It may not be available in 2009. Key review questions and answers for the second volume of sixth grade science at the end of the semester
Unit 1 Tiny World
1 Magnifying Glass
① A magnifying glass is a (convex lens). A convex lens has the function of (magnifying the image of an object). When observing an object with a magnifying glass, you can see (more details). ②(Magnifying glass) is widely used in many aspects of people’s life and production. ③The characteristics of the magnifying glass lens are (transparent) and (thick in the middle). ④The magnification power of a magnifying glass has nothing to do with (the diameter of the lens), but is related to (the convexity of the lens). The greater the convexity of the magnifying glass, (the greater the magnification power), the magnification power of (spherical) transparent objects (maximum ). ⑤ As long as the structure has a transparent magnifying lens and a thick middle, such as a beaker filled with water, a flask, etc., it will have the same (magnifying) function.
2 The world of insects under a magnifying glass
① Using tools can observe many (details) that cannot be observed with (the naked eye). ②More details about insects can be observed through (magnifying glass): the fly's (compound eye); the cricket's ears are on the (inside of the foot); the colorful small scales covered on the butterfly wings are (flat fine hairs). ③Scientific research shows that the (antennae) on the heads of insects is their (nose), which can distinguish various smells and is much more (sensitive) than the human nose.
3 Crystals under a magnifying glass
① The particles of sugar, salt, alkaline noodles, and MSG are all solids (with regular geometric shapes). People regard such (solid substances) It's called (crystal). ②Most (solid substances) in nature are (crystals) or composed of (crystals). The shapes of crystals are diverse, but they all have (rules).
4 How to make the object bigger
① The magnification of a convex lens is (limited). Combining two (convex lenses) can make the (image of the object bigger) , this is the (early) microscope. ②The invention of (magnifying glass) and (microscope) has broadened our (field of vision). The microscope is an important observation tool for human beings to understand (microscopic world). ③The Dutch biologist (Leewenhoek) made the world's first (microscope) that can magnify nearly (300 times) metal structures, and used it to discover (microorganisms). ④The invention of the microscope is a great leap forward in mankind’s understanding of the world, bringing mankind into a microscopic world. ⑤In order to see smaller objects, people have developed (electron microscope) and (scanning tunneling microscope). The electron microscope can magnify objects up to (2 million times).
5 Use a microscope to observe the living world around you (1)
①The epidermis of onions is made up of (cells). ②The British scientist (Robert Hooke) was the first to discover the biological (cell) structure under the microscope. ③The object must be made (slide specimen) before its (fine structure) can be observed under a microscope. ④The main structures of an optical microscope are (eyepiece), (adjustment knob), (objective lens), (stage), (reflector). ⑤ Methods and steps for using the microscope correctly: (See page 13 of the textbook).
6 Use a microscope to observe the living world around you (2)
① (Biology) are composed of (cells). ②The (forms) of biological cells are diverse, the cells (of different organisms) are different, and the cells of organisms (different organs) are also different. ③ (Cell) is the most basic (structural unit) of biology and the most basic (functional unit) of biology. ④(Robert Hooke) The first person to discover the name (cell), and the establishment of (cell theory) is known as one of the three major discoveries of natural science in the 19th century.
7 Use a microscope to observe the living world around you (3)
① Use (microscope) to see (tiny organisms) that cannot be seen with the naked eye. ② There are many (microorganisms) of different forms living in the water, such as (paramecium), (amoeba), etc., and they are also composed of (cells). ③Microorganisms usually have special structures and functions to adapt to their surrounding environment. ④ (Microorganisms) are (organisms) that have the same characteristics (characteristics) as other organisms, such as: having certain needs for the environment, responding to external stimuli, and being able to reproduce, etc.
8 The Tiny World and Us
① Due to the improvement of (observation tools), the scope of human observation (expanded), and many things in nature that cannot be discovered by the naked eye (cannot be discovered) have been discovered Secret: (naked eye) can see insects and other smaller animals clearly - (magnifying glass) can see clearly things smaller than a millimeter that cannot be seen with the naked eye - (optical microscope) can see cells and microorganisms clearly - (electron microscope) can See the smaller atoms and molecules that make up matter.
②The results of human exploration (micro world) have promoted the (development) of science and technology, the (progress) of society and the (improvement) of human life. For example: (1) Use microscopes to discover (bacteria), (viruses), and resist diseases (2) Clone (biology) (3) Use microorganisms (wine making), (bread dough), make (soy sauce), (vinegar), ( Yoghurt), etc. (4) Use microorganisms to treat (garbage) and (sewage). ③Before the invention of magnifying glasses and microscopes, people could only use five sense organs (eyes), (ears), (nose), (tongue), and (hands) to explore the world. At that time, the smallest animals that people could observe were (ants) and other insects. The invention of (magnifying glass) and (microscope) allowed us to see (microorganisms) and (cells).
