"Animal Reproduction" New Life PPT Courseware 2

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"Animal Reproduction" New Life PPT Courseware 2

The students have known a lot of animals. Can you tell me how they reproduce?

1. No matter how animals reproduce, they cannot do without the union of male and female animals. The combination of the two produces fertilized eggs in the female mother. It is precisely because of the production of eggs that animals can reproduce.

2. Under natural conditions, most of the new individuals of animals we see can only be produced through the combination of male and female.

3. Animal reproduction includes a series of complex behaviors such as male and female identification, mating (formation of fertilized eggs in the body), production, and nurturing of offspring. These behaviors are all instincts of animals.

The two most basic methods of reproduction

Viviparous A method of reproduction in which animals directly give birth to young, as in mammals such as horses and cats.

Oviparous A method of reproduction in which eggs are laid or laid, as in animals such as fish and chickens.

viviparous animals

The fertilized eggs of some animals develop into new individuals within the mother's body. Such animals are called "viviparous animals"; this method of reproduction is called "viviparous".

Example: Most mammals

oviparous animal

The fertilized eggs of some animals hatch and develop into new individuals outside the mother's body. Such animals are called "oviparous animals"; this method of reproduction is called "oviparous".

Examples: Most animals such as reptiles, insects, birds, fish, and amphibians

Question: What are the similarities and differences between viviparous and oviparous?

Similarities: Whether they are viviparous or oviparous animals, fertilized eggs are produced within the mother's body through the union of a male and a female.

the difference:

1. Viviparous animals must develop well inside the mother's body before they can give birth to babies. Egg-laying animals grow up outside the mother's body.

2. Animals that are born viviparous need to drink their mother’s milk, while those that lay eggs (mother birds) need to feed their babies bugs. For example, frogs and turtles just leave their babies alone after giving birth and let them live independently.

parthenogenesis

Refers to the reproductive method in which gametes develop directly into new individuals without union. It is a special type of sexual reproduction.

Parthenogenesis: the direct development of new individuals from female gametes, which is more common in the plant kingdom. For example, the eggs of dandelions, bluegrass and other plants can directly develop into embryos without fertilization.

It also occurs in animals, such as bees, ants, termites and other insects. Male individuals develop from unfertilized eggs. Parthenogenesis is also found in the life histories of animals such as rotifers and aphids.

In plant cell engineering research, tissue culture methods are used for artificial parthenogenesis to maintain the excellent characteristics of organisms and speed up the cultivation of new varieties.

Summarize

There are many wonders in this world. In order to adapt to the living environment, animals have chosen to adapt to their own reproduction methods in nature.

Today we have learned about viviparous, oviparous and some special reproduction methods. This is only a small part of the knowledge. There is still a lot of knowledge worthy of further study. I hope that students can use popular science books or search online to enrich themselves with more knowledge.

Cut the inner egg shell membrane with scissors and pour the contents into the petri dish. You can see:

1. There are many transparent gel-like objects, which are ( ) and contain ( );

2. There is a yellow spherical gel object, which is ( ) and is rich in ( );

3. There is a thin film on the outside of the yolk, which is ( ); the white strip-like substance at both ends of the yolk is ( ), and its function is ( );

4. There is a small white dot on the yolk, which is ( ), formed by the division of ( ), and is the part where ( ) is performed.

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Update Time: 2024-11-16

This template belongs to science courseware Fourth Grade Science Volume 2, Textbook Edition industry PPT template

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