Traditional Culture Encyclopedia - Weather forecast - Biogeographic review materials

Biogeographic review materials

Geographical natural environment

First, the largest continent in the world.

1. Location of the Earth: Most of Asia is located in the Eastern Hemisphere and the Northern Hemisphere.

2. Close to the ocean: the Arctic Ocean in northern Asia, the Pacific Ocean in the east and the Indian Ocean in the south.

3. Continent and dividing line: Northwest Asia is bounded by Ural Mountain, ural river, Caspian Sea, Caucasus Mountain, Black Sea, Turkish Strait and Europe; Southwest Asia is bounded by Suez Canal and Africa; South faces Oceania across the sea; The northeast faces North America across the Bering Strait.

4. Asia is the largest continent in the world, with the widest latitude and the farthest distance from east to west.

5. Asia Division: Asia is divided into East Asia, Southeast Asia, South Asia, West Asia, Central Asia and North Asia according to geographical location.

China is located in East Asia, which also includes North Korea, South Korea, Japan and Mongolia.

7. China borders North Asia to the north, West Asia and Central Asia to the west, South Asia to the southwest and Southeast Asia to the south.

Second, topography and rivers.

1, Asian topographic features: the ground is undulating, high in the middle and low around; The terrain is complex and diverse, mainly plateaus and mountains.

2. Major rivers and oceans: ob river, Yenisei River and Lena River flow into the Arctic Ocean; The Yellow River, the Yangtze River and the Meigong River flow into the Pacific Ocean, and the Ganges River flows into the Indian Ocean.

3. Distribution characteristics of rivers: Most rivers originate from the mountains and plateaus in the middle and flow radially to the surrounding oceans. The reason is that the terrain in Asia is high in the middle and low around.

4. Lake: Caspian Sea ~ ~ The largest lake in the world, saltwater lake; Lake Baikal ~ ~ the deepest freshwater lake with the largest storage capacity in the world; Dead sea ~ ~ the lowest point of the world land.

Third, the complex climate.

1. Climate characteristics: complex and diverse, with remarkable monsoon climate and the widest continental climate distribution.

2. Climate influencing factors: latitude factors ~ ~ Asia spans tropical, temperate and cold zones, and the higher the latitude, the lower the temperature; Land and sea factors ~ ~ Asia is close to the ocean on three sides, with more precipitation in the east and south and less precipitation in the central and western regions; Topographic factors ~ ~ Qinghai-Tibet Plateau and Pamirs have high altitude, resulting in plateau mountain climate.

3. Main climate types: tropical rain forest climate, tropical monsoon climate, subtropical monsoon climate, temperate monsoon climate, temperate continental climate, tropical subtropical desert climate, Mediterranean climate, plateau mountain climate and cold zone climate.

4. temperate continental climate: it is the most widely distributed climate type in Asia, covering central and western Asia. Its climate is characterized by long and cold winters, short and warm summers, and scarce precipitation throughout the year.

5. Monsoon climate: It is mainly distributed in the east and south of Asia, and is characterized by large seasonal changes in wind direction and seasonal changes in precipitation throughout the year. The disadvantage is that it is prone to droughts and floods.

6. Characteristics of climate distribution in Africa: with the equator as the center, the climate types are symmetrically distributed in the north and south; The tropical climate is dominant, and the tropical rain forest and savanna climate are widely distributed.

cultural context

First, the most populous continent.

In 2000, the total population of the world was 6.055 billion, and the population of Asia was about 3.68 billion, accounting for 665.438+0% of the total population, making it the most populous continent.

2. Countries with a world population of over 6,543.8 billion: China, India, the United States, Indonesia, Brazil, Pakistan, Bangladesh, Russia, Japan and Nigeria.

There are six in Asia: China, Indian, Indonesian, Pakistani, Bangladeshi and Japanese.

Except Antarctica, the population of all continents in the world is in descending order.

Asia, Africa, Europe, Latin America, North America, Oceania, Antarctica

4. Except Antarctica, the average natural population growth rate is from high to low.

Africa, Latin America, Asia, Oceania, North America, Europe,

Asia has a large population, which puts great pressure on resources and environment.

Japan

1. Japan is an island country in the northwest Pacific Ocean. Its territory consists of four big islands, including Hokkaido, Honshu, Shikoku and Kyushu, and thousands of small islands.

