Seeking knowledge points in the second volume of science in grade six of Education Press

1, the magnifying glass is (convex lens), and the convex lens has the function of (magnifying the image of the object). You can see more details by observing the object with a magnifying glass.

2. The characteristics of magnifying glass lens are (transparent, thick in the middle and thin in the edge). The methods of self-made magnifying glass are: jar, glass, flask, beaker and plastic bag (box) filled with water. Ice cubes, water drops and transparent glass balls all have magnifying functions. (Note: horizontal amplification, not vertical amplification).

3. Particles of salt, sugar, alkaline noodles and monosodium glutamate are all solids with regular geometric shapes. People call this solid substance (crystal).

4. Many rocks are composed of (mineral crystals). For example, granite is composed of mineral crystals such as feldspar, mica and quartz.

Most solid substances in nature are (crystals) or consist of (crystals) (glass, rosin, amber, pearls, etc.). Not a crystal). The crystal shape is very regular. Some crystals are larger and visible to the naked eye, while others are smaller and can only be seen under a magnifying glass or microscope.

6. Biologists (Levin? Hooke) made the world's earliest microscope with metal structure, which can be magnified nearly 300 times. In order to see smaller objects, people developed (electron microscope) and (scanning tunneling microscope). An electron microscope can magnify an object 2 million times.

7. British scientist (Robert? Hook) sawed (cells) with a self-made compound microscope for the first time in the world.

8. The microscope is mainly composed of (eyepiece) (adjusting knob) (objective lens) (objective stage) (reflector) and so on.

9. A lot of research facts show that life is made up of (cells).

10, we can also use (hay) to cultivate microorganisms.

1 1, (Pasteur) was the first to point out the relationship between microorganisms and human health.

12. Through observation, we know that the TV screen is actually composed of three colors (red), (blue) and (green).

The invention of 13, (magnifying glass) and (microscope) has opened the door to the micro-world for human beings, and is an important observation tool for human beings to understand the micro-world. Not all microorganisms are harmful to human beings. Many microorganisms are not only beneficial to human beings, but also indispensable to us. Hybrid rice (Yuan Longping) is a kind of yeast, which can decompose sugar in flour to produce carbon dioxide, which expands rapidly after being heated, thus making steamed bread and bread porous.

14. The achievements of human exploration of the tiny world have promoted the development of science and technology, the progress of society and the improvement of human life. Such as: anti-homogeneous diseases, brewing, pickles, dough making, yogurt making, biological cloning, garbage and sewage treatment.

15, material changes are different, some are fast and some are slow, and some changes just change the state, shape, size and so on. And a new material different from the original material is not generated. We call such changes (physical changes), some changes produce (new materials), and we call changes with new materials (chemical changes); In the process of change, some substances will undergo chemical and physical changes. For example, candles burn and white sugar melts and changes color when heated.

16, some substances will not generate new substances after mixing, such as (sand) and (beans); Some substances will produce new substances after mixing, such as (baking soda) and (white vinegar)

17, baking soda and vinegar mixed to produce a large number of bubbles, generating a new gas-carbon dioxide gas, which can extinguish the burning thin sticks, indicating that this gas (does not support combustion).

18, rice becomes (sweet) during chewing, because there is something called (starch) in rice, which changes during chewing-starch becomes maltose.

19, starch will turn (blue) when it meets iodine, producing a new blue substance. This characteristic can be used to test whether there is starch in food.

Material changes in the world around us generally fall into two categories, namely, (physical changes) and (chemical changes). There are many phenomena related to chemical changes, and the most important feature is (producing new substances).

2 1, the process of chemical change of substances is often accompanied by various phenomena, such as (luminescence and heat generation), (gas generation), (color change), (precipitate generation) and so on.

22. Through the observation and comparison of iron sheet and rust, I found that rust is (reddish brown), (notched), (dull), (nonconductive), (unable to be attracted by magnets), (rough) and so on.

23. The gas (carbon dioxide) produced by mixing baking soda and white vinegar has the characteristics of (no combustion-supporting), (heavier than air) and (colorless and transparent).

24. What foods contain starch?

Category food name

Starch-containing foods include corn, potatoes, sweet potatoes, apples, bread, steamed bread, pumpkins and so on.

Starch-free foods include broccoli, carrots, white radishes, spinach, tomatoes, oranges, sugar and onions.

25. The moon is the earth's (satellite), its radius is about the radius of the earth (1/4), its gravity is about the earth's (1/6), the average distance between the moon and the earth is about (380,000 kilometers), and the temperature difference between day and night is (3 10℃).

26.1In July 1969, the American manned spacecraft (Apollo 1 1) successfully landed on the moon. The first man to land on the moon was an American (Armstrong).

27. In the speculation about the formation of lunar craters, the accepted view is (meteorite impact theory).

28. The moon is a (unlit) (opaque) sphere, and the moonlight we see is the light it reflects (the sun).

29. The various shapes of the moon during the alternation of full and short periods are called (moon phases). The moon phase is actually the part of the moon that people see from the earth that is illuminated by the sun.

