Why do you need to take the inner epidermis when making temporary tablets of onion scale leaf epider

1.The outer epidermal cells of onions are generally purple in color, which affects the observation effect.

2.Compared with the outer epidermal cells, the inner epidermal cells have small cells, thin cell walls, tight cytoplasm, and large nuclei.

Here are the steps to make a temporary mount of onion scale leaf epidermal cells:

1.Prepare experimental utensils such as glass slides, coverslips, absorbent paper, droppers, knives, tweezers, and dissecting needles.

2.Wipe the slides and coverslips clean with clean gauze.

3.Use a knife to cut small rectangular pieces of skin on onion scale leaves.

4.Carefully remove the epidermis by pinching the corner of the epidermis with forceps.

5.Drop a drop of water on the slide**.

6.Place the epidermis in a drop of water on a glass slide and carefully place the epidermis with a dissecting needle.

7.Cover the epidermis with a coverslip.

8.Use absorbent paper to absorb excess water.

9.The temporary loading is complete, and you can start observing.

The above steps are for your reference, please adjust the specific operation according to the actual situation.

Some textbooks have an outer epidermis, while others have an inner epidermis.

The outer epidermis is purple for easy observation of plasmo-wall separation.

However, it is difficult to take the outer epidermis, and it is easy to take mesophyll cells and it is difficult to observe.

If you use the inner epidermis for experiments, you must first remove the onion phosphorus stems one by one, and cultivate them under scattered sunlight to make it purple before you can use it, and it is easy to tear it up.

Epidermal !! Trouble to see clearly!! The inner epidermal vacuole is colorless, and the phenomenon cannot be observed by the separation of the plasma wall, while the outer epidermal vacuole is colored, and the obvious phenomenon can be seen. Got it...

The steps to make a temporary mount of onion scale leaf epidermal cells are as follows:

1. Wipe the slides: wipe the slides and coverslips with clean gauze.

2. Drip water: drop a drop of water on the glass slide (in an appropriate amount, the water droplets are too small and easy to produce bubbles or dry up, and the water droplets are too large and easy to spill the slide and pollute the microscope).

3. Material: Use tweezers.

Tear off a small piece of onion scales with a thin film of the inner epidermis of the leaf.

4. Flattening: Place the peeled film in a drop of water on the slide** and flatten it with tweezers.

5. Coverslip: Pick up the coverslip with tweezers, and gently cover it on the epidermis, let the coverslip touch the edge of the water droplets on the slide first, and then slowly put it down to avoid bubbles;

6. Staining: drop 1 2 drops of iodine solution on one side of the coverslip; Hail plum on the other side of the coverslip with absorbent paper to attract iodine solution.

The steps to make onion scale leaf epidermal cells are simple to memorize: rubbing, dripping, tearing, spreading, covering, and dyeing. The step is staining, and the dropwise addition of liquid is iodine solution, which is able to transfer the nucleus.

Dyed dark for easy observation; The liquid added dropwise is water, which is beneficial for maintaining the normal morphology of the cells.

Precautions

1) When covering the coverslip, pick up the coverslip with tweezers, so that one side of it first touches the water droplets on the slide, and then slowly lowers it and covers the material to be observed. The purpose of this is to prevent the formation of bubbles.

2) When staining, a drop of dilute iodine solution should be placed on one side of the coverslip and attracted from the other end of the coverslip with absorbent paper to infiltrate the entire specimen.

3) When we use a microscope to observe the temporary mounting of onion scale leaf epidermal cells, the eyepiece used for wide rolling is 15, the objective lens is 10, and the magnification is 150.

Answer]: Observation of the structure of epidermal cells in onion scales is generally used by temporary loading method.

Steps: 1) Take a clean slide and coverslip, and add a drop of distilled water to the slide**.

2) Tear open the onion scales and tear off a small piece of the inner epidermis (because the inner epidermis of the onion scales is made up of a single layer of cells), about the size of the onion scales.

Place in a drop of water on a glass slide, flatten, and cover the coverslip. Note that when adding the coverslip, one side of the coverslip should be in contact with the water droplets on the slide, and then the coverslip should be bent and slowly lowered, so that there are no air bubbles in the temporary loading (air bubbles will interfere with observation). Squeeze the slide gently and use absorbent paper to absorb excess water.

3) Put the prepared temporary mount under a microscope for observation.

Observations: 1) Under the microscope, it can be seen that the inner epidermis of onion scales is composed of a layer of cells, each cell is composed of cell wall, cell membrane, cytoplasm and nucleus, and the cells are closely arranged.

2) By leaving the temporary piece in the air for a little longer, the plasmo-wall separation can be seen under the microscope, so that the cell membrane separated from the cell wall can be seen. If the nucleus cannot be observed with water droplets, it can be stained with potassium iodine monoiodide solution to see the nucleus stained yellow.

Preparation should be made when making onion scales, leaf epidermis and sensitive cells for temporary loading (wipe the slides and coverslips clean with clean gauze; Put the slide on the test bench, use a dropper to drop a drop of water on the ** of the slide), and then make a temporary loading.

1) When covering the coverslip, use forceps.

Clamp the coverslip so that one side of it touches the water droplets on the slide first, then slowly lowers it over the material to be observed. The purpose of this is to prevent the formation of bubbles.

2) When staining, a drop of dilute iodine solution should be placed on one side of the coverslip and attracted from the other end of the coverslip with absorbent bridge paper to infiltrate the entire specimen

3) When we use a microscope to observe the temporary loading of onion scale leaf epidermal cells, the eyepiece used is 15, the objective lens is 10, and the magnification is 150

Answer] B Answer Analysis] Test Question Analysis: The process of making temporary mounting of onion scale leaf epidermal cells can be summarized in a few words: rubbing, dripping, tearing, spreading, covering, dyeing, and sucking.

Therefore, the correct steps before opening the eyes should be: wipe the glass slide and coverslip clean; Drop a drop of water on the slide**. Flatten the inner epidermis of the torn onion scale leaf into the water droplets on the glass slide; Cover the coverslip; Dyeing confession. Therefore, only B can be selected for this question

The key to answering this question is that candidates must be familiar with the production steps of temporary filming, and in order to facilitate memory, they can summarize the production process in a few words.

The experimental procedure for making temporary loading of onion epidermal cells is summarized simply: rubbing, dripping, tearing, putting, spreading, covering, dyeing, and suctioning

wipe the slides and coverslips with clean gauze;

drop", put the slide on the experimental table, and use a dropper to drop a drop of water on the ** of the slide;

tear", break the onion scale leaf outward, and tear a piece of film from the inner surface of the onion scale leaf with tweezers;

"Exhibition", put the torn film in the water droplet of the glass slide**, and gently put the film in the water droplet with a dissecting needle;

cover", clamp the coverslip with forceps so that one end of it first touches the droplet on the slide, and then slowly flattens;

Dyeing", add iodine solution dropwise on one side of the coverslip, attract with absorbent paper on the other side, repeat 2 3 times, so that the staining solution infiltrates all the specimens Therefore, the general steps for making temporary mounting of epidermal cells in onion scale leaves are: rubbing, dripping, tearing, spreading, covering, and staining

Therefore, the answer is: rub, drop, tear, put, spread, cover, dye, suck

In the process of making the temporary loading of onion scale leaf epithelial cells, the liquid added to the clean liquid glass slide is water, and in the case of making the temporary loading of oral epithelial cells, in order to maintain the normal morphology of oral epithelial cells, normal saline with the same concentration as body fluid must be added to the glass slide