"Growth and Change of Animals" Growth and Change PPT Courseware

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"Growth and Change of Animals" Growth and Change PPT Courseware

Recall what growth periods a person has experienced in his life?

Infancy and early childhood →

Adolescence →

Puberty→

Adulthood→

old age

What are the growth periods of animals? Are they all the same?

Growth and Development of Frogs

Question: What stages does a frog go through in its growth and development?

The growth and development process of frogs

Frogs have a distinctive feature during their development. Have you discovered it?

Compete, compete

Use your existing knowledge combined with pictures to analyze the differences between tadpoles and adult frogs to see who knows the most.

Like frogs, a type of development that undergoes great changes in life and morphological structure during the development process from larvae to adults is called metamorphosis.

animal reproductive methods

Sexual reproduction: the combination of sperm and egg cells to form a fertilized egg to produce a new individual

Asexual reproduction: no need for sperm and egg to combine to directly produce new individuals

Most are sexual reproduction

1. Different methods of fertilization

fertilization method

In vitro fertilization: The fertilization process takes place outside the body

Such as: fish, amphibians

Internal fertilization: The process of fertilization takes place inside the body

Such as: insects, reptiles, birds, mammals

2. Different ways of embryonic development

Note: Among mammals, the platypus and echidna are oviparous, while the rest are viviparous.

discuss:

1. The eggs of oviparous animals are much larger than those of viviparous animals. What does this mean for embryonic development?

The nutrients required by oviparous animals throughout the entire process of embryonic development are provided by the yolk, and more nutrients must be stored in the egg.

2. What significance do viviparous and lactation have to mammalian reproduction? Tell me why.

Viviparous and lactating provide a stable living environment and nutritional source for the larvae, greatly improving the survival rate.

Paramecium Reproduction

1. Fission reproduction: a mother body splits into two offspring of roughly the same size and shape.

2. Budding reproduction: The mother's body grows a bud that resembles the mother's body in a certain part, gradually grows up, and becomes an independent and complete new individual after breaking away from the mother's body.

think:

What characteristics do these two modes of reproduction have in common, and what are their essential differences from animal sexual reproduction?

A reproductive method that does not require the union of sperm and egg cells and produces new individuals directly from one mother is called asexual reproduction

think

Who has more advantage, asexual reproduction or sexual reproduction?

The significance of sexual reproduction: offspring possess the genetics of both parents, have greater vitality and variability, and can adapt to changing environments.

The significance of asexual reproduction: It has advantages in a single and unchanged environment, but is at a disadvantage when the environment changes.

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Update Time: 2024-09-07

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