In ancient times, people had a special name for the moon phase. The "first day" is called (new moon) and the "fifteenth day" is called (full moon).

3 1, the change law of the moon phase in a month is: from missing to round in the first half of the lunar calendar, and from round to missing in the second half. (1, the moon phase changes through the process of new moon-first quarter moon-full moon-second quarter moon-waning moon. 2. In the first half of the month, the bright surface area of the moon gradually becomes larger until the full moon, and the bright surface is on the right side; In the second half of the month, the bright surface area of the moon gradually decreases until the new moon, and the bright surface is on the left. )

32. There are three kinds of eclipses (total solar eclipse) (partial solar eclipse) (annular solar eclipse), and only two kinds of eclipses (total lunar eclipse) (partial lunar eclipse); The solar eclipse occurs on the first day of the lunar calendar, and the lunar eclipse occurs on the fifteenth or sixteenth day of the lunar calendar.

33. The sun is the only star in the solar system, with a diameter of about (654.38+04,000) kilometers.

34. The solar system is a celestial system centered on (the sun) and composed of (eight planets), (dwarf planets) and (small celestial bodies). The average distances from these planets to the sun are (Mercury), (Venus), (Earth), (Mars), (Jupiter), (Saturn), (Uranus) and (Neptune).

35. People divide the stars that seem to keep the same distance from each other into a group of different regions and name them after the shapes of people, animals or other objects. People call these areas (constellations). One of the constellations is particularly famous for its meteor shower. This constellation is Leo.

36. The obvious sign of Ursa Major is the seven bright stars (the Big Dipper) that we are familiar with. There is a famous (Polaris) in Ursa minor in the northern sky.

37. The Milky Way shining in the sky is actually a cluster of stars, which is called (Galaxy) by people and (Galaxy) by Europeans, and its diameter is about (654.38+ million light years).

38. The speed of light is 300,000 kilometers per second, and (light years) is the distance that light travels in one year.

39. The Milky Way is not the whole universe. There are 654.38+000 billion galaxies similar to the Milky Way, collectively referred to as extragalactic galaxies.

40. Star life: The gas and dust in the nebula contract-the protostar-runs out of fuel, expands into a giant star or Supergiant star-explodes into a supernova-becomes a black hole or neutron star; Or the gas and dust in the nebula contract-the protostar-a small and medium-sized star becomes a red giant-the fuel runs out and contracts into a white dwarf-the energy runs out and becomes a black dwarf).

4 1, China is recognized as the birthplace of rockets in the world; China's space technology occupies an important position in the world; The manned spacecraft Shenzhou 5 and Shenzhou VI have realized the flying dream of China people. Now the Chang 'e-1 lunar exploration satellite has been successfully launched, and Chinese astronauts will also visit the moon in the near future.

42. At present, the main methods of garbage disposal are (landfill) and (incineration). Simple landfill and incineration will also cause environmental pollution.

43. (Reducing the amount of garbage) is the way to solve the garbage problem from the source. What garbage can be reduced in daily life: (1) Double-sided printing can save paper. (2) Bring your own drinking cup to go out and buy less bottled drinks. (3) Use disposable goods as little as possible or not, and reduce the discarding of paper and plastic. ……

44. (Reuse) refers to the reuse of used items for many times or in another way, which is also an important way to reduce garbage. Some raw materials in garbage can be recycled, including paper, metal, plastic and glass. Recycling waste from garbage can save resources, energy, cost, garbage and pollution, which is a good thing without harm.

45. Garbage can be divided into kitchen waste, recyclable garbage, toxic harmful waste and other garbage. Domestic garbage can generally be divided into recyclable garbage, kitchen waste and other garbage.

46. Kitchen waste includes peels, leftovers, etc. Recyclable garbage includes: paper products, metal products, plastic products, glass products and rubber; Toxic and harmful wastes include expired drugs, syringes, waste batteries, waste fluorescent tubes and waste water silver thermometers; Other rubbish includes: bricks and tiles, ceramics and toilet waste paper.

47. (Composting) can effectively reduce garbage and form fertilizer.

48. Sources of water pollution may come from (agricultural sewage), (industrial sewage) and (domestic sewage), and may also come from animal carcasses. It can be seen that water pollution is mainly caused by human activities.

49. In most areas, tap water comes from (reservoirs), (lakes) and (rivers). Tap water is the main source (drinking water), so you can't take a bath.

50, sewage treatment is more complicated, generally through three methods, namely (precipitation), (filtration), dosing sterilization to get purification. Purification is usually achieved by three methods (physical method, biological method and chemical method). The physical method is mainly to separate impurities and larger particles in water, including plastic bags, vegetables and weeds. The biological method is to decompose the dirt in water through bacteria; Disinfection mainly adopts chemical methods, and the usual practice is to add monochloro, a human chemical, to water, through which pathogenic microorganisms in water can be effectively killed.

