"Reproduction and Development of Amphibians" Reproduction and Development of Biological Organisms PPT Courseware 2

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"Reproduction and Development of Amphibians" Reproduction and Development of Biological Organisms PPT Courseware 2

1. Reproduction of frogs

What's the meaning of the frog's cry?

Courtship, attracting female frogs to cuddle with each other

The male frog has a pair of singing sacs at the corners of its mouth, which bulge and then deflate. During the breeding season, male frogs chirp as a way to court mates, so frog chirping is of great significance to the reproduction of the population.

What is the significance of the frog's embrace?

in vitro fertilization

Holding the baby right will help the semen to be discharged directly onto the egg cell, which will increase the fertilization rate of the egg.

2. Development of frogs

Developmental characteristics of frogs: metamorphosis

There are significant differences between larvae and adults in terms of morphological structure and living habits.

Amphibians:

The larvae live in water and breathe with gills; they metamorphose and develop into adults; the adults live on land or in water, breathing mainly with lungs and assisted by skin.

3. The relationship between amphibian reproductive development and the environment

A survey of global amphibians conducted by scientists showed that the number of frogs, toads and salamanders around the world is declining. In 2004, 168 species of amphibians became extinct globally, and the survival of 1/3 of amphibians is threatened, mainly due to their natural habitats. The living space has been destroyed. Half of all amphibians may become extinct within the next 100 years.

discuss

1. Deformed frogs appear in some areas. What may be the cause?

Deformed frogs may be caused by water environment pollution, which will inevitably affect the survival of amphibians and lead to a decrease in their numbers.

2. What lessons have you learned from the above examples?

In order to protect all living things, including us humans, we must care for the environment, protect the environment, and prevent the environment from being polluted. Reduce the use of pesticides, discharge of sewage, and protect the water environment.

According to research by scientists, it has been proven that the reproduction and development of amphibians are inseparable from water, and adults need to live on land. This leaves most amphibians confined to moist areas near water.

Environmental change is also an important factor affecting the distribution of amphibians. As ponds, rivers, lakes and other water environments shrink, the distribution range of amphibians is also getting smaller and smaller.

Reasons for the decline of amphibians:

1. Self-cause: Reproduction and development cannot be separated from water

2. Environmental reasons: ① Climate drought ② Human activities

Practice in class

1. The _____ and _____ of amphibians must be carried out in the water, and the larvae must go through _____ before they can live on land.

2. Which of the following is not an amphibian? ( )

A. Giant salamander B. Turtle C. Frog D. Toad

3. The frog that can chirp is ( )

A. Female frog B. Female frog and male frog

C. Male frog D. Female or male frog

4. Which of the following are amphibians ( )

A. Turtle B. Giant salamander C. Crocodile D. Chinese sturgeon

5. The mature frog will return to the water ( )

A. Catch flies B. Get all the food

C. Breeding D. Moisten gills

6. The reproduction and development of frogs take place in �().

A. In water and on land B. In water

C. Proceed on land D. Proceed in mother body

7. The reproductive method of frogs is: ( )

A. In vitro fertilization, egg laying B. In vitro fertilization, metamorphosis

C. Internal fertilization, egg laying D. internal fertilization, metamorphosis

8. The ontogeny of frogs has gone through ( )

A. Egg----embryo----young frog----adult frog

B. Egg----embryo----tadpole----adult frog

C. Fertilized egg----tadpole----adult frog

D. Fertilized eggs----tadpoles----young frogs----adult frogs

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Update Time: 2024-09-09

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

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