Solving the puzzles of cutin and suberin polymer biosynthesis
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小学上册英语第二单元期中试卷英语试题一、综合题(本题有50小题,每小题1分,共100分.每小题不选、错误,均不给分)1 A __________ is a mixture that can be separated by filtration.2 What color is a stop sign?A. YellowB. GreenC. RedD. Blue答案: C3 The sea turtle lays its eggs on the ________________ (沙滩).4 A whale is a ______ that lives in the ocean.5 I keep a journal to write about my ________ (梦想) and aspirations for the future.6 What is the opposite of 'happy'?A. JoyfulB. SadC. ExcitedD. Angry答案:B7 What do you call a group of wolves?A. PackC. ColonyD. Swarm8 My sister enjoys __________ (野营).9 A cat's purring is often a sign of ________________ (放松).10 A ____ is often found resting on leaves during the day.11 What is 8 3?A. 4B. 5C. 6D. 7答案: B12 My dad drives a _____ (car/bike).13 _____ (饲料) is made from certain types of plants.14 The chemical formula for nitric acid is ______.15 The __________ of a fish can help it steer while swimming.16 What do you call a story that is passed down through generations?A. FolktaleB. LegendC. MythD. Fable答案:A17 What is the name of the famous wizarding school in Harry Potter?A. HogwartsB. NarniaD. Middle-Earth答案:A18 What is the opposite of empty?A. FullB. VacantC. UnoccupiedD. None of the above答案:A19 The ______ (蝴蝶) flew over the flowers. It was very ______ (美丽).20 The garden is full of ________ (植物).21 We have a _____ (test/exam) on Friday.22 What shape has three sides?A. SquareB. TriangleC. CircleD. Rectangle23 My friend is _______ (在弹吉他).24 Fermentation produces alcohol and ______.25 I enjoy ______ (参加) school clubs.26 My friend is a skilled __________ (艺术家) with a unique style.27 What is the largest bird in the world?A. EagleB. PenguinC. Ostrich答案:C28 What do you call a group of bees?A. SwarmB. PackC. FlockD. Colony答案: A29 A _____ (植物园) showcases various species.30 She is a historian, ______ (她是一名历史学家), preserving important stories.31 The Crab Nebula is a famous ______ remnant.32 The process of heating something to kill bacteria is called ______.33 I like to ___ (listen) to podcasts.34 What do we call a written work that tells a story?A. PoemB. NovelC. EssayD. Article35 Fire of London led to new ________ (建筑规范). The Grea36 In a chemical reaction, the total mass of the reactants equals the total mass of the _____.37 A telescope helps us see ______ in the sky.38 The capital of Togo is __________.39 The Amazon River Basin is home to many _______ species.40 What is the capital of Mexico?B. GuadalajaraC. TijuanaD. Mexico City答案: D41 My parents encourage me to be ______ (诚实) and kind to others. It's important to treat people with ______ (尊重).42 Which sport is played on ice?A. SoccerB. BasketballC. HockeyD. Tennis43 I enjoy playing ________ (桌游) on rainy days.44 I can ______ (make) a sandwich by myself.45 What is the term for a young male goat?A. KidB. BuckC. BillyD. Ram46 The stars are ___ (shining/dimming).47 The ______ (植物分类法) organizes different species.48 What is 2 + 3?A. 4B. 5C. 6D. 749 My dad encourages healthy __________ (生活方式).50 Caterpillars eat a lot before becoming ______.51 The _______ (Age of Exploration) led to the discovery of new lands and trade routes.52 My favorite way to relax is ______.53 Chemical reactions can be classified as ________ or endothermic.54 The first successful vaccine was developed by __________ (爱德华·詹纳).55 The capital of the Philippines is _____.56 What do we call the study of birds?A. OrnithologyB. ZoologyC. BotanyD. Ecology答案: A57 The ancient Greeks believed in many _______.58 The peacock has beautiful _______ (羽毛).59 Cleopatra was the last active ruler of the __________. (埃及)60 What is the name of the famous bear created by A.A. Milne?A. PaddingtonB. Winnie-the-PoohC. Yogi BearD. Baloo答案:B61 The __________ (历史的交互) enhances engagement.62 The __________ (历史的图谱) illustrates progression.63 Which of these animals can live both in water and on land?A. FishB. FrogC. EagleD. Dog答案:B64 My aunt loves to cook ____ (southern cuisine).65 The _______ (Mayan calendar) predicted