5 1. The pollution we are facing is (garbage pollution) (water pollution) and (air pollution). In addition, there are environmental problems such as "white pollution" (plastic products) and (accelerated extinction of species).

52. Many biological resources are on the verge of exhaustion due to (indiscriminate hunting) and (over-exploitation).

53. Establishing nature reserves is an effective way to protect biodiversity.

54, the advantages and disadvantages of landfill and incineration:

Methods of landfill and incineration

Has the advantages of convenience, low cost and promotion of garbage decomposition. It occupies less land, avoids groundwater pollution and uses heat.

The problem occupies a lot of land, and the garbage is decomposed slowly, which may pollute groundwater, consume electricity, leave residue and possibly cause secondary pollution.

55, the role of each part of the landfill:

Cushion: to prevent direct contact between garbage and soil;

Filtrate collection pool and treatment pool: prevent polluted water from infiltrating into soil and groundwater;

Exhaust pipe: exhaust combustible gas and toxic gas produced by fermentation.

Monitoring well: monitor the status of soil and groundwater near the landfill site at any time.

56. The gas related to global warming is mainly carbon dioxide; Sulfur dioxide produced by burning fossil fuels (oil, natural gas and coal) is the main cause of acid rain.

57. The ways to reduce garbage are: (1) reduce the discard; (2) reuse; (3) recycling.

Short answer questions:

1, the cause of the solar eclipse? A: When the moon moves between the sun and the earth, if they are in the same straight line, the moon will block the light from the sun to the earth. People in the shadow on the earth can only see part or all of the sun, so this happened. Eclipses are divided into (total solar eclipse), (partial solar eclipse) and (annular solar eclipse). (P54) Several characteristics of solar eclipse: (1), the sun is blocked by objects, (2), the light blocking object is spherical (3), the earth, the light blocking object and the sun are almost in the same line (4), and the light blocking object is moving. Eclipses usually occur on the first day of the first month of the lunar calendar and always start from the west of the sun's nimbus.

2. What is the cause of the solar eclipse? A: When the moon moves to the back of the earth and enters the shadow of the earth, an eclipse will occur. Solar eclipses occur around the fifteenth day of the lunar calendar, including total lunar eclipse and partial lunar eclipse. (can draw)

Relatively speaking, eclipses occur more frequently than eclipses. Both eclipses are determined by the moon's rotation around the earth and the earth's rotation around the sun, which are directly related to the shadow of celestial bodies.

What are the main environmental problems facing the world now? A: 1, garbage pollution; 2. Water pollution; 3. Air pollution. In addition, there are: white pollution, sharp decline in species, land desertification, acid rain and so on.

5. Please make a family water-saving plan: A: 1, wash your face with a basin; 2. Taomi water is used to wash dishes; 3, shower water is used to flush the toilet; Fish water is used to water flowers and plants; Use water-saving appliances, etc.

6. What will you do to reduce the environmental problems of "white pollution"? A: Bring your own shopping bag when shopping; The store gives less plastic bags; Reuse existing plastic bags; Bring a vegetable basket and a cloth bag when buying food; Bring your own tableware when dining at work or school; Go out to eat and use less plastic fast food boxes. Collect waste plastic products and sell them to waste purchasing stations for recycling and refining.

7. Observing the development process of tools: smaller animals such as insects can be seen with naked eyes → magnifying glass → optical microscope → cells and microorganisms → electron microscope → atoms and molecules with smaller components can be seen → scanning tunneling microscope: nanotechnology.

18. In production practice, what methods do people generally adopt to prevent and slow down the rust of iron products? Answer: (1) alloy material; (2) coating a protective layer on the surface of the iron product; (3) Keep the surface of iron products clean and dry.

Experimental questions:

1, how to separate salt from water? Reduce moisture, that is, air dry or heat the solution to evaporate its moisture and reprecipitate the substance.

2. Step of obtaining crystals: firstly, salt is made into solution, and then 1-2 is dropped on the glass slide with a dropper or a glass rod. In order to evaporate quickly, shake it gently after dripping, let the solution dilute evenly, and then put it in a ventilated place. You can also clamp the glass slide with a clamp and heat it on an alcohol lamp. When heating, the glass slide should be kept away from the flame and slowly dried. Never touch the solution with your hands or utensils when it evaporates.

3. Observe onion skin with microscope: (1) material, beaker, clear water, dropper, tweezers, knife, glass slide, cover glass, iodine, Petri dish and absorbent paper. (2) Slice specimen making steps: a, dropping a drop of water on a clean glass slide; B, use tweezers to place the specimen to be observed in the center of the water drop on the glass slide, and pay attention to spreading the specimen horizontally and not folding it; C, covering the sample obliquely and slowly with a cover glass or another glass slide; When placing the cover glass, put one end first, and then slowly put down the other end, taking care not to have bubbles; For specimens that need to be dyed, they can be removed from the specimens.