Chapter II Steady State of Biological Individuals
The first section of the steady state of the human body
First, the physiological significance of steady state
1, internal environment:
(1) Single-celled organisms directly exchange substances and energy with the external environment, while human cells can only exchange substances and energy with the external environment through the internal environment.
(2) the composition of the internal environment:
intracellular fluid
Humoral plasma
Extracellular fluid tissue fluid
Lymphatic fluid (internal environment)
(3) Internal environment is the medium of material exchange between cells and external environment;
Cells can directly exchange substances with the internal environment, continuously obtain substances needed for life activities, and at the same time continuously discharge waste generated by metabolism. The process of material exchange between internal environment and external environment requires the participation of various organ systems in the body.
2. Steady state
(1) Concept: Under the adjustment of the nervous system and endocrine system, the body will make corresponding adjustments to various changes in the internal environment, so that the temperature, osmotic pressure, pH and various chemical components of the internal environment remain relatively stable, which is called steady state.
(2) Significance: Maintaining the internal environment within a certain range is a necessary condition for normal life activities.
(3) regulation mechanism-feedback regulation
Positive feedback: The feedback information plays the same role as the original input information, further enhancing the adjustment function of the output information.
Negative feedback: The feedback information plays the opposite role to the original input information and weakens the output information.
Second, thermoregulation.
1, the concept of body temperature: refers to the average temperature inside the human body.
2. Body temperature measurement site: rectum, mouth and armpit.
3. The reason why the body temperature is relatively constant: Under the simultaneous adjustment of the nervous system and endocrine system, the process of heat generation and heat dissipation of human body keeps dynamic balance.
Thermogenic organs: mainly liver and skeletal muscle.
Heat dissipation organs: skin (blood vessels, sweat glands)
4. Thermoregulation process:
(1) cold environment → cold receptor (in skin) → hypothalamic thermoregulation center.
→ Skin blood vessels contract, sweat secretion decreases (heat dissipation decreases),
Skeletal muscle tension increases, and adrenal glands secrete adrenal hormones (increased thermogenesis).
→ Body temperature remains relatively constant.
(2) Thermal environment → Thermoreceptor (in skin) → Hypothalamic temperature regulation center.
→ Skin blood vessels dilate and sweat secretion increases (heat dissipation increases).
→ Body temperature remains relatively constant.
5. The significance of constant body temperature: it is a necessary condition for normal life activities of human body, which is mainly reflected by regulating the activity of enzymes.
Third, the adjustment of water balance.
1, the dynamic balance of water in human body is achieved through the dynamic balance of water intake and discharge.
2. The main source of water in human body is diet, and a small part comes from the water produced in the process of material metabolism. Water is mainly discharged through the urinary system, and then some water can be discharged from the skin, lungs and large intestine. The main excretory organ of human body is kidney, and the basic unit of its structure and function is nephron.
3. Water regulation (osmotic pressure regulation of extracellular fluid): (negative feedback)
Process: too little water, too salty food, etc. → Increased osmotic pressure of extracellular fluid → Hypothalamic osmotic pressure receptor → Pituitary gland → Antidiuretic hormone → Increased absorption of water by renal tubules and collecting ducts → Decreased osmotic pressure of extracellular fluid and decreased urine output.
Summary: The regulation of water is mainly accomplished by the kidney under the regulation of nervous system and endocrine system. The main hormone is antidiuretic hormone, which is produced by hypothalamus and released by pituitary gland. Its function is to promote the reabsorption of water by renal tubules and collecting ducts, thus reducing the amount of urination.
Fourthly, the adjustment of inorganic salt balance.
1, the dynamic balance of inorganic salts in human body is achieved through the dynamic balance of inorganic salt intake and discharge.
2. Inorganic salts needed by human body mainly come from diet, and inorganic salts are excreted through urine, sweat and feces.
3. There are many kinds of inorganic salts needed by human body, such as Na+, K+, Ca2+, Zn2+, Fe3+, I- and so on.
4. Inorganic salt adjustment: (negative feedback)
Process: increase of blood potassium, decrease of blood sodium → secretion of aldosterone by adrenal cortex → increase of sodium absorption and excretion in renal tubules and collecting ducts → decrease of blood potassium and increase of blood sodium.
Conclusion: Inorganic salts are mainly regulated by endocrine system and kidney. The main hormone is aldosterone, which is secreted by adrenal cortex, and its main function is to absorb sodium and expel potassium.
