"Diversity and Unity of Cells" Approaching Cells PPT

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"Diversity and Unity of Cells" Approaching Cells PPT

Part 1: Essential knowledge and foundation of literacy

1. Use a high-power microscope to observe cells

1. Basic steps for using a microscope: take the lens → place → focus → press → focus → observe.

2. The "four-character formula" for using high-magnification lenses:

3. Eyepieces and objective lenses of microscopes and their magnification:

In the above figure, a, b, c, and d represent the lenses of the microscope, then:

(1) The objective lens is _____, the eyepiece is _____, and the basis for judgment is _______________________________.

(2) The combination of objective lens and eyepiece with the highest magnification is _____, and the magnification is ____.

4. Microscopic observation results:

The picture above is the field of view observed by the four combinations of objective lens and eyepiece, then:

(1) If the eyepieces used in the two fields of view A and B are the same, then the objective lens used in the field of view __ (fill in the letter) is longer, and the distance between the objective lens and the glass is ___ (fill in "large" or "small").

(2) The darkest field of view is __ (fill in the letter). The adjustment method for an image that is too dark is ____________________.

(3) If you want to move the cells labeled

【Doubtful】

When observing E. coli with a microscope, the image is magnified 100 times. Has the area or volume of the bacteria been magnified 100 times?

Hint: No. The magnification of a microscope refers to the magnification of the length or width of an object, not the area or volume.

2. Prokaryotic cells and eukaryotic cells

1. Classification basis:_______________________________.

2. Common prokaryotes and eukaryotes (connected):

3. Comparison of two prokaryotes:

(1) Name: A is _______, B is __________.

(2) Structure: ① is the cell wall, ② is _______, ③ is _______, ④ is _____, ⑤ is _______, ⑥ is flagellum.

(3) Lifestyle: Because the cells of organism A contain _______ and _______, they can carry out photosynthesis and are _____ organisms; most species of organism B live saprophytic or parasitic lives and are _____ organisms.

【Doubtful】

Lactic acid bacteria in yogurt and yeast in dough are both single-cell organisms. What is the main basis for distinguishing them?

Tip: Is there a nucleus bounded by the nuclear membrane? Lactic acid bacteria have no nuclear membrane and are prokaryotes; yeast have a nuclear membrane and are eukaryotes.

Diversity and Unity of Cells PPT, Part 2 Content: Key Competencies·Quality Formation

Knowledge point 1: Use of high-power microscope

1. Magnification related analysis:

2. Basis and method for judging the moving direction of objects:

(1) Basis: The image formed by the microscope is an inverted magnified image, that is, the image of the object and the real object are inverted up and down, left and right.

(2) Method: relative to the center of the field of view, move the film in whichever direction the object image deviates, that is, "move in the same direction."

3. Comparison between low-magnification lens and high-magnification lens:

【Think·Discussion】

When classmate Xuan Xuan used a microscope to observe human oral epithelial cells mounted on slides, he found that the observation results were not ideal. Please help him solve the following two questions: (Scientific Inquiry)

(1) The field of view is too bright and the object image cannot be seen. The solution is _______________________________.

(2) A foreign object is found in the low-magnification field of view. When the film is moved and mounted, the foreign object does not move. After switching to a high-magnification objective lens, the foreign object cannot be observed. The foreign object exists on ________.

【Literacy Case】

Picture A is a set of lenses with eyepieces marked 6× and 16× and objective lenses marked 10× and 20×. Picture B is the image observed by a set of lenses selected in Picture A that can magnify 160 times. To observe the cells on the upper right side of the slide at 320 times magnification, which of the following statements is wrong ()

A. Move the slide to the upper right until the cells on the upper right are in the center of the field of view

B. Increase the aperture of the microscope and adjust the reflector to a concave mirror

C. There is no need to change the eyepiece. Turn the converter to replace the objective lens with the lens ③

D. After changing to a higher magnification lens, the number of cells in the field of view in picture B will become 2.

【Problem Solving Guide】

(1) Illustrated information: In Figure A, ①② lenses have no threads and should be eyepieces; ③④ lenses have threads and should be objective lenses, and ③ lens is longer than ④ lens, then ③ is a high-power lens and ④ is a low-power lens.

