The scientific knowledge of junior high school should be summarized in every unit from grade one to grade three. Trouble! China Normal University Edition!

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Summary of life science review

The theme 1 constitutes the hierarchy of the life system.

It is suggested to grasp three lines:

1. Levels of life system: cells → tissues → organs → systems → biological individuals.

Population → Community → Ecosystem → Biosphere.

2. Adaptability of organisms to the environment: the morphology, structure, physiological functions and living habits of organisms are adapted to the environment.

3. Biodiversity on Earth: the diversity of biological species and the differences of the same species.

First, observe all kinds of creatures.

1. Basic characteristics of living things

(1) has a rigorous structure-all living things are made up of cells except viruses.

(2) Both of them have metabolic effects. (3) There is pressure.

(4) Growth phenomenon. (5) Both can reproduce and develop.

(6) Both of them have the characteristics of heredity and variation. (7) can adapt to a certain environment, but also can affect the environment.

2. Structure, principle and use of microscope

Microscope is the most commonly used observation tool in life science research, which can help people observe tiny objects or fine structures invisible to the naked eye.

(1) Structure of microscope:

(2) Imaging principle of microscope: the eyepiece sees the inverted image; The slide moves in the opposite direction to the target image. When you see the object in the field of vision, it is the lower left, and the specimen can only be moved to the center if it is moved to the lower left.

(3) How to use a microscope

Its operation steps are: taking the mirror → placing → aiming at the light → adjusting the focal length → placing the glass slide → observing. Before observation, turn the coarse focusing screw. When the lens barrel descends, the eyes must look at the objective lens from the side to avoid touching the slide, otherwise it will crush the slide and damage the objective lens (lens). When observing, you must slowly turn the coarse focus screw to make the lens barrel rise slowly, so as to avoid objects passing by or not being noticed at all.

(4) Calculate the total magnification of the observed object: the total magnification of the observed object = the magnification of the eyepiece × the magnification of the objective lens being used.

3. Species, forms and life characteristics of common organisms

(1) Common animal groups (2) Common plant groups

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4. Observe snails, learn to describe their morphology and living habits, and learn to use a magnifying glass.

5. Biodiversity and its significance: There are about 5 million kinds of creatures on the earth now, and human beings should protect these creatures.

(1) Meaning: There is a close relationship between creatures in nature, and any change of one creature will affect other creatures related to it.

(2) The reasons for the extinction of most species: habitat loss, deforestation, land reclamation at will, uncontrolled discharge of pollutants, etc.

Second, cells

1. Make a temporary film

When observing the microstructure of organisms with a microscope, the biological materials to be observed must be made into slide specimens so that light can pass directly. There are three kinds of slide specimens: slicing, smearing and loading.

(1) Make temporary slices of onion epidermal cells.

① Drop a drop of water in the center of a clean slide.

② Tear off a thin layer of epidermis from the inner epidermis of onion scales with tweezers and put it into water drops.

(3) flatten with tweezers and cover with cover glass. When covering the cover glass, let one side of the cover glass touch the water drop, lift the other end with tweezers, and then gently put down the glass to avoid bubbles.

(4) in order to observe clearly, dye with dilute iodine solution or red ink. Drop a drop of iodine solution on one side of the cover glass and suck it from the other side with absorbent paper to make the dye solution soak the whole specimen.

(2) making temporary human oral epithelial cells.

Preparation (cleaning, dropping physiological saline); Make (scratch a few times, smear; Cover glass); Dyeing (dropping iodine solution and absorbing water)

2. Cellular structure

(1) cells are the basic units of life activities.

The basic structure of cells: cell membrane, cytoplasm and nucleus.

Cell membrane: it can protect the internal structure of cells and control the entry and exit of substances.

Cytoplasm: the place where substances are synthesized and decomposed.

Nucleus: nearly spherical, containing genetic material.

But plant cells also have cell walls, vacuoles and chloroplasts, and animal cells generally do not have these structures, which is the main difference between animal cells and plant cells.

(2) Prokaryotic cells and eukaryotic cells: bacterial cells have no nucleus and belong to prokaryotes; The cells of plants, animals and fungi all have nuclei and belong to eukaryotes.

