PEP Compulsory 2 Summary of Biological Knowledge Points

Compulsory ② Chapter 1, Section 1 1. Mendel discovered the law of biological inheritance by analyzing the results of pea hybridization experiment. 2. When Mendel did the hybridization experiment, he first removed all the stamens of the immature flowers, which is called castration. 3. Different manifestations of the same biological trait are called relative traits. 4. Mendel called the traits revealed by F 1 dominant traits, and the traits not revealed were recessive traits. In hybrid offspring, the phenomenon that dominant traits and recessive traits appear at the same time is called trait separation. 5. Mendel put forward the following hypothesis about the cause of separation: (1) The traits of organisms are determined by genetic factors, in which the dominant genetic factors determine the apparent traits, which are represented by capital letters, and the recessive genetic factors determine the recessive traits, which are represented by lowercase letters. (2) Genetic factors in somatic cells exist in pairs. Individuals with the same genetic factors are called homozygotes, while individuals with different genetic factors are called heterozygotes. (3) When organisms form germ cells-gametes, pairs of genetic factors are separated from each other and enter different gametes, and each gamete contains only one genetic factor of each pair. (4) In the process of fertilization, the combination of male and female gametes is random. 6. Test crossing is to cross F 1 with recessive homozygote. 7. Mendel's first law is also called separation phenomenon. In somatic cells of organisms, genetic factors controlling the same trait exist in pairs and do not fuse. When gametes are formed, the paired genetic factors are separated, and the separated genetic factors enter different gametes and are passed on to the offspring with the gametes. Chapter 1, section 2, 1. Mendel crossed pure yellow pea and pure green wrinkled pea as parents, and the seed (F 1) was yellow round regardless of cross or reverse cross. This shows that yellow grains and round grains are dominant traits, while green grains and wrinkled grains are recessive traits. 2. Mendel selfed F 1 with yellow round grains, and found yellow round grains and green wrinkled grains, as well as the combination of green round grains and yellow wrinkled grains that parents did not have. 3. The genetic factors of pure yellow pea and pure green wrinkled pea are yyrr and YyRr, respectively, and the genetic factor of F 1 produced by them is YYRR, that is, yellow pea. 4. In Mendel's cross experiment of two pairs of relative traits, when F 1(YyRr) produces gametes, each pair of genetic factors is separated from each other, and different pairs of genetic factors can be freely combined. F 1: yR, Yr, Yr produced four kinds of female gametes and four kinds of male gametes, and the quantitative ratio was:1:1:1:1. During fertilization, the combination of male and female gametes is random. There are 16 combinations of male and female gametes and 9 combinations of genetic factors: YYrr, yyyr, yyyr, yyyr, yyyr, yyyr, yyyr and YYRR. There are four characters: yellow round grain, yellow wrinkled grain, green round grain and green wrinkled grain, and the quantitative ratio between them is 9: 3: 3: 1. 5. Cross the progeny F 1(YyRr) with the recessive homozygote (YyRr). Whether F 1 is the female parent or the male parent, the offspring have four phenotypes: yellow round grain, yellow wrinkled grain, green round grain and green wrinkled grain, and the ratio between them is 9: 3: 3: 1. 6. Mendel's second law is also called the law of free combination. The separation and combination of genetic factors controlling different traits do not interfere with each other. When gametes are formed, the genetic factors that determine the same trait are separated from each other, and the genetic factors that determine different traits are freely combined. 7. 1909, Danish biologist Johnson named Mendel's "genetic factor" gene and put forward the concepts of phenotype and genotype. 8. Phenotype refers to the traits displayed by biological individuals. Genes controlling relative traits are called alleles, and gene composition related to phenotype is called genotype.