significant events in their culture.66 Which planet is known as the "Red Planet"?A. EarthB. MarsC. JupiterD. Saturn67 How many months are there in a year?a. 10b. 11c. 12d. 13答案:c68 What do we call the area of land where crops are grown?A. FarmB. GardenC. OrchardD. Ranch69 The wallaby is smaller than a ______ (袋鼠).70 The bat is a flying ______ (哺乳动物).71 The main source of energy for chemical reactions in living things is ______.72 We are going to ___ a party. (have)73 What do you call a story that is not true?a. Factb. Fictionc. Historyd. Biography答案:b74 My favorite activity is ______ (打篮球).75 My sister is having a birthday ____ (party) next week.76 What color are most bananas?A. GreenB. YellowC. RedD. Brown答案: B77 I want to ___ a story. (tell)78 It is _____ (raining) outside.79 What do we call the act of using your hands to create something?A. CraftingB. BuildingC. MakingD. All of the above80 Constellations can change depending on the ______.81 The bee gathers nectar from _______.82 The chemical formula for benzene is ______.83 What do you call the book that tells you about words?A. DictionaryB. EncyclopediaC. StorybookD. Novel答案: A84 In conclusion, my favorite season is ______ because it brings joy and happiness. I look forward to it every year!85 What is the primary language spoken in the USA?A. SpanishB. FrenchC. EnglishD. Chinese答案: C86 The capital of Thailand is __________.87 I read a ___ (book) before bed.88 What is the main ingredient in a salad?A. FruitB. LettuceC. MeatD. Bread答案:B89 What do you call the light that comes from the sun?A. MoonlightB. StarlightC. SunlightD. Firelight90 A gas that can be dissolved in water is called a ______ gas.91 The _____ (沙滩) is sandy.92 A homogeneous mixture is also known as a _______.93 The chemical symbol for yttrium is _____.94 What is the term for animals that can live both in water and on land?A. MammalsB. ReptilesC. AmphibiansD. Fish答案:C95 We created an obstacle course with ________ (玩具车) in the backyard. It was a fun ________ (挑战).96 What do we call the sweet substance made by bees?A. SyrupB. SugarC. HoneyD. Jam答案:C97 The _____ (flower/tree) is blooming.98 I share secrets with my __________. (朋友)99 What do we call a baby duck?A. ChickB. DucklingC. GoslingD. Calf答案: B100 My mom loves to __________ (和家人聚会).。
中考英语家庭生活阅读理解25题1<背景文章>In a happy family, there are many wonderful activities that bring everyone closer together. On weekdays, after a long day at school and work, the family enjoys cooking dinner together. The kitchen is filled with laughter and the delicious smell of food. Mom is an expert at making pasta dishes, while Dad is great at grilling steaks. The kids help by washing vegetables and setting the table.After dinner, they often watch a movie. They cuddle up on the couch, sharing a bowl of popcorn. Sometimes they watch a comedy that makes them laugh out loud, and other times they choose an adventure movie that takes them on exciting journeys.On weekends, the family goes on outings. They might visit a park and have a picnic, or go to the beach and build sandcastles. They also love to explore new places and try different cuisines.This family values quality time spent together. They know that these moments are precious and will create lasting memories.1. What do the kids do when the family cooks dinner?A. They watch TV.B. They wash vegetables and set the table.C. They play outside.D. They do their homework.答案:B。
六安一中2024年春学期高二年级期末考试英语试卷时间:120分钟第一部分听力(共两节,满分30分满分:150分)做题时,先将答案标在试卷上。
录音内容结束后,你将有两分钟的时间将试卷上的答案转涂到答题卡上。
第一节(共5小题;每小题1.5分,满分7.5分)听下面5段对话。
每段对话后有一个小题,从题中所给的A、B、C三个选项中选出最佳选项。
听完每段对话后,你都有10秒钟的时间来回答有关小题和阅读下一小题。
每段对话仅读一遍。
1.How would the woman like her steak today?A.Rare.B.Medium.C.Well-done.2.What is the relationship between the speakers?A.Teacher and student.B.Librarian and library user.C.Shop assistant and customer.3.Why does the woman call the man?A.To ask for a favor.B.To say thanks.C.To make a complaint. 4.Where does the conversation take place?A.At the airport.B.On a plane.C.In a taxi.5.What seems to be the man’s problem?A.He gets bored of reading.B.He is disturbed by the noise.C.He hates the hot weather today.第二节(共15小题;每小题1.5分,满分22.5分)听下面5段对话或独白。