3. Cell division and its significance

(1) Cell division: Cell division refers to the process that one cell divides into two cells. In this process, the nucleus is divided into two parts, then the cytoplasm is divided into two parts, each part contains a nucleus, and finally a new cell membrane is formed in the center of the original cell. Plant cells also form new cell walls. The most important change in cell division is the change of chromosomes in the nucleus. In the process of cell division, chromosome replication doubles. With the progress of cell division, the chromosome is divided into two identical parts and enters two new cells respectively.

(2) The significance of cell division: the replication and even division of chromosomes are realized, and the genetic material contained in daughter cells and new cells is guaranteed to be the same. It is the basis for the growth, development and reproduction of all living things.

4. Cell growth and differentiation

(1) Cell growth: refers to the process in which cells grow from small to large. Biological growth refers to the increase in the number, volume and intercellular substance of cells in organisms.

(2) Cell differentiation: With the proliferation of cells, the number of cells increases, and the morphology and function of cells gradually differentiate, eventually forming cells with different shapes and functions. The change process of cells from general to special and from the same to different is called cell differentiation.

5. Tissues, organs and systems

(1) Tissue: Cells with the ability of continuous division, growth and differentiation can form cell groups with the same morphology and function. This cell group is tissue. The basic tissues of plants include protection tissue, transportation tissue, nutrition tissue, mechanical tissue, meristem and so on. The basic tissues of human body are epithelial tissue, connective tissue, muscle tissue and nerve tissue.

A, plant tissue:

Meristem: Cells have the ability to divide. Protection organization: it has protection function.

Nutritional tissue: It can store or synthesize nutrients. Transport organization: transport water, inorganic salts and nutrients.

Mechanical organization: plays an auxiliary role.

B, the main organizations of animals and people:

Epithelial tissue: it has protective effect. Connective tissue: It has the functions of support, connection, protection and nutrition.

Muscle tissue: It can contract and relax to produce movement. Nerve tissue: stimulation can produce excitement and conduction excitement.

(2) Organ: Different tissues gather together in a certain order to complete certain functions and form an organ. Angiosperms consist of six organs: roots, stems, leaves (vegetative organs), flowers, fruits and seeds (reproductive organs). The human body consists of heart, lungs, brain, stomach, bones, blood vessels and other organs.

(3) System: It can be combined with multiple organs that perform one or several physiological functions in a certain order to form a system. The human body consists of eight systems: digestive system, circulatory system, respiratory system, urinary system, reproductive system, nervous system, exercise system and endocrine system.

Multicellular organisms have obvious structural levels, from low to high: cells → tissues → organs → systems (animals) → individuals.

Three. Population, biota, ecosystem and biosphere

1. Units, methods and key tables of biological classification

Units and methods of biological classification: according to the characteristics of biological evolution and morphological structure, modern biologists divide organisms into seven levels: boundary, phylum, class, order, family, genus and species, of which boundary is the largest category.

The higher the classification level, the less similarity, and the lower the classification level, the more similarity.

2. Population

(1) Concept of population: A population refers to the sum of the same species living in the same place.

(2) Population characteristics: including population density, birth rate and mortality rate, age composition, sex ratio, etc. The change of population is closely related to these characteristics of population.

3. Biological communities

(1) The concept of biome: The sum of all kinds of organisms that are directly or indirectly related to each other in a certain natural area is called biome, or community for short.

(2) Community stratification: In the forest community, tall trees form tree layer, shrubs and small trees form shrub layer, herbs form herb layer, and plants such as moss and lichen form moss lichen layer, forming vertical stratification phenomenon. The distribution of animals in the community also has a similar vertical stratification phenomenon.

(3) the concepts of plant community and vegetation

The sum of all plants living in a natural area is called a plant community. The plant community covering the earth's surface is called vegetation. Divided into natural vegetation and artificial vegetation.

4. Ecosystem

The concept of (1) ecosystem

The unified whole formed by the interaction between biological community and its inorganic environment is called ecosystem. The largest ecosystem on the earth is the biosphere, which includes all living things on the earth and abiotic factors in their living environment. The biosphere can also be divided into many ecosystems of different sizes.

