Why are flowers so red?

Red flowers are passionate colors, strong, unrestrained, exciting and inspiring. Red and purple spring is full of vigor and vitality. Why are flowers so red? While people are admiring, they can't help asking questions and seeking scientific explanations. Why are flowers so red? First of all, it has its material basis. Both safflower and red leaf contain anthocyanins converted from glucose in their cell sap. When it is acidic, it looks red. The stronger the acidity, the redder the color. When alkaline, it is blue, more alkaline and turns blue-black, such as black chrysanthemum and black peony. When it is neutral, it is purple. Colorful, red and blue intersection, are anthocyanins in different acid-base reactions. Besides red flowers, there are yellow and orange flowers. Orange is similar to the color of citrus, pumpkin and other fruits, the most typical one is carrot, so the pigment expressing this color is called carotene. As for white flowers, that's because there is no pigment in the cell fluid. Some white flowers, such as chrysanthemums, are reddish before withering, indicating that they also contain a small amount of anthocyanins. A special example of discoloration is hibiscus mutabilis, which has white flowers in the morning, red flowers at noon and crimson flowers in the afternoon. Three times a day, more and more beautiful. Another example is hydrangea, which is white and slightly green at first, and turns red or slightly blue in a few days. It doesn't bloom and wither at dusk like colored hibiscus. As for ordinary flowers, most of them are bright at first, and then they fade. Why are flowers so red? It needs to be explained by physical principles. Sunlight will be divided into seven colors: red, orange, yellow, green, cyan, blue and purple after being refracted by prism or water drops. The wavelengths of these seven colors are different, and the wavelengths of red light and purple light are all short. Acidic anthocyanins will reflect long red light waves into our eyes, and we will think they are bright red flowers. Similarly, neutral anthocyanins reflect purple light waves, alkaline anthocyanins reflect blue light waves, and carotene components are different, so they reflect yellow light waves or orange light waves respectively. White flowers contain no pigment, but the tissue contains air, which reflects all light waves. Some petals, with more tiny and neatly arranged glass balls on the surface, look like velvet, which can reflect light as strongly as diamonds and have brighter colors, such as some Chinese rose flowers. Why are flowers so red? And its physiological needs. Different wavelengths of light contain different amounts of heat: red, orange and yellow wavelengths contain more heat; Blue light and purple light have short wavelengths and less heat. The tissues of flowers, especially petals, are generally tender. In the wild, red, orange and yellow flowers all grow in places with strong sunshine, reflecting long-wave light waves containing a lot of heat, which will not cause burns and have a protective effect. Blue flowers grow under trees and grass, reflect short light waves, absorb weak long light waves, and have more heat, which is beneficial to their physiological functions. There are also many negative plants with white flowers, some of which open at night and reflect all light waves, which is another adaptation measure. There are few black flowers in nature, only a few flowers occasionally have black spots, because black absorbs all the light waves and has too much heat, so it is easy to be hurt. Why are flowers so red? From the perspective of evolution, it has a development process. The flowers of gymnosperms are primitive and all green, while the anthers and pollen are yellow. In the spectrum, adjacent to green, one end of long wave is yellow, orange and red, and the other end of short wave is cyan, blue and purple. We can say that the color starts from green, develops to the long wave end, changes from yellow to orange, and finally appears red; To the short wave end, it is blue and purple. Red should be the latest color, and it is also the most dazzling color in the evolutionary journey. Why are flowers so red? According to Darwin's theory of natural selection, insects play an important role. Hundreds of millions of years ago, when gymnosperms appeared on the earth, there were not many insects. Anthocyanins are light, pollinated and fertilized, and they are all wind-borne flowers. Later, angiosperms appeared and insects flourished. The flowers of angiosperms are divided into calyx and corolla with perianth (perianth and corolla are collectively called petals). Petals are no longer green, but more conspicuous yellow, white or other colors. The shape is also large, some have nectar glands, which secrete nectar, and some give off fragrance and become insect-borne flowers. "Bees compete for the fragrance of butterflies", and insects pollinate and fertilize flowers. Insects have a special habit of collecting honey and pollinating, that is, they often only interview the flowers of the same plant. This habit is conducive to ensuring cross-pollination of the same plant and breeding offspring. This can fix the characteristics of species, including the color of flowers. We can imagine that if there is a plant with a reddish color at the beginning, because the obviously reddish flowers are easily noticed by insects, there will be more opportunities for pollination. After countless generations of selection, insects have created pure, obvious and bright red flowers for this plant for a long time. Insects participate in natural selection, producing different plants and different colors. Why are flowers so red? Finally, it is due to manual selection. The process of natural selection is slow, and it takes a long time to show its function. Artificial selection has greatly accelerated its process and achieved remarkable results in a short time. Peony, for example, has created a wild primitive species through hundreds of millions of years of natural selection. The flower is single, with only one pink color. After artificial cultivation, in the middle of the Northern Song Dynasty (1 1 century), a petal created different postures, such as leafy, chiba (double petal), Lou Zi (flower heart protruding) and parallel pedicle. Pink creates beautiful colors such as crimson, flesh red, purple, deep purple, yellow and white. Another example is Dahlia, which is native to Mexico and has only eight red petals. The history of artificial cultivation is only two or three hundred years, but there are thousands of varieties with different shapes and colors. Another example is corn poppy, which has cultivated four colors of red, yellow, orange and white, but blue has never appeared. At the end of last century, Pubank, a famous American horticultural breeder, discovered a kind of corn poppy with a layer of mist on its petals and specially cultivated it. By the beginning of this century, various shades of blue corn poppy have been cultivated, adding new varieties to flower gardening. Flowers are so red, which is a masterpiece of nature and the result of artificial cultivation.

