Report on the development of biological science and technology by research topic investigation media
1. Teaching purpose
1. Through the investigation of recent newspapers and magazines and other media, we can understand the recent development of biological science and technology and its influence on human society.
2. Learn the methods of collecting and processing biological science and technology information.
3. Improve the ability of language expression and information exchange by making communication reports and discussions in the class.
second, teaching suggestions
teachers should pay attention to the following points when guiding students to carry out this research.
1. Provide students with the names of the media that report the development of biological science and technology in our school or local area, such as newspapers, magazines, books, TV programs, radio programs and the Internet, and guide students to analyze the information characteristics of different media reports, focusing on comparing their differences in timeliness, accuracy, popularity and authority.
2. In order to reduce students' repetitive work as much as possible, teachers should divide students into several groups, at least six groups, and investigate the reports of different media on the development of biological science and technology.
3. It is best to specify the time range for investigating media reports, such as news reports in recent 1 ~ 2 years.
4. Teachers should roughly define the scope of information collection, such as new discoveries, inventions, new technologies and new progress. Students should also be required to collect new progress in other natural disciplines for quantitative comparison with new progress in biological science and technology.
5. organize students to discuss the information obtained by students through media surveys and guide them to classify (there may be different classification methods).
6. Teachers should guide students to complete the communication report independently, and the form of the report need not be unified. Students should be encouraged to play their own wisdom and determine the form of the report that can play their own specialties. For example, a written explanation can best be illustrated; Draw a chart, concise and to the point, which can explain the problem; Making slides can integrate pictures, charts and brief text descriptions; To make a video tape, you can combine the similar content played in the relevant TV programs and make a video clip, preferably with a voice-over to explain it; You can also make computer courseware.
7. The way of communication and presentation of reports can be arranged according to the conditions of our school. For example, use the blackboard newspaper in the class to regularly publish the development information of biological science and technology collected by students. It can also be displayed in a centralized way in the form of information tabloids on the development of biological science and technology, and students within and between classes can be organized to visit and read. You can also use about 1 hours of extracurricular activities to focus on playing video clips or courseware made by students, which will be explained by students themselves. Conditional schools can also organize students to hold "press conferences" or "academic reports".
8. When organizing students' discussion, students are required to evaluate the timeliness and authority of the information they have collected.
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2. Learn to observe the phenomena in the experiment, analyze the observed phenomena and come to your conclusion.
Second, teaching suggestions
Teachers should pay attention to the following points when guiding students to carry out this research project.
1. Teachers should make necessary preparations for students to design experimental schemes and conduct experiments.
(1) Introduce some relevant reference materials to students, such as the textbook Plant Physiology, Biology Bulletin, middle school biology experiment books, biotechnology activity books, flower cultivation books, etc.
(2) Introduce the Chinese names of some commonly used auxins and their analogues to students and compare them with the abbreviations of English abbreviations. For example, indole acetic acid (IAA), indole propionic acid (IPA), indole butyric acid (IBA), naphthylacetic acid (NAA) and 2,4- dichlorophenoxyacetic acid (2,4-D).
(3) Introduce the characteristics of auxin and several auxin analogues to students, and provide the basis for selecting materials for designing experiments.
IAA: unstable in plants, easily decomposed by strong light, and unstable in effect, not as good as IBA and NAA.
IBA: it is not easy to be oxidized and decomposed, and it is easy to remain in the treated part. Strong action, long action time, many and long roots, but the price is more expensive.
NAA: The effect is similar to that of IBA, and the induced roots are few and thick. It is cheap and safe to use.
(4) Introduce the use of auxin and its analogues. In experiments, three different substances, aqueous solution, powder or lanolin ointment containing drugs, are usually treated, and their concentration unit is mg/L. When in use, the plant organs to be treated are soaked in water solution for a certain period of time, or dipped in powder, or coated with lanolin ointment.
2. Before designing the experiment, the teacher should teach the students the idea of designing the experiment.
(1) Determine the topic Because the topic scope of this "research topic" is large, teachers can guide students to choose a smaller suitable topic for research according to the local actual situation and the conditions of our school, such as "the influence of NAA on the rooting of XX plant cuttings" or "the influence of 2,4-D on the fruit of XX plant".
(2) make assumptions about your own experimental content. For example, NAA can restore the dividing ability of parenchyma cells at the base of cuttings (treated with NAA), produce callus and grow adventitious roots.