(2) the type of ecosystem

(3) the composition of the ecosystem

(4) Food chain and food web

In an ecosystem, a kind of connection between various organisms due to food relationship is called food chain. Many food chains are usually interwoven into a network called a food web.

(5) Functions of the ecosystem: Energy flow and material circulation are the main functions of the ecosystem, which are carried out simultaneously, interdependent and inseparable. The energy flow in the ecosystem begins after the green plants fix the solar energy in the body, and then it is transmitted along each trophic level of the food chain or food web, and finally it is lost in the form of heat energy during breathing. The energy flow is gradually decreasing in one direction, and the general transfer efficiency is 10-20%. The material flow in the ecosystem is endless, that is, some basic chemical elements that make up organisms can appear and circulate repeatedly between biological communities and inorganic environments.

5. Interaction between biology and environment

(1) Living things are influenced by abiotic factors in the environment, such as light, water, temperature, food and wind. , but also by other creatures.

Environmental factors affecting biological survival:

Abiotic factors (sunlight, temperature, water, atmosphere, soil, etc. ); Biological factors (intraspecific relationship, interspecific relationship)

Intraspecific relationship: refers to the relationship between individuals of the same species (intraspecific mutual assistance and intraspecific struggle)

Interspecific relationship: refers to the relationship between individuals or populations of different species.

* * * Habitat: The phenomenon that two animals that can live independently live together and benefit from each other (the relationship between hermit crab and anemone).

* * * Life: Two organisms * * * live together, depend on each other and benefit from each other. If separated, neither side or one side can survive (the relationship between algae and fungi).

On the other hand, biological activities (including human activities) have certain influence on inorganic environment and other organisms.

(2) Adaptation to the living environment

All living things have certain adaptability to their living environment, that is, the universality of adaptation. For example, the leaf thorns and fleshy stems of cactus adapt to arid environment; Adaptability of leaf morphological structure of sunny plants and shady plants to light intensity and water transpiration: the adaptability of earthworm morphological and structural characteristics to soil burrowing life; Adaptability of arctic fox and desert fox to environmental temperature. There are also protective colors (insects, arctic foxes, bears, etc. ), warning color (poisonous snake, wasp, etc. ) and mimicry (stick insects).

Topic 2 Metabolism of living things

First, the metabolism of green plants.

[Knowledge Network]

Three metabolism:

(1) Water metabolism: water absorption (root hair) → transportation (conduit) → utilization → loss (transpiration).

(2) Inorganic salt metabolism: inorganic salt absorption (root hair) → transportation (conduit) → utilization.

(3) Organic matter metabolism: organic matter production (photosynthesis) → transportation (sieve tube) → decomposition (respiration) → utilization.

Three functions: transpiration, photosynthesis and respiration.

1. the relationship between plants and mineral elements

The concept of (1) mineral elements

Mineral elements generally refer to elements except C, H, O, which are mainly absorbed by roots from soil, such as N, P, K, etc. Mineral elements usually exist in various inorganic salts in ionic form.

(2) The role of mineral elements in plants: ① It is used to synthesize some complex compounds, such as nitrogen, which is the main raw material for synthesizing many important substances such as protein and nucleic acid. ② Participate in the activities of enzymes and assume the function of regulating life activities.

(3) the role of mineral elements in agricultural production

Different crops need different mineral elements: the demand for inorganic salts is small at seedling stage, large at vigorous stage, and small at fruit and seed maturity. Therefore, reasonable fertilization should be carried out according to different kinds of crops and different growth and development stages.

(4) Important chemical fertilizer for plant growth

Important chemical fertilizer elements indicate the effect on plants after the lack of action, and the plant species that should be applied with this fertilizer more.

Nitrogen fertilizer N is an important component of protein, chlorophyll, enzymes and other substances. Sufficient nitrogen can make the leaves dark green, improve photosynthetic efficiency, grow healthily, the plants are short, the leaves are yellow, the growth is delayed, the plants are thin, and leafy crops such as Chinese cabbage and spinach are heading late.

Phosphorus fertilizer P can improve the ability of drought resistance, cold resistance, disease resistance, lodging resistance and acid and alkali resistance of plants, promote plant growth and development, promote flower bud differentiation, shorten flower bud differentiation time, thus promoting crops to bloom early and mature plants to be dark green.

