Does the sixth grade of primary school have an answer to the second volume of scientific review questions?

It's a Small World

1, it can be clearer and more subtle when observed with a magnifying glass.

2. Use of magnifying glass: The magnifying glass is close to the observed object; The magnifying glass is close to the eyes.

3. Features of magnifying glass: The greater the convexity, the greater the magnification.

4. All transparent and convex objects can be enlarged.

5. The compound eye of insects can form multiple images at the same time, which can be applied to cameras.

6. The natural enemies of aphids are Chrysopa and its larvae.

7. Under the magnifying glass: the crystal of salt is gray powder, the crystal of sugar is white block, the crystal of monosodium glutamate is white strip, and the crystal of alkali surface is white powder. (experiment)

8. Regular solid particles are called crystals.

9. Making crystals: suck a little concentrated salt water or concentrated sugar water with a dropper, drop it on the glass, and then look at the crystals with a magnifying glass. (experiment)

10, Levin Hook of the Netherlands put two magnifying glasses with different convexities together and invented the microscope. Microbes were found (300 times).

1 1, and the current electron microscope can be enlarged by 2 million times; It has created favorable conditions for scientific research in the micro world.

12, cells found in Hooke, England; Cell composition: cell membrane, cytoplasm and nucleus.

13. How to use the microscope: put the microscope flat and face the light; Adjust the mirror; Until you see white light.

14. Observing onion epidermal cells with microscope: pick up onion epidermal inner membrane cells with tweezers, put them on a glass slide, drop a little water with a dropper, cover the cover glass, fix them under the light hole of the microscope, and adjust the focal length to be clear. (experiment)

15, onion epidermal cell structure: reddish, long, neatly arranged, with horns at both ends and a nucleus in the middle.

Changes in matter

16, starch and iodine will turn blue. (chemical change)

17, vinegar and baking soda will soon produce carbon dioxide. (chemical change) (experiment)

18, carbon dioxide is heavier than air. If it sinks to the bottom of the cup, it will go out if it is lit or poured on the flame of the candle.

19. Iron rusts easily when exposed to air (oxygen) and water. (chemical change)

20. There is no new substance called physical change, and there is a new substance called chemical change; The main chemical changes are: discoloration, luminescence, gas generation, sediment generation, etc.

2 1, methods to prevent iron from rusting: dry water, enamel coating, zinc plating, anti-rust paint spraying, vacuum, etc.

22. Cement production process: limestone and clay are evenly mixed in proportion, and then calcined and ground at high temperature to become cement.

23. Matter is immortal. Nitrate, sulfur and charcoal can be mixed to make black powder (Tang Dynasty). One of the four great inventions, including compass (Warring States), papermaking (Cai Lun in the Eastern Han Dynasty) and movable type printing (Bi Sheng in the Northern Song Dynasty).

universe

24. The first man to go to space was Gagarin of the Soviet Union (196 1 4, 12, East), and the first man to land on the moon was Armstrong of the United States (1969, 7, 16, Apollo/6).

25. The distance from the earth to the moon is 384,403 kilometers, and the moon makes one revolution around the earth in 27.3 days (plus the earth rotates exactly one month, and the moon rotates one month). The gravity of the moon is one sixth of that of the earth.

26. Moon phase change law: Emei moon, first quarter moon, convex moon, full moon, waning moon, second quarter moon, Emei moon and new moon.

27. The craters on the moon were formed by the impact of meteorites. Experiments can throw pebbles into the sand. )

28. An eclipse is the shadow left by the sun on the earth by the moon, and an eclipse is the shadow left by the moon on the moon by the earth. (Demonstration experiment)

29. The surface temperature of the sun is about 6 thousand degrees, and the internal temperature is about 20 million degrees. (The distance between the earth and the sun1.500 million kilometers)

Eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

There are eight planets, dwarf planets, asteroids, satellites, comets and meteors in the solar system.

32. Know Ursa major (white seven stars), Polaris, Vega, Altair, etc.

According to the blue constellation, we can know more constellations.

34. The Milky Way has a diameter of 654.38+ million light years and contains 200 billion stars. The sun is 30,000 light-years away from the center of the Milky Way and rotates counterclockwise around the Milky Way at a speed of 250 kilometers per second. It takes 250 million years to rotate once. Life or habitable stars may appear on planets 200-300 million light years away from the center of the Milky Way.

35. At present, human beings can observe the universe within 654.38+0.5 billion light-years with radio telescopes, and 654.38+0 billion extragalactic galaxies have been discovered, but the edge of the universe has not yet been discovered, and the universe is still expanding rapidly.

36. 1 100 million years later, the sun may explode into a supernova and become a red giant. Humans must move to Mars (500 million years), then Titan (500 million years), and then livable stars in the Milky Way or extragalactic system.

Environment and us

37. The average person produces 300-700 grams of garbage every day.

38. A large amount of garbage is dragged to the landfill, and rainwater seeps into the garbage underground, which will seriously pollute the groundwater.

39. Garbage should be buried in the designated landfill. Parks and stadiums can be built on landfills, but houses and crops cannot be built.

40. In order to reduce garbage, garbage should be divided into recyclable (plastic, glass, metal, paper), non-recyclable and pollution.

4 1, a waste battery will make 1 square meter of soil lose 100 years of use value and pollute 600 tons of water.

42, the lack of fresh water, everyone should have a strong sense of water saving, so that the outflow of water can be used many times.

43. Sewage treatment: sedimentation, filtration, sunshine and air purification. Experiment: precipitation with beaker; Filter with two coke bottles (with sand); The beaker is filled with water and dried in the sun. (Add a little bleach)

44. For serious sewage sources such as paper mills and cement plants, the relevant departments should be ordered to treat the sewage before discharging it.

45. Investigate the waters of hometown: whether there is waste water discharge, look at the color, whether there are animals and plants, and whether the water surface is polluted. Take a bottle of water sample back to observe: see if there is precipitation, see if there are microorganisms in the water with a microscope, and write an investigation report. (Collatable)

46. Reducing the emissions of industrial waste gas, automobile exhaust gas and freon gas and prohibiting the use of halons are the fundamental ways to control air pollution. Relevant departments should strengthen supervision and reward new energy units that use environmental protection.

47. Protecting the environment is not a slogan, but everyone's action!