Until photosynthesis was discovered in the middle of18th century, people always thought that all the nutrients in plants were obtained from the soil, but they didn't think that plants could get anything from the air. 177 1 year, British scientist priestley found that it is not easy to extinguish the lighted candle in a closed glass cover with green plants. When mice are placed in a glass cover with green plants, they are not easy to suffocate. Therefore, he pointed out that plants can renew the air. But he didn't know which pattern plants were updated in the air, and he didn't find the key role of light in this process. Later, after many scientists' experiments, the places, conditions, raw materials and products of photosynthesis were gradually discovered. 1864, a german scientist saxophone made an experiment: put the green leaves in the dark for several hours in order to consume the nutrients in the leaves. Then expose half of the blade and cover the other half. After a period of time, the leaves were treated with iodine vapor, and it was found that half the color of the dark side of the leaves remained unchanged, while the exposed half was dark blue. This experiment successfully proved that green leaves produce starch in photosynthesis. 1880, German scientist engelmann conducted an experiment on the photosynthesis of Spirogyra: put a temporary package containing aerobic bacteria in a dark environment without air, and then irradiate Spirogyra with a very thin beam. Through microscopic observation, it was found that aerobic bacteria only concentrated near the position where chloroplasts were irradiated by light beams. If the temporary package is completely exposed to light, aerobic bacteria will concentrate around all the light-receiving parts of chloroplasts. Engelmann's experiment proves that oxygen is released from chloroplast, which is the place where green plants carry out photosynthesis.
The process of photosynthesis: 1 The chemical reaction in the first stage of photosynthesis must have light energy, which is called photoreaction stage. The chemical reaction in the photoreaction stage is carried out on the thylakoids of chloroplasts. The chemical reaction in the second stage of photosynthesis in the dark reaction stage can be carried out without light energy. This stage is called dark reaction stage. The chemical reaction in the dark reaction stage is carried out in the matrix in chloroplast. The light reaction stage and dark reaction stage are a whole, which are closely related and indispensable in the process of photosynthesis. The Significance of Photosynthesis Photosynthesis provides material and energy sources for the survival of almost all living things, including human beings. Therefore, photosynthesis is of great significance to human beings and even the whole biological world. First, make organic matter. The amount of organic matter produced by green plants through photosynthesis is huge. It is estimated that the green plants on the earth produce about 450 billion tons of organic matter every year, far exceeding the total output of industrial products on the earth every year. Therefore, people compare the green plants on the earth to a huge "green factory". The survival of green plants is inseparable from the organic matter produced by photosynthesis. Food for humans and animals also comes directly or indirectly from organic matter produced by photosynthesis. Second, convert and store solar energy. Green plants convert solar energy into chemical energy through photosynthesis and store it in organic matter produced by photosynthesis. Almost all living things on the earth use this energy directly or indirectly as the energy of life activities. In the final analysis, the energy contained in fuels such as coal, oil and natural gas was stored by ancient green plants through photosynthesis.
Third, make the contents of oxygen and carbon dioxide in the atmosphere relatively stable. It is estimated that all living things in the world consume an average of 10000 t/s (ton/s) by breathing and burning various fuels. At this rate of oxygen consumption, the oxygen in the atmosphere will be exhausted in about two thousand years. However, this did not happen. This is because green plants are widely distributed on the earth, constantly absorbing carbon dioxide and releasing oxygen through photosynthesis, so that the contents of oxygen and carbon dioxide in the atmosphere remain relatively stable. Fourthly, it plays an important role in biological evolution. Before the appearance of green plants, there was no oxygen in the earth's atmosphere. Only 2 billion to 3 billion years ago, green plants appeared on the earth and gradually took advantage, and the earth's atmosphere gradually contained oxygen, thus enabling other creatures on the earth to have aerobic respiration. Because part of the oxygen in the atmosphere is converted into ozone (O3). The ozone layer formed by ozone in the upper atmosphere can effectively filter out the ultraviolet rays that have a strong destructive effect on organisms in solar radiation, so that aquatic organisms can gradually live on land. After a long process of biological evolution, a variety of animals and plants widely distributed in nature finally appeared.
Plant cultivation and rational utilization of light energy are the driving forces of photosynthesis of green plants. In plant cultivation, reasonable use of light energy can make green plants fully carry out photosynthesis. The rational utilization of light energy mainly includes two aspects: prolonging the time of photosynthesis and increasing the area of photosynthesis.
Prolonging the time of photosynthesis and prolonging the time of photosynthesis of green plants per unit land area throughout the year are important measures for rational utilization of light energy. For example, planting and harvesting wheat once a year on the same land, instead of harvesting wheat once a year and then planting and harvesting corn again, can increase the yield per unit area.
Increasing the area of photosynthesis and reasonable close planting are important measures to increase the area of photosynthesis. Reasonable close planting refers to planting plants with appropriate density on unit area of land according to soil fertility.