And harvest fruit crops (such as tomatoes, peanuts and so on. ) with a little red

Potassium fertilizer K can improve the tolerance of plants to drought, low temperature, salt damage and other adverse environments, as well as the resistance to pests and lodging. The plant is short, and there are many brown spots on the leaves to harvest stem and root crops (such as sweet potatoes and potatoes).

2. The process of water absorption, utilization and loss by plants.

(1) The main part of plants to absorb water and mineral elements is the root hair area of root tips. This can be proved by the control experiment of normal plants after root tip removal.

(2) Whether plants can absorb water from the environment depends on the relationship between the solute mass fraction of environmental solution (such as soil solution) and the solute mass fraction of cell fluid of root hair cells. Therefore, in agricultural production, one-time fertilization should not be too much.

(3) the transport process of water and inorganic salts by plants

Root tip absorption → vessel transport in xylem of roots and stems → vessel in petiole → photosynthesis of mesophyll cells or transpiration loss of leaf stomata.

(4) The process of water utilization and loss by plants.

① Utilization of water by plants: Water absorbed by roots is transported to the aboveground parts of plants through conduits in roots, stems and leaves. Generally, only about 65,438+0% of the water that enters plants remains in plants and participates in photosynthesis and other life activities.

② the concept of transpiration

The phenomenon that water is lost from the surface of plants (mainly stomata on the leaves) to the outside in gaseous state is called transpiration. About 99% of the water entering plants is lost by transpiration, and only about L% is really used in various physiological processes and remains in plants.

The significance of transpiration: firstly, it provides power for plants to absorb and transport water; Second, it can promote the transportation of mineral elements; The third is to reduce the body temperature of plants, especially the surface temperature of leaves.

④ Practical application:

Transplanting with soil and watering to enhance water absorption function.

Cut off some branches and leaves, shade them, and transplant them in the evening as far as possible-reduce transpiration and prevent plants from dying of water loss.

3. Photosynthesis of green plants and its significance

(1) The concept of photosynthesis: Photosynthesis refers to the process that green plants use light energy to convert carbon dioxide and water into organic matter for storing energy and release oxygen.

(2) The process of photosynthesis can be summarized by the following reaction formula:

(3) The significance of photosynthesis

Photosynthesis has achieved two most important changes on the earth: one is to synthesize simple inorganic substances into complex organic substances and realize the transformation of substances; The second is to convert solar energy into chemical energy and store it in organic matter, so as to realize energy conversion.

① Photosynthesis provides material and energy sources for the survival of all living things.

② Photosynthesis is contrary to biological cell respiration and various combustion reactions. It consumes carbon dioxide and releases oxygen, so it plays a great role in maintaining the stability of oxygen and carbon dioxide content in the atmosphere.

4. The respiration of plants

(1) the concept of respiration: respiration (mainly aerobic respiration) refers to the process of oxidative decomposition of organic substances such as sugars to produce carbon dioxide and water with the participation of oxygen and the catalysis of related enzymes in plant cells, and at the same time release a lot of energy.

(2) The process of plant respiration: On the surface, the process of respiration seems to be just the opposite of photosynthesis, but respiration cannot be regarded as the reverse reaction of photosynthesis. Because respiration is another complicated process in life activities, its place and the enzymes it needs are different from photosynthesis. Moreover, photosynthesis generally exists only in green plants, and respiration exists in all living things. In addition, the energy released by breathing is the energy source of all life activities.

(3) Using germinated seeds to explore the respiration of plants.

The germination process of seeds is essentially a process of improving the level of cell respiration in seeds. Because the germinated seeds have strong respiration, they are good materials for studying the respiration of plants. In the experiment, we can test the consumption of oxygen by respiration by extinguishing burning wood, and test the release of carbon dioxide by clarifying limewater to make it turbid.

The difference between photosynthesis and respiration;

Photosynthetic respiration

(1) in chloroplasts of plants.

(2) under the light.

③ Absorb carbon dioxide and release oxygen.

④ Making organic matter and storing energy.

(5)CO2+H2O- organic matter +O2

(1) The plant survival part can be carried out.

(2) With or without light.