Verb (abbreviation for verb) blood sugar regulation
1, meaning of blood sugar: glucose in plasma (normal fasting concentration: 3.9-6. 1mmol/L).
2. Sources and ways of blood sugar:
3. Hormones that regulate blood sugar:
(1) insulin: (hypoglycemic)
Secretion site: islet B cells
Mechanism of action:
① Promote blood sugar to enter tissues and cells, and oxidize and decompose in tissues and cells to synthesize glycogen and convert it into non-sugar substances such as fatty acids.
② Inhibit the decomposition of glycogen and the transformation of non-sugar substances into glucose (inhibit two sources and promote three ways).
(2) Glucagon: (Increase blood sugar)
Secretion site: islet A cells
Mechanism of action: promoting the decomposition of liver glycogen and the transformation of non-sugar substances into glucose (promoting two sources)
4. Adjustment of blood sugar balance: (negative feedback)
Increased blood sugar → insulin secretion by islet B cells → decreased blood sugar.
Decreased blood sugar → glucagon secreted by islet A cells → increased blood sugar.
5, blood sugar imbalance: too low-hypoglycemia; Hyperglycemia-diabetes
6. Diabetes
Etiology: islet B cells are damaged, resulting in insufficient insulin secretion.
Symptoms: drinking more, eating more, urinating more, losing weight (three more and one less)
Prevention and treatment: regulating diet, taking oral hypoglycemic drugs and injecting insulin.
Detection: Lin Fei reagent, urine sugar test paper.
Sixth, maintain the human body's homeostasis through immunization.
1, composition of immune system:
Immune organs: tonsils, thymus, spleen, lymph nodes, bone marrow, etc.
Lymphocytes: B lymphocytes, T lymphocytes.
Immune cell macrophage
dendritic cell
Immune molecules: antibody, cytokine, complement.
2. Immune type:
Nonspecific immunity (congenital, with anti-epidemic effect on various pathogens)
The first line of defense: skin, mucosa and their secretions.
The second line of defense: phagocytosis, antibacterial protein and inflammatory reaction.
Specific immunity (acquired, resistance to pathogens)-the third line of defense
humoral immunity
cytoimmunity
3. Humoral immunity: an immune mode in which B lymphocytes produce antibodies to achieve immune effect.
antigenic stimulation
↓
B lymphocytes proliferate and differentiate into effector B cells.
Memory cells proliferate and differentiate into effector B cells when the same antigen is stimulated again.
↓
Effector B cells secrete antibodies.
↓
Antibody clearance antigen
4. Cellular immunity: an immune method that exerts immune function through T lymphocytes and cytokines.
Stimulation of target cells (cells invaded by antigens) or macrophages that have swallowed antigens.
↓
T lymphocytes proliferate and differentiate into effector T cells.
Memory cells → The same target cells proliferate and differentiate into effector T cells when stimulated again.
↓
Effector T cells lyse target cells until they die,
(effector T cells release some cytokines (such as interferon) to enhance the role of immune cells)
↓
Antigens released into body fluids are eliminated by antibodies in humoral immunity.
5, the difference between humoral immunity and cellular immunity:
* * * Similarity: It belongs to specific immunity against an antigen.
Distinguish humoral immunity from cellular immunity
Host cells (i.e. target cells) whose target antigens are invaded by antigens.
Mode of Action The antibody produced by effector B cells specifically binds to the corresponding antigen 1, and effector T cells are in close contact with the target cells.
2. The role of cytokines released by effector T cells in enhancing cellular immunity.
6. AIDS:
(1) Name of disease: AIDS
(2) Name of pathogen: human immunodeficiency virus (HIV), whose genetic material is two single-stranded RNA.
(3) Pathogenesis: After HIV enters human body, it mainly attacks T lymphocytes, paralyzing human immune system.
(4) Transmission route: blood transmission, sexual contact transmission and mother-to-child transmission.
Section 2 Adjustment of Human Life Activities
First, the human nerve regulation.
1. The basic structure and functional unit of neuromodulation is neurons.
The function of neurons: receiving stimulation produces excitement, conducting excitement, and then regulating other tissues.
Structure of neuron: It consists of cell body, dendrites (short) and axons (long). The latter two are collectively called nerve fibers.
2. Reflection: It is the basic activity mode of the nervous system. It refers to the regular response of animals or human bodies to changes in internal and external environment with the participation of the central nervous system.