Photosynthesis refers to the process that green plants use light energy through chloroplasts to convert carbon dioxide and water into organic substances that store energy and release oxygen. We breathe in oxygen released by photosynthesis all the time. The food we eat every day also comes directly or indirectly from organic matter produced by photosynthesis. So, how was photosynthesis discovered?
Until photosynthesis was discovered in the middle of18th century, people always thought that all the nutrients in plants were obtained from the soil, but they didn't think that plants could get anything from the air. 177 1 year, British scientist priestley found that it is not easy to extinguish the lighted candle in a closed glass cover with green plants. When mice are placed in a glass cover with green plants, they are not easy to suffocate. Therefore, he pointed out that plants can renew the air. But he didn't know which pattern plants were updated in the air, and he didn't find the key role of light in this process. Later, after many scientists' experiments, the places, conditions, raw materials and products of photosynthesis were gradually discovered. 1864, a german scientist saxophone made an experiment: put the green leaves in the dark for several hours in order to consume the nutrients in the leaves. Then expose half of the blade and cover the other half. After a period of time, the leaves were treated with iodine vapor, and it was found that half the color of the dark side of the leaves remained unchanged, while the exposed half was dark blue. This experiment successfully proved that green leaves produce starch in photosynthesis. 1880, German scientist engelmann conducted an experiment on the photosynthesis of Spirogyra: put a temporary package containing aerobic bacteria in a dark environment without air, and then irradiate Spirogyra with a very thin beam. Through microscopic observation, it was found that aerobic bacteria only concentrated near the position where chloroplasts were irradiated by light beams. If the temporary package is completely exposed to light, aerobic bacteria will concentrate around all the light-receiving parts of chloroplasts. Engelmann's experiment proves that oxygen is released from chloroplast, which is the place where green plants carry out photosynthesis. The process of photosynthesis: 1 The chemical reaction in the first stage of photosynthesis must have light energy, which is called photoreaction stage. The chemical reaction in the photoreaction stage is carried out on the thylakoids of chloroplasts. The chemical reaction in the second stage of photosynthesis in the dark reaction stage can be carried out without light energy. This stage is called dark reaction stage. The chemical reaction in the dark reaction stage is carried out in the matrix in chloroplast. The light reaction stage and dark reaction stage are a whole, which are closely related and indispensable in the process of photosynthesis. The Significance of Photosynthesis Photosynthesis provides material and energy sources for the survival of almost all living things, including human beings. Therefore, photosynthesis is of great significance to human beings and even the whole biological world. First, make organic matter. The amount of organic matter produced by green plants through photosynthesis is huge. It is estimated that the green plants on the earth produce about 450 billion tons of organic matter every year, far exceeding the total output of industrial products on the earth every year. Therefore, people compare the green plants on the earth to a huge "green factory". The survival of green plants is inseparable from the organic matter produced by photosynthesis. Food for humans and animals also comes directly or indirectly from organic matter produced by photosynthesis. Second, convert and store solar energy. Green plants convert solar energy into chemical energy through photosynthesis and store it in organic matter produced by photosynthesis. Almost all living things on the earth use this energy directly or indirectly as the energy of life activities. In the final analysis, the energy contained in fuels such as coal, oil and natural gas was stored by ancient green plants through photosynthesis.
Third, make the contents of oxygen and carbon dioxide in the atmosphere relatively stable. It is estimated that all living things in the world consume an average of 10000 t/s (ton/s) by breathing and burning various fuels. At this rate of oxygen consumption, the oxygen in the atmosphere will be exhausted in about two thousand years. However, this did not happen. This is because green plants are widely distributed on the earth, constantly absorbing carbon dioxide and releasing oxygen through photosynthesis, so that the contents of oxygen and carbon dioxide in the atmosphere remain relatively stable. Fourthly, it plays an important role in biological evolution. Before the appearance of green plants, there was no oxygen in the earth's atmosphere. Only 2 billion to 3 billion years ago, green plants appeared on the earth and gradually took advantage, and the earth's atmosphere gradually contained oxygen, thus enabling other creatures on the earth to have aerobic respiration. Because part of the oxygen in the atmosphere is converted into ozone (O3). The ozone layer formed by ozone in the upper atmosphere can effectively filter out the ultraviolet rays that have a strong destructive effect on organisms in solar radiation, so that aquatic organisms can gradually live on land. After a long process of biological evolution, a variety of animals and plants widely distributed in nature finally appeared.
Plant cultivation and rational utilization of light energy are the driving forces of photosynthesis of green plants. In plant cultivation, reasonable use of light energy can make green plants fully carry out photosynthesis. The rational utilization of light energy mainly includes two aspects: prolonging the time of photosynthesis and increasing the area of photosynthesis.
Prolonging the time of photosynthesis and prolonging the time of photosynthesis of green plants per unit land area throughout the year are important measures for rational utilization of light energy. For example, planting and harvesting wheat once a year on the same land, instead of harvesting wheat once a year and then planting and harvesting corn again, can increase the yield per unit area.
Increasing the area of photosynthesis and reasonable close planting are important measures to increase the area of photosynthesis. Reasonable close planting refers to planting plants with appropriate density on unit area of land according to soil fertility.