Surrounding waters, the capital is Tokyo.

2. The terrain of Japan is dominated by mountains and hills, and the plain area is narrow. The highest mountain is Mount Fuji, which is a famous active volcano. Japan is located.

There are many volcanic earthquakes at the junction of Asia-Europe plate and Pacific plate. Transportation is mainly by sea.

3. Japan is located in the middle latitude, and its climate is dominated by subtropical monsoon climate and temperate monsoon climate.

4. Japan is rich in water resources and has a high forest coverage rate.

Japan is short of natural resources, and the raw materials and fuels needed for its development mainly depend on imports.

6. Japan is the only developed country in Asia, with strong scientific and technological strength, most of its products are sold to the international market, and its economy is highly dependent on foreign countries.

Japan's industrial layout is coastal. In order to facilitate the introduction of raw materials, export industrial products, reduce transportation costs and reduce costs,

Japan's industries are mainly distributed along the Pacific coast and the Seto Inland Sea coast.

Southeast Asia

First, the location of the intersection:

Southeast Asia: Indian zhina Peninsula and Malay Archipelago.

Malacca Strait is an important sea passage: it is located between the Malay Peninsula and Sumatra Island, and it is an important passage from the Indian Ocean to the Pacific Ocean and from Asia to Oceania. Second, the tropical climate and agricultural production:

Climate characteristics of tropical rain forest: high temperature and rainy all year round; Distribution: Southern Malay Peninsula and Malay Archipelago.

Tropical monsoon climate characteristics: high temperature all year round, concentrated precipitation in rainy season and uneven seasonal distribution; Distribution: zhina Peninsula and northern Malay Peninsula.

Agricultural production: rice (Thailand, Vietnam and Myanmar are important rice exporters in the world), rubber (Thailand is the world's largest rubber producer), palm oil (Malaysia is the world's largest palm oil producer), coconut (Malaysia is the world's largest producer and the Philippines is the largest exporter) and banana (the Philippines is the largest producer).

The favorable conditions for developing rice production in the southeast are: high temperature and rainy climate, fertile land along the Yangtze River and the downstream delta plain, abundant irrigation water, long history of rice planting and sufficient labor force.

Third, mountains and rivers alternate with each other, showing a columnar distribution.

Four, the most concentrated areas of overseas Chinese:

Race: Most of them are yellow.

The area where overseas Chinese are most concentrated.

Rich in tourism resources

India

The largest country in South Asia.

Topographic features of India: The three landforms are divided into three topographic regions, namely Himalayan Mountains in the northwest, Ganges Plain in the middle and Deccan Plateau in the south. Most of the territory is below 65,438+0,000m above sea level.

The second most populous country: the population has exceeded 654.38+0 billion.

Ancient world civilization: one of the three cradles of Asian civilization.

Tropical monsoon climate is dominant: tropical monsoon climate is characterized by high temperature all year round, with summer precipitation concentrated in June-September and uneven seasonal distribution of precipitation.

Monsoon and precipitation: frequent droughts and floods.

Influence of monthly wind direction on precipitation

The northeast has a light wind in January and a dry season.

It is windy in the southwest in July and rainy season.

Flood and drought

The change of southwest wind comes early and retreats late, strong wind comes late and retreats early, and the wind force is insufficient.

Topographic precipitation in crop distribution area

There are many plains in the Northeast Peninsula and many rice areas along the coast.

There are almost no plateaus and mountains in the upper reaches of Ganges River in the northwest of Maidegan Plateau.

World agricultural power

Traditional industry: iron and steel industry

Summary of resource status of distribution center in industrial sector

Iron and Steel Industry Kolkata Coal, Iron and Manganese

Cotton textile industry Mumbai, New Delhi, Bangalore cotton

Hemp textile industry

High-tech industries: atomic energy, aerospace and computer software are developed.

Industrial center is close to the origin of raw materials, that is, the principle of proximity. Such an industrial layout can save freight and reduce costs, so the factory should be built near the origin of raw materials or the consumer market.

Russia

1. Russia is the largest country in the world, with a length of 1000 kilometers from east to west and a width of about 4,000 kilometers from north to south, with an area of17,075,400 square meters.

Kilometers, the territory spans Asia and Europe. The capital is Moscow.

