"There are certain regularities in the inheritance of traits" PPT

"There are certain regularities in the inheritance of traits" PPT

Part One: Review the past and learn the new

1. What are the traits of an organism?

Tip: Morphological characteristics and physiological properties of organisms. For example, a person's facial features, skin color, body height, blood type, etc.

2. The characteristics of living things are controlled by -.

3. How do genes on chromosomes exist in somatic cells and germ cells?

Tip: Chromosomes and genes exist in pairs in somatic cells and in single pairs in reproductive cells.

There are certain regularities in trait inheritance PPT, part 2: collaborative exploration

Explore theme one

Trait expression depends on genetic makeup

Explore theme two

Genes are passed down from generation to generation with gametes

Read the textbook and explore and answer the following questions

1. What are the existence and sources of paired genes in human cells?

Tip: Paired genes in somatic cells are located on paired chromosomes and are combined with the combination of sperm and egg cells. One comes from the father and the other comes from the mother.

2. In the process of biological reproduction, through what medium is genetic material transmitted?

Tip: Gametes (reproductive cells) are the bridge between the previous and next generations and the only medium for transmitting genetic material. Genes can be passed on from generation to generation with gametes.

3. Under what circumstances would a couple with earlobes give birth to a child without earlobes?

Tip: When the couple's genotype is both Aa, it is possible to give birth to a child without earlobes.

There are certain regularities in the inheritance of traits PPT, the third part of the content: Life links

1. A classmate’s appearance is similar to that of his father. The classmate believes that his father passed on more genes to him. Is this view correct and why?

Hint: Incorrect. Pairs of genes in body cells, one from the father and one from the mother. The correct statement is that his father passed down more dominant genes to him.

2. Jia has single eyelids, and his parents both have double eyelids. Please explain the reason.

Tip: The genotype of Jia’s parents is Aa, and Jia’s genotype is aa.

There are certain regularities in trait inheritance PPT, part 4: basic compliance

1. Multiple choice questions

1. (Selected and refined·Changchun High School Entrance Examination) The scientist known as the "Father of Genetics" is ( )

A. Darwin B. Fleming

C. Mendel D. Leeuwen Hooke

[Analysis] Choose C. Darwin is a British scientist and the founder of the theory of evolution. "The Origin of Species" is the masterpiece of Darwin's theory of evolution; Fleming is the discoverer of penicillin and is known as the "father of antibiotics"; Mendel is the founder of genetics and is known as the "father of antibiotics". "Father of Genetics"; Leeuwen Hooke was a Dutch microscopist and pioneer of microbiology.

2. The shape of pea seeds can be round or wrinkled, which depends on the shape of the pea seeds ( )

A. Genetic composition B. Chromosome composition

C.DNA composition D.Protein composition

[Analysis] Choose A. The expression of the traits examined in this question is determined by genetic makeup. Trait expression is controlled by corresponding specific genes. The round kernel trait of pea seeds is determined by the round kernel gene, and the wrinkled kernel trait of pea seeds is determined by the wrinkled kernel gene.

3. (Selected and refined·Hegang Test) The genetic material from the previous generation to the next generation is passed on ( )

A. Fertilized egg B. Gamete C. Protein D. Character

[Analysis] Choose B. This question examines genes that are passed down from generation to generation through gametes. The father produces sperm, and the mother produces egg cells. After the sperm and egg cells combine, a fertilized egg is formed. The combination of sperm and egg cells means the combination of genes that control the traits of both parents.

4. (Selected and refined·Chaohu test) The statement about the dominant and recessive nature of genes is wrong ()

A. Dominant genes control dominant traits, and recessive genes control recessive traits.

B. Dominant genes have a masking effect on recessive genes

C. Only dominant traits are expressed when the paired gene Aa exists

D. Only traits that cannot be expressed are recessive traits

[Analysis] Choose D. This question examines the relationship between genes and traits. Dominant genes control dominant traits, and recessive genes control recessive traits. As long as there is a dominant gene, it will be a dominant trait; if there is no dominant gene, it will be a recessive trait.

2. Non-choice questions

11. The picture shows the changes in the number of chromosomes during human reproductive development. Please complete the following questions based on the picture:

(1)a and b represent the somatic cells of the parents respectively, and their number of chromosomes is ______.

(2)A represents the process by which parents produce germ cells respectively. Germ cells c and d are called ______ and ______ respectively. Their number of chromosomes is ______, which is ______ less than a and b.

(3) Process B is ______. The e-cell formed is called ______, and its number of chromosomes is ______ pairs, which has returned to the same number as the ______ cell.

