1. Little knowledge about Plants
Plants are a big category in the biological world. Plants can be divided into spore plants and seed plants. There are chlorophyll and substrates that animals don't have, which can carry out photosynthesis. Plants have nuclei, which can convert inorganic substances into organic substances. Some special cases can't convert inorganic substances into organic substances. Some have no chlorophyll and other photosynthetic elements. < P > Plants have cell walls, no nervous system and no feelings. There are algae, lichens, mosses, ferns and seed plants, and seed plants are divided into gymnosperms and angiosperms, with more than 3 thousand species. Plants are multicellular eukaryotes capable of photosynthesis. But many multicellular algae are also photosynthetic organisms, and the most important difference between them and plants is aquatic and terrestrial. We can make such a definition; Plants are multicellular photosynthetic eukaryotes suitable for terrestrial life, which are composed of roots, stems and leaves. There are cuticular membranes, stomata, conducting tissues and female/male gametophytes on the surface, and embryos develop in gametophytes. These important differences show that plants are very different from algae, so algae is included in the protozoa in the five-realm system.
2. Biology tips
1. Why do the stars twinkle? We see the stars shining, not because the luminosity of the stars themselves changes, but because of the occlusion of the atmosphere.
The atmosphere is between us and the stars. When starlight passes through the atmosphere, it will be affected by the density and thickness of the atmosphere. The atmosphere is not absolutely transparent, and its transparency will change according to the density.
So when we look at the stars through it on the ground, we will see that the stars seem to be flashing. 2. Why do people yawn? When we feel tired, a lot of carbon dioxide has been produced in our bodies.
when there is too much carbon dioxide, oxygen must be added to balance the body's needs. Because these residual carbon dioxide will affect the functional activities of our body, then the body will send out a protective reaction, so it yawns.
yawning is a deep breathing action, which will make us breathe in more oxygen and expel carbon dioxide than usual, and it can also eliminate fatigue. 3. Why can snakes walk without feet? Snakes have many scales, which is the outermost layer of armor on their bodies.
Scales are not only used to protect the body, but also can be their "feet". When a snake crawls forward, its body will be S-shaped.
And every scale outside the S-shape will tilt up to help the snake catch the uneven road when it moves forward. These scales cooperate with the snake's muscles and can push the body forward, so the snake can walk without feet! 4. Why do sunflowers always bloom towards the sun? There is a substance called "auxin" in the stem under the sunflower disk.
This substance has the function of accelerating reproduction, but it is anti-optical. Whenever it meets light, it will run to the backlight side. So when the sun rises, the stem of the sunflower immediately hides to the backlight side, and it seems that the whole plant bends in the direction of the sun.
5. Why does hair turn white when people get old? There is a substance called melanin in our hair. The more melanin there is, the darker our hair will be. If there is less melanin, the hair will turn yellow or white.
When people get old, all kinds of functions of the body will gradually decline, and the formation of pigment will be less and less, so their hair will gradually turn white! 6. Why do fireflies glow? Fireflies emit light because there is a light emitter at the end of their abdomen, which is filled with many phosphorus-containing luminescent substances and luminescent enzymes, so that fireflies can emit flashing light. The purpose of fireflies is not only to illuminate, but also to courtship, vigilance, trapping and other purposes.
This is also a communication tool for them. Different kinds of fireflies emit light in different ways, frequencies and colors, so they can convey different messages. 7. Why do you growl when you are hungry? When you are hungry, you will purr. This is because the food you have eaten before is almost digested. Although the stomach is empty, the gastric juice in the stomach will continue to secrete.
At this time, the contraction of the stomach will gradually expand, and the liquid and gas inside will be stirred up, causing a purring sound. Don't feel embarrassed about your stomach growling next time! Because this is a normal physiological action.
8. Why can't ostrich fly? A kind of huge ostrich, but they can't fly to the sky! This is not because their wings are useless, but because their feathers are too soft and their wings are too small to fly at all. In addition, the ostrich's muscles are underdeveloped and its sternum is flat, which is not helpful for flying.
ostriches live in Africa. Because they have lived in desert areas for a long time, their bodies gradually evolved into what they are now in order to adapt to the environment. 9. Why can't canned food go bad easily? Lunch meat, black bean shad, tomato sauce beans.