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Jia Zuzhang (190 1- 1988) was born in Haining, Zhejiang. 1920 graduated from Zhejiang First Normal University. He used to be the editor of Commercial Press and Ming Kai Bookstore. After the establishment of People's Republic of China (PRC), he served as deputy editor-in-chief and editor-in-chief of China Youth Publishing House, deputy editor-in-chief of Popular Science Publishing House, consultant of Fujian Association for Science and Technology, consultant of Fujian Publishers Association, vice chairman of China Popular Science Creation Association, chairman of Fujian Popular Science Creation Association and member of the Standing Committee of China Democratic Progressive Party. Mr. Jia Zuzhang is a famous biological science writer. As early as 1930s, he was one of the pioneers of China's scientific sketches, and has been creating for more than 60 years. His work

This product vividly spreads the scientific knowledge based on biology and realizes the marriage of science and literature in a colorful literary form. His popular science works have played a subtle role in popularizing scientific knowledge, inspiring people's patriotic enthusiasm and enhancing national self-esteem, self-confidence and cohesion. He takes colorful nature as the object of description, and combines rich scientific knowledge, historical knowledge and literary knowledge. It depicts all kinds of interesting stories in the wonderful biological world to readers with vivid and unique scientific prose style. Jia Zuzhang spent his youth in the Qing Dynasty, witnessed and experienced the sufferings of ordinary people, and deeply felt that the people's wisdom could not be separated and the country was backward, all of which were caused by political corruption and poor science. So after he graduated from Zhejiang No.1 Normal School, he began to create popular science at the age of 22 and published his first popular science book at the age of 28. From the publication of Birds and Literature by 193 1 to the publication of Flowers and Literature before his death, Mr. Jia Zuzhang wrote and translated nearly 3 million words in 60 years. His works always integrate science and art, and many chapters become excellent essays, which have a far-reaching impact on society. It can be said that there are few scholars in China who have not studied Jia Zuzhang's works. His "Labor Created Man" is one of the required books for cadres to learn the history of social development in the early days of the founding of the People's Republic of China. His books Why Flowers Are So Red, Litchi Dan in Zhou Nan in June, Orchids and Orchids, and Cicada have all been selected as textbooks for senior high schools and junior high schools. 1934, Taibai magazine opened a column of "scientific sketch", and Jia Zuzhang, Zhou, Gu and others wrote articles for this column. At the same time, a variety of teaching materials of zoology and botany have been compiled for Ming Kai Bookstore, which has done a lot of pioneering work for popular science work in China. That is, from then on, he embarked on the arduous road of popular science creation, editing and translation. His life's works include Bird Studies, Birds and Literature, Biological Sketch, Heart of a Child, Resilience of Life, Biological Fragments, Flowers and Literature, Selected Works of Jia Zuzhang's Popular Science Creation, Selected Works of Jia Zuzhang's Popular Science, and 26 popular science books. He also wrote Biology of Enlightened High School. He struggled all his life and contributed a lot of scientific, national and popular popular science works to the people. At the same time, Jia Zuzhang is a famous publisher. He compiled 65,438+00 textbooks on nature, animals, plants, biology and natural history for primary and secondary schools, which inspired several generations of students. Periodicals were edited from 1936, among which the famous periodicals are Middle School Students, Progressive Youth, Traveler, Rural Youth, Knowledge is Power, Popularization of Science, Learning Science, etc. This is also an important part of his commitment to popular science. Life practice is the foundation and source of Jia Zuzhang's writing. The scientific sketches written by Jia Zuzhang describe flowers, birds, fish and insects, and outline the magnificent and colorful biological world with their unique and in-depth observation, delicate and accurate brushwork and concise language. Jia Zuzhang loved books all his life. He read, edited and wrote books, and spent his life with books. After years of editing work, he