每段对话或独白后有几个小题,从题中所给的A、B、C三个选项中选出最佳选项。
听每段对话或独白前,你将有时间阅读各个小题,每小题5秒钟;听完后,各小题将给出5秒钟的作答时间。
小学上册英语第四单元真题英语试题一、综合题(本题有100小题,每小题1分,共100分.每小题不选、错误,均不给分)1.The ice cream is melting ________ (在阳光下).2.The _______ (小狮子) plays with its siblings in the grass.3.I use my ________ (玩具名称) to solve puzzles.4.What do you call a collection of songs?A. AlbumB. PlaylistC. CompilationD. MixtapeA5.What is the name of the famous wizarding school in Harry Potter?A. HogwartsB. BeauxbatonsC. DurmstrangD. IlvermornyA6.Where do penguins live?A. DesertB. ForestC. ArcticD. AntarcticD7. A rabbit has long _______ to listen carefully.8.I need to _______ (finish) my homework.9.The first successful combined organ transplant was performed in ________.10. A mixture of two or more liquids is called an ______.11.The process of a solid turning into a liquid is called _______.12.The chemical symbol for iodine is _______.13.What is the name of the famous bridge in San Francisco?A. Brooklyn BridgeB. Golden Gate BridgeC. Hoover DamD. London BridgeB14.I like to ___ (color) in my coloring book.15.The capital of Russia is _____.16.What instrument do you blow into to play?A. FluteB. GuitarC. PianoD. DrumA17.The boiling point of ethanol is ______ degrees Celsius.18.The _______ (猴子) is very intelligent and playful.19.The __________ (历史的平衡) requires multiple viewpoints.20.在中国,古代的________ (ceremonies) 反映了人们的信仰与文化。
小学下册英语第六单元真题(含答案)英语试题一、综合题(本题有100小题,每小题1分,共100分.每小题不选、错误,均不给分)1.There are _____ (four/five) seasons in a year.2.This ________ (玩具) opens doors to creativity.3.The chemical formula for phosphoric acid is _______.4.Astronomers use _______ to observe distant stars and planets.5. Pyramid of Giza was built as a __________. (陵墓) The Grea6.I have ________ apples in my bag.7.My cat loves to _______ (探索) the house.8.The bird is ________ in the sky.9.What do we call the study of the universe?A. AstronomyB. GeologyC. BiologyD. Physics10. A ____(population density) measures how many people live in an area.11.The cat is ______ at the butterfly. (staring)12.She wants to be a ________.13.My aunt loves to travel to ____.14.ts are adapted to _____ (极端) environments. Some pla15.What is 5 + 3?A. 10B. 7C. 8D. 6答案:C16.The _____ (章鱼) can squirt ink to escape danger.17.What is the capital city of Slovenia?A. LjubljanaB. MariborC. CeljeD. Kranj18. A _______ helps illustrate the concept of buoyancy.19.I see _____ (clouds) in the sky.20.What is the time when the sun goes down called?A. SunriseB. SunsetC. NoonD. Midnight答案:B21.The ancient Egyptians built their temples to honor _____.22.The Earth’s atmosph ere protects us from ______ rays.23. A _______ is a measure of how much solute is present in a solution.24.What is the opposite of big?A. HugeB. SmallC. LargeD. Tall答案:B25.The stars twinkle ________ (在夜空中).26.The ________ (天气预报) said it would rain today.27.The ancient Romans had a system of ________ for voting.28.My ______ enjoys hiking in the mountains.29. A bumblebee helps ______ (授粉) flowers.30.The apples are _______ (ripe) and ready to eat.31.The _______ of sound can travel through solids, liquids, and gases.32. A _______ is a reaction that produces a gas as a product.33. A __________ (酸碱指示剂) changes color to indicate pH levels.34.What is the capital of Iraq?A. BaghdadB. MosulC. BasraD. Erbil35.What is the favorite food of a panda?A. MeatB. BambooC. FishD. Fruit答案:B36.How do you say "friend" in French?A. AmiB. FreundC. AmigoD. Compagnon37.What is the capital of China?A. BeijingB. ShanghaiC. Hong KongD. Taipei答案:A38.What do we call the process of changing from liquid to gas?A. FreezingB. MeltingC. EvaporationD. Condensation答案:C Evaporation39.What is the capital of Dominica?A. RoseauB. PortsmouthC. SalisburyD. Cottage答案:A40.What do you call a person who designs clothes?A. Fashion designerB. TailorC. SeamstressD. All of the above答案:D41.I like to _______ (参加) science fairs at school.42.Objects in motion tend to stay in ______.43._______ can be used for cooking and seasoning.44. A ______ is a type of sea creature with tentacles.bustion of hydrocarbons produces _____ (carbon dioxide and water).46.What is the name of the fairy tale character who lost her shoe?A. Sleeping BeautyB. CinderellaC. Snow WhiteD. Rapunzel47.What is 25 5?A. 15B. 20C. 10D. 5答案:B48.I always do my homework ________.49. A chemical reaction that occurs between an acid and a base is called a ______ reaction.50.What is the opposite of ‘safe’?A. SecureB. DangerousC. ProtectedD. Free51.What is the name of the famous detective created by Arthur Conan Doyle?A. Hercule PoirotB. Sherlock HolmesC. Miss MarpleD. Sam Spade52.What do we call the time it takes for the Earth to make one complete revolution around the sun?A. YearB. MonthC. DayD. Hour答案:A53.What do you call a baby rabbit?A. KitB. PupC. CalfD. Cub54. A ______ is a graphical representation of results.55.The __________ is a city known for its film industry. (好莱坞)56.The blue jay is a type of _________. (鸟)57.The dog is _____ with its favorite toy. (playing)58.The _____ (大雁) migrates to warmer places in the winter.59.The flowers smell _____ (good/bad).60.The goldfish is swimming in its _________. (鱼缸)61.The chemical formula for magnesium hydroxide is ______.62.I think it’s essential to be ________ (诚实) and trustworthy in all relationships.63.What do you call the time of day when the sun rises?A. MorningB. NoonC. EveningD. Night答案:A64.My dad is my strong _______ who helps me overcome challenges.65.I enjoy _______ (骑马) on weekends.66. A rainbow is formed by the refraction of _______.67.The __________ (历史的动力) fuels change.68.Concentration refers to the amount of solute present in a given _____ of solution.69.I enjoy _______ (烹饪) new recipes.70.The store is _____ (open/closed) now.71.The ancient Egyptians practiced ______ (农业) along the Nile River.72.She has a ________ (plan) for her career.73. A __________ is a type of solid that has a regular geometric shape.74.The __________ (历史的动力) often comes from change.75.What do you call a vehicle with two wheels?A. CarB. TruckC. BicycleD. Bus答案:C76.The __________ River flows through Egypt. (尼罗河)77.Which instrument has strings and is played with a bow?A. GuitarB. ViolinC. FluteD. Trumpet答案:B78.How many letters are in the English alphabet?A. 24B. 25C. 26D. 2779.What is the currency used in Japan?A. DollarB. YenC. EuroD. Pound答案:B80.Do you know my _____ (邻居)?81. A frog can leap very ______ (远) to catch insects.82.The __________ (历史的探讨) encourages open dialogue.83.The city of Baku is the capital of _______.84.My dad is a __________ (金融分析师).85.ts can be _____ (有毒) if ingested. Some pla86.What do we call the main character in a story?A. AntagonistB. ProtagonistC. Supporting characterD. Minor character答案:B87.The __________ (历史的探讨) fosters dialogue.88.What do we call the study of ancient civilizations?A. ArchaeologyB. AnthropologyC. SociologyD. History答案:A89.The _______ can help support diverse wildlife.90.I like to ______ (参与) in environmental awareness programs.91.The __________ is a region known for its cultural heritage.92.The __________ is a large area of wetlands in Florida. (大沼泽地)93.The clock is on the ___. (wall)94.The chemical formula for sodium thiosulfate is _____.95.What is the name of the famous fairy tale character who lost her glass slipper?A. CinderellaB. BelleC. Snow WhiteD. Rapunzel96.I want to ___ (play/finish) my game.97.The _____ (绿色植物) can purify the air.98.What is the name of the famous artist known for his "Les Demoiselles d'Avignon"?A. Pablo PicassoB. Henri MatisseC. Vincent van GoghD. Claude Monet答案:A99. A __________ (实验室记录) is essential for reproducing results.100.What do you call the act of giving or receiving money for work done?A. DonationB. PaymentC. TradeD. Exchange答案:B。