They are all delicious canned foods, and they can be stored for a long time without spoiling easily.
This is because the can is sealed, so bacteria can't enter. When people make canned food, they pump all the air out of the canned food and then seal it.
in the absence of air, even if the food inside is stained with a little bacteria, they can't survive or reproduce! 1. Why do babies cry all the time when they are born? Babies will cry when they are born, not because they are unhappy, but because they are taking their first breath of air! When babies leave their mother's body and are born, the first breath of air they breathe will rush to their throats, which will violently impact the vocal cords, make them vibrate, and then make a sound similar to crying. 11. Why do lizards keep bouncing when their tails are broken? In order to protect themselves, many lizards also protect their eyes and ears; When some lizards are attacked, their tails will be broken due to the severe contraction of muscles.
Based on the broken tail, some nerves are still alive, and it will keep bouncing, thus distracting the enemy and escaping. Don't think that their lives will end like this. In fact, it only takes a few months, and their tails will grow back and move on.
12. Why is the squirrel's tail so big? Don't look at the tail of the relaxed mouse! While the squirrel is jumping around the tree, its tail is playing a great role. It can balance the squirrel when jumping on the tree and avoid falling and being injured.
In addition, this big tail can play a protective role in winter, and it is convenient and practical to tightly surround the squirrel's body. 13. Why can't a person have one or three thumbs? The average person has five fingers, and the length of each finger is different.
However, does anyone realize that besides the thumb, other fingers also have three sections, but only the thumb has two sections? It turns out that its number of joints just matches the other four fingers. If it is three knots, the thumb will appear powerless, so that it can't lift heavy objects; If there is only one section, it can't freely cooperate with the other four fingers to grasp things! 14. Why don't you feel itchy when you scratch yourself? When others scratch ourselves, we will feel itchy and laugh constantly; However, when we scratch ourselves, we not only don't laugh, but also don't feel itchy.
Based on our mental preparation, our brains will send out a message that there is no danger, and our nerves will relax, so we won't laugh and feel itchy! 15. Why is the sea water mostly blue and green? Looking at the sea, I often find that the sea water is blue and green. However, when you pick up the sea water, you can only see it as transparent and colorless as the old water.
It turns out that seawater itself has nothing to do with the water we come into contact with every day.
3. Twenty biological tips ()
1. Most infectious diseases of plants are caused by fungi.
2. According to the degree and height of lignification of stems, plants can be divided into four types: arbor; Shrub; Herbs; Lianas.
3. The lower plants are divided into 12 phyla: Cyanophyta, Rhodophyta, Chlorophyta, Euglenophyta, Dinophyta, Chrysophyta, Phaeophyta, Fungus, Charophyta, Bacteria, Myxomycetes and Lichens.
4. The highest flying bird in the world is a swan.
5. The pregnancy of an elephant takes 22 months.
6. marine life accounts for about 99% of the total life on earth.
7. The largest pair of salivary glands in the human body is the parotid gland located in front of the ear.
8. There are about 35 bones in a baby's body.
9. The human spine has four physiological bends.
1. There are 6 muscles in the human body.
11. Thymus only exists from infancy to adolescence in human life.
12. There are often more cold sensation receptors under human skin than hot sensation receptors.
13. Fingerprints can be divided into three categories: bucket shape; Basket-shaped; Bow.
14. A person's nail is composed of three parts: deck, nail bed and nail root. There are blood vessels and nerves in the nail bed.
15. Why does hair turn white when people get old?
There is a substance called melanin in our hair. The more melanin, the darker our hair will be. If there is less melanin, the hair will turn yellow or white. When human beings reach old age, the various functions of the body will gradually decline, and the formation of pigments will be less and less, so the hair will gradually turn white!
16. Why do fireflies glow?
Fireflies glow because there is a light emitter at the end of their abdomen, which is filled with many phosphorus-containing luminescent substances and luminescent enzymes, so that fireflies can emit flashing light.
Fireflies are used for lighting, courtship, vigilance and trapping. This is also a communication tool for them. Different kinds of fireflies emit light in different ways, frequencies and colors, so they can convey different messages.
17. Why do the stars twinkle?
We see the stars shining, not because the luminosity of the stars themselves changes, but because of the occlusion of the atmosphere.
