Zhejiang Education Edition Seventh Grade Science Volume 2

Description

"Reproduction of Bacteria and Fungi" PPT courseware

Part One: Mold

In humid and warm environments, some fluffy, flocculent or cobweb-like mycelium visible to the naked eye will grow on many items such as food, fruits, and clothes.

Types of mold: Common molds include Rhizopus, Penicillium, and Aspergillus

Mold reproduction: The reproduction ability of mold is extremely strong and it relies on the spores of mycelium to reproduce. Mold has a particularly large number of spores and a very small size. Each spore can grow into a new individual under suitable conditions.

Mold applications:

The fermentation process of food, sauce making, and fermented soy products are all attributed to mold.

Many commonly used antibiotics are extracted from molds, such as penicillin, erythromycin, chlortetracycline, streptomycin, etc.

Some molds are harmful, such as mildew on objects;

Some molds are pathogenic (fungal infections);

Aflatoxins can cause cancer.

Reproduction of bacteria and fungi PPT, Part 2: Edible fungi

Edible fungi are delicious and nutritious, and are a delicacy that people love very much.

Mushrooms are easy to pick from moist tree trunks or grass in the early morning or after rain in summer or autumn.

This shows that fungi are suitable for living in warm, moist and organic-rich environments.

Note: Some wild large fungi are very toxic and should not be picked and eaten at will!

Propagation of edible fungi:

Place the cap of the mushroom flat on the white paper with the gills facing down, and cover it with an inverted glass. After two or three days, open the glass and pick up the mushrooms. You can see _________ and _______________ on the white paper.

Reproduction of bacteria and fungi PPT, Part 3: Microorganisms

They are a group of tiny organisms that exist in nature with tiny shapes, simple structures, and invisible to the naked eye. They can only be observed with the help of optical or electron microscopes that magnify hundreds, thousands, or even tens of thousands of times.

Bacteria and fungi are commonly referred to as microorganisms.

Almost all foods contain microorganisms to some extent.

What are the conditions for microorganisms to grow on food?

(1) Suitable temperature

(2) Moisture

(3) Oxygen

To avoid food spoilage, efforts must be made to prevent or slow the growth of microorganisms. Do you know what common food preservation methods are there?

Reproduction of bacteria and fungi PPT, Part 4: Food preservation methods:

1. Refrigeration method: Low temperature environment can slow down the growth of microorganisms.

2. Heating method: The food is heated (sterilized by high temperature) and then sealed (to prevent contact with microorganisms).

3. Dry storage method: remove the moisture in food to prevent the growth of bacteria and fungi.

4. Pickling method: Pickle foods with sugar, salt, soy sauce, vinegar, etc.

5. Vacuum preservation method: extract the air from the packaging bag to isolate the food from the air.

Reproduction of bacteria and fungi PPT, Part 5 content: Practice:

1. Among the following organisms, the ones that are prokaryotes are -------- ( )

A. E. coli B. Fungus C. Yeast D. Mold

2. The biggest difference in cell structure between fungi and green plants is ( )

A. No vacuoles B. No cell wall

C. No chloroplasts D. Amorphous nucleus

3. Food spoilage is often caused by the growth of ________. Pasteurization can kill most of the ________ in food. In addition, the methods of preserving food include _______, _______, _______, _______ wait.

4. In summer, Xiao Ming bought a piece of meat from the market in the morning to eat at night, but he was worried that the meat would go bad at night. Please give Xiao Ming some advice.

① Sprinkle some salt on the meat ② Cook the meat ③ Put the meat in the refrigerator

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"Reproduction of Bacteria and Fungi" PPT:

"Reproduction of Bacteria and Fungi" PPT Part One Content: Pre-class exercises: 1. When grafting, which part of the structure of the two plants should be closely connected? ( ) A. Xylem B. Phloem C. Cambium D. Outer bark 2. Plants cultivated by gardeners..

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Update Time: 2024-10-02

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