(2) Key knowledge: When changing from a low-power lens to a high-power lens, you should first move the observed object image to the center of the field of view. When moving and mounting the film, you should follow the "object and image move in the same direction".

[Analysis] Choose D. The observed object image is located in the upper right corner of the field of view, so the mount should be moved to the upper right side so that the cells in the upper right corner are located in the center of the field of view. Item A is correct. After replacing the high-power lens, the field of view will become darker, so the aperture of the microscope should be adjusted. Large, the reflector is adjusted to a concave mirror, item B is correct; the original magnification is 160 times, and the current magnification is 320 times. It is necessary to change the objective lens from 10× to 20×, that is, from the low-power objective lens ④ to the high-power objective lens ③. Item C is correct; magnification refers to the length or width of magnification. The field of view in Figure B is filled with 4 cells. After magnifying 2 times, the number of cells in the field of view is 4×(1/2)2=1. Item D is incorrect.

Knowledge Point 2: Diversity and Unity of Cells

1. Reflection of cell diversity:

(1) Morphologically: eukaryotic cells are diverse, and prokaryotic cells are diverse.

(2) Structurally: Eukaryotic cells have a nucleus bounded by the nuclear membrane, while prokaryotic cells do not.

(3) Functionally: For example, cyanobacteria can perform photosynthesis, but E. coli cannot perform photosynthesis.

2. Reflection of cell unity:

(1) Same origin: All cells are derived from preexisting cells.

(2) Similar chemical composition: Different cells have the same chemical elements and compounds.

(3) Similar basic structures: eukaryotic cells and prokaryotic cells both have cell membranes, cytoplasm, ribosomes and other structures.

① Common characteristics of eukaryotic cells: they all have structures such as cell membrane, cytoplasm, and nucleus.

② Common characteristics of prokaryotic cells: they all have cell membrane, cytoplasm, nucleoid and other structures.

(4) The genetic material is the same: both eukaryotic cells and prokaryotic cells use DNA as their genetic material.

【Think·Discussion】

American researchers have discovered a rare bacterium containing light-collecting green bodies, each of which contains a large amount of chlorophyll. Try to analyze the aspects in which this bacterium is unified compared with cyanobacteria. (scientific thinking)

Tip: They all have cell membranes, cytoplasm, chlorophyll, DNA, etc., and can all carry out photosynthesis.

【Literacy Case】

As shown in the figure, four organisms, namely phage, cyanobacteria, amoeba and chlamydomonas, are divided into four groups according to different classification basis. Which of the following statements is wrong ()

A. No organism in Group A has a cell wall

B. Group A and Group B can be classified based on the presence or absence of chloroplasts

C. Group C and Group D can be classified based on the presence or absence of chromosomes

D. All biological cells in group D have nuclear membranes

【Problem Solving Guide】

(1) Recognize the types of organisms: Bacteriophages are viruses, cyanobacteria are prokaryotes, amoeba are lower animals, and Chlamydomonas are lower plants.

(2) Determine the basis for classification: viruses and animals do not contain cell walls, viruses and prokaryotes do not contain chloroplasts, prokaryotes and lower plant cells all contain cell walls, and lower animals and lower plants are all eukaryotes.

[Analysis] Choose B. Bacteriophage is a virus and does not have a cell structure. Amoeba is a lower animal and does not contain a cell wall. Choice A is correct. Both phage and amoeba do not contain chloroplasts. Cyanobacteria are prokaryotes and do not have chloroplasts. Chlamydomonas is a lower plant. Contains chloroplasts, item B is wrong; bacteriophages do not have a cellular structure and do not contain chromosomes, cyanobacteria are prokaryotes and do not contain chromosomes, amoebae and chlamydomonas are both eukaryotes and contain chromosomes, that is, group C does not contain chromosomes and group D Contains chromosomes, option C is correct; Amoeba and Chlamydomonas are both eukaryotes, and both have nuclear membranes in their cells, option D is correct.

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Update Time: 2024-11-16

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