3. Reflex arc: it is the structural basis and functional unit of reflection activity.
Receptor: sensory nerve endings and various specialized structures connected with them, which are excited when stimulated.
afferent nerve
Composition of nerve center: In the gray matter of brain and spinal cord, the cell bodies of neurons with the same function gather together.
efferent nerve
Effector: Motor nerve endings and their controlled muscles or glands.
4. Transmission of excitement on nerve fibers
(1) Excitement: It refers to the process that some tissues (such as nerve tissues) or cells in an animal or human body change from a relatively static state to a remarkably active state after feeling external stimuli.
(2) Excitement is conducted along nerve fibers in the form of electrical signals, which is also called nerve impulse.
(3) the conduction process of excitement: at rest, the membrane potential is positive outside and negative inside → stimulated; In the excited state, the potential outside the membrane is negative and positive → excited part and unactivated part form local current due to potential difference (outside the membrane: unactivated part → excited part; Inside the membrane: excited part → unexcited part) → excite the unexcited part.
(4) The conduction direction of excitement: two-way.
5, the transmission of excitement between neurons:
The excitation transmission between (1) neurons is realized through synapses.
Synapse: including presynaptic membrane, synaptic space and postsynaptic membrane.
(2) Transmission direction of excitement: Since neurotransmitters only exist in synaptic vesicles of synaptosomes, excitement is between neurons.
Transmission (that is, at the synapse) is unidirectional, and it can only be: presynaptic membrane → synaptic gap → postsynaptic membrane.
(Axon of the last neuron → cell body or dendrite of the next neuron)
6. Advanced functions of the human brain
(1) Composition and function of human brain;
Brain: The cerebral cortex is the highest center for regulating body activities, and it is also the structural basis of higher nervous activity. It consists of advanced centers such as language, hearing, vision and movement.
Cerebellum: It is an important center of movement regulation and maintains the balance of the body.
Brainstem: There are many important life activity centers, such as respiratory center.
Hypothalamus: It has a thermoregulatory center and osmotic pressure receptors, and is the general center for regulating endocrine activities.
(2) Language function is a unique advanced function of human brain.
The position and function of language center;
Written language center → agraphia (can listen, speak and read, but can't write)
Motor language center → motor aphasia (listening, reading and writing, but not speaking) → auditory aphasia (speaking, writing and reading, but not listening) → visual language center → alexia (listening, speaking and writing, but not reading).
Second, the hormone regulation of the human body
1. Hormone regulation plays an important role in body fluid regulation.
2. The main hormones in the human body and their functions
The main role of hormone names in hormone secretion sites
Hypothalamic antidiuretic hormone regulates water balance and blood pressure.
A variety of hormones release hormones to regulate endocrine and other important physiological processes.
Pituitary growth hormone promotes the synthesis and growth of protein.
A variety of gonadotropins control the activities of other endocrine glands.
Thyroid hormone promotes metabolic activity; Promote growth and development (including the development of the central nervous system) and improve the excitability of the nervous system;
Thymic hormone promotes the development of T lymphocytes and enhances the function of T lymphocytes.
Adrenal hormones in adrenal gland are involved in many life activities, such as stress response and thermoregulation.
Insulin and glucagon regulate the dynamic balance of blood sugar.
Ovarian estrogen promotes the development of female sexual organs, the development and ovulation of eggs, and stimulates and maintains secondary sexual characteristics.
Testicular androgen promotes the development of male sexual organs and the production of sperm, and stimulates and maintains male secondary sexual characteristics.
3, the relationship between hormones:
Synergism: such as thyroid hormone and growth hormone.
Antagonism: such as insulin and glucagon.
Section 3 Management of Animal Hormones
◆ Application of animal hormones in production
What is often used in production is not animal hormones themselves, but hormone analogues.
1, aphrodisiac improves the pregnancy rate of fish: Use aphrodisiac to induce fish to estrus and lay eggs to improve the pregnancy rate of fish.
2. Synthetic insect hormones to control pests: A certain amount of sex attractants (sex pheromone analogues) can be sprayed in the field to interfere with the normal mating of male and female insects.
3, castrate pigs and other animals to increase production: inject growth hormone into some meat animals to accelerate their growth. Castration of pigs reduces the content of sex hormones, thus shortening the growth cycle and increasing the yield.
4. Synthetic insect hormones can improve the yield: juvenile hormones can be sprayed artificially to prolong the larval stage and improve the yield and quality of silk.