高考英语阅读理解强化训练Day 64Passage 1Exposing living tissue to subfreezing temperatures for long can cause permanent damage. Microscopic ice crystals(结晶体)cut cells and seize moisture(潮气), making donor organs unsuitable for transplantation. Thus, organs can be made cold for only a few hours ahead of a procedure. But a set of lasting new antifreeze compounds(化合物)—similar to those found in particularly hardy(耐寒的)animals—could lengthen organs’ shelf life.Scientists at the University of Warwick in England were inspired by proteins in some species of Arctic fish, wood frogs and other organisms that prevent blood from freezing, allowing them to flourish in extreme cold. Previous research had shown these natural antifreeze molecules(分子)could preserve rat hearts at ‘1. 3 degrees Celsius for up to 24 hours. But these proteins are expensive to extract(提取)and highly poisonous to some species. “For a long time everyone assumed you had to make synthetic(人造的)alternatives that looked exactly like antifreeze proteins to solve this problem, ”says Matthew Gibson, a chemist at Warwick who co’authored the new research. “But we found that you can design new molecules that function like antifreeze proteins but do not necessarily look like them. ”Most natural antifreeze molecules have a mixture of regions that either attract or repel water. Scientists do not know exactly how this process prevents ice crystal formation, but Gibson thinks it might throw water molecules into push pull chaos that prevents them from tuning into ice. To copy this mechanism, he and his colleagues synthesized spiral shaped molecules that were mostly water repellent—but had iron atoms at their centers that made them hydrophilic, or water’ oving. The resulting compounds were surprisingly effective at stopping ice crystals from forming. Some were also harmless to the roundworm Caenorhabditis elegans, indicating they might be safe for other animals.“These compounds are really cool because they are not proteins—they are other types of molecules that nonetheless can do at least part of what natural antifreezeproteins do, ”says Clara do Amaral, a biologist at Mount St. Joseph University, who was not involved in the research. Gibson’s antifreeze compounds will still need to be tested in humans, however, and may be only part of a solution. “We don’ t have the whole picture yet, ”do Amaral adds. “It’s not just one magical compound that helps freeze’tolerant organisms survive. It’s a whole suite of adaptations.1. What will happen if organs are kept for a long time in temperatures below zero?________A. They will have ice crystal formation inside.B. They will not suffer permanent damage.C. They will have longer shelf life.D. They will be fit for transplantation.2. What can we learn about natural antifreeze proteins?________A. They look like Gibson’s antifreeze compounds.B. They are composed of antifreeze molecules harmless to other species.C. They are spiral’shaped and have iron atoms at their centers.D. They can be found in organisms living in freezing cold weather.3. How are antifreeze molecules prevented from ice crystals?________A. By creating compounds both water’repellent and water’loving.B. By extracting the proteins from some hardy animals.C. By making synthetic alternatives like antifreeze proteins.D. By copying spiral’shaped molecules mostly water’resistant.4. What’s the main idea of the passage?________A. Push’pull chaos might prevent water molecules from turning into ice.B. The final solution to preserving donor organs has been found recently.C. Chemicals inspired by Arctic animals could lengthen organs’ shelf life.D. Gibson’s antifreeze compounds can do what natural antifreeze proteins do.Passage 2Sudoku (数独) puzzles give your brain a hard time: Every number from 1 to 9 must appear in each of the nine horizontal (横向的) rows, in each of the nine verticalcolumns and in each of the nine boxes.For many of us, this can be a reason for a headache, but in the very rare case of a German man, a Sudoku puzzle even caused seizures (痉挛).In a new case study from the University of Munich, published in the Journal of the American Medical Association, Dr. Berend Feddersen introduces a student who was 25 years old when he was buried by a snow slide during a ski tour. For 15 minutes, he didn't get enough oxygen, which