Popular Science 15 Short Science Knowledge

1. Rabbits communicate by patting ground with their feet. Most rabbits that pat ground with their hind feet are male rabbits, which is a way for female rabbits to express their emotions.

2. The largest monkey in world is baboon, and smallest is tamarin.

3. The real name of "Four different elephants" is elk, a rare animal in our country.

4. Why does sorbet smoke?

Sorbet smokes because there is a lot of invisible water vapor in outside air. When it encounters a very cold sherbet, it turns into mist and surrounds sherbet when it is cold. It seems that sorbet "gassing" "The same.

5. Why do sunflowers always face sun?

Sunflower stems contain wonderful auxin. This auxin is very sensitive to light. When it meets light, it moves to backlight side, and at same time stimulates cells on backlight side to multiply rapidly, so backlight side grows faster than light side, which causes sunflower to produce phototropic bending.

6. Why do cicadas shed their skin?

The shell (exoskeleton) of cicada is hard and cannot expand as cicada grows. When cicada grows to a certain stage, cicada's exoskeleton restricts cicada's growth, and cicada removes original exoskeleton, this is cicada's swamp.

7. How do bees make honey?

The bees first spit sweet juice from picked flowers into empty hive. At night they suck sweet juice into their honey stomach to cook it, then they spit it out and swallow it again. 100 to 240 times finally into sweet honey.

8. Why do stars twinkle?

We see twinkling of stars not due to a change in brightness of stars themselves, but due to occlusion of atmosphere. The atmosphere is between us and stars. As starlight travels through atmosphere, it is affected by density and thickness of atmosphere. The atmosphere is not absolutely transparent, its transparency depends on density. Therefore, when we look through it at earth at stars, we see that stars seem to twinkle.

9. Why do people yawn?

When we feel tired, body produces a lot of carbon dioxide. When there is too much carbon dioxide, oxygen must be added to balance body's needs. Since this residual carbon dioxide will affect functional activities of our body, at this time body sends a defensive reaction, so we yawn. Yawning is a deep breathing action that allows us to take in more oxygen and exhale carbon dioxide than usual, and also eliminates fatigue.

10. Why can snakes walk without legs?

Snakes have many scales, which are outer layer of armor on their bodies. The scales are used not only to protect body, but also their "legs". As snake crawls forward, its body takes on an S-shape. Each scale outside of S-shape will be raised to help snake grab ontobumpy road as she moves forward. These scales interact with snake's muscles and can push body forward to crawl, so snake can walk without legs!

11. Why does hair turn gray with age?

There is a substance in our hair called melanin. The more melanin it contains, darker hair will be. And if there is little melanin, hair will turn yellow or white. When people reach old age, various functions of body gradually decrease, and production of pigment becomes less and less, so hair gradually becomes white!

12. Why do fireflies glow?

Fireflies will glow because they have a light emitter at end of their abdomen, filled with a variety of phosphor luminescent substances and luminescent enzymes, so that fireflies can emit flashes of light. The purpose of light of fireflies is not only for illumination, but also for courtship, warning, trapping and other purposes. It is also a tool for their communication. Different types of fireflies have different methods of emitting light, frequencies and colors of emitting light, and they use this to convey different messages.

13. Why does my stomach growl when I'm hungry?

When you're hungry, you'll grumble. This is because food you ate before is almost overcooked. Although stomach is empty, gastric juices in stomach will continue to flow. At this time, contractions of stomach will gradually expand, and liquid and gas inside will agitate, causing a gurgling sound. Don't be embarrassed that your stomach will growl next time! Because it is a normal physiological action.

14. Why doesn't an ostrich fly?

A species of ostrich with a big body, but they can't fly! It's not that their wings don't work, it's that their feathers are too soft and their wings are too small to fly. In addition, ostrich has underdeveloped muscles and a flat sternum, which is not conducive to flight. Ostriches live in Africa. Since they lived in desert areas for a long time, their bodies gradually evolved into what they are today to adapt to environment.

15. Why doesn't jar food spoil?

Breakfast meat, dace in black bean sauce, beans in tomato sauce... all these are delicious canned foods that can be stored for a long time without spoiling. This is because jars are sealed so bacteria cannot get inside. When people make canned food, all air is pumped out of can, and then it is sealed. In absence of air, even if food inside is colored by a small amount of bacteria, they cannot survive or reproduce!