10 Scientific Facts You Didn't Know

1. Rabbits communicate by patting ground with their paws. Most rabbits that pat ground with their hind legs are male rabbits, which is a way of expressing their emotions to females.

2. Why do sunflowers always face sun? Sunflower stems contain a 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.

3. Why do cicadas shed their skin? The shell (exoskeleton) of cicadas is hard and cannot expand as cicadas grow. When original exoskeleton is removed, it turns into a cicada husk.

4. 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.

5. Why does my stomach growl when I'm hungry? When you are hungry, you will 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.

6. Why can't a person's thumb have one or three knots? The average person has five fingers, and length of fingers varies. However, has anyone noticed that, in addition to thumb, other fingers also have three joints, and thumb has only two joints? .. It turns out that its number of joints exactly matches other four fingers. If there are only three joints, thumb will appear weak and will not be able to lift heavy objects; if there is only one joint, it won't be able to interact with other four fingers to grasp objects freely!

7. Why is seaside air particularly fresh? Waves crash against shore every day, and tides bring beautiful scenery and pleasant waves to shore, as well as moist sea air. Seaside air contains a lot of negative oxygen ions, called "air vitamins", which can enter human body when breathing, improve ventilation function of lungs, increase amount of oxygen inhaled and amount of carbon dioxide exhaled. In public places of city 10-20 negative oxygen ionsode per cubic centimeter, indoors 40-50, on green lawns 100-200, by sea more than 10,000. A hundred times! Negative oxygen ions are negatively charged ions that have a bactericidal effect and can inhibit growth of bacteria in air. A large amount of negative oxygen ions improves functioning of a person's sympathetic nerves, makes a person alert and energetic, and can also increase hemoglobin content in blood. Therefore, many sanatoriums have been built on seashore, because seaside air has a healing effect on people suffering from emphysema, hypertension, neurasthenia, asthma, anemia and other diseases, which has a beneficial effect on health of human body and invigorates it. spirit.

8. It is not recommended to drink milk in morning on an empty stomach. Because gastrointestinal motility speeds up when human body is starving, nutrients in milk often rush into colon before they can be absorbed. In addition, it is not recommended to drink milk with large mouths because it will reduce chance of mixing with saliva in mouth, which does not promote digestion and absorption. It is best to eat cookies, pastries, etc. before drinking milk, or drink milk during a snack.

9. Milk is better to drink at night. Scientific studies have established that calcium metabolism in human body has a special rule: at night, especially at midnight, a “dip” occurs in plasma calcium content, forcing body to replenish calcium reserves through mechanism of regulation of transport part. bones. Thus, while calcium in blood is temporarily retained, calcium in bones is reduced. Milk is rich in calcium, so a glass of milk before bed compensates for body's need for calcium at night.

10. They say that a woman consists of water. In fact, water in body of a boy is 90%, and that of a girl is 80%.