severely damaged certain parts of his brain. "He had to receive treatment on the scene. Luckily he survived," says Feddersen, the author of the study.Weeks after the accident, when the young man was ready for recovery treatment, something bizarre happened: When the patient solved Sudoku puzzles, he suddenly had seizures of his left arm — something the medical world hadn't seen before.Feddersen explains: "In order to solve a Sudoku, the patient used parts of his brain which are responsible for vision’s pace tasks. But exactly those brain parts had been damaged in the accident and then caused the seizures once they were used."This particular case is an example of what doctors call reflex epilepsy (反射性癫痫), according to Dr. Jacqueline French, professor from NYU Langone School of Medicine."You have to have an injury of your brain first, and then seizures like that can happen," she says.In the meantime, the patient from the case study stopped solving Sudoku puzzles forever and has been seizure free for more than five years. "Fortunately, he can do crossword puzzles. He never had problems with those," Feddersen says.1. In the accident, the student________ .A. began to experience seizures in his left armB. got the vision’s pace part of his brain damagedC. had to be sent to hospital as soon as possibleD. found his Sudoku ability seriously weakened2. It can be learned from the text that________ .A. the man cannot complete crossword puzzles nowB. it is Sudoku playing that brings about his seizuresC. the man's symptoms are common and widely observedD. the seizures cause much trouble to the man's daily life3. This text can be best described as________ .A. a medical testB. a warning to skiersC. a news reportD. a research paperPassage 3Goldie's SecretShe turned up at the doorstep of my house in Cornwall. No way could I have sent her away. No way, not me anyway. Maybe someone had kicked her out of their car the night before. “We're moving house.” “No space for her any more with the baby coming.” “We never really wanted her, but what could we have done? She was a present.” People find all sorts of excuses for abandoning an animal. And she was one of the most beautiful dogs I had ever seen.I called her Goldie. If I had known what was going to happen I would have given her a more creative name. She was so unsettled during those first few days. She hardly ate anything and had such an air of sadness about her. There was nothing I could do to make her happy, it seemed. Heaven knows what had happened to her at her previous owner's. But eventually at the end of the first week she calmed down. Always by my side, whether we were out on one of our long walks or sitting by the fire.That's why it was such a shock when she pulled away from me one day when we were out for a walk. We were a long way from home, when she started barking and getting very restless. Eventually I couldn't hold her any longer and she raced off down the road towards a farmhouse in the distance as fast as she could.By the time I reached the farm I was very tired and upset with Goldie. But when I saw her licking (舔)the four puppies (幼犬)I started to feel sympathy towards them. “We didn't know what had happened to her,” said the woman at the door. “I took her for a walk one day, soon after the puppies were born, and she just disappeared.” “She must have tried to come back to them and got lost,” added a boy from behind her.I must admit I do miss Goldie, but I've got Nugget now, and she looks just like her mother. And I've learnt a good lesson: not to judge people.1. How did the author feel about Goldie when Goldie came to the house?A. Shocked.B. Sympathetic.C. Annoyed.D. Upset.2. In her first few days at the author's house, Goldie ______.A. felt worriedB. was angryC. ate a littleD. sat by the fire3. Goldie rushed off to a farmhouse one day because she ______.A. saw her puppiesB. heard familiar barkingsC. wanted to leave the authorD. found her way to her old home4. The passage is organized in order of ______.A. timeB. effectivenessC. importanceD. complexityPassage 