Through consulting and collecting data, we can understand the practical value and efficacy of plant essential oil. Collect the effective methods of extracting essential oil in industrialization and laboratory, select the most suitable experimental method, formulate the experimental scheme and implement it. According to the experimental results, adjust the experimental scheme, sum up experience, improve it, and conduct the second experiment. Finally, the results of the two experiments were analyzed, and the best scheme of essential oil extraction was obtained. Key words: essential oil The plant essential oil extracted by steam distillation of rose is the source of floral fragrance, which has medical function and is also very expensive. After discussion, my team members think that by collecting the data of plant essential oil extraction, we can deepen our understanding of this extraction industry. Choosing and drawing up the experimental scheme in person can improve our scientific inquiry level. The unpredictable changes brought by experiments can make us feel that the success of scientific experiments is hard-won. Finally, the topic is determined as follows: the selection of extraction methods of plant essential oil and experimental exploration. After setting the subject of research study, we first collected the relevant information about the extraction methods of plant essential oil. The main extraction methods are: steam distillation, chemical solvent extraction, oil separation (liposuction), freeze compression (squeezing) and carbon dioxide extraction. These five methods have their own characteristics: steam distillation: the simplest operation and lower cost are the most commonly used extraction methods. Chemical solvent (organic matter) extraction method: it is a common extraction method of flower essential oil. Oil separation (liposuction): it is an expensive extraction method of flower essential oil. Freeze compression method (squeezing method): it is specially used to extract essential oil stored in peel, such as citrus fruits. Carbon dioxide extraction: This is a very expensive method. The quality of the extracted essential oil is almost perfect and the price is very expensive. Considering the cost and difficulty of the experiment, combined with the existing experimental conditions in our school, we finally decided to choose steam distillation and organic extraction to extract essential oil. Step 2, select experimental materials (plant varieties): among many plants (lemon citronella, lavender, rosemary, geranium, tea tree, sandalwood, bergamot, eucalyptus, pine tree, rose, rose, mint, etc.), we finally choose rose petals as our experimental materials from the aspects of the price of experimental materials, the difficulty of transportation and the prediction of experimental results. After the preparation for the experiment is ready, we set about the experiment: after discussion, we decided to draw up the first experiment scheme according to the textbook: materials and appliances: extract, distilled water, alcohol, phenol, NaCl, catheter, conical flask, distillation equipment, beaker, rubber stopper, thin glass tube, thermometer, hob, mortar, alcohol lamp, glass rod and other experimental steps: after assembling the extraction equipment as shown in the figure, put α. After the water boils, the evaporated gas will condense at the condenser tube, flow out from the trumpet tube and enter the conical flask. Collect the extract. Collect about 20ml of extract and stop collecting. Put out the alcohol lamp. The extracts were divided into four groups: A 1, A2, A3 and A4, and put into test tubes. A teaspoon of NaCl was put into group a 1, phenol was put into group A2, NaCl and phenol were put into group a3, and a4 was the control group. The boiled solution (yellow) in the flask was filtered and collected and divided into four equal groups B 1, B2, B3 and B4. The experimental steps are the same as the former. Put the petals of group γ into a burning cup, add ethanol, stir the petals evenly in the ethanol solution with a glass rod, and let stand. After the ethanol solution was dyed rose, the obtained solution was divided into four groups: r 1, r4. The experimental steps are the same as group A. Cover all test tubes with rubber plugs and seal them. Theoretical basis: after the extraction of essential oil, it will form turbid liquid, which is not easy to precipitate because its density is close to that of solution. The purpose of adding NaCl is to increase the density of the solution, so that the essential oil floats on the upper layer of the liquid and is separated by a separatory funnel to obtain the essential oil. The purpose of adding phenol and alcohol is to use the solubility of essential oil in organic solvents to achieve the purpose of purification. The experiment shows that the contents of essential oil in the experimental device of group A and group B are compared with each other, and the experimental device for extracting essential oil is higher. Comparing the liquid in the same position in the horizontal direction of the device, which extraction method is more ideal? A2, B2 and R4 can compare the extraction effects of ethanol and phenol solutions on different essential oils. Experimental results: After standing for 1 week, the state of group A was the same as that before 1 week, and there was no phenomenon. Through careful observation of group B, it was found that there was a very small amount of flocculent precipitate at the bottom of group b3, and the other groups were light yellow at first, but all had a faint plant fragrance. An unknown substance floating in the upper layer of R 1 R4 test tube. There is a strong alcohol smell after opening the test tube mouth. Maybe it diluted the fragrance of essential oil, and we didn't smell it. The result of the first experiment was far beyond our expectation. This almost declared the failure of the experiment. We immediately started to check the problems and carefully analyzed the possible defects in each step. There are mainly the following four points: 1, the petals added to the flask have not been ground, which may affect the extraction of essential oil. The effect is not obvious. 