③ Absorb oxygen and release carbon dioxide.

(4) decompose organic matter and release energy.

(5) Organic matter +O2-→ CO2+H2O energy

The relationship between photosynthesis and respiration;

Photosynthesis provides matter for respiration, and respiration provides energy for photosynthesis. They are interdependent and antagonistic.

Second, the metabolism of the human body.

[Knowledge Network]

Material metabolism: the process of material transformation, synthesis and decomposition.

Metabolic energy metabolism: the process of energy storage, release, transfer and utilization.

Digestive system: digestion of food and absorption of nutrients.

Four respiratory systems: gas exchange

System circulation system: material transportation

Urinary system: urine formation and excretion of metabolic end products.

1. Food digestion and absorption

(1) Composition of digestive system

(2) Composition and function of food

Sugar: ① It is the most important energy-supplying substance for human cells.

② A component of human cells.

Protein: ① It is the main raw material for cell growth and repair.

② Provide energy for human life activities.

③ Participate in various physiological activities of the human body.

Fat: a substance that stores energy in an organism.

Water: ① An important part of cytoplasm.

② The basis of various physiological activities.

Inorganic salt: a substance necessary to form tissues and maintain normal physiological functions.

Vitamins: trace organic substances indispensable for maintaining normal physiological activities of human body.

Crude fiber: derived from plant food, it can absorb and retain water and assist the human body to digest and absorb food.

(3) Digestion and absorption of food

① Digestion includes physical digestion and chemical digestion. Physical digestion is mainly through tooth chewing and gastrointestinal peristalsis; Chemical digestion mainly uses digestive enzymes to change nutrients in food into absorbable substances through chemical changes.

② Digestion of various ingredients in food. Water, inorganic salts and vitamins in food can be directly absorbed without digestion; Dietary fiber can not be digested; Protein is eventually broken down into glycerol and fatty acids.

③ The small intestine is the main place for food digestion and absorption, and its corresponding structural characteristics are: (1) The small intestine is long and villi are formed on the inner wall, which can expand the surface area of the small intestine; (2) Small intestinal villi are rich in capillaries and lymphatic capillaries, which is beneficial to the absorption of nutrients; (3) The small intestine contains a variety of digestive enzymes secreted by digestive glands, which can thoroughly digest various ingredients in food.

2. The important role of enzymes in life activities

(1) The concept of enzyme: enzyme is a biocatalyst and a catalytic protein produced by living cells. Enzymes can make chemical reactions in organisms proceed quickly without changing themselves, similar to inorganic catalysts.

(2) Characteristics of enzymes

① High efficiency: The catalytic efficiency of enzyme is generally 107 ~ 10 13 times that of inorganic catalyst.

② Specificity: An enzyme can only catalyze the chemical reaction of one or a class of compounds.

③ Instability: High-temperature, low-temperature, peracid and overbase will all affect the enzyme activity. In other words, the catalysis of enzymes requires suitable conditions. Temperature and pH will affect the activity of enzyme.

(3) Functions of enzymes: Enzymes are necessary for normal metabolism of organisms.

3. The role of digestive enzymes in human digestion.

(1) Digestion process of various nutrients in food

Except water, inorganic salts and vitamins, all kinds of nutrients in food can be directly absorbed by the digestive tract. Other macromolecular organic compounds with complex structure and insoluble in water, such as sugar, protein and fat, must be digested in the digestive tract and decomposed into water-soluble organic molecules before they can be absorbed by the digestive tract wall. The digestion process of sugar, protein and fat must be completed under the catalysis of various digestive enzymes.

The digestion steps of starch, protein and fat and the types of related digestive juices can be summarized as follows:

Starch maltose glucose

alimentary canal

Digest starch protein fat

Oral cavity √××××

Stomach ×√×

Small intestine √√√

Protein amino acid

Fatty acid+glycerol

(2) The role of digestive enzymes in human digestion.

① Saliva in the oral cavity contains salivary amylase, and the oral cavity can decompose some starch in food into maltose.

② There is pepsin in acidic gastric juice, which can decompose protein into peptides.

