The square of a + the square of B + the square of C + 2Ab + 2Ac + 2BC = (a + B + C) is proved by factorization

The square of a + the square of B + the square of C + 2Ab + 2Ac + 2BC = (a + B + C) is proved by factorization

a^2+b^2+c^2+2ab+2ac+2bc
=a^2+b^2+2ab+c^2+2ac+2bc
=(a+b)^2+2c(a+b)+c^2
=(a+b+c)^2

Summary of biology knowledge points in the seventh grade of PEP

Unit 1 biology and biosphere
Chapter one understanding biology
Section 1 biological characteristics
1、 Biological characteristics:
1. Biological life needs nutrition. 2. It can breathe. 3. It can excrete waste
4. 5. It is composed of cells (except viruses) 6. It grows 7. It can reproduce 8. It has genetic variation
2、 Observation P2
The second section investigates the living things around us
1、 General methods of investigation
Steps: make clear the purpose of the investigation, determine the object of the investigation, formulate a reasonable investigation plan, record the investigation, sort out the investigation results and write the investigation report
2、 Classification of organisms
According to the morphological structure: animals, plants, other organisms
According to the living environment: terrestrial organisms, aquatic organisms
According to the use: crops, poultry, livestock, pets
The biosphere is the home of all living things
Section 1 biosphere
1、 The scope of the biosphere: the bottom of the atmosphere: flying birds, insects, bacteria, etc
All of the hydrosphere: the water layer within 150 meters of sea level
The surface of lithosphere is the foothold of all terrestrial organisms
2、 Biosphere provides basic conditions for living things: nutrients, sunlight, air and water, suitable temperature and certain living space
Section 2 impact of environment on organisms
1、 Effects of abiotic factors on organisms: light, moisture, temperature, etc
2、 An experiment on the influence of light on the life of rat shrews
3、 The process of inquiry: 1. Finding problems, asking questions, 2. Making hypotheses, 3. Making plans, 4. Implementing plans, 5. Drawing conclusions, 6. Expressing and communicating
4、 Control experiment p15
5、 The influence of biological factors on organisms is as follows
According to the relationship between the same species or different species, biological factors can be divided into two kinds: 1. Intraspecific relationship: intraspecific mutual assistance (ant moving food), intraspecific struggle (two leopards competing for antelope and habitat)
2. Interspecific relationships: parasitism (Ascaris lumbricoides), competition (lions and leopards competing for food), mutual assistance (rhinoceros and rhinoceros)
Section 3 adaptation and impact of organisms on the environment
1、 Adaptation of organisms to the environment: an example of P19
2、 Biological effects on the environment: transpiration of plants regulates air humidity, dead leaves and branches of plants can regulate soil fertility, animal manure can improve soil, earthworm can loosen soil
Section 4 ecosystem
1、 Composition of ecosystem:
1. Biological part: producer, consumer and decomposer
2. Non biological part: sunlight, water, air, temperature
2、 Food chain and food web:
1. The food chain starts with producers
2. Matter and energy flow along the food chain and food web
3. The higher the trophic level, the less the number of organisms; the higher the trophic level, the more toxic substances accumulated, such as Shuiwu disease in Japan
3、 The ecosystem has a certain ability of automatic regulation
In general, the number and proportion of organisms in the ecosystem are relatively stable. However, this automatic regulation ability is limited to a certain extent. If it is exceeded, it will be destroyed
The biosphere is the largest ecosystem
1、 Types of ecosystem P29
Forest ecosystem, grassland ecosystem, farmland ecosystem, marine ecosystem, urban ecosystem, etc
2、 Biosphere is a unified whole P30
Unit 2 biology and cells
The first chapter is to observe the cell structure
Section 1 practice using a microscope
1、 1. Structure of microscope
Mirror base: stable mirror body;
Mirror column: supporting the part above the mirror column;
Mirror arm: the part holding the mirror;
Stage: the place where the slide specimen is placed. There is a through hole in the center and a pressing clip on each side to fix the observed object
Shading device: there are round holes of different sizes on it, called aperture. Each aperture can be aimed at the through-hole. Light is used to adjust the intensity of light
Reflector: it can be rotated to reflect light through the through-hole
Lens barrel: the upper end is equipped with an eyepiece, the lower end is equipped with a converter, the converter is equipped with an objective lens, and the rear is equipped with a quasi focus screw
Quasi focus helix: coarse quasi focus helix (also known as coarse adjustment): when rotating, the lens barrel rises and falls greatly; fine quasi focus helix (also known as fine adjustment)
The relationship between the rotation direction and the up and down direction: rotate the quasi focus screw clockwise, the lens barrel will drop; otherwise, it will rise
3、 How to use the microscope
1. The observed image is opposite to the actual image
2. Magnification = objective x eyepiece
3. The biological specimen observed under microscope should be thin and transparent, and light can pass through, so it must be processed into slide specimen
Section 2 observation of plant cells
1、 The difference between slicing, smearing and loading
2、 Experiment process p43-44
3、 The basic structure of plant cells
1. Cell wall: support and protection
2. Cell membrane: control of material in and out
3. Cytoplasm: liquid, mobile
4. Nucleus: storage and transmission of genetic information
5. Chloroplast: the site of photosynthesis
6. Vacuole: cell fluid
7. Mitochondria: the place of breathing
Section 3 observation of animal cells
1、 Observe the oral epithelial cell experiment P47
2、 The structure of animal cells
1. Cell membrane: control of material in and out
