The fifth part
Chapter I Inheritance and Variation of Organisms
Six, biological genetic phenomenon:
The phenomenon that biological characteristics are passed on to future generations is called heredity.
The traits of animals and plants are mainly passed on to offspring through germ cells.
Seven, chromosomes and genes:
Some substances in the nucleus that are easily dyed dark by alkaline dyes are called chromosomes. Chromosomes exist in pairs in somatic cells (father and mother) and alone in germ cells (23 pairs in human cells and 23 pairs in human germ cells). It is composed of protein and deoxyribonucleic acid (DNA for short) and is the main genetic material. The small unit in DNA that determines biological characteristics is called gene. Genes exist in somatic cells, but exist alone in germ cells.
Eight, dominant and recessive genes
When a pair of genes controlling traits in a cell are recessive (aa), traits controlled by recessive genes will be displayed, otherwise (Aa, AA) are dominant traits.
Dominant (capital a) recessive (lowercase a)
Nine, prohibit consanguineous marriage
The closer the blood relationship is, the closer the genetic similarity is, and the greater the possibility that the children born after marriage will get genetic diseases.
X. biological variation phenomenon
Differences in characteristics between parents and offspring, as well as between offspring individuals.
XI。 Genetic variation and non-genetic variation
Twelve, favorable variation and unfavorable variation
Variation provides raw materials for biological evolution.
Thirteen. Significance of variation in biological evolution
Fourteen Application of variation in agricultural production
Chapter II Biological Evolution
First, the origin of life:
Primitive ocean is the cradle of life, and primitive life originates from inanimate matter.
Second, the course of biological evolution:
The process of plant evolution:
Primitive unicellular animals
Primitive life, primitive moss
Primitive algae primitive gymnosperms
Primitive ferns, primitive angiosperms
The course of animal evolution: primitive birds
Primitive fish, primitive amphibians, primitive reptiles and primitive mammals
Evolutionary principles: from simple to complex, from low to high, from aquatic to terrestrial.
Third, the emergence of human beings:
Humans and apes are close relatives, and humans gradually evolved from forest apes.
Plants are separated from seed plants, invertebrates from arthropods, and vertebrates from reptiles.
Fourth, the evidence of biological evolution:
The main evidence is fossils (biological relics, relics or traces of life are buried in the stratum for various reasons and gradually formed after tens of thousands of years of complex changes). The older the strata, the simpler the fossils, the lower the fossils, and the more aquatic fossils. In the later strata, the more complex and higher the fossils, the more terrestrial fossils. There are no biological fossils in the oldest strata.
Five, artificial selection:
Choosers: human outcomes: meeting various human requirements. Speed: faster.
Concept: The process of forming new biological species through continuous selection according to human needs and hobbies.
Sixth, natural selection.
Selector: various environmental conditions in nature. Results: Adapted to the environment and constantly evolved.
Speed: It takes a long time to form new species.
Concept: The creatures in nature, through fierce competition for survival, the fittest survive and the unsuitable are eliminated.
Chapter III Biology and Environment
First, the meaning of environment
The living environment of living things refers not only to the place where they live, but also to various factors that exist around them and affect their lives.
Second, ecological factors: other biological and abiotic factors in the environment that affect the life of a certain organism.
Abiotic factors-sunlight, temperature, water, air, etc.
Biological factors-other organisms that affect the life of an organism.
Third, the relationship between biology and environment.
1, environmental impact organisms
2, biological adaptation to the environment
3, biological impact on the environment
Fourthly, the concept of ecosystem.
A unified whole formed by biology and environment in a certain area.
Verb (abbreviation of verb) the composition of ecosystem
Plant producers (inorganic matter, photosynthetic organic matter)
Biological part-animals-consumers (using organic substances)
Bacterial fungi-decomposers (organic-inorganic)
Abiotic parts-sunlight, air, soil, water, temperature, etc.
Intransitive verbs food chain and food web
There is a relationship between producers and consumers to eat and be eaten, forming a food chain. In an ecosystem, interrelated food chains form a food web. Such as: grass rabbit fox
Seven. ecological balance
The number and proportion of all kinds of organisms in the ecosystem have always remained in a relatively stable state, which is called ecological balance.
Eight, China's wildlife resources
The gymnosperm resources in China rank first in the world.
Giant panda, golden monkey, baiji dolphin, Chinese alligator and Nuo deer, among which, Cathaya argyrophylla, Cynanchum bungeanum and Davidia involucrata are rare animals and plants unique to China.
1. Many wild animals and plants can be used as medicinal materials.
2, can provide a large number of industrial raw materials.
3. Provide food for human beings.
4. It has important scientific research value.
Nine, environmental pollution
Air pollution, water pollution, solid waste pollution, soil pollution and noise pollution.
X. Environmental protection (basic national policy)
In order to protect the natural environment and wildlife resources, China has established hundreds of nature reserves, such as Wolong, Wang Lang and Jiuzhaigou (giant pandas and golden monkeys) in Sichuan, and Huaping Nature Reserve (silver fir) in Guangxi. Enterprises that seriously pollute the environment, waste resources and affect the normal life of nearby residents should be treated or stopped within a time limit. Start from me, establish environmental awareness and cultivate people who care for the environment.