2. Essential oil is insoluble in distilled water, which leads to the solution obtained after distillation close to distilled water. 3. The smell of alcohol is so strong that the aromatic smell of essential oil can't be smelled. 4. It is impossible to extract and determine whether the "suspicious substance" is really rose essential oil. In view of the problems existing in the first experiment, we designed the second experimental scheme: materials and utensils: extraction solution, alcohol, NaCl, catheter, conical flask, distillation equipment, rubber stopper, thermometer, iron shelf, water bath pot, mortar and other experimental steps: after assembling the extraction equipment as shown in the figure, put the ground petals into the flask and add 1/2 parts of refined wine. Turn on the alcohol lamp and control the alcohol temperature at about 78 degrees Celsius. Continuously collect 10ml distillate. They were divided into two groups: D 1 and D2. D 1 group was placed in NaCl solution, and D2 group was the control group. Put them into conical bottles respectively, cover the bottle mouth with plastic wrap, and punch holes to make alcohol volatilize and dust difficult to enter. The experiment shows that in this experiment, we have crushed the petals to avoid the problem of 1 Since the last experiment has confirmed that the essential oil is really soluble in alcohol (the color of alcohol changes, resulting in membrane-like substances), we decided to extract rose petals with alcohol and distill at the same time, so that the alcohol vapor can bring out the essential oil. Essential oil is soluble in alcohol, which avoids the emergence of problem 2. Because the boiling point of alcohol is 78 degrees Celsius, we decided to control the liquid temperature at the boiling point of alcohol in order to avoid the consequences that the essential oil cannot be collected because the liquid temperature in the bottle is too high (higher than the boiling point of essential oil). So that essential oil and alcohol can be "cooperatively" distilled. In view of the strong smell of alcohol and the determination of essential oil components, we decided to use the volatile characteristics of alcohol to volatilize alcohol and complete the final purification work. Experimental results and remarks: You can smell the obvious plant fragrance from the liquid in the conical flask. This shows that the distillate already contains essential oil components (a major breakthrough). After standing for a week, it was found that there was no significant difference between group D and group E, and the liquid was transparent and colorless. There is a faint plant fragrance. So far, the alcohol volatilization in Group D and Group E has not been completed. No obvious signs of essential oil (flocculent precipitation) were found. Summary of two experiments: in the first experiment, we designed the experimental scheme according to the description in the book. The problems existed for the first time were well solved in the second self-designed experiment. The direct effect is to extract a liquid with strong aromatic smell (compared with the first experiment). Although we can't try to use the essential oil extracted by ourselves so far, our harvest is far more than 10 test tube and 2 bottles of fragrance liquid. In the preparation, planning and implementation of two inquiry learning experiments, we have a clear understanding of the real inquiry experiment. The main gains are as follows: I personally feel the omnipotence of books: books are only limited to describing the general steps of experiments, but many important details related to the success of experiments are not detailed. The discoverers of these details are often those who have personally experienced the failure of the experiment. Our experience is that we can't blindly believe what is taught in textbooks. Practice is the only criterion for testing truth. We have practical experience in scientific experiments: through the reproduction and improvement of textbook experiments, we design and implement the experimental scheme ourselves. The experimental results were not presented to us until the last minute. It's like conducting a real scientific discovery experiment. Such an independent inquiry experiment from beginning to end has never been experienced before. From this, we can understand the hard course of being a real scientific researcher. We experienced not only the pleasant fragrance of essential oil ... we learned that the successful experimental results were hard to come by: the team members invested a lot of time and energy in the design, implementation and analysis of the two experiments. But the experimental results are not satisfactory. While disappointed, calm down and think about it. What are the major scientific and technological achievements in the world that only need two experiments to succeed? The development of science is a process of continuous discovery and perfection. Tears of failure are always accompanied by smiles of success. If we want to succeed in the experiment, we must constantly sum up experience and lessons and constantly improve the scheme. After many failures, success can only favor us. And the spirit of insisting on experiments is unshakable. Conclusion: The expected purpose of understanding the essential oil extraction industry has been achieved, and two experiments have been completed, from which practical experience that cannot be obtained in books has been obtained. From this, I experienced the discovery process of independent inquiry; From it, I learned that scientific achievements are hard-won ... I achieved the purpose of the course and successfully completed the research-based learning project in Grade One.

