"Reproduction and Development of Amphibians" Reproduction and Development of Biological Organisms PPT Courseware 3

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"Reproduction and Development of Amphibians" Reproduction and Development of Biological Organisms PPT Courseware 3

What kind of animals are called amphibians?

The larvae of frogs, toads, giant salamanders, and salamanders live in water and breathe with gills; most adults live on land, breathing with lungs and using their skin to assist breathing. Such animals are called amphibians.

Amphibian reproductive development and environmental conditions

On a road near a forest farm somewhere in my country, more than 100,000 frogs migrated in clusters. Research shows that these frogs are looking for spawning sites with abundant water and good water quality.

Based on relevant knowledge of geography and biology, scientists infer that the development of amphibians in the biosphere has gone from prosperity to decline, as shown in the following table

In 1995, middle school students in Minnesota, USA, discovered deformed frogs in rivers and swamps: some frogs had bent, incomplete legs, and some frogs had extra legs. This caught the attention of scientists. After investigation, deformed frogs were found in the southern, eastern, central United States and Canada. Historically, the proportion of deformed frogs has been very low; in some places surveyed, the proportion of deformed frogs has been as high as 96%. Along with their deformed appearance, these frogs often also have severe defects in their reproductive and digestive systems, and rarely survive their first winter. In 2010, some scientists believed that some deformed frogs discovered in recent years were infected by parasites, and that the discharge of domestic sewage into rivers and ponds may increase the number of parasites.

1. The above examples illustrate what impact environmental changes have on the reproduction of amphibians?

Environmental changes destroy the environment required for amphibian reproduction and development, making amphibians unable to carry out normal reproductive activities. At the same time, environmental changes also affect the normal development of amphibians, ultimately leading to a decline in the ability of amphibians to reproduce, and the population size and Reduced variety.

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

Deformed frogs may be caused by water environment pollution. After the water is polluted, the number of substances that affect the normal development of frogs or other organisms (such as parasites) increases.

3. Environmental factors are divided into abiotic factors and biotic factors. Information 3 can explain the relationship between these two factors?

Abiotic factors can affect the life and distribution of organisms, and organisms living in the same environment may also affect the life and distribution of other organisms.

4. What lessons have you learned from the above facts?

Organisms must adapt to the environment to survive, so organisms have a certain ability to adapt to the environment, but this ability is limited. Once the changes in the environment exceed the ability of organisms to adapt to the environment, the life and distribution of organisms will be affected.

1. Newly hatched tadpoles will not feed. They are often adsorbed on egg shells or aquatic plants, and rely on the remaining yolk to obtain nutrients. They will only start to eat algae and water fleas after 2 to 3 days.

2. During the development process of tadpoles, as the limbs gradually grow, the tail gradually disappears. Scientists have found that this developmental phenomenon of tadpoles is controlled by genes (genetic material), as if the cells in the tadpole's tail die and disappear according to a programmed "program", so scientists call this "programmed cell death" .

3. From the perspective of biological evolution, amphibians are a group of vertebrates that transition from aquatic to terrestrial. During the ontogeny of frogs, tadpoles live in water and have the characteristics of fish-like appearance and breathing with gills. This explains During the process of ontogeny, organisms still retain the characteristics of their aquatic ancestors living in the water.

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"Reproduction and Development of Amphibians" Biological Reproduction and Development PPT Courseware 6:

"Reproduction and Development of Amphibians" Reproduction and Development of Organisms PPT Courseware 6 Amphibians contain two meanings: First, from the perspective of the evolutionary history of vertebrates, amphibians are a group that transitioned from aquatic to terrestrial. The second is from the individual findings of amphibians...

"Reproduction and Development of Amphibians" Biological Reproduction and Development PPT Courseware 5:

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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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