"Human Gender Inheritance" Biological Inheritance and Variation PPT Courseware 2

Description

"Human Gender Inheritance" Biological Inheritance and Variation PPT Courseware 2

Review questions:

1. Is a person’s gender a trait?

2. What controls traits?

3. Where are genes located in cells?

Question outline:

(1) Which pair of chromosomes is different between males and females? What might be the difference between these chromosomes?

(2) Among the two pictures, which one is the male chromosome and which one is the female chromosome?

(3) Which are autosomes and which are sex chromosomes?

(4) Which one is the X chromosome and which one is the Y chromosome in the picture? What are the morphological differences between the two?

(5) In terms of sex chromosomes, how many sex chromosomes should there be in sperm produced by men and in eggs produced by women? How many types of sperm and egg cells are there?

(6) The number and expression of chromosomes in male and female somatic cells, sperm and egg cells?

Between menstruation, a woman produces an egg containing an X chromosome. Men send out hundreds of millions of sperm during a reproductive activity. These sperm contain only two types of sex chromosomes, one containing the X chromosome and the other containing the Y chromosome. They have an equal chance of combining with the egg cell.

If this is the case, are the chances of having a boy or girl equal?

Purpose:

1. Make students clear about the reasons why boys and girls are born, and explain the reasons why boys and girls have equal opportunities.

2. Improve students’ awareness and ability of experimental inquiry.

3. Cultivate students’ interest in learning biology.

Experiment preparation:

1. Before class, each group prepares Go pieces, using white pieces to represent sperm containing X chromosomes, black pieces to represent sperm containing Y chromosomes, and white pieces to represent egg cells. Divide the chess pieces into 8 groups, with two opaque containers in each group, respectively containing "sperm" (40 black and white pieces) and "egg cells" (40 pieces).

2. Divide the students into eight groups, with six people in each group. Appoint a student with strong sense of responsibility and ability as the group leader. The group leader and the group members will jointly arrange the experimental operator, disciplinary supervisor and experimental recorder.

experiment procedure:

Communication between groups, teachers guide improvement plans, and students conduct experiments as planned:

One classmate randomly took out a "sperm" from the paper bag containing "sperm", and another classmate took out an "egg cell" from the paper bag containing "eggs", put them together to represent the fertilized egg, and said "fertilized egg" The type of sex chromosomes contained, so as to learn the gender of the new individual, is repeated 20 times. Note: The removed chess pieces should be put back into the paper bag before the next experiment. Teachers inspect and guide, urging students to keep records and fill in data in forms.

The dangers of gender imbalance

Imbalanced gender ratio will lead to the phenomenon of "marriage and gender squeeze", and will greatly lead to illegal and criminal activities such as marriage-shopping, abduction and trafficking of women, and various complex social problems, seriously hindering the harmonious, sustainable and healthy development of our country's population.

Do you have any questions about human gender inheritance?

The inheritance of biological traits is controlled by genes. So, is human gender determination related to sex chromosomes and not to genes?

After studying in this class, can you now use what you have learned in this class to explain whether it is a woman's responsibility to give birth to a boy or a girl?

Some people still have the idea of ​​​​valuing boys over girls, which leads to a deviation in the gender ratio. How do you view this problem? What is the right thing to do?

expand

Why do some twins we see in life have the same gender and some have different genders?

Identical twins: Monozygotic twins are one fertilized egg produced by the union of one sperm and one egg. This fertilized egg splits in two, forming two embryos. Because they come from the same fertilized egg and receive exactly the same chromosomes and genetic material, they have the same sex.

Fraternal twins: For some reason, a woman releases two eggs at the same time and fertilizes them at the same time, forming two different fertilized eggs. Then they develop into two independent individuals. When they grow up, the differences are relatively large, and they can be of the same sex or the opposite sex. Twins develop from two different fertilized eggs.

training ground

1. How many sex chromosomes are there in a sperm? ( )

A. 1 B.2 C.3 D. 4

2. The gender of the newborn mainly depends on ( )

A Mother’s somatic cells B Father’s somatic cells C Type of egg cell D Type of sperm

3. A couple gave birth to a girl in their first child, and they really want another boy. Then, the probability of having a boy in their second child is ( )

A 100% B 50% C 25% D 0%

4. The chromosome composition of normal male somatic cells is ( )

A 23 pairs +X B 23 pairs +Y C 22 pairs +XX D 22 pairs +XY

5. If a trait is always passed directly from father to son, and from son to grandson, then the most likely location of the gene that controls this trait is ( )

A is located on the autosome B is located on the Y stain

C is on the X chromosome D is on the sex chromosomes

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For more information about the PPT courseware "Inheritance of Biological Inheritance and Variation and Gender Inheritance in Humans", please click the Inheritance of Biology and Variation ppt Gender Inheritance in Humans ppt tag.

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Update Time: 2024-07-30

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

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