"Bacteria" Bacteria and Fungi PPT Courseware 5

"Bacteria" Bacteria and Fungi PPT Courseware 5

class disscussion

1. What personal hygiene habits should primary and secondary school students develop?

1. Open windows frequently for ventilation

2. Wash your hands frequently, bathe frequently, and do not share towels and toiletries.

3. Cover your mouth and nose when coughing or sneezing, and do not spit anywhere.

4. Do not eat food that has not been cleaned and do not drink raw water.

2. What is the significance of good personal hygiene?

Developing good personal hygiene habits can reduce the number of bacteria you carry and reduce the possibility of getting sick from bacterial infection.

think

1. What effect did the invention of the microscope have on the development of science?

The discovery of the microscope accelerated mankind's understanding of the microscopic world and enabled people to deeply appreciate the huge role that technological progress plays in promoting scientific development.

2. Where do bacteria come from?

Before the mid-19th century, people idealistically believed that bacteria occurred naturally.

In the mid-19th century, the French scientist Pasteur conducted a famous experiment, which overturned people's original beliefs and proved that the bacteria in the broth did not occur naturally, but were produced by bacteria that were already in the air.

Little information

1. About 1 billion bacteria piled up would be as big as a millet.

2. 300 bacteria arranged vertically are only as thick as an ordinary piece of paper.

Bacteria are tiny, usually measured in microns (1um=1/1000mm). The minimum resolution of the naked eye is 0.2mm. Therefore, to observe the morphology and structure of bacteria, you must use an optical microscope to magnify it hundreds to thousands of times.

Self-study guidance

Data analysis and the last natural paragraph of textbook 73. Summarize the structure and function of bacteria

Nutritional methods of bacteria:

Heterotrophic: unable to produce organic matter by itself and relying on ready-made organic matter to sustain life.

Points: parasitic and saprophytic

Saprophysis: Obtaining organic matter from animal remains

Parasitism: Absorption of organic matter by living plants and animals

theory and practice

1. What characteristics of bacteria are related to their wide distribution?

Small in size, easily carried by various media

Fission reproduction, fast reproduction and large numbers

Some bacteria form spores in the later stages of growth and development to resist adverse external environments and spread easily

Use your hands and brain to do it

1. The "Father of Microorganisms" is: ( )

A. Robert Hooke B. Leeuwen Hooke C. Louis Pasteur D. Watson

2. The main difference between bacteria and plant cells is: ( )

A. Bacteria have a cell wall B. Bacteria have a formed nucleus C. Bacteria have an unformed nucleus D. Bacteria have a cytoplasm

3. How do bacteria deal with adverse environments? ( )

A. Hibernation B. Death when encountering adverse environment C. Formation of spores D. Formation of germ cells

4. Individual bacteria are very ______. The main forms of bacteria are _______, _______ and _________.

5. The reason why bacteria are widely distributed is because:

A. Individual bacteria _______.

B. Bacteria reproduce ______ and reproduce very quickly.

C. The dormant body of bacteria - _______ has strong resistance to adverse environments and can also float around.

The structural characteristics of bacteria are:

1. Although bacteria have genetic material DNA, they do not have ________.

2. Have a cell wall like plant cells, but no ________.

3. Some bacteria also have ________ and ________ on the outside of their cell walls.

Speed ​​Q&A

game rules:

1. The whole class is divided into 4 groups. After successfully answering the questions, questions can be asked for other groups to answer.

2. Each person can only play the role of question maker or answerer once.

3. The time to ask a question shall not exceed 10 seconds, and the time to answer a question shall not exceed 30 seconds.

4. The questioner must clarify the question before asking the question and evaluate the other party's answer.

Experience success

1. In the description about bacteria, the correct one is: ( )

A. Stained bacteria can be observed with a low-power microscope

B. Bacterial cells also contain chromosomes

C. Each bacterium lives independently

D. A bacterium is also a cell, so it also has a complete cell wall, cell membrane, cytoplasm and nucleus.

2. The main characteristics that distinguish bacteria from plant cells in cell structure are: ( )

① There is a cell wall ② There is no chloroplast ③ There is no formed nucleus ④ There is a flagellum

A, ①② B, ②④ C, ②③ D, ③④

3. What do you think spores are ( )

A. It is a dormant body of bacteria

B． Less resistant to adverse environments

C. is formed during the early stages of bacterial development

D. a germ cell

Explore the paradise

Suppose a bacterium divides every 20 minutes, and the daughter cells all survive and multiply at the same rate. The table below shows the number of bacteria counted every hour for 5 hours.

(1) Please use the data in the table to make a curve graph:

(The abscissa is time, the ordinate is the number of bacteria)

(2) Use the curve graph created to explain why the bacterial proliferation rate is so fast?

Bacteria multiply by dividing into two, that is, one bacterium splits into two, two bacteria split into four, four splits into eight... In this way, as time goes by, the number of bacteria will increase. Grows exponentially (2n). When environmental conditions permit, the bacterial proliferation rate is very fast.

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