(3) Design control experiments In this study, in order to explore the concentration range of an auxin analog that affects the growth and development of plants, several experimental groups with different concentrations must be designed as mutual controls. When designing the experimental device, students should be reminded that the design of the device should be conducive to observation. For example, the experiment of promoting rooting can be observed by hydroponics.
(4) Observe and record the phenomena or results in the experiment, and record them carefully.
(5) After the verification experiment is completed, if time permits, it is best to repeat the original experiment. If it can be repeated successfully, the hypothesis is established.
3. In order to reduce the repeated experiments among students as much as possible, teachers should distribute the experimental contents (sub-topics) as much as possible. As the same auxin analogue affects the growth and development of different plants, different organs of the same plant, and different auxin analogues affect the growth and development of an organ of a certain plant. At the end of the experiment, students with the same experimental content or similar experimental content will be organized for comparative analysis.
4. Teachers should ask students to carefully observe and record the changes of plant growth and development before, during and after the experiment. It is necessary to record not only the phenomena that are consistent with expectations, but also the phenomena that are inconsistent with expectations. For the data that can be collected during the experiment, we should collect as much as possible.
5. After the experiment, teachers should teach students how to analyze the experimental results carefully and deal with the experimental data scientifically, such as using tabular or functional charts as far as possible. It is also necessary to guide students to use experimental facts for scientific reasoning and draw corresponding conclusions. Finally, complete the experimental report.
6. The experimental part of this topic is all arranged after class or at home.
7. After the project report is completed, teachers should organize students to communicate. When organizing students to exchange reports, teachers should not only let students exchange their own experimental reports, but also let students report their experiences in completing this topic, such as experiences, lessons and ways to overcome difficulties.
III. References
Physiological function of IAA
1. Promotion. IAA promotes the formation of adventitious roots and lateral roots, the elongation of stems, the expansion of leaves, the shedding of old leaves, the formation of flowers in some plants, the increase of female flowers, the growth of ovary walls, parthenocarpy, fruit growth, fruit setting, seed growth and seed germination.
2. inhibition. IAA makes lateral branches grow, tubers form, young leaves fall off, flowers fall off and fruits fall off.
whether IAA promotes or inhibits leaf abscission depends on the source of IAA. If IAA is transported from stem to leaf, it will promote the shedding of old leaves. If IAA is transported from leaf to stem, it will inhibit the shedding of its own leaves. The promotion and inhibition of fruit abscission by IAA are similar.
Physiological effects of auxin analogues
1.IBA, NAA and 2,4-D can promote some plants (such as tung tree, apple, pear, plum and apricot) to take root smoothly, and the concentration used is generally 11 ~ 111 mg/L.
2. Promote fruiting. Spraying tomato flower clusters with 11 mg/L 2,4-D solution can promote fruit setting and the formation of seedless fruits.
3. Promote pineapple flowering. Any pineapple plant that has reached the vegetative growth period of 14 months can blossom after 2 months if it is treated with 5 ~ 11 mg/L NAA or 2,4-D in any month of the year.
4. Stop organs from falling off. Applying 11 mg/L NAA or 1 mg/L 2,4-D can keep cotton buds and bolls.
5. inhibit flower bud differentiation and delay flowering. The chrysanthemum sprayed with 1.11mg/L 2,4-D showed the first flower bud. Chrysanthemum sprayed with 1.1 mg/L of 2,4-D has swollen buds and transparent colors. Spraying chrysanthemum flower buds with 5 mg/L 2,4-D, the flower buds are still small; While the chrysanthemum in the control group is in full bloom.
spraying 251 mg/L IBA on rooting plants can prolong flowering for 2 weeks.
spraying 51 mg/L NAA on the abscission part in bud stage can prolong the flowering period of potted phyllanthus for 21 days.
