing the structural characteristics of plant cells.
Third, teaching difficulties: making temporary films; Practice drawing the structure diagram of plant cells.
Materials and utensils: onion scales, physiological saline, dilute iodine solution, tweezers, blades, droppers, gauze, water absorbent, glass slides, cover glasses and microscopes.
Process:
(1) Sit in groups before entering the laboratory. Each group quickly took out the microscope and aimed at the light. The teacher reviewed the usage of the microscope.
Using microscope observation, in addition to aiming at light, adjusting focal length, placing and moving slide specimens, it is also necessary to make visible light pass through the observed object to see the image of the object clearly. Therefore, the observation material must be thin and transparent. In order to do this, it is necessary to process the observed materials, make slide specimens and then observe them. There are three commonly used slide specimens:
Slice-made of thin slices cut by organisms (usually made of solid materials);
Smear-made of liquid biological materials (such as yeast liquid, blood, etc.). );
Packaging-made of a small amount of materials (such as onion skins and cabbage leaves) torn or picked from organisms.
The above three kinds of slide specimens can be made into permanent specimens (long-term preservation) or temporary specimens (non-long-term preservation)
Save)
(2), a method for manufacturing the temporary load of onion epidermal cells comprises the following steps:
Prepare:
1. Wipe the slide and cover glass with clean gauze. (wipe)
2. Put the slide on the experimental platform, and drop a drop of physiological saline in the center of the slide with a dropper. (drops)
Perform temporary loading:
3. Tear off a small piece of transparent film-inner epidermis from the inside of onion scales with tweezers. (Tear or take)
4. Infiltrate the torn inner epidermis into the water drops on the glass slide and flatten it with tweezers. (Exhibition)
5. Pick up the cover glass with tweezers, so that one side of the cover glass first touches the water drops on the glass slide, and then slowly put it down and cover it on the material to be observed, so as to avoid the bubbles under the cover glass from affecting the observation. (cover)
Dyeing:
6. Drop a drop of dilute iodine solution on one side of the cover glass. (dyeing)
7. Absorb from the other side of the cover glass with absorbent paper, so that the dye solution can soak all specimens. (Inhale)
(3), practice drawing cell structure map
(4) Put the microscope back after the observation.