"Causes of Biological Evolution" Biological Evolution PPT Courseware 4

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"Causes of Biological Evolution" Biological Evolution PPT Courseware 4

How are the various morphological structures and life habits of organisms adapted to the environment formed?

What drives biological evolution?

1. Analyze the causes of biological evolution

1. The basis of biological evolution: ____________.

2. The external driving force of biological evolution: ____________.

3. Living things can survive and reproduce only if they ____________.

2. Natural selection

What are the causes of biological evolution?

ANALYSE information

1. An annual plant only produces 2 seeds. It is expected that there will be 1,048,576 offspring in 20 years.

2. Elephants are animals that reproduce very slowly, and their life span is generally 100 years. A pair of elephants can give birth to 6 calves in their lifetime, and in 740 to 750 years the offspring of a pair of elephants is expected to reach 19 million.

From reading the information, do you know what this phenomenon is? Does this phenomenon actually happen? Why?

natural selection

Concept: Living things struggle for survival, with the fittest surviving and the unfit being eliminated.

Meaning: Living things continue to evolve through inheritance, mutation and natural selection.

Natural selection is a long-term and continuous process. Organisms continue to evolve under the influence of genetic variation and natural selection. They are always in the process of development and will never stop at the same level.

Manual selection:

The process of continuously selecting and cultivating new biological varieties according to human needs and hobbies.

test you

1. Generally speaking, ________ is non-directional, while ________ is directional. When an organism mutates, it is up to _________ to determine its survival or elimination.

2. If you use an antibiotic for a long time, you will find that the effectiveness of the antibiotic becomes worse and worse. The reasons are:

A. The result of directional mutation

B． Result of continuous selection of pathogenic bacteria by antibiotics

C. The result of generation-by-generation selection of antibiotics by pathogenic bacteria

D. genetic result

3. An incorrect understanding of Darwin's theory of natural selection is:

A. Choice is non-directional

B． Mutation is generally non-directional

C. Heritable variation is the basis of biological evolution

D. After long-term natural selection and accumulation, beneficial mutations of organisms may produce new types of organisms.

Exercise: P63

1. Reduce emissions and protect the environment. Stop or reduce soot emissions from factories and restore the natural environment to normal as much as possible.

2. Artificial selection takes less time and is faster than natural selection.

3. Natural selection. Winged insects are easily blown out to sea by strong winds and gradually eliminated.

4. Mutations occurred, and a small number of bacteria were resistant to penicillin and survived through selection by penicillin.

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For more information about the PPT courseware "Evolution of Organisms and Reasons for Evolution of Organisms", please click the Evolution of Organisms ppt Reasons for Evolution of Organisms ppt tag.

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Update Time: 2024-11-22

This template belongs to biology courseware People's Education Edition Biology for Grade 8, Volume 2 industry PPT template

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