2. The main landforms of Russia are Eastern Europe Plain, Western Siberia Plain, Central Siberia Plateau and Eastern Siberia Mountain from west to east.

3. The Volga River in Russia is the longest inland river in the world, and Lake Baikal is the deepest lake and a freshwater lake in the world.

4. Russia is located in the middle and high latitudes, with a temperate continental climate, with long and cold winters and short and warm summers.

Siberia, a part of Asia, is the source of cold air in winter, with low annual average temperature.

5. Find out the main Russian rivers on the map: ob river, Yenisei River and Lena River. (All injected into the Arctic Ocean from south to north)

6. Russia is rich in natural resources and developed in heavy industry.

7. Russia has a complete transportation department, with developed railway, highway, aviation, inland river, ocean and pipeline transportation, but the transportation lines are in the European part.

And parts of Asia are unevenly distributed.

Middle East.

1. In southwest Asia and northeast Africa, the Middle East is located in the land of "three continents and five seas". The three continents refer to Asia, Europe and Africa, and the Caspian Sea in the five seas is a lake. The Middle East includes West Asia (except Afghanistan) and Egypt in North Africa.

2. It is the region with the largest oil reserves, the largest oil production and export volume in the world, mainly distributed in the Persian Gulf and its coastal areas, and the oil produced is exported to Western Europe, the United States, Japan and other places; The climate in the Middle East is dry, rivers are scarce and water resources are scarce. The Arabian Peninsula in the Middle East is the largest peninsula in the world. The Suez Canal is located in Egypt. The tropical desert climate here leads to the shortage of water resources here and becomes the fuse of war;

The main race in the Middle East is white. Most residents believe in Islam, and a few residents believe in Christianity, Judaism and other religions. Islam, Judaism and Christianity all regard Jerusalem as the holy city.

4. Oil transportation routes

Route A: Arabian Sea-Indian Ocean-Malacca Strait-South China Sea-Pacific Ocean-Japan.

Route B: Indian Ocean-Cape of Good Hope-Atlantic Ocean-USA.

Route C: Indian Ocean-Red Sea-Suez Canal-Mediterranean-Atlantic-Western European countries.

Western Europe

1. Western Europe has a dense population and many countries, most of which are developed countries. Its economy is diversified, mainly in manufacturing, traditional animal husbandry and prosperous tourism.

2. The European Union is a regional international organization with close political and economic ties. At present, * * * has 25 member countries, using the unified currency euro.

3. London, France, Rome, Italy and Berlin, Germany.

4. Most of Western Europe is located in the north temperate zone, and the temperate maritime climate is widely distributed. The terrain is mainly plain and the animal husbandry is developed. People call pasture "green gold". British animal husbandry accounts for 70% of the total agricultural output value. Holland and Denmark are world-famous dairy countries.

There are many tourist destinations in western Europe, such as London Bridge in England, windmill in Holland, Eiffel Tower in Paris, France, bullfighting in Spain, and fjord scenery in Norway.

Sub-Saharan Africa.

Located between the Tropic of Cancer. Mainly black, it is called "the hometown of black people". Due to the long-term occupation and plunder by colonialism, most countries in this region have formed a "single commodity economy", exporting cheap primary products and importing expensive industrial products, which is at a disadvantage in international trade. The natural population growth rate in this area ranks first in the world. Coupled with the influence of natural conditions, food shortage has become a common problem for all countries in this region. Africa's climate is mainly savanna climate, and its distribution characteristics are: centered on the equator, symmetrically distributed in the north and south.

export

Developed countries in Africa

Imported?

Solution: Strive to develop national industries and diversified agriculture, and change the situation that the domestic economy depends on a single commodity.

Australia

1. The southern hemisphere countries and Australia, known as the "World Museum of Living Fossils", have the most sheep and exported wool in the world, and are called "countries riding on the back of sheep". Australia is rich in mineral resources, concentrated in coastal areas, with a large export ratio, and is known as a "mine car" country. At present, the service industry has become a pillar industry in Australia.

2. Sheep are concentrated in the mixed agricultural belt along the southeast and southwest coasts. Due to the vast territory and sparse population, the agricultural and animal husbandry production is highly mechanized, and most products are exported, including wool, wheat and beef. The two animals on the national emblem are kangaroos and emus, and the endemic animals are koalas and platypus. Canberra, the capital, is the largest industrial center and port city, and Melbourne is the second largest city.