Section 4 Regulation of Plant Life Activities
1, the discovery of auxin
(1) Darwin's experiment:
Experimental process:
① Under unilateral illumination, the coleoptile bends and grows towards the light source-phototropism;
(2) Cut off the tip of the coleoptile and the coleoptile will not grow;
(3) opaque tin foil paper covers the top of the coleoptile, and the coleoptile grows upright;
(4) The opaque tin foil cap covers the lower end of the coleoptile, and the coleoptile bends and grows towards the light source.
(2) Winter's experiment:
Experimental process: put the agar block touching the top of the coleoptile on the side of the coleoptile with the top cut off, and the coleoptile bends to the opposite side to grow;
The agar block that does not touch the top of the coleoptile is placed on the side of the coleoptile with the top cut off, and the coleoptile does not grow.
(3) Pueraria experiment: Plant growth promoting substances were isolated, identified as indoleacetic acid and named as auxin.
Summarize three experimental conclusions: the synthesis site of auxin is the top of coleoptile;
The photosensitive part is the top of the coleoptile;
The action site of auxin is below the top of coleoptile.
2. Explanation of phototropism of plants
On the one hand, it affects the distribution of auxin, so that the auxin in the backlight side is more than that in the smooth side, and the cells in the backlight side are elongated faster than those in the smooth side. As a result, the stem bends and grows in the direction of the light source.
2. Method of judging coleoptile growth
See if there is auxin, and it will not grow long.
Second, see if it can be transported downward, but not long.
Third, see if it is evenly conveyed downwards.
Unification: vertical growth
Uneven: curved growth (curved to the side with less auxin)
3. Auxin production sites: buds, leaves and developing seeds.
Transportation direction of auxin: transverse transportation: light side → backlight side.
Polar transportation: upper form → lower form
(The mode of transportation is active transportation)
Distribution of auxin: It exists in all organs, concentrated in buds, meristems at the top of roots, developing seeds and fruits, etc.
4. Physiological functions of auxin:
Auxin plays a dual role in regulating plant growth. Generally speaking, low concentration promotes plant growth, while high concentration inhibits plant growth (the concentration is subject to the optimal concentration of auxin in each organ).
Different organs of the same plant have different responses to auxin concentration, and the sensitivity from high to low is: root, bud, stem (see right).
The promotion and inhibition of auxin on plant growth are related to the concentration of auxin, the types of plant organs and the age of cells.
The apical advantage is that the terminal bud is long and the lateral bud is inhibited. The reason is that the auxin produced by the terminal bud is transported downwards, which makes the auxin concentration in the lateral bud near the top higher, thus inhibiting the growth of the lateral bud in this part.
5. Application of auxin analogues in agricultural production;
Promoting rooting of cuttings [experiment];
Prevent falling flowers and fruits;
Promoting fruit development (spraying auxin analogues on unpollinated pistil stigma to promote ovary development and fruiting, forming seedless tomatoes);
Controlling gender differentiation (promoting flower bud differentiation into female flower, thereby increasing yield)
6, other plant hormones
The main function of the name
Gibberellin promotes cell elongation, plant height and fruit growth.
Cytokinins promote cell division.
Abscisic acid promotes the senescence and abscission of leaves and fruits.
Ethylene promotes fruit ripening.
7. The differentiation of plant cells, the occurrence, development, maturity and senescence of organs, and the growth of the whole plant are all the results of the coordination and joint regulation of various hormones.
Chapter III Succession of Biological Communities
Section 1 The basic unit of biological community-population
1, the concept of population: all individuals of the same species occupy a certain space in a certain period of time. Population is the basic unit of biological community.
Population density (the most basic quantitative characteristic of population)
Birth rate and death rate
Quantitative characteristics age structure
Ratio of male to female population
2. Characteristic mobility and mobility of population.
Spatial characteristics
hereditary feature
3. Methods of investigating population density:
Sample method: a method of estimating the overall average density by using the average density of several samples (random sampling).
Mark recapture method:
4. The law of population growth.
"J" curve of population growth: Nt= N0λt
(1) Conditions: Under ideal conditions such as adequate food (nutrients), suitable space conditions, suitable climate and invincibility.
(2) Characteristics: The number of individuals in the population is increasing; Constant growth rate
The "S" curve of population growth;
(1) Condition: In a limited environment, the population density increases, the competition among individuals within a species intensifies, and the number of predators increases.
(2) Characteristics: When the number of individuals in the population reaches the maximum value (k value) allowed by environmental conditions, the number of individuals in the population will not increase; The population growth rate changes, with the fastest growth rate at K/2 and 0 at k.