③ Intestinal digestive juice includes intestinal juice, pancreatic juice and bile. Intestinal juice and pancreatic juice contain digestive enzymes, which can digest sugar, protein and fat respectively. Although bile does not contain digestive enzymes, it can emulsify fat and turn it into tiny particles, thus increasing the contact area between fat and various digestive juices, which is beneficial to the digestion of fat. So the small intestine is the main place to digest food.

4. Respiratory function of human body

(1) Structure of respiratory system: The respiratory system consists of respiratory tract and lungs.

The respiratory tract consists of nasal cavity, pharynx, larynx, trachea and bronchus.

The lung is located in the chest cavity, one left and one right, and consists of many alveoli.

What structural characteristics of alveoli are compatible with respiratory function? Large number, thin wall, and tightly wound capillaries around.

(2) The place and process of gas exchange when breathing.

① Concept of gas exchange: gas exchange is realized by gas diffusion, that is, a gas always diffuses from a place with high concentration to a place with low concentration until it reaches equilibrium.

② The concept of human respiration: The human body continuously oxidizes and decomposes organic matter, releases energy, supplies the needs of various activities of the human body, and constantly produces wastes such as carbon dioxide. Therefore, the human body must constantly absorb external oxygen and excrete carbon dioxide in time. This gas exchange process between the human body and the outside world is called breathing.

③ Complete breathing process: lung ventilation (exchange of external gas and gas in alveoli) → exchange of gas in alveoli and blood → transport of gas in blood → exchange of blood and tissue cells. Through this process, oxygen reaches the tissue for use by cells, and carbon dioxide produced by cells is excreted.

(2) Breathing provides the necessary conditions for the human body to use energy.

Through respiration, venous blood with low oxygen content becomes arterial blood with high oxygen content when it flows through the capillaries of alveoli (most of the oxygen in blood exists in the form of oxygenated hemoglobin). When arterial blood flows through the capillaries between tissues and cells, the concentration of oxygen in cells is lower than that of arterial blood, and the concentration of carbon dioxide is higher than that of arterial blood, because cells constantly consume oxygen and produce carbon dioxide during metabolism. Therefore, oxygen in blood quickly separates from hemoglobin and diffuses into cells through capillary walls, while carbon dioxide produced in cells diffuses into blood. After such gas exchange, arterial blood flowing through tissue cells becomes venous blood.

5. The production and excretion of urine in human body

(1) Formation process of urine in human body

① filtration function of glomerulus: The function of glomerulus in human body is similar to that of filter. When blood flows through the glomerulus, except blood cells and macromolecular protein, some substances such as water, inorganic salts, glucose and urea in plasma can be filtered out by the glomerulus. In the renal capsule cavity, protourine is formed. Except protein, other components and concentrations in urine are basically the same as those in plasma.

② Renal tubular reabsorption: When the original urine flows through the renal tubular, substances useful to human body can be reabsorbed into the blood, including all glucose, most water and inorganic salts. Therefore, renal tubular reabsorption is selective. After the original urine is reabsorbed, the remaining wastes, such as urea, uric acid, some water and inorganic salts, become urine.

(2) The role of human urination: Urine excretion not only plays a role in excreting waste, but also plays an important role in regulating the balance of water and inorganic salts in the body, maintaining the relative stability of the internal environment and maintaining the normal physiological functions of tissues and cells. Therefore, people should drink water in moderation every day.

6. Human blood circulation

(1) heart

① Structure of the heart: The heart is the hub of blood circulation, mainly composed of myocardium, which is divided into two unconnected parts. The left and right parts are divided into upper and lower cavities by valves. Therefore, the heart is divided into four chambers: left and right atria and left and right ventricles. Atrium is connected with vein, and ventricle is connected with artery. Between atrium and ventricle, between ventricle and artery, there are valves that can be opened and closed, which are called atrioventricular valve and arterial valve respectively.

Blood flow direction: only from atrium → ventricle → artery → vein, without reflux.

(2) Type, function, distribution and characteristics of blood vessels.

Vascular functional quantity division docking point

Arteries transport blood from the heart to all parts of the body, most of which are located in deeper parts. The wall of the tube is thick and elastic, and the blood flow velocity in the tube is fast.

Veins send blood back to the heart from all parts of the body, which are deep and shallow, with thin wall, small elasticity and large lumen.