tirelessly read books on biology, literature and history, from which he learned nutrition, accumulated knowledge, expanded his thinking, and explored and enriched writing materials. Many of his works involve man and nature, ecological environment, advocating science, getting rid of pseudoscience, superstition and heresy and many other aspects. Criticize "Silkworm eggs turn into goldfish" and "rotten grass turns into fireflies" in Goldfish and Fireflies; By analyzing the relationship between the omnivore of sparrows and crops, the scientific and realistic spirit embodied in Bird's Eye still has practical significance and beneficial enlightenment for protecting the ecological environment and wildlife today. 193 1 Birds and Literature written by Mr. Jia Zuzhang, combined with the scientific knowledge of birds (including morphology, habits, species, etc. ) and related literary content (including historical poems, myths, folklore, etc. In the author's words, "This is to write a scientific book with more interesting words". Nature, which published these articles at that time, created a column called "Interesting Science". And revealed the name of the new style of "scientific sketch" for the first time. Therefore, birds, literature and biological sketch are the early achievements of China's "scientific sketch" genre. Now it seems that this series of works by Mr. Jia Zuzhang. In the history of popular science creation in China, it is indeed of fundamental and groundbreaking significance. Today, thousands of middle school students in Qian Qian can still read such exquisite masterpieces as Why Flowers Are So Red and Litchi Dan in June in Zhou Nan from textbooks. His two books, Birds and Literature and Flowers and Literature, should be the two treasures in the creation of scientific sketches in China. It not only reflects the creative process of Jia Lao's life, but also reflects the development track of popular science creation in China from one side. Jia Zuzhang's popular science writing can be roughly divided into three periods: First, from the 1920s to the 1940s, he wrote a lot of energetic works. Birds and Literature, Biological Sketch and Loyal Soul are the representative works of this period. Second, I wrote some essays before the founding of New China and the "Cultural Revolution". Such as "Evening Banquet with Autumn Chrysanthemum", "White Silk Feather with Dansha Top" and "Like a crab but not a crab". 3. After the Third Plenary Session of the Eleventh Central Committee of the Party, Jia Zuzhang was over eighty years old; Bathed in the sunshine and rain of spring, I once again rejuvenated my creative youth and wrote many works. "Why Flowers Are So Red" won the first prize of the National New Long March Popular Science Creation, and was selected as a model textbook for senior high schools and technical secondary schools together with "Zhou Nan June Litchi Dan", "Cicada" and "Lan Lan". After ten years of turmoil, Jia Zuzhang was in a helpless mood at this time, but he didn't want to waste time. He went alone to the paddy fields, vegetable gardens and orchards in the wild to observe the dynamics of plant growth, insect activities and bird reproduction. At the same time, I also read many books on science and technology and agricultural technology that I could find at that time. During the six years from 1970 to 1976, * * * wrote 50 reading notes. The practice and reading during this period have accumulated a lot of materials for the popular science creation after the arrival of the scientific spring, and won the first prize of "New Long March Popular Science Creation", and some famous works such as "Litchi Dan in June in Zhou Nan", "Lan Lan" and "Cicada" were published. When Fujian Health News was first reissued, it was a four-page tabloid. Jia Lao, vice chairman of China Popular Science Creation Association, chairman of Fujian Popular Science Creation Association and consultant of Fujian Science and Technology Association, is very concerned about the growth of this newspaper. He not only often reads this newspaper and puts forward many valuable opinions and suggestions, but also writes popular science articles himself. More than ten articles have been published in the popular science section of this newspaper, such as how to plant trees, cockroaches from the age of dinosaurs to the present, physiological changes of young people, attention to mental health, talking about tuberculosis from colds, and diseases from mouth to mouth. , add a lot of color to this newspaper, the editors are rigorous and realistic, hard-working and left a deep impression.