Unit 2: Changes in Matter
1 Material around us
①The world is made of (material), matter is (changed), material Changes have similarities and differences. ② Some changes in matter (new matter is produced), while other changes only change the shape and size of matter (no new matter is produced).
2 What changes have occurred in matter?
① Changes in matter can be divided into two categories (physical changes) and (chemical changes). The difference between them is (whether new ones are produced) substance). ② Some substances will undergo both (chemical change) and (physical change) during the process of change, such as candles burning and sugar melting and changing color when heated. ③ In the process of change, (cannot produce) new substances, such as beans and sand do not change before and after mixing and separation, we call it (physical change). ④ In the process of change, the change of (that can produce) new substances, like the change of heating white sugar and changing from white sugar to black charcoal, produces new substances, we call it (chemical change).
3 Changes in rice, starch and iodine
① (Chemical changes) will occur when (rice) interacts with (saliva) in the mouth. ② (Starch) and (Iodine) will undergo chemical changes, and the new substances generated are (blue-purple). This characteristic can be used to test whether food contains (Starch). ③Saliva can sweeten starch, and the non-sweet sugar is (starch).
4 Changes in Baking Soda and White Vinegar
① When (baking soda) and (white vinegar) are mixed, a chemical reaction will occur, producing a new substance - (carbon dioxide gas), like this Changes are (chemical changes). ②(Carbon dioxide) is a gas with special properties.
5 Iron rusts
① Iron rusting is a (chemical change), and (rust) is a new substance different from (iron). ②The reasons why iron rusts are related to (water) and (air).
6 Phenomena accompanying chemical changes
① (Chemical changes) will be accompanied by various phenomena, such as: (change of color), (luminescence and heat), (production of precipitates), ( (Generate gas). Based on these phenomena, it can be preliminarily judged whether the substance has undergone chemical changes. ②(Copper sulfate solution) and (Iron Nail) will have a (Chemical Reaction) and produce (New Substance).
7 Control the speed of iron rusting
① The simultaneous action of (water) and (air) causes iron to rust. ②In daily life, the speed of iron rusting is closely related to (the amount of water). ③Isolating iron from (water) and (air) is a good way to prevent (iron from rusting), such as painting, electroplating, etc.
8 Material changes and us
① Material changes are closely related to human production and life. All production activities and human life carried out by human beings make use of ( changes in matter). ②The world around us is composed of (matter), and matter (changes). There are two types of material changes: (physical changes) and (chemical changes). The most important characteristic of chemical changes is (the production of new substances). ③Physical changes (certainly) occur during the chemical changes of substances. ④ Due to the sharp increase in the consumption of fossil fuels such as coal and oil, a large amount of (carbon dioxide) is produced, which causes the carbon dioxide content in the air (continuously increasing), leading to global (climate warming), (soil desertification), continental and bipolar ( Melting glaciers), causing huge pressure on the global (environment).
Unit 3: The Universe
1 The Earth’s Satellite—The Moon
① (The Moon) is the Earth’s (satellite). In terms of movement and volume It is different from the Earth in many aspects such as size, gravity, and surface characteristics. ②In July 1969, the (U.S.) (Apollo 11) manned spacecraft successfully landed on the moon, (Armstrong) leaving the first human footprint on the moon. ③The moon orbits the earth (counterclockwise). The Moon's gravity is approximately (1/6) that of the Earth. ④The topography of the moon is (craters) and (lunar maria).
2 Moon phase changes
①The moon phases have different (shapes) at different periods of (a month). ②The moon phase changes are formed during the revolution of (the moon) around (the earth), and the changes follow certain rules. ③The various (shapes) that appear during the process of the moon (circle and waning changes) are called (moon phases). ④The first half of the lunar month (from missing to round), and the second half of the month again (from round to missing). ⑤The moon is a (non-luminous), (opaque) (sphere), and the moonlight we see is its (reflected) light from the sun. ⑥The moon phase is actually what people see from the earth (the part of the moon illuminated by the sun). ⑦Due to different observation angles, the moon phases (bright side size) and (direction) seen are also different. ⑧Observe the moon phase during the daytime every day (evening) and (early morning).
3 Let’s build “craters”
① (Craters) are the main features of the lunar terrain. Some of their diameters are less than (one thousand meters), and some can reach (one thousand meters). hundreds of kilometers). ②The formation of craters is related to many factors, (meteorite impact) is the main reason. ③ Regarding the cause of the formation of craters, the currently recognized view is (impact theory). This view believes that craters are traces left after long-term impacts (meteors) and (meteorites). Because there is no (air) on the moon, it is equivalent to less A layer of protection is provided to make impacts more violent and frequent.