United States of America

1. The United States is located on the North American continent and consists of 50 states, including 48 states on the mainland and the District of Columbia, where the capital, Washington, is located.

There are also two overseas states, Alaska and Hawaii. The main body of the United States is located in the north temperate zone, and Alaska is located in.

In the northern cold zone, Hawaii is located in the tropics.

2. The main part of the United States (mainland) is bordered by the Atlantic Ocean in the east, the Pacific Ocean in the west and the Gulf of Mexico in the south.

3. The topography of the United States is columnar in north and south, with Rocky Mountains in the west, Central Plains in the middle and Appalachian Mountains in the east.

The Mississippi River in the United States is the fourth longest river in the world, and the Great Lakes Group at the border with Canada is the largest freshwater lake group in the world.

Among them, Lake Superior is the largest freshwater lake.

The agriculture and industry in America are very developed, which is the most developed country in the world.

6. American agriculture is characterized by specialization. The proportion of the population engaged in agriculture in the United States is very small, but it is highly efficient and produces a lot. America is

The country that exports the most agricultural products in the world. Remember the distribution of agricultural belts in the United States with maps. Corn belt and dairy belt

7. American industry is dominated by high-tech industries. Among the three industrial zones, the northeast industrial zone is dominated by traditional industries, and the southern industrial zone is dominated by aerospace.

Industry-oriented, the western industrial zone is dominated by electronics industry.

8. The developed economy of the United States is based on the massive consumption of global resources and the destruction of the earth's environment, and it is the largest resource consumer and waste emitter in the world. Washington, the capital, and new york, the largest city.

Brazil

1. location: western hemisphere and southern hemisphere; East of South America, east of the Atlantic Ocean. The largest country in South America,

2. Capital: Brasilia. The population accounts for half of the total population in South America and is the most populous country in South America.

3. Topography: plains and plateaus are dominant, and topography: high in the south and low in the north.

Amazon Plain: The largest plain in the world, and the tropical rain forest here is the largest existing tropical rain forest area in the world.

B. Brazilian Plateau: the largest plateau in the world.

4. Climate: It is dominated by tropical rain forest climate and savanna climate. The climate is hot and humid.

5. River: Amazon River, the longest river in the world and the second longest river in the world.

7. Language: The folk entertainment of the Brazilian people is samba, and there is a carnival every year. Language-Portuguese.

Agriculture is an important basic sector of Brazil's national economy. There are many kinds of tropical cash crops, and the output of coffee, sugarcane and citrus ranks first in the world. Coffee beans, sucrose, citrus juice and soybeans are important export products. Brazil is called the "coffee kingdom", as long as the coffee gardens are distributed in the southeast.

9. Industry: A. Mainly distributed in the southeast, because ① there are many ports and convenient transportation. ② Coastal plain ③ The climate is mild and humid. There are rich minerals around. In modern industry, steel, shipbuilding, automobile and aircraft manufacturing have leapt to the ranks of important producers in the world. Gradually form a relatively complete industrial system from a single agricultural product exporting country.

B. With industrial sectors such as mining, steel, aircraft manufacturing, automobiles, shipbuilding and food, it is an important producer of steel, ships, automobiles and aircraft in the world, and its industrial output value ranks first in South America. Among them, 3/4 industries are distributed in the southeast coastal areas.

10. Population and cities: mainly distributed in the southeast coastal areas, with few population and cities in the Amazon Plain. Brasilia, the capital, and Sao Paulo, the largest city. Sao Paulo is the largest winter night center and city, and it is also a megacity in the world.

1 1. Crisis of tropical rain forest: The existing problems are as follows: ① Multinational companies cut down a lot of trees in order to build large trunk roads. ② Develop mining industry and open up large farms. (3) The primitive immigrant agriculture of poor farmers who cultivated land. Rainforest area is greatly reduced, soil erosion is serious, precious wild animals are plundered, and the global ecological environment is seriously threatened. Therefore, the whole world hopes that Brazil will focus on protecting this primitive tropical rain forest.

Antarctic region

1. Location: The Antarctic continent south of the Antarctic Circle and the surrounding oceans constitute the Antarctic continent.

