Take root tip cells of onion to observe mitosis, where ③ stands for making slices, that is, dissociation → rinsing → dyeing → making slices.
Take onion epidermal cells to observe the separation and recovery of plasma wall. C treated with sucrose solution separated the plant cells from the plasma wall, and E treated with clear water restored the cells from the plasma wall separation.
(1) In the grinding step of extracting pigment from onion mesophyll cells, it is necessary to add anhydrous ethanol (pigment extraction), calcium carbonate (protective pigment) and silicon dioxide (accelerated grinding) into the mortar. Because of the low chlorophyll content in the material, after chromatography for a period of time, the two pigment bands under the filter paper strip are very light in color.
(2) The moving direction of the object image is opposite to the actual situation. To clearly observe the chromosome morphology and the number of cells to be observed in the metaphase, this cell is located at the upper right of the visual field, and move the film to the upper right to make the cells that meet the requirements be located in the center of the visual field; If the cell is dead when it is dissociated, it cannot enter the next division stage after clear observation.
(3) In the experiment of "water absorption and water loss of plant cells", the operation process of step c: drop sucrose solution on one side of the cover glass, and blot the other side of the cover glass with absorbent paper for several times; The reason of plasma wall separation is that the concentration of external solution is greater than that of cell fluid; Because the cell wall is completely permeable, ⑥ it is filled with sucrose solution; During the plasma-wall separation, cells should remain alive, otherwise the plasma-wall separation cannot be restored.
(4) (4) The only basic unit of DNA is thymine deoxynucleotide; According to the line graph, BE marks the cell entering the division stage, which represents a cell cycle = 25.5-3.5 = 22h.
So the answer is:
(1) The chlorophyll content in quartz sand and calcium carbonate materials is low (or the selected leaves are yellow, so it is reasonable).
(2) The upper right cell has died.
(3) Drop sucrose solution on one side of the cover glass, and blot the other side with absorbent paper for several times.
The concentration of external solution is greater than that of cell fluid. Sucrose solution (or external solution) cells lose too much water and die.
(4) Deoxyribonucleic acid 22
Comments:
The test center of this topic: the extraction and separation experiment of chloroplast pigment; Observe the separation and recovery of plant cytoplasmic wall; The concept of cell cycle; Observe the mitosis of cells.
Test center comments: This topic examines the experimental principles and operational knowledge of pigment extraction and separation, mitosis, plasma wall separation and repair, aiming at examining students' ability to read pictures and judge.