4 Solar and lunar eclipses
① (Solar eclipse) and (lunar eclipse) are astronomical phenomena caused by the movement of the sun, the earth, and the moon. ② (Moon) moves between (Sun) and (Earth), and the three are in a straight line. When the Earth is in the shadow of the moon, (the Moon blocks the light from the sun shining on the Earth), a (solar eclipse) is formed. ③ (Moon) moves into the shadow of (Earth), the three are in a straight line, the Earth is between (Sun) and (Moon), (the Earth blocks the light from the sun to the moon), and a (lunar eclipse) occurs ).
5 Solar System
① (Sun) and the (planets), (dwarf planets) and (small celestial bodies) that move around it constitute the (solar system). The solar system is a larger (celestial system). ②(Sun) is the only luminous (star) in the solar system. ③There are (eight major planets) in the solar system, and their order is: (Mercury), (Venus), (Earth), (Mars), (Jupiter), (Saturn), (Uranus), (Neptune). ④The celestial body system with (the sun) as the center and including the (eight planets) (including satellites orbiting the planets), (dwarf planets), (small celestial bodies) (including asteroids, meteors, comets, etc.) rotating around it is called (solar system). ⑤The diameter of the sun is: (1,400,000 kilometers).
6 In the Starry Sky (1)
① (Constellations) are (stars) with different distances and no connections in the sky (visual images). The graphics look different if viewed from different angles. ②(Big Dipper) is the main symbol of (Ursa Major). The famous (Polar Star) belongs to (Ursa Minor). ③In order to facilitate the identification of stars, people group the seemingly motionless stars into groups and divide them into different (regions). They imagine the shapes of (people), (animals) or (other objects) according to their shapes, and name them. , these artificially divided areas are called (constellations). ④ (Ursa Major) The obvious symbol is the familiar seven bright stars (Big Dipper). ⑤ (Polaris) can help everyone identify the direction at night. You can find it relatively easily by using (the Big Dipper in Ursa Major): Extend the leading edge of the Big Dipper spoon (extending the line connecting the two stars) at a distance approximately equivalent to the two stars. At a distance of (5 times), there is a relatively bright star, that is (Polaris).
7 In the Starry Sky (2)
① As the seasons change, different representative constellations will appear in the sky, (constellations) in the sky (movement changes) . ②The shape (graphic) composed of bright stars is the main symbol of the constellation. ③There are many bright stars in the summer sky, among which three bright stars (Deeb) ---- belong to (Cygnus), (Vega) ---- belong to (Lyra) and (Altair) ---- belong to ( Aquila) forms a huge triangle, which is called the Summer Triangle.
8 Exploring the Universe
① There are (celestial body systems) of different sizes distributed in the universe. ②The universe is (moving and changing) and (expanding), and the (celestial bodies) that make up the universe are also moving and changing. ③ (The universe) is a huge system composed of celestial bodies of different sizes, such as the solar system, the Milky Way, and extragalactic galaxies. It is constantly moving and changing. ④The solar system and many stars together form a (star group), which is called (Milky Way). ⑤The Milky Way is composed of approximately (100 billion-200 billion) stars and has a diameter of (100,000 light-years).
⑥The propagation speed of light is (300,000 kilometers per second), (light year) is the distance traveled by light in (one year), and it is the unit used to measure (distance) between stars. ⑦The Milky Way is not the entire universe. Galaxies similar to the Milky Way are such as: (Andromeda Galaxy) and (Canes Canes Galaxy). Currently, humans have discovered more than (10 billion). They are collectively called (extragalactic galaxies). ⑧Now people have used astronomical telescopes to observe the depths of the universe (12 billion light years) away from us, but they still have not seen the universe at the (edge); the universe is an (expanding) and (full of vitality) universe. ⑨Our country is recognized as the birthplace of rockets in the world. As early as 1,700 years ago (the Three Kingdoms era), the name (rocket) appeared in ancient books. ⑩China’s aerospace technology occupies an important position in the world: the manned spacecraft (Shenzhou 5) and (Shenzhou 6) have fulfilled the Chinese people’s dream of flying into space; now (Chang’e 1 lunar exploration satellite) has been successfully launched; soon In the future, Chinese astronauts will also conduct (lunar landing expeditions).
Unit 4 The Environment and Us
1 One Day’s Garbage
① People produce a large amount of complex components (garbage) in their lives. ②Discarded garbage (harming the environment).