2. Terrain: Plateau is the main terrain.

3. Features: Climatic features-split wind, dryness and severe cold. Known as the "ice and snow plateau"; Precious freshwater reservoir for human beings;

Antarctic continent is the coldest continent in the world, with the most frequent snowstorms and the strongest winds. The difference between winter and summer; The "white desert" on the earth.

4. Poles: The poles are south and north along the rest of the meridian, and the earth rotates clockwise.

5. Representative animal: penguin

6. Investigation: Great Wall Station and Zhongshan Station have been established successively in China.

Arctic region

1. Location: the area north of the Arctic Circle, including most of the Arctic Ocean, as well as the northernmost continent and many coastal islands in Asia, Europe and North America.

2. Features: Greenland is the largest island on earth; Bering strait

3. Pole: the pole is north, the rest along the meridian is south, and the earth rotates counterclockwise.

4. Representative animals: China, the polar bear, established the Great Wall Station in Antarctica in February 1985, and Zhongshan Station in Antarctica in February 1989.

Biology senior high school entrance examination outline:

1. scientific inquiry

2. Structural levels of organisms

3. Biology and environment

4. Green plants in the biosphere

5. People in the biosphere

6. Animal movement and behavior

7. Biological reproduction, development and inheritance

8. Biodiversity

9. Biotechnology

10. Healthy living

First, scientific inquiry.

1, understanding scientific inquiry

(1) Experiencing scientific inquiry is one of the important ways for people to acquire scientific knowledge and know the world.

(2) Recognizing that asking questions is the basis of scientific inquiry, and solving scientific problems often requires making assumptions.

(3) realize that scientific inquiry can obtain facts and evidence through observation, experiment and investigation.

(4) Recognize that scientific inquiry needs not only observation, experiment and investigation, but also reasoning and judgment.

(5) I realize that scientific inquiry needs correct expression and communication and cooperation with others.

2. Cultivate the ability of scientific inquiry.

Second, the structural level of organisms.

1. Cells are the basic units of life activities.

Explain the basic structure and function of microscope.

Make temporary films with microscopes and imitations.

It is expounded that cells are the basic structure and functional unit of life activities.

It shows that single-celled organisms can complete life activities independently.

The main differences between animal and plant cell structures.

Describe the important role of nucleus in biological heredity.

2. Cells divide and differentiate to form tissues.

Describe the basic process of cell division.

To sum up, all kinds of biological tissues are formed by cell division and differentiation.

Identify several basic tissues of the human body.

Identify several main tissues of plants.

3. Structural levels of multicellular organisms

Describe the structural levels of green flowering plants: the structural levels of cells, tissues, organs and individuals.

Describe the structural level of human body: the structural level of cells, tissues, organs, systems and individuals.

The basic structure of (1) unit is:, and.

(2) What are the main differences between animal and plant cell structures?

Three. Biology and environment

1. Biology depends on a certain environment.

For example, water, temperature, air and light are all environmental conditions for living things.

For example, biology is closely related to biology.

2. Biology and environment form an ecosystem.

Summarize the composition of the ecosystem.

List different ecosystems.

Describe the food chain and food web in the ecosystem.

It shows that some harmful substances will accumulate through the food chain.

It shows that the self-regulation ability of ecosystem is limited.

3. The biosphere is the home of human beings and other creatures.

The biosphere is the largest ecosystem.

Establish the consciousness of protecting the biosphere.

Analyze and discuss biological and abiotic factors, food chain and food web, energy flow and material cycle in the biosphere.

Fourth, green plants in the biosphere.

1. The life of green flowering plants

Describe the conditions and process of seed germination.

Describe the process of bud development and root growth.

Summarize the process of flowering and fruiting.

2. The life of green plants needs water and inorganic salts.

It shows that the life of green plants needs water and inorganic salts.

Describe the transpiration of green plants.

3. Photosynthesis and respiration of green plants

Explain the photosynthesis of green plants.

Examples are given to illustrate the application of photosynthesis principle of green plants in production.

Describe the respiration of green plants.

Explore the conditions, raw materials and products of photosynthesis.

Relevant measures for the application of plant photosynthesis and respiration principles in production.

4. Green plants play an important role in the biosphere.

Green plants provide food and energy for all living things.

It shows that green plants help to maintain the balance of carbon and oxygen in the biosphere.

Describe the role of green plants in the biosphere water cycle.

Verb (abbreviation for verb) People in the biosphere.

