People's Education Press seventh grade biology book volume 2

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"Human Reproduction" The Origin of Man PPT Courseware

Human Reproduction Humans produce new individuals through reproduction

Reproduction refers to the process by which organisms produce offspring and reproduce races. It is a common life phenomenon in the biological world. Reproduction is the production of young individuals by organisms to produce offspring. Reproduction is one of the basic characteristics of life.

After an organism reaches a certain stage of growth and development, it can produce offspring individuals similar to itself.

Human beings are divided into males and females, and offspring individuals need to be combined by the combination of reproductive cells of both sexes. Paternal and maternal genetic information are carried to offspring by male germ cells and female germ cells respectively. Reproduction is a method of passing seeds from generation to generation.

①The ancestors of us humans are ancient apes, so how did you come to this world?

②Why does it take two people, father and mother, to give birth to you?

③Think about how angiosperms reproduce?

④ It seems that the reproductive cells of your parents must also be combined to form a fertilized egg before you can be born. It can be seen that our human reproduction is not mysterious, but a common phenomenon in the biological world and a common characteristic of all living things.

⑤So what are our human reproductive cells called? How did it come about? How is it combined? We have to start with another system of our human body—the reproductive system.

Self-study outline:

1. What are the germ cells in men and women? What are their respective characteristics?

2. What are the components of the male and female reproductive systems and the functions of each structure?

3. Which organs produce and transport sperm and egg cells? What are the organs that the fetus develops and produces in the mother's body?

4. What is fertilization? Where is the site of fertilization?

5. At what week does the embryo begin to develop into a human form?

6. What are the organs for material exchange between the fetus and the mother? What kind of material exchange is carried out?

7. How long does it take during pregnancy for the fetus to mature?

Review and Thoughts:

1. What are the main male reproductive organs? What is the role of each?

2. What are the main female reproductive organs? What is the role of each?

Sperm: It is the smallest cell in the male body.

Sperm is very small, shaped like a tadpole, with a total length of 60 microns, making it the smallest cell in the male body. The speed of the long tail is 18 cm/hour. The volume of semen discharged by men each time is about 2-5 ml, and there are about 100 million sperm in each ml.

Egg cell: spherical, with a diameter of more than 0.1 mm, and is the largest cell in the human body. There is yolk in the cell, and the yolk contains a certain amount of nutrients to provide nutrients for the early development of the embryo. The egg cannot move freely and must rely on the contraction of the fallopian tube smooth muscle and the ciliary movement of the epithelium to passively move toward the uterine cavity.

I will fill in

1.The starting point of a new life______

2. The most important sexual organ of men and women______

3. Place of fertilization______

4. The place where embryos and fetuses develop is ______

5. The organ that exchanges substances between the fetus and the mother is ______

6. Germ cells refer to ______

Expand knowledge

1.Twins

If the ovary eliminates two mature egg cells at the same time, and the two combine with two sperm to form two fertilized eggs, they will develop into two new individuals in the future - fraternal twins.

During the process of division and development, a fertilized egg may develop into two embryos for some reason, forming two new individuals - identical twins (due to the same genetic material and living environment, it is likely that there will be consequences for a certain event. Same idea, etc.)

Give it a try:

1. The place where the embryo and fetus develop is ( )

A. Ovary B. Uterus

C. Fallopian tube D. vaginal

2. When does new life begin? ( )

A. Egg cell and sperm B. Fertilized egg

C.Embryo D.When the baby is born

3. Fetus refers to ( )

AThe embryo from the fertilized egg to the time before the baby is born

B. The embryo from when the fertilized egg divides until the baby is born

C. From the end of the first month of embryonic development to the embryo before birth

D. The end of the second month of embryonic development, to the embryo before birth.

4. Which of the following are germ cells ( )

① Sperm ② Egg cell ③ Semen ④ Ovary ⑤ Testis

A.①②③④⑤ B. ①②③ C. ①② D. ②④

2. Judgment questions:

The formation of a fertilized egg is the beginning of a new life

People often say "Ten months of pregnancy, one day of delivery", which means that the fetus must be pregnant in the mother's body for ten months

The uterus is the reproductive organ that secretes estrogen

Twins are produced by the union of two sperm and one egg.

The blood type of the fetus can be different from that of the mother. Under normal circumstances, blood agglutination does not occur because the blood of the mother and the fetus are not directly connected.

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For more information about the PPT courseware "The Origin of Man and Human Reproduction", please click on the "Origin of Man ppt Human Reproduction ppt" tag.

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Update Time: 2024-10-31

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