2. Nucleus: storing and transmitting genetic information
3. Cytoplasm: liquid, mobile
Chapter 2 cell life
Section 1 the life of cells needs material and energy
1、 Matter is made up of molecules, which are in constant motion
Molecules are not the smallest particles of matter. Molecules are made up of atoms. Atoms are the smallest units of matter, while cells are the structural and functional units of organisms
2、 Substances in cells
Organic matter (generally containing carbon, can be burned): sugars, lipids, proteins, nucleic acids, these are macromolecules
Inorganic matter (generally without carbon): water, inorganic matter, oxygen, etc. These are small molecules
3、 The cell membrane controls the material in and out, has the selectivity to the material, the useful material enters, the waste discharges
4、 Intracellular energy converters:
Chloroplast: photosynthesis is the process of hydration of carbon dioxide and carbon dioxide into sugar and oxygen
Mitochondria: respiration, is the "power plant" and "engine" in cells
Section 2 the nucleus is the genetic information base
1、 Genetic information exists in the nucleus
Example of Dolly sheep p55
2、 The carrier of genetic information in nucleus -- DNA
1. The structure of DNA is like a spiral ladder
2. A gene is a segment of DNA with specific genetic information
3、 DNA and protein make up chromosomes
1. The shape and number of chromosomes are totally different in different organisms
2. In the same species, the number and shape of chromosome keep a certain level
3. Chromosomes are easy to be dyed dark by basic dyes
4. The number of chromosomes should be kept constant, otherwise there will be serious genetic diseases
4、 The control center of a cell is the nucleus
The third cell produces new cells by division
1、 The growth of organisms from small is due to the growth and division of cells
2、 Cell division
1. Chromosome replication
2. The nucleus is divided into two equal nuclei
3. The cytoplasm is divided into two parts
4. Plant cells: the formation of new cell membranes and cell walls between protocells
Animal cells: two new cells are formed when the cell membrane is gradually invaginated. Chapter 3 how do cells form organisms
Section 1 the structure of animal body
1、 The concept of cell division and differentiation
3、 All kinds of cells formed by cell differentiation gather together to perform their functions. The cell group formed by the aggregation of cells with similar morphology and structure and same function is called tissue
4、 Several kinds of tissues are arranged together in a certain order and connected with each other to form a structure with a certain shape, which can complete a variety of functions to meet the needs of a certain aspect of plant life activities. Such a structure is called an organ
5、 Animal and human basic tissues can be divided into four types: epithelial tissue, connective tissue, muscle tissue and nerve tissue
6、 Four kinds of tissues are formed in a certain order, and one of them is the main organ
7、 Multiple organs in animal or human body can perform one or several physiological functions together and form a system in a certain order
8、 The basic structural levels of animals and human beings are: cells → tissues → organs → systems → animal bodies and human bodies
9、 P65 question 3
10、 Names of eight systems
Section 2 the structural levels of plant body
1、 Six organs of color flowering plants
1. Vegetative organs: root, stem and leaf 2. Reproductive organs: flower, fruit and seed
2、 Plant tissue
Meristem, protective tissue, vegetative tissue, transport tissue, etc
Section 3 organisms with only one cell
1、 Single cell organisms: yeast, paramecium, Chlamydomonas, Euglena, amoeba
2、 Paramecium
Structure: cilia, epimembrane, collecting tube, contractile vesicle, crissum, oral groove, food vesicle, cytoplasm, nucleus (macronucleus, micronucleus)
Function: Notes
3、 The relationship between single celled organisms and human beings
1. Useful: Notes
2. Harmful aspects: Notes
Unit 3 green plants in the biosphere
Section 1 algae, mosses and ferns
1、 The aerial part of fern is not stem, but compound leaf; the underground part is underground stem and root
2、 Pteridophytes have differentiation of root, stem, leaf and other organs, and also have transport tissue and mechanical tissue
3、 Spore is a kind of germ cell, sporangia can not be seen at any time, but can be seen in summer. When spore germinates, protoplast can be formed
4、 The economic significance of pteridophytes lies in: (1) some are edible; (2) some are medicinal; (3) some are ornamental; (4) some can be used as good green manure and fodder; (5) the remains of ancient pteridophytes have become coal after a long time
5、 There are two types of bryophytes: one is the differentiation of stems and leaves, but the stems are very small, and the leaves are small and thin, such as calabash moss and wallwort moss; the other is the flat thallus without differentiation of stems and leaves, such as Digitaria
6、 The roots of bryophytes are pseudoroots, which can't absorb water and inorganic salts, while the stems and leaves of bryophytes have no conducting tissues and can't transport water. Therefore, bryophytes can't be separated from the environment of boiling water
7、 Bryophytes grow intensively, and the gap between plants can store water. Therefore, bryophytes play a certain role in soil and water conservation of forest land and mountains
8、 Bryophytes are very sensitive to sulfur dioxide and other toxic gases, and it is difficult to survive in cities and factories with serious pollution. Bryophytes are used as indicator plants to monitor the degree of air pollution
9、 The main characteristics of algae are: simple structure, unicellular or multicellular individuals, no differentiation of roots, stems, leaves and other organs; chloroplasts in cells, which can carry out photosynthesis; most of them live in water
10、 The organic matter produced by algae through photosynthesis can be used as bait for fish and release oxygen