The blood in the tube flows slowly.

Arteries and veins with the smallest capillary connection are widely distributed, and the tube wall is composed of a layer of epithelial cells.

The blood flow in the tube is very slow.

(3) Human blood circulation: It is proved that the contraction and relaxation of the heart are the driving force of blood circulation.

Blood circulation includes systemic circulation and pulmonary circulation. Of course, these two parts are actually interrelated and carried out simultaneously.

Systemic circulation: blood enters the aorta from the left ventricle, then flows through the arteries, capillary networks and veins of the whole body, and finally gathers in the superior vena cava and inferior vena cava and flows back to the right atrium. This blood circulation is called systemic circulation. In systemic circulation, when blood flows through the capillary network around various parts of the body and cells, oxygen and nutrients are given to cells, and wastes such as carbon dioxide produced by cells are taken away. Therefore, the bright red arterial blood from the left ventricle, after systemic circulation, becomes dark red venous blood and flows back to the right atrium.

Pulmonary circulation: the blood circulation from the right ventricle into the pulmonary artery, through the capillary network around the alveoli, and then back to the left atrium from the pulmonary vein is called pulmonary circulation. In pulmonary circulation, venous blood entering pulmonary artery from right atrium exchanges gas with air in alveoli when it flows through pulmonary capillary network. The carbon dioxide in the blood enters the alveoli, and the oxygen in the alveoli enters the blood to combine with hemoglobin, so the dark red venous blood becomes bright red arterial blood, which flows back to the left ventricle from the pulmonary vein.

The blood microcirculation of fish can be observed: arterioles → capillaries → venules.

7. Blood related knowledge

(1) Main components of blood and their functions

(2) hematopoietic function of bone marrow

All kinds of adult blood cells are derived from bone marrow, and some of them are even stored in bone marrow and released into the blood circulation regularly. Under normal circumstances, adult bone marrow hematopoiesis is limited to red bone marrow, but under abnormal circumstances, when hematopoiesis needs to be increased, yellow bone marrow without hematopoietic function can restore hematopoietic function. Bone marrow has hematopoietic function because there is a hematopoietic stem cell in bone marrow.

(3) ABO blood group and blood transfusion

① ABO blood group in human body: There are many blood group systems in human body, and ABO blood group system is the earliest one, which has an important relationship with clinical medicine. There are two kinds of lectins on red blood cells of blood, which are called lectin A and lectin B respectively. Serum contains two kinds of lectins which are relatively resistant to it, namely anti-A lectin and anti-B lectin. At the same time, everyone's serum does not contain lectin opposite to their own erythrocyte lectin.

② Blood transfusion

During blood transfusion, it is mainly considered whether agglutination reaction will occur between the red blood cells of the donor and the serum of the recipient. According to this principle, it can be inferred that the relationship between ABO blood types during blood transfusion is as follows ("+"means agglutination reaction, "one" means no agglutination reaction):

Blood donor's red blood cells and blood recipient's serum (containing lectin)

(containing lectin) Type 0 (anti-A, anti-B) Type A (anti-B) Type B (anti-A) Type A) AB (None)

Type 0 (None)

Type a (a)

Type b

Type AB (a, b) I

ten

ten

eleven

one

ten

eleven

ten

one

ten

However, blood transfusion between different blood types should not be too fast, otherwise lectin can not be diluted in time, which may cause agglutination reaction. Therefore, blood transfusion should be based on the principle of allogeneic blood transfusion.

(4) Agree that blood donation is a civic obligation.

8. Characteristics of material and energy changes in biological metabolism

(1) related concepts

① Substance metabolism refers to the process of substance exchange between organisms and the external environment and the transformation of substances in organisms.

(2) Energy metabolism refers to the process of energy exchange between organisms and the environment and the transformation of energy in organisms.

(3) Assimilation refers to the process that organisms transform nutrients obtained from the external environment into their own components and store energy.

(4) Alienation refers to the process that an organism decomposes a part of its constituent substances, releases its energy, and excretes the final product of decomposition.

(2) The characteristics of substance and energy changes in biological metabolism.

There are complex relationships among material metabolism, energy metabolism, assimilation and alienation in metabolism, as shown below.