membershipChemistry and Life
Cheats. 1.Chemistry and Human Life in Gansu High School Entrance Examination proposition is mainly based on basic topics, often combined with some common foods or health products in life, to examine the relationship between the six major nutrients and human healthThe effects of chemical elements on human health and preventive measures, etc., the main types of questions are multiple-choice questions and fill-in-the-blank questions. Dietary health issues are mentioned as an important agenda in life, so the direction of the exam is to examine the six major nutrients to become a hot spot in the high school entrance examination, especially the types of the six major nutrients, physiological functions, food, deficiencies, precautions when ingesting, etc., although the difficulty of the test questions is smaller, but the frequency of occurrence is higher.
2.Chemistry is the focus of the examination in life, but also in service and life, and the knowledge of chemistry in life is the focus of the examination. It is mainly manifested in the elements in the human body and the important role of elements in the health of the human body;The properties of chemicals such as nitrite and formaldehyde and human health are also high-frequency test points.
3.Chemistry and materials are mainly basic topics in the propositions of the high school entrance examination, which mainly examines the identification of organic synthetic materials and their understanding of their properties and usesClassification and simple identification method of organic polymer materials;The two-sided nature of synthetic materials;Development and utilization of new materials and technologies;"White pollution" brought by waste plastics;Classification of domestic garbage, etc. The main types of questions are multiple-choice questions and fill-in-the-blank questions.
4.The judgment of material category is a compulsory question in the high school entrance examination, which will test the identification of synthetic materials, their characteristics and uses from the perspective of promoting social development, combined with common materials in real life. Materials and fibers are both natural and synthetic, and it is necessary to pay attention to the description when doing the question, while plastics are only synthetic, and there is no natural one.
Knowledge is a must-have. 1. Important nutrients for human beings
Six essential nutrientsIncluding proteins, sugars, oils, vitamins, inorganic salts, water.
The main functions of each type of nutrient and food**
Special reminder] Starch and cellulose are all sugars. Balanced nutrition: We need to ensure a balanced intake of various nutrients every day.
2. Chemical elements and human health
1) There are more than 50 kinds of elements in the group. There are 11 kinds of elements that are abundant in the human body.
2) in the human body content more than 001% of the elements, called constant elements. Such as oxygen, carbon, hydrogen, nitrogen, calcium, etc.
3) The content is 0Elements below 01% are called trace elements. Such as iron, copper, zinc, fluorine, iodine, selenium, etc.
4) Macroelement in the human body: calcium.
*: Milk, green vegetables, aquatic products, meat, legumes.
Manifestations of excessive calcium intake: stones, thickening of bones.
Manifestations of calcium deficiency: rickets (in adolescents), stunted growth;Osteoporosis (in the elderly).
99% are found in bones and teeth.
*Contains about 1 calcium in the body2kg, mainly in the form of calcium hydroxyphosphate.
5) Sodium and potassium.
Na+: Present in extracellular fluid, contains 80 120g of sodium in the human body.
K+: Present in intracellular fluid, ** contains about 2g of potassium per kilogram.
Function: Maintain water in the human body and maintain a constant pH of body fluids.
5) Trace elements in the human body.
Essential elements (more than 20 types).
Trace elements such as aluminum, barium, and titanium are non-essential elements for the human body. Mercury, lead, cadmium, etc. are elements that are harmful to the human body. Even essential elements should be consumed in a reasonable manner.
Special reminder] In daily life, it is better to drink bottled mineral water than distilled water, because mineral water contains trace elements and minerals required by the human body;
Insufficient or excessive intake of essential elements is detrimental to human health.
3. Elements and substances harmful to human health
Elements harmful to human health: Mercury (Hg), lead (PB), cadmium (CD), arsenic (AS), etc.
Some substances that are harmful to human health
Other hazardous substances: melamine, industrial gelatin, copper sulfate, etc.
Special reminder] Food additives mainly refer to a class of chemically synthesized or natural substances used to improve food quality, extend food shelf life, and increase food nutrients, including sweeteners, umami agents, preservatives, antioxidants, nutritional enhancers, etc. It should be consumed in moderation, as too much will be harmful to human health.
4. Organic synthetic materials
Compounds are divided into two categories: inorganic and organic。Organic compounds contain the element carbon, and a few compounds containing the element carbon, such as carbon monoxide, carbon dioxide, and calcium carbonate, have the characteristics of inorganic compounds, therefore, they are regarded as inorganic compounds.
Classification
Supplements] Other materials.
Inorganic materials include: metal materials (bronze, iron, stainless steel, etc.) and inorganic non-metallic materials (glass, ceramics, etc.).
Composite materials: materials formed by combining two or more materials into one, such as fiberglass, reinforced concrete, etc.
New materials: photosensitive materials, heat-sensitive materials, high-performance materials, fluorosilicon materials, functional polymer materials, etc.
Advantages and disadvantages of natural organic materials versus organic synthetic materials
Compared with natural fibers, synthetic fibers have the advantages of high strength, good elasticity, wear resistance and chemical corrosion resistance, and the disadvantages are poor water absorption and air permeability.
Compared with natural rubber, synthetic rubber has the advantages of high elasticity, good insulation, oil resistance, high temperature resistance and not easy aging, etc., and the disadvantages are poor strength and chemical corrosion resistance.
Identification of natural fibers from synthetic fibers
The environmental impact of the use of synthetic materials
The use of organic synthetic materials can have an impact on the environment, such as "white pollution".