The atmosphere is between us and the stars. When starlight passes through the atmosphere, it will be affected by the density and thickness of the atmosphere. The atmosphere is not absolutely transparent, and its transparency will change according to the density. So when we look at the stars through it on the ground, we will see that the stars seem to be flashing.
18. Why do people yawn?
when we feel tired, a lot of carbon dioxide has been produced in our bodies. When there is too much carbon dioxide, oxygen must be added to balance the body's needs. Because these residual carbon dioxide will affect the functional activities of our body, then the body will send out a protective reaction, so it yawns.
yawning is a deep breathing action, which will make us breathe in more oxygen and expel carbon dioxide than usual, and it can also eliminate fatigue.
19. Why can snakes walk without feet?
snakes have many scales, which is the outermost layer of armor. Scales are not only used to protect the body, but also to be their "feet".
when a snake crawls forward, its body will be S-shaped. And every scale outside the S-shape will tilt up to help the snake catch the uneven road when it moves forward. These scales cooperate with the snake's muscles and can push the body forward, so the snake can walk without feet!
2. Why do sunflowers always bloom toward the sun
There is a substance called "auxin" in the stem under the sunflower disk. This substance has the function of accelerating reproduction, but it is anti-optical, and whenever it encounters light, it will run to the backlight side.
So when the sun rises, the stem of sunflower immediately hides to the backlight side, and it seems that the whole plant bends in the direction of the sun.
4. There is an urgent need for 2 biological tips.
1. Most infectious diseases of plants are caused by fungi.
2. According to the degree and height of lignification of stems, plants can be divided into four types: arbor; Shrub; Herbs; Lianas. 3. Lower plants are divided into 12 phyla: Cyanophyta, Rhodophyta, Chlorophyta, Gymnophyta, Chrysophyta, Phaeophyta, Fungus, Charophyta, Bacteria, Myxomycetes and Lichens.
4. The highest flying bird in the world is a swan. 5. The pregnancy of an elephant takes 22 months.
6. marine life accounts for about 99% of the total life on earth. 7. The largest pair of salivary glands in the human body is the parotid gland located in front of the ear.
8. There are about 35 bones in a baby's body. 9. The human spine has four physiological bends.
1. There are 6 muscles in the human body. 11. Thymus exists only from infancy to youth in human life.
12. There are often more cold sensation receptors under human skin than hot sensation receptors. 13. Fingerprints can be divided into three categories: bucket shape; Basket-shaped; Bow.
14. A person's nail is composed of three parts: deck, nail bed and nail root. There are blood vessels and nerves in the nail bed.
15. Why does hair turn white when people get old? There is a substance called melanin in our hair. The more melanin there is, the darker our hair will be. If there is less melanin, the hair will turn yellow or white.
When people get old, all kinds of functions of the body will gradually decline, and the formation of pigment will be less and less, so their hair will gradually turn white! 16. Why do fireflies glow? Fireflies emit light because there is a light emitter at the end of their abdomen, which is filled with many phosphorus-containing luminescent substances and luminescent enzymes, so that fireflies can emit flashing light. The purpose of fireflies is not only to illuminate, but also to courtship, vigilance, trapping and other purposes.
This is also a communication tool for them. Different kinds of fireflies emit light in different ways, frequencies and colors, so they can convey different messages. 17. Why do the stars twinkle? We see the stars shining, not because the luminosity of the stars themselves changes, but because of the occlusion of the atmosphere.
The atmosphere is between us and the stars. When starlight passes through the atmosphere, it will be affected by the density and thickness of the atmosphere. The atmosphere is not absolutely transparent, and its transparency will change according to the density.
So when we look at the stars through it on the ground, we will see that the stars seem to be flashing. 18. Why do people yawn? When we feel tired, a lot of carbon dioxide has been produced in our bodies.
when there is too much carbon dioxide, oxygen must be added to balance the body's needs. Because these residual carbon dioxide will affect the functional activities of our body, then the body will send out a protective reaction, so it yawns.
yawning is a deep breathing action, which will make us breathe in more oxygen and expel carbon dioxide than usual, and it can also eliminate fatigue. 19. Why can snakes walk without feet? Snakes have many scales, which is the outermost layer of armor on their bodies.
Scales are not only used to protect the body, but also can be their "feet". When a snake crawls forward, its body will be S-shaped.
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