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The first lesson: teaching objectives 1. Clarify the order of explanation and appreciate the beauty of using literary language and methods in explanation. 2. Let students understand the text knowledge by looking for materials and doing experiments. Teaching focuses on clarifying the order of explanation and understanding the beauty of using literary language and methods in explanation. Difficulties in teaching How to find out the language features of expository writing? Teaching methods: main teaching AIDS, experimental materials, method guidance, exploration, cooperative blackboard design, why flowers are so popular, basic physics, physical principles, physiological needs, evolutionary views, natural selection, artificial selection, after-class reflection time, target teaching content, teacher activities, student activities, 1. Show what the students know and stimulate their interest in the text knowledge. 2.3. Clear the order of explanation and appreciate the beauty of using literary language and methods in explanation. Further master the content of the text, understand the text, and cultivate students' generalization, expression and practical ability. 1. Import: (1) There are so many beautiful and delicate flowers in nature. Why are there so many flowers of different colors? (2) The article "Why are flowers so red" is like a key, which has solved the mystery for us. Read the text and tell me why the flowers are so red. Clear: There are many reasons for extra points, and the text is explained from six aspects. That is, Fundamentals of Physics, Chemistry and Physics, Plant Biology, Evolution, Natural Selection and Artificial Selection have made scientific, vivid and interesting explanations on the causes of "extra points". 3. What are the characteristics of the text structure? The author used the phrase "Why are flowers so red" seven times in the article, all of which appeared in the form of rhetorical questions, forming seven paragraphs of juxtaposition, which is called interval repetition in rhetoric. In the first paragraph, "Why are flowers so red" appears for the first time, which plays a general role, while in the following paragraphs, it plays the role of prompting to explain the angle and content, making the article clear in level, prominent in the center, rich in language rhythm and beauty, and enhancing the literary color of the explanatory text. Now that we only know the factor of bonus, who can explain the real mystery in detail? It depends on the ability of our team. Now, six teams have contracted one aspect respectively, and explained the reason of the bonus in the form of language, blackboard writing or experiment. (1) Experiment 1: Soak a red peony flower or other safflower in alkaline water or soapy water and observe the color change. After the safflower turns blue, soak the blue flower in vinegar and observe the process from blue to red to verify the different color changes in the acid-base reaction. (2) explain various reasons: 5. Summary: 1. Question 2. Listen to the text and summarize the answers. 3. Guide, prompt and summarize. 4. Put forward requirements, guide each group and participate in group discussions. (1) Guidance (2) Listening and commenting 1. Answer 2. Read the text and think about the answers. 3. Research and discussion. Read the text, discuss and learn to express the language, and prepare for the experiment. (1) Do experiments (2) Explain various reasons. The second category: teaching objectives 1. Clear logical order. 2. Learn to consolidate knowledge about expository writing, accumulate language, form a good sense of language, and pay attention to the accuracy and vividness of written expression. 3. Expand students' reading horizons. Teaching emphasis 1. Explain the accuracy and vividness of written language. 2. Explain the difficulties in teaching. Analyze the logical structure of classroom teaching. Explain the teaching methods of reading class. Instruct, discuss and explore the design of blackboard. Why are flowers so red? Explanation sequence: internal conditions and factors (material basis) of bonus points-internal and external reasons of main bonus points (natural selection and artificial selection)-external explanation methods: examples, classification, numbers and comparison. Language: exactly "only, only, only" after-school reflection time stage target teaching content teacher activities student activities 1. Do a good job of connecting old and new knowledge. 2. Understand its strict logical order. 3. Consolidate the explanation method and understand the content and writing of the text. 4. Accumulate language, form a good sense of language, and pay attention to the accurate and vivid expression of words. 5. Understand the role of the topic. 1. Import: Recall the last lesson. 2. Question: Explain the reasons for the bonus from six aspects. Can they be reversed? Why? Clear: The authors are arranged in the order of primary and secondary and from the inside out, which can be divided into two layers. The first layer (1-7) explains the internal conditions and factors of the bonus, and the important factor is the "material basis". The second layer (paragraph 8- 10) explains the external reasons for the bonus. In-depth, accurate and rigorous. 