Not long ago, our family moved into a new house. Just moved home, my uncle and aunt sent some pots of flowers and trees. Bonsai is placed at the door, living room, room and balcony. I said to my father, "We have a botanical garden at home. Why do we have so many plants? " Dad smiled and said, "Plants can create an atmosphere and purify the air. People and animals cannot do without them. " People or animals cannot live without plants? Why can't people or animals live without plants? I'll be skeptical. Decided to do a few small experiments to prove the problem.
On Sunday, I caught two mice from the garage. These two poor little mice will be my experiments. They have been struggling, and the round disposable film tablecloth stared at me with small eyes. I put the first mouse in a big fish tank and sealed the glass bottle tightly, for fear that the air in the bottle would communicate with the outside air. I watched carefully and saw the little mouse running quickly around the bottom of the cylinder against the wall. Hey, isn't the mouse alive and well? Isn't it true what dad said? However, in a few minutes, I saw the little mouse winding slower and slower until it was stagnant and dying. Suddenly, I gently removed the disposable film tablecloth, grabbed the first mouse, put the second mouse in, and moved into four pots of leafy plants. Then gently cover the disposable film tablecloth. I kept patting the fish tank and saw the little mouse scurrying about in panic. After a long time, I don't want to die. This experiment proves that plants can transport the oxygen that animals need.
In order to further prove the dependence of humans and animals on plants. I came to a feed processing factory near our hometown. The air there is full of dust noise, which makes me cough. I feel very uncomfortable. Then, I ran to a bamboo forest behind our house. It is a place with fresh air, and I feel extremely refreshing. This experiment proves that plants can purify the air. Let people breathe smoothly.
These two experiments prove that the survival of human beings and animals is closely related to plants. How scientific is this? Our scientific and technological team came to the library to consult a lot of scientific and technological books, and also went to the electronic north reading room of the school for online inquiry, and summarized the following points: ① People must rely on plants to provide oxygen, and only plants can make oxygen. If a person doesn't eat or drink for a few days, he may die in a few minutes. Oxygen is the first need of human life activities! An adult breathes about 20,000 times a day, inhaling 0.75 kg of oxygen and exhaling 0.9 kg of carbon dioxide. (2) Breathing of animals and plants and burning of substances also consume oxygen and release carbon dioxide. So, isn't there more oxygen in the air every day? Don't! The reason why there has never been such a crisis between heaven and earth is that plants are both "factories" of natural oxygen and "broad markets" of carbon dioxide. According to statistics, 1 hectare of broad-leaved forest can produce 750 kilograms of oxygen and eat 1 1,000 kilograms of carbon dioxide every day during the growing season. Therefore, as long as there are 6,543,800 square meters of trees, it can supply a person with oxygen demand and absorb exhaled carbon dioxide. Because there are plants that constantly supplement oxygen, the oxygen in the air can be kept basically constant. On the contrary, if there are no plants, the oxygen on the earth can be used up in about 500 years.
Therefore, human beings and animals can sustain life, and the oxygen needed for activities must be attributed to green plants. Plants are closely related to our human and animal lives. Here, the students in Class 4 (1) of our experimental primary school appeal to people in the whole society to stop cutting down plants and make them our best friends.
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Explore the swim bladder
I remember once grandpa killed crucian carp, and I stood by and watched. Grandpa peeled the belly of crucian carp and took out a white peanut-like thing for me to play with. I asked my grandfather, "What is this?" Grandpa said, "It's a swim bladder." I took it in my hand curiously and found it was empty. I asked curiously, "What's the use of this thing?" Grandpa said, "Ask your teacher when you go to school. Grandpa doesn't know what's the use. " One day at noon, I ate in the school cafeteria, and there was braised crucian carp in the dish box. Suddenly my brain recalled the swim bladder that my grandfather gave me, and my curiosity about the swim bladder came up again. So, I happily ran to ask the teacher: "Teacher Yu, what is the swim bladder for?" The teacher looked at me in surprise and then smiled: "The swim bladder is a structure in the fish, which is full of air. When it is filled with a lot of air, it can make fish float in the water; When the air inside is squeezed out, the swim bladder will shrink and the fish will sink. " I seem to understand, "well, do all fish have swim bladders?" I don't know where the idea came from, so I asked. The teacher frowned and thought for a moment. Some fish have no swim bladder, such as sharks and some deep-sea fish. "So, how do fish swim up and down without swim bladder?" The teacher frowned and didn't speak for a long time, then looked at me with a smile and stroked my head and said, "Kid, you are so smart! Your question stumped the teacher! If you are interested, how about we do experiments together and check the information together to solve this problem? " I nodded vigorously with pleasure. One day later, in the afternoon, Teacher Yu gathered me and several classmates in a classroom. Start our experiment to explore the function of swim bladder. Experiment 1 Explore whether the ups and downs of fish in water are related to the size of the swim bladder. Question: Is the fluctuation of fish in water related to the size of swim bladder? Hypothesis: the fluctuation of fish in water is related to the size of swim bladder. Experimental design: Four live crucian carp were selected, and two of them were carefully cut into the abdomen, and the swim bladder was taken out with tweezers, cut with a knife, stitched with a needle and thread, and marked. The remaining two fish served as the control group without any operation. Put four fish into the water and observe their ups and downs and suspensions carefully. Experimental phenomenon: 1. The results showed that the two marked fish (crucian carp with its swim bladder cut) were not flexible, but they could rise and fall in the water. 2. When all four fish are ups and downs, their fins are constantly moving. Experimental conclusion: the ups and downs of fish have little to do with the swim bladder, but with the fins. So, we did the second experiment. Experiment 2 explores the relationship between fish's ups and downs in water and fins. Experimental steps: 1. Select some live crucian carp and divide them into four groups, 3 in each group. The first group, carefully cut off the pectoral fin and ventral fin of the fish; The second group, carefully cut off the tail fin; In the third group, all fins were carefully cut off; The fourth group did not cut any fins, and only served as the control group. Put four groups of fish into the fish tank and carefully observe their ups and downs and suspensions in the water. Observation record: in the first group, the fish can float freely, but they can't suspend or stop to rest. The second group of fish can float and sink, but the balance is not good and the speed is slow. The third group of fish is very slow, unstable and poorly balanced. Experimental conclusion: The fish's ups and downs in water are really related to fins, and the fish's ups and downs in water are mainly realized by the movement of fins, especially the movement of tail fins. After the experiment, we consulted a lot of facts and related materials with the teacher, and then came to the conclusion that the relationship between the fish's ups and downs and the size of the swim bladder is not very big, which is mainly realized by the movement of the fins. The volume change of the swim bladder is passive during the ups and downs, and the swim bladder can be used as an auxiliary respiratory organ to provide oxygen for the fish.
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