2 Disposal of garbage
① The current methods of treating garbage include (landfill), (incineration), etc., but the landfill method will (contaminate groundwater), and the incineration method will (pollution of the atmosphere) affects the environment. ② (Rationally designed) (landfills) can effectively reduce environmental pollution. ③The hazards of landfills to the surrounding environment include: (1) emitting stench and polluting the air (2) breeding mosquitoes and flies, causing diseases (3) causing soil pollution and affecting agricultural production, etc. ④ Advantages of burning garbage: (1) It occupies a small area and reduces the amount of garbage (2) Avoids contamination of groundwater (3) The heat generated can be used to generate electricity; Disadvantages: (1) Consumes a large amount of electricity (2) Leaves residue (3) ) causing secondary pollution. ⑤After the landfill is filled with garbage, it can be used to (build parks) and (stadiums), but it cannot be used to (plant banks).
3 Reduce discard and reuse
① (Reduce garbage) is very important. Commonly used methods are (Reduce discard) and (Reuse). ②(Excessive packaging) will cause (waste of resources) and generate a lot of garbage. ③The following waste can be reduced in daily life: (1) Double-sided printing can save paper, (2) Bring your own drinking cup when going out, buy less bottled drinks, (3) Use as little or no disposable items as possible to reduce Disposal of paper and plastic, etc. ④ (Reducing the amount of garbage) is a way to solve the garbage problem from the source. ⑤ (Reuse) refers to using used items multiple times or in another way. It is also an important method to reduce waste.
4 Classification and recycling
① Some raw materials in garbage can be reused (recycled), including paper, metal, plastic, glass, etc. This can (reduce garbage) and (save resources). ② Garbage classification and packaging facilitate garbage (recycling) and some (toxic waste) processing. ③(Composting method) can effectively reduce waste and form (fertilizer). ④ To effectively recycle garbage, we must change the habit of (mixing garbage) and carry out (classification) and (separate packaging) of domestic garbage. ⑤ Three of the five substances that pose the greatest threat to the natural environment are included in batteries: (mercury), (lead), and (cadmium). ⑥The scientific methods to reduce solid waste are (reduce discarding), (reuse) and (recycle).
5 One-day domestic water use
① People use a lot of water in their lives, and (freshwater resources) are in short supply. ② Due to (rapid population growth), (environmental pollution) and (global warming), 60% of the continent currently faces insufficient freshwater resources, and more than 100 countries are seriously short of water, with the most serious countries reaching (more than 40). ③ (Freshwater) is a necessity for the survival of us humans and other creatures.
6 Sewage and sewage treatment
① In the case of shortage of fresh water resources, water pollution poses a threat to humans and other organisms. Water pollution is mainly caused by (human activities). ②The source of water pollution may come from (agricultural pesticides, fertilizers), etc., may come from (industrial wastewater, oil pollution), etc., may come from (household detergents, human excrement), or may come from (animal carcasses) wait. Sewage requires complex treatment before it can be used. ③ In addition to (precipitation) and (filtration), fresh water in the water plant must also be added with drugs (sterilization treatment), so that it can meet the standards we use. ④Sewage needs to go through (complex treatment) before it can be used. Generally, it needs to be purified through three methods (physical method), (biological method), and (chemical method).
(Physical method) is mainly to (separate) debris and larger particles in the water, such as plastic bags, vegetable leaves and weeds, etc.; (Biological method) is to decompose dirt in the water through (bacteria); (Chemical method) Mainly used for (disinfection), the usual method is to add (chemical agent) - (chlorine) to the water, through which it can effectively kill the pathogenic microorganisms in the water.
7 Investigate the natural waters in your hometown
①Water pollution is mainly caused by (human activities). Water pollution seriously affects people (production) and (life). ②The water quality can be analyzed from aspects such as (color), (smell), (whether it is turbid), (whether there are impurities), etc.
8 Environmental issues and our actions
①The current prominent environmental issues include (garbage), (water pollution), (air pollution), (white pollution), (species extinction) (speed is accelerating), etc., humans are focusing on corresponding environmental protection actions. ②(Reducing waste gas) and (Waste emissions) are the most fundamental ways to control air pollution. In recent years, our country has actively promoted (Car-Free Day) activities to save energy and protect the environment. ③Methods to reduce white pollution (plastic waste) include: (1) using paper bags and cloth bags (2) carrying vegetable baskets to the market (3) reducing plastic packaging (4) using degradable plastic bags. ④ Due to (massive destruction of global forests) and (deterioration of the marine environment), the extinction rate of existing biological species is (1,000 times) the natural extinction rate. Human beings (indiscriminate hunting) and (over-exploitation and utilization) have brought many biological resources to the verge of exhaustion. ⑤ (Establishing nature reserves) is an effective method to protect biological diversity. Nature reserves have been established in my country's (Jiuzhaigou), (Changbai Mountain), (Sichuan Wolong) and other places. ⑥Many environmental problems are caused by (human activities), but human activities can also improve the environment.