C4 factory or C4 factory. The initial product of CO2 assimilation is not the three-carbon compound 3- phosphoglyceric acid in the photosynthetic carbon cycle, but the four-carbon compound malic acid or aspartic acid. Also known as C4 plants. Such as corn and sugar cane. Plants whose initial product is 3- phosphoglyceric acid are called C3 plants. Many four-carbon plants have a special structure in anatomy, that is, there are two different types of cells around the vascular bundle: the inner cells near the vascular bundle are called sheath cells, and the outer cells around the sheath cells are mesophyll cells. Phosphoenolpyruvate (PEP) in mesophyll cells combines with CO2 through PEP carboxylase to form malic acid or aspartic acid. These tetracarboxylic acids are transferred to sheath cells, and CO2 is released by decarboxylase. The latter enters the photosynthetic carbon cycle through RuBP carboxylase in chloroplasts of sheath cells. This metabolic pathway is formed by PEP and then decarboxylated to release CO2, which is called the four-carbon pathway. About 800 species of C4 plants have been found, which are widely distributed in 18 different families of flowering plants. Most of them originated in the tropics. Because four-carbon plants can use ATP produced under strong light to promote the combination of PEP and CO2, improve the photosynthetic rate under strong light and high temperature, partially shrink stomatal aperture during drought, reduce transpiration and water loss, and the decrease of photosynthetic rate is relatively small, thus improving the water utilization rate of four-carbon plants. These characteristics have obvious selection advantages in dry and hot areas. An important difference between C4 plants and C3 plants is that the CO2 compensation point of C4 plants is very low, while that of C3 plants is very high, so the survival rate of C4 plants is higher when the CO2 content is low. C4 Plants In the 1960s, Australian scientists Hatch and slack discovered that tropical green plants such as corn and sugarcane, besides having calvin cycle like other green plants, CO2 was first fixed in a special way. This route is also called hatch slack route. C4 plants mainly live in arid and tropical areas. In this environment, if plants open their stomata for a long time to absorb carbon dioxide, it will lead to the rapid loss of water through transpiration. Therefore, plants can only open their stomata in a short time, and the intake of carbon dioxide is bound to be less. Plants must use this small amount of carbon dioxide for photosynthesis and synthesize substances needed for their own growth. There is a vascular bundle sheath around the vascular bundle of C4 plants, which is composed of chloroplasts, but there is no grana or abnormal development. Here, mainly calvin cycle. Its mesophyll cells contain a unique enzyme, namely phosphoenolpyruvate carbon oxidase, which makes carbon dioxide assimilated by a three-carbon compound-phosphoenolpyruvate to form a four-carbon compound oxaloacetic acid, which is also the origin of this dark reaction type name. After oxaloacetic acid is converted into malic acid, it enters the vascular bundle sheath, which will decompose and release carbon dioxide and a molecule of glycerol. After carbon dioxide enters calvin cycle, it goes through C3 process. Glycerol will synthesize phosphoenolpyruvate again, consuming ATP. The advantage of this type is that the carbon dioxide fixation efficiency is much higher than that of C3, which is beneficial to the growth of plants in arid environment. Starch obtained by photosynthesis of C3 plants will be stored in mesophyll cells, because this is the site of calvin cycle, and vascular bundle sheath cells do not contain chloroplasts. The starch of C4 plants will be stored in vascular bundle sheath cells, because the calvin cycle of C4 plants occurs here. C4 plants are: corn, chrysanthemum, amaranth, Chinese cabbage and water spinach.