6. inhibit fruit ripening. Spraying potted orange with 11 mg/L 2,4-D in bud stage or young fruit stage can prolong the fruit-bearing time.
preparation methods of aqueous solution, powder and lanolin ointment containing auxin analogues
1. aqueous solution (taking NAA as an example)
NAA is colorless powder with purity ranging from 99% to 81%. Insoluble in cold water, but soluble in alcohol, acetic acid and boiling water. How much NAA powder with a certain purity is needed to prepare a certain concentration of liquid medicine can be calculated by the following formula:
original drug content × original drug dosage (mg)= used concentration (mg/L)/1 111× used liquid medicine dosage (mL). For example, when preparing 111 mL NAA mother liquor with a concentration of 1,111 mg/L, first calculate how much 99% NAA powder is needed: 99% × x = 1,111/1,111× 111, x = 111 mg. Then, 111 mg of 99% NAA powder is weighed, dissolved in a small amount of 95% alcohol solution by volume, and diluted to 111mL with distilled water, so that 1111 mg/L NAA mother liquor can be obtained.
NAA solutions with different concentrations can be prepared by NAA mother liquor. If 41 mg/L NAA solution is prepared, 4 mLNAA mother liquor can be absorbed and diluted to 111mL with distilled water.
2. powder
firstly, the medicine is dissolved in 95% alcohol solution by volume, and then the prepared alcohol solution is evenly stirred in inert powder (such as talcum powder), and heated properly until all the alcohol is evaporated, so that the powder is obtained.
3. Lanolin Ointment
First, prepare the medicine into a certain concentration of water solution, and then mix it with melted lanolin. For example, when preparing 1511 mg/L NAA lanolin ointment, first weigh 1.5 gNAA, dissolve it in 1 mL of 95% alcohol solution, then pour it into a beaker, add distilled water to 1111 mL, and heat and stir until it is fully dissolved. If the volume decreases due to heating, it should be made up to 1 111 mL；. Take another 511 g of lanolin, put it into a 1111 mL beaker, heat it slightly to melt it, then take 251 mL of 1511 mg/L NAA solution, inject it into the melted lanolin, and stir well to get 1 511 mg/L NAA lanolin ointment.
How to use several auxin analogue preparations
1. Spraying, such as spraying flowers and fruits with 2,4-D aqueous solution.
2. soaking, such as soaking the base of cuttings with NAA aqueous solution.
3. Dip in powder such as NAA with the base of cuttings.
4. if you apply NAA lanolin ointment to the treated parts (such as stems), it is best to gently wrap the outside with cotton.
experimental design example of auxin analogues on plant growth and development
1. Experimental topic: Effects of IAA on seed germination and seedling growth.
2. experimental principle: IAA can promote seed germination and seedling growth.
3. objective requirements: (1) learn to design and observe the effects of NAA on seed germination and seedling growth.
(2) Observe and analyze the phenomena in the experiment and draw appropriate conclusions.
4. Materials and utensils: seeds (such as radish seeds), test tubes, pipettes, Petri dishes, filter paper and IAA solution.
5. Experimental hypothesis: A certain concentration of IAA solution can promote seed germination and seedling growth.
6. It is expected that the seeds treated with different concentrations of IAA solution will have different germination and seedling growth after 1 weeks.
7. method steps:
(1) prepare IAA solutions with concentrations of 1111 mg/L, 11 mg/L, 1.1 mg/L, 1 μg/L and 1.11 μg/L respectively.
(2) Take 6 test tubes and number them. Add 5 mL IAA solution with different concentrations to test tubes 1 ~ 5, and 5 mL distilled water to test tube 6.
(3) Put 21 seeds in each of the 6 test tubes.
(4) Take out the seeds after 24 hours. Take six Petri dishes (No.1 ~ No.6), pad filter paper in each Petri dish in advance, soak No.1 ~ No.5 with IAA solution of different concentrations (the serial number should correspond to the test tube number), and soak the filter paper in No.6 Petri dish with distilled water. Put the seeds taken out from test tubes 1 ~ 6 into corresponding Petri dishes 1 ~ 6, and put them evenly. Cover the Petri dish and put it in the dark.
(5) observation and statistics. After 1 weeks, observation, measurement and statistics were carried out.
8. Experimental records:
9. Experimental results and conclusions:
(1) Analysis of experimental results
① Reliability of analysis data.
② draw a function chart according to the obtained data.
③ According to the function chart, the relationship between the germination rate of radish seeds, the growth status (length) of young roots and hypocotyls and IAA concentration was analyzed.
④ find out the optimum concentration of IAA solution to promote radish seed germination and seedling growth.
(2) Derivation conclusion According to the analysis of the experimental results, the corresponding conclusions are drawn.
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2. Get to know someone through investigation.