(4)C process is called ______. Cell f is the daughter's ______ cell, and its number of chromosomes is ______.

(5) It can be seen from the above that the number of chromosomes in the somatic cells of human beings is ______. Each pair of chromosomes in an organism's cells has one chromosome from ________ and one from ______. Therefore, offspring individuals have ______ genetic material.

[Analysis] (1) This question tests the number of chromosomes in somatic cells. Chromosomes in human somatic cells exist in pairs and have a constant number. There are 23 pairs of chromosomes (46) in human cells.

(2) When forming germ cells, paired chromosomes will separate in pairs, which means that each germ cell contains half of the chromosomes of the somatic cells. For the human body, there are 23 chromosomes in the germ cells.

(3) Hermaphrodite germ cells form a fertilized egg through fertilization. The chromosomes in the two germ cells merge into one again, and the chromosomes in the somatic cells of the offspring return to the same number as the parents.

(4) Process C is when the fertilized egg cell develops into a new individual through embryonic development. The number of chromosomes in the somatic cells of the new individual is the same as that of the fertilized egg, which is 46.

(5) The chromosomes in the fertilized egg exist in pairs, one from the father and one from the mother. The number is the same as the somatic cells of the parent. The constant number of chromosomes is of great significance to maintaining the stability of the species.

There are certain regularities in trait inheritance PPT, Part 5: Ability improvement

1. (Selected and Refined·Rizhao Academic Examination) A pair of white sheep raised by Xiao Ming’s family mated and gave birth to one white sheep and two black sheep. He used the biological knowledge he learned to infer the genetic phenomena of the sheep. Among them What is wrong is (the relevant gene is represented by Ee) ( )

A. White color is a dominant trait B. The genetic makeup of the ewe is EE

C. Black color is a recessive trait D. The genetic makeup of black sheep is ee

[Analysis] Choose B. A pair of white sheep mate to produce a white sheep and a black sheep, indicating that white is a dominant trait and black is a recessive trait. The genetic makeup of the offspring black sheep is ee, and the parent white sheep all have an e, so the genetic makeup of the parent white sheep are all Ee.

2. The father’s genetic makeup is AA, the mother’s genetic makeup is aa, and the genetic makeup of their child is ( )

A.AaB.AAC.aaD. All of the above are possible

[Analysis] Choose A. This question examines the inheritance laws of genes. According to the knowledge learned, its genetic diagram is as follows:

3. The picture shows a pair of genes that control the presence or absence of earlobes in human body cells located on a pair of chromosomes. Which of the following statements is incorrect ( )

A. The B on the chromosome indicates a dominant gene

B. If B comes from the father's side, then b comes from the mother's side

C. Individuals whose genes are composed of Bb show traits controlled by gene B.

D. The traits controlled by gene b cannot be expressed in offspring

[Analysis] Choose D. This question examines the inheritance of traits. A pair of genes that control a trait are located on a pair of chromosomes, one from the father and one from the mother; dominant genes are represented by capital letters such as B, and recessive genes are represented by lowercase letters such as b; when the genotype controlling the trait is bb , the offspring will express the traits controlled by gene b.

[Rule method] The law of gene transmission through germ cells

(1) Genes that control biologically identical traits exist in pairs in somatic cells, such as round grains and wrinkled grains in peas, and red and yellow fruits in tomatoes. There are three types of genotypes in somatic cells (DD, Dd, dd).

(2) In the gametes (sperm, egg cells) of organisms, genes that control the same trait exist alone, and there are only two situations (D and d).

(3) Genes control genetic traits or determine a certain function, such as catalytic function (enzymes) and regulatory functions (hormones). In the process of biological reproduction, it is the genes that are passed on, not the traits themselves.

(4) Dominant genes control dominant traits, and recessive genes control recessive traits. When the genotype is AA or Aa (or BB, Bb...), it shows a dominant trait; when the genotype is aa (or bb...), it shows a recessive trait.

Keywords: Beijing Normal University version of the eighth grade biology PPT courseware for the first volume is free to download, there are certain regularity in trait inheritance PPT download, .PPT format;

For more information about the PPT courseware "The inheritance of biological inheritance and mutation traits have certain regularity", please click the "Heredity and mutation inheritance of living things have certain regularity" PPT courseware.

"There are certain regularities in the inheritance of traits" PPT courseware:

"There are certain regularities in the inheritance of traits" PPT courseware Part One: Reviewing the past and learning the new 1. In human body cells, there are _____ chromosomes. 2. In somatic cells, the _______ that controls biological traits is located on the paired _______, so it is also ______..