(3) Application: After the habitat of the giant panda is destroyed, the range of activities is reduced due to the decrease of food, and its K value becomes smaller. Therefore, establishing nature reserves, improving habitat environment and increasing K value are the fundamental measures to protect giant pandas. The control of harmful animals such as rats should reduce their K value.
5. The significance of studying the change of population number: it is of great significance to the prevention and control of harmful animals, the protection and utilization of wildlife resources, and the rescue and recovery of endangered animal populations.
6.[ Experiment: Dynamic Changes of Yeast Population in Culture Solution]
Planning and experimental methods: cultivate a yeast colony → observe with a microscope, count the number of yeasts in 10ml culture solution within 7 days with a "blood cell counting plate" → calculate the average value, and draw a "yeast colony growth curve".
The results showed that the environmental conditions such as space and food could not be met indefinitely, and the number of yeast population increased in an "S" curve.
Section II Composition of Biological Communities
1. The concept of biological community: a collection of various biological populations that occupy a certain space at the same time and are directly or indirectly related to each other. Community is composed of certain animal, plant and microbial populations.
2. Biological community structure
Community structure is formed by the interaction of various populations in the community during the evolution process, which mainly includes vertical structure and horizontal structure.
(1) Vertical structure: refers to the stratification phenomenon of the community in the vertical direction. Due to the uneven distribution of ecological factors-light in the community, plants are divided into tree layer, shrub layer and herb layer from high to low. Animal stratification is mainly due to the different levels of food and microenvironment in the community.
(2) Horizontal structure: refers to the horizontal pattern or flaky distribution of various groups in the community. Influencing factors: topography, light, humidity, human and animal influence, etc.
3. Significance: The ability of biological utilization of environmental resources has been improved.
Section III Succession of Biological Communities
1, main inheritance:
(1) Definition: Biological succession occurs on the bare land where there was no biological growth or biological growth but was completely eliminated.
(2) Process: lichen stage → herb stage → shrub stage → forest stage.
2. Secondary succession
(1) Definition: When a community is disturbed by flood, fire or human activities, the vegetation in the community is seriously damaged, and the exposed land is called secondary bare land. The biological succession that began in the secondary bare land is called secondary succession.
(2) External factors causing secondary succession:
Natural factors: fire, flood, pests and diseases, severe cold.
Human activities (main factors): excessive logging, grazing, reclamation and mining; Completely cut down or burned forests, abandoned farmland
3. The invasion and settlement of plants (including the reproduction of seeds and fruits) is the primary condition for the formation of communities and the main basis for the succession of plant communities.
Chapter IV Steady State of Ecosystem
Section 1 Ecosystem and Biosphere
1, the concept of ecosystem:
Ecosystem refers to an ecological functional unit formed by the interaction and interdependence of biological components (communities) and abiotic components (inorganic environment) in a certain space through material circulation, energy flow and information transmission.
The biggest ecosystem on the earth is the biosphere.
3. Ecosystem types:
It can be divided into aquatic ecosystem and terrestrial ecosystem. Water ecosystem mainly includes marine ecosystem and fresh water ecosystem. Terrestrial ecosystems include natural ecosystems such as frozen primitive ecosystems, desert ecosystems, grassland ecosystems, forest ecosystems, and artificial ecosystems such as agricultural ecosystems and urban ecosystems.
4, the structure of the ecosystem
(1) composition:
Abiotic components: inorganic salts, sunlight, temperature, water, etc.
Producer: mainly green plants (the most basic and key component)
Green plants synthesize inorganic substances into organic substances through photosynthesis.
Consumers of biological components: mainly animals.
Decomposer: mainly saprophytic bacteria and fungi, including saprophytic animals such as earthworms.
They can decompose animal and plant debris, feces and so on. Finally, the organic matter is decomposed into inorganic matter.
(2) Nutritional structure: food chain and food web.
The same organism can occupy different trophic levels in different food chains.
Plants (producers) are always the first trophic level;
Phytophagous animals (primary/primary consumers) are the second trophic level;
The trophic levels of carnivores and omnivores are not static. For example, when owls prey on mice, they are in the third trophic level. Owls are in the fourth trophic level when they prey on insect-eating birds.
Section II Steady State of Ecosystem
I. Energy flows in ecosystems
1, process
2. Features:
One-way flow: the energy in the ecosystem can only flow from the first trophic level to the second trophic level, and then to the next trophic level in turn, and cannot flow reversely or circularly.
Gradually decreasing: energy decreases step by step in the process of flowing along the food chain, and the transmission efficiency of energy between two adjacent trophic levels is10%-20%; It can be represented by an energy pyramid.
