"Distribution of Bacteria and Fungi" Bacteria and Fungi PPT Courseware

Description

"Distribution of Bacteria and Fungi" Bacteria and Fungi PPT Courseware

Think about it, discuss it

This is a picture of a modern chicken farm. A chicken farm is not a hospital, so why do the breeders wear white coats like doctors? Why don’t you wear a white coat when feeding free-range chickens?

Avoid bringing in germs.

Small quantity, large space, strong resistance.

learning target

1. Name the characteristics of the distribution of bacteria and fungi.

2. Try to use general methods of bacterial and fungal culture to explore the distribution of bacteria and fungi.

3. Use experiments to detect bacteria and fungi in different environments.

4. Develop the ability to observe, discover and analyze problems by exploring the distribution of bacteria and fungi;

5. By actively participating in the formulation of the research plan, timely exchange experiences with each other in the process of completing experiments with group members, and cultivate a sense of cooperation among people.

1. Observe the colonies

The bacterial colonies are small and the surface is either smooth and sticky or rough and dry

Fungal colonies are generally several or dozens of times larger than bacterial colonies. Mold colonies are velvety, flocculent or spider web-shaped, and sometimes appear in different colors such as red, brown, green, black, and yellow.

A visible aggregate of bacteria or fungi that multiply.

2. General steps for cultivating bacterial colonies

1. Prepare culture medium: (agar, nutrients)

2. High temperature sterilization: (Purpose: to remove miscellaneous bacteria and eliminate interference)

3. Inoculate after cooling

4. Constant temperature culture (in an incubator or a warm place indoors)

3. Distribution of bacteria and fungi

Explore: Examine bacteria and fungi in different environments

Ask a question:

Are bacteria and fungi found in different environments? Which environment is more common? Which environment is less common? In which environment is there none at all?

Explore ideas

If you were asked to help the kindergarten teachers think of a way to let the children know that there are bacteria or fungi on their hands and they must wash their hands before eating, what would you do? Refer to the picture below.

Materials and tools

Each group has two sets of petri dishes with beef juice culture medium (high-temperature sterilized), sterile cotton swabs, transparent tape, label paper, and magnifying glass.

hint:

1. Do not open the petri dish before thinking about how to work. Think about it, why use two sets of culture dishes? What are the benefits of each?

The purpose is to set up controls. One set is not treated and is the control group; the other set is treated and is the experimental group.

2. Mark the group, experiment date, and number (No. 1 or 2) on the label paper, and stick the label on the bottom of the petri dish.

3. Collect bacteria and fungi in their respective selected environments.

4. Consider the environmental conditions under which the culture should be cultured. Do the culture dishes of both sets of culture media need to be cultured in the same environment?

Both sets of petri dishes need to be cultured under constant temperature conditions.

5. Design a form for observation records and plan the time and frequency of observations.

discuss

(1) Why must the petri dishes and culture media used for culture be treated at high temperatures before inoculation? Why use sterile cotton swabs?

After high temperature treatment, the spores of bacteria or fungi mixed on the petri dish and in the culture medium can be killed, thus eliminating contamination from other environments outside the experiment.

Sterile cotton swab: The purpose is to prevent microorganisms on the cotton swab from contaminating the culture medium.

(2) Which step in the general culture method of bacteria and fungi is equivalent to Tip 3?

The operation in Tip 3 is equivalent to the inoculation step in general culture methods.

(3) Through communication among each group, what do you think is the distribution of bacteria and fungi?

Bacteria and fungi are almost everywhere, but the distribution in different environments is different. For example, more bacteria and fungi are attached to hands and coins.

1. Decide whether the following statements are correct. Draw "" for correct ones and "×" for wrong ones.

(1) There are generally no bacteria and fungi in high-temperature sterilized petri dishes. (√ )

(2) Since both bacteria and fungi can form colonies, it is impossible to distinguish bacteria and fungi from colonies. (×)

2. In which of the following environments is mold most likely to grow? (C)

A. Dry leather shoes; B. Boiled but sealed beef juices;

C. Wet grain pile; D. Wet sandy soil.

3． A classmate inoculated two bacteria, A and B, on an agar medium for culture. At the same time, he also placed pieces of paper soaked in salt water on the medium. After one day of constant temperature incubation, only A bacteria grew around the salt paper. How do you interpret the results of this experiment?

Bacteria A can survive in a salt water environment, but bacteria B cannot survive in a salt water environment. By analyzing the experimental results, it can be shown that different bacteria require different survival conditions.

4. The principle of making kimchi is to use lactic acid bacteria to make the organic matter in vegetables produce lactic acid. The structure of the kimchi jar requires both a lid and a circle of water to seal it. Can you guess the scientific reason behind it?

The kimchi jar is covered with water and sealed with water. The purpose is to prevent air from entering the jar and maintain an oxygen-deficient environment in the jar. Because lactic acid bacteria can only survive in an oxygen-deficient or anaerobic environment, they can decompose organic matter in vegetables into lactic acid.

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Update Time: 2024-06-29

This template belongs to biology courseware People's Education Edition Biology for Grade 8, Volume 1 industry PPT template

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