1. Human food comes from the environment.

Name the main nutrients that the human body needs.

Describe the composition of human digestive system.

Summarize the process of food digestion and nutrient absorption.

Design a nutritious and reasonable recipe.

Pay attention to food safety.

Explore the chemical digestion that takes place in the mouth.

2. Energy supply of human life activities

Describe the composition of human blood circulation system.

Overview of blood circulation.

Describe the composition of the human respiratory system.

Summarize the gas exchange process between human lung and tissue cells.

It shows that energy comes from the oxidative decomposition of organic matter in cells.

3. Discharge of human metabolic waste

Describe the composition of human urinary system.

Summarize the process of urine formation and excretion.

Describe other ways of excretion.

4. The human body regulates life activities through the nervous system and endocrine system.

Describe the composition of human nervous system.

Summarize the basic ways of human nerve regulation.

To sum up, the human body obtains information through sensory organs such as eyes and ears.

Examples show that hormones in the human body participate in the regulation of life activities.

Man is a member of the biosphere.

Summarize the origin and evolution of human beings.

Give examples to illustrate the influence of human beings on the biosphere.

Six, the movement and behavior of animals

1。 The movement of animals

List all kinds of sports forms of animals.

It shows that the movement of animals depends on a certain structure.

Observe the basic structure of vertebrate muscles, bones and joints.

2。 animal behavior

Distinguish between innate behavior and learning behavior of animals.

Give examples to illustrate the social behavior of animals.

Seven, biological reproduction, development and inheritance

1. Human reproduction and development

To summarize the structure and function of male reproductive system.

Summarize the structure and function of female reproductive system.

Describe the fertilization process.

Describe the embryonic development process.

2. Animal reproduction and development

Illustrate the reproduction and development process of insects with examples.

Describe the reproductive and developmental process of amphibians.

Describe the breeding and development process of birds.

3. Plant reproduction

It shows that DNA is the main genetic material.

Describe the relationship between chromosomes, DNA and genes.

For example, biological traits are controlled by genes.

Explain people's gender decisions.

Agree with prenatal and postnatal care.

Give an example of biological variation.

The application of genetic breeding in practice is illustrated with examples.

Eight. biodiversity

1. Biodiversity

Try to classify organisms according to some characteristics.

Describe the main characteristics of viruses and bacteria and their relationship with human life.

Describe the main characteristics of fungi and their relationship with human life.

Summarize the main characteristics of plants (such as algae, ferns, seed plants, etc.). ) and their relationship with human life.

The main characteristics of invertebrates (such as annelids, arthropods, etc.). ) and its relationship with human life are summarized.

Summarize the main characteristics of vertebrate groups (such as fish, birds, mammals, etc.). ) and their relationship with human life.

Pay attention to the rare animals and plants unique to China.

Explain the importance of protecting biodiversity.

2. The origin of life and biological evolution

Describe the process of the origin of life.

Summarize the main course of biological evolution.

Form the basic viewpoint of biological evolution.

Nine. biotechnology

1. Biotechnology in daily life

Examples are given to illustrate the role of fermentation technology in food production.

Explain the causes of food corruption.

Use the general method of food preservation.

2. Modern biotechnology

Examples are given to illustrate the application of cloning technology.

Examples are given to illustrate the application of transgenic technology.

Paying attention to the development of biotechnology will have an impact on the future of mankind.

Ten, live a healthy life

1. Healthy adolescence

Describe the developmental characteristics of adolescence.

Develop adolescent health care habits.

2. Infectious diseases and immunization

Explain the causes, transmission routes and preventive measures of infectious diseases.

List common parasitic diseases, bacterial infectious diseases (including gonorrhea) and viral infectious diseases (including AIDS).

Describe the epidemic prevention effect of rabbits on human body.

Distinguish specific rabbit epidemic from nonspecific rabbit epidemic.

Explain the significance of planned immunization.

3. The main diseases that threaten human health at present.

Pay attention to the harm of cardiovascular diseases.

Pay attention to the harm of cancer.

4. drink. Harm of smoking and drug abuse

Explain the harm of alcoholism to human health.

Explain the harm of smoking to human health.

Reject drugs

5. Medical knowledge

Name some commonly used drugs and their functions.

Summarize the common sense of safe medication.

Use some first aid methods