3. Analyze the interpretation method of each paragraph. Thinking: What explanation methods are used in the article? Clear: (1) Example, classification: Take peony as an example, it is a wild primitive species, which has been selected for hundreds of millions of years. Flowers are single, with only one pink color. After artificial cultivation, just take the middle period of the Northern Song Dynasty as an example. In the past few decades, a petal has created many different postures, such as leafy, chiba, louzi and ice flute. Pink creates beautiful colors such as crimson, flesh red, purple, deep purple, yellow and white. There are many examples of sentences ... (2) Numbers, for example: Dahlia, native to Mexico, has only eight red petals. The history of artificial cultivation is only two or three hundred years, but there are thousands of varieties with different shapes and colors. Analysis: Using three interpretation methods, it shows that manual selection has greatly accelerated the process of adding points and achieved remarkable results in a short time. (3) Comparative classification: in spectrum, it is adjacent to green, with yellow, orange and red at one end of long wave and cyan, blue and purple at the other end of short wave. We can say that the color starts from green and develops to long wave, from yellow to orange, from orange to red; To the short wave end, it is blue and purple. Red flowers are the most dazzling and can be said to be the most successful in the evolution process. Analysis: It shows that safflower is the best in the evolution process. Please experience the expression accuracy of some of these words. Clear: "only" emphasizes that it is limited to pink varieties, and the word "JIU" emphasizes that artificial cultivation has created colorful flowers with different shapes in a short time. The three adverbs of degree "zui" emphasize the bright, dazzling and successful degree of safflower. The short time of the word "only" shows that manual selection has accelerated the process of adding points. 5. The title of the text borrows the name of an episode in The Visitor on the Iceberg. Do you think this is a good idea? Why? Clear: first, prompt the content to be explained in the text; The second is to stimulate readers' reading interest and thirst for knowledge. 6. Introduce the knowledge about flowers or "100,000 whys". Please choose one of them and let the students share your happiness. 7. homework: 1. Two minutes ahead. Ask questions and summarize 3. Ask questions and participate in each group discussion. Judge and explain. 4. Prompt for comment 5. Question 1. Memories 2. Think, discuss and answer 3. Read the text silently, circle the outline and discuss. Analyze and answer. 4. Think and answer 5. Thinking and discussing. Introduce flowers or "100,000 whys". Overall impression: 1. The title of the article was originally a lyric. What rhetoric is used? What are the advantages of using it to do problems? Clarity: The text topic "Why are flowers so red" is a rhetorical question, which plays three expressive roles: First, it helps to reveal the center of the article by grasping the characteristics of the well-known flower ("red") and asking questions; Second, it is attractive to arouse interest by setting doubts; Thirdly, considering the structure of the full text, the main part expounds flowers red's reasons from six aspects, and each explanation begins with "Why are flowers so red", which makes the article clear in context, lively in rhythm and adds artistic interest. Read the text carefully: 1, paragraphs 2-6, and 7- 10. What is the interpretation order? In what ways do you explain why flowers are so red? Clear: Paragraphs 2-6 are arranged in logical order. Explain "why flowers are so red" from the perspectives of material basis, physical principles and physiological needs. The 7th 7- 10/0 natural section uses time series to explain "why flowers are so red" from the perspectives of evolution, natural selection and artificial selection. 2. What explanation methods are used in the article? Clarity: (1) Examples and classification: For example, "Peony ... pink ... creates many beautiful colors such as crimson, flesh red, purple, dark purple, yellow and white." Another example: "Dahlia, native to Mexico, has only eight red petals. The history of artificial cultivation is only two or three hundred years, but there are thousands of varieties with different shapes and colors. " Analysis: Using three interpretation methods, it shows that manual selection has greatly accelerated the process of adding points and achieved remarkable results in a short time. (3) Comparative classification: "We can say that the color starts from green and develops to long wave, from yellow to orange and from orange to red; To the short wave end, it is blue and purple. Safflower is the most dazzling and can be said to be the most successful in the evolution process. " Analysis: It shows that safflower is the best in the evolution process. 3. Experience the expression accuracy of bold characters. (1) Peony, a wild original species caused by natural selection for hundreds of millions of years, has a single petal and only one pink color. After artificial cultivation, just take the middle period of the Northern Song Dynasty as an example. In the past few decades, a petal has created many different postures, such as leafy, chiba, louzi and ice flute. Clear: "only" emphasizes the word "nine", which is limited to pink varieties, and emphasizes artificial cultivation to create flowers with bright colors and different shapes in a short time. (2) Safflower is the most dazzling and can be said to be the most successful in the evolution process. "Ming: The adverb" Zui "of three degrees emphasizes the bright, dazzling and successful degree of safflower. The word "only" is extremely short, which shows that manual selection has accelerated the process of adding points. 4. The tenth paragraph of the study text: (1) This paragraph lists three typical cases of peony, dahlia and corn poppy, and compares the natural flowers with the artificially cultivated flowers from what aspects, highlighting the remarkable achievements in seed selection. Clear: the length, shape, color and variety of time. (2) What is the center of this paragraph? Clear: the role of artificial selection in accelerating the process of color change. (3) What is the explanatory structure of this paragraph? Clarity: the structure of total division. Note 1, selected from Biological Fragments, Fujian Science and Technology Press 1980, with changes. 2. Anthocyanin: A substance in plants that turns blue when dissolved in plant cells and red when exposed to acid. 3. Prism: an optical instrument with a triangular cross section made of transparent materials, also called "prism".