In an ecosystem, the more trophic levels, the more energy consumed in the process of energy flow.
3. The significance of studying energy flow:
(1) can help people plan and design artificial ecosystems scientifically and make the most effective use of energy.
(2) It can help people to rationally adjust the energy flow relationship in the ecosystem, so that energy can flow to the most beneficial part of human beings continuously and efficiently. For example, in farmland ecosystem, weeds must be removed to prevent crop diseases and insect pests.
Second, the material cycle in the ecosystem-carbon cycle
1, carbon mainly exists in the form of CO2 and carbonate in inorganic environment; Carbon exists in all kinds of organisms in the biological community in the form of carbon-containing organic matter, and is transmitted in the biological community through the biological chain; The circulating form of carbon is carbon dioxide.
2. The main way for carbon to enter biological community from inorganic environment is photosynthesis; The main ways for carbon to enter inorganic environment from biological communities are the respiration of producers and consumers, the decomposition of decomposers and the production of CO2 by burning fossil fuels.
3. Process:
Third, information transmission in the ecosystem.
1. The basic functions of an ecosystem are material circulation, energy flow and information transmission.
2, the main forms of information transmission in the ecosystem:
(1) Physical information: light, sound, heat, electricity, magnetism, temperature, etc. Such as phototropism of plants.
(2) Chemical information: sex pheromone, warning pheromone, urine, etc.
(3) Behavior information: dancing, sports, etc. Animals are courting.
(4) Nutritional information: the quantity and types of food, etc. Such as food chains and food webs.
3, the role of information transmission in agricultural production:
First, increase the output of agricultural and livestock products, such as short-day treatment can make chrysanthemum blossom ahead of schedule;
The second is to control harmful animals, such as spraying synthetic pheromone analogues to interfere with pest mating.
Fourth, the stability of the ecosystem.
1. Concept: The ability of an ecosystem to maintain or restore the relative stability of its own structure and function is called the stability of the ecosystem.
2. The reason why the ecosystem can remain relatively stable is because it has the ability of self-regulation. Self-regulating energy of ecosystem
Powerful. The foundation is negative feedback. The more kinds, the more complex the nutritional structure and the greater the self-regulation ability.
3. The stability of ecosystem is relative. When large-scale disturbance or external pressure exceeds the self-renewal of the ecosystem
And it may lead to the destruction of ecosystem stability and even the collapse of the system.
4, measures to improve the stability of the ecosystem:
On the one hand, it is necessary to control the degree of interference with the ecosystem, and the utilization of the ecosystem should be moderate, and it should not exceed the self-regulation ability of the ecosystem;
On the other hand, for the ecosystem with high utilization intensity, corresponding material and energy input should be implemented to ensure the coordination of the internal structure and function of the ecosystem.
6, when making ecological bottle should pay attention to:
① The environmental protection bottle must be transparent;
(2) There should be a nutritional relationship between the organisms put in the ecological bottle, and the quantity ratio should be reasonable;
③ The water in the ecological bottle should account for 4/5 of its volume, leaving a certain space and air;
④ Ecological bottles should be sealed;
⑤ The ecological bottle should be placed in a well-lit place, but it should avoid direct sunlight;
⑥ Don't move the eco-bottle at will before the end of the study.
Chapter V Protection of Ecological Environment
1. The essence of environmental problems caused by population growth is that human activities exceed the carrying capacity of the environment and destroy the structure and function of the ecosystem on which human beings depend.
2. Global eco-environmental problems mainly include: global climate change, water shortage, ozone layer destruction, acid rain, soil desertification, marine pollution, sharp decline of biodiversity, vegetation destruction, soil erosion and environmental pollution.
3. Biodiversity includes three levels: genetic diversity (all genes owned by all living things), species diversity (all animals, plants and microorganisms in the biosphere) and ecosystem diversity.
4. Significance of biodiversity protection: Biodiversity is the basis of human survival and development, and is of great significance to biological evolution and maintaining the stability of the biosphere. Therefore, for the sustainable development of mankind, biodiversity must be protected.
5. Biodiversity conservation measures:
(1) In-situ conservation: Nature reserves and national forest parks are places for in-situ conservation of biodiversity.
(2) Ex-situ conservation: zoos, botanical gardens and endangered species protection centers.
(3) Strengthen publicity and law enforcement.
(4) Establish sperm bank and seed bank, and use biotechnology to protect the genes of endangered species.