4I started reading Shakespeare when I was nine, after my grandfather, an actor, sent me a copy of Romeo and Juliet. The story and the language attracted me. I found out about Shakespeare Globe Centre New Zealand (SGCNZ) and started volunteering for them when I was about 10. When I was 13, I managed to run a film project with SGCNZ.I’m home-educated and a part-time correspondence student(函授生) as well. We have a drama group made up of quite a few people who are also home-educated. I’ve also joined Wellington Young Actors, a youth theatre company. There are many similarities and differences between being home-educated and attending a five-day programme. I love hearing other students’ reactions when meeting them and share my different ways of experiencing the world with them. While explaining the way I learncan be a challenge, I love helping people to understand there isn’t just one way of learning.Being home-educated has offered me the freedom to have an individualized education and to pursue my passions. My education has always been about making those focuses but I do lots of the same things as people who attend five-day programs do. Shakespeare is a great approach to lots of things around English, history and the arts. I think something you learn when you perform is connection. You have to have a connection with your fellow actors, with the audience and with Shakespeare. I learn this from actually being on stage and from taking part in different Shakespeare festival programs.I believe it’s the emotion in Shakespeare that makes it relevant today. You can be reading something that was written 400 years ago and be able to see parts of your life in the work as it shows you how to understand the world and explore a lot of different ideas.1. What can “a five-day program” be?A. A film project.B. A reading activity.C. School education.D. Stage performance.2. Why does the author choose home education?A. To be different from others.B. To better focus on his passions.C. To enjoy more personal freedom.D. To improve his academic performance.3. What do we know about the author?A. A famous young actor.B. A loyal program volunteer.C. A home education writer.D. A devoted Shakespeare-lover.Passage 5Dark Sky Parks around the WorldWarrumbungle National ParkSituated in the central west slopes of New South Wales is Australia’s only dark sky park, Warrumbungle. The park has served as a dark sky park since July 2016. Its crystal-clear night skies and high altitude make it a natural, educational, andastronomical heritage site in the southern half of the earth. Tourists can use Australia’s largest optical telescope within the park boundaries to view the auroras(极光), the Milky Way, and faint shooting stars.SarkSark is a Channel Island near the coast of Normandy under the protection of the UK. It was the World’s First Dark Sky Island set up in January 2011. Its historical and cultural blend attracts over 40,000 tourists annually. With no motor vehicles and public lighting on the island, there is an exceptional view of the dark skies. A rich Milky Way is visible in the dark night skies from the shores of the island.Pic du Midi de BigorrePic du Midi de Bigorre in France was designated as a dark sky park in December 2013 making it the second largest dark sky park in the world. The park covers 3. 112 square kilometers spread across the Pyrenees National Park and UNESCO’s World Heritage site, Pyrenees-Mont Perdu. The park attracts over one hundred star watchers every year. The Observatory Midi-Pyrenees, which was built in 1870, is one of the world’s highest museums at a height of 2,877 meters above sea level.Ramon Crater/Makhtesh RamonRamon Crater is a unique 1,100-square-kilometer nature reserve located in the Negev Desert in Israel. In 2017, the Ramon Crater became the first designated dark sky park in the Middle East. Its location, rough climate, and forbidding landscape that are characteristic of the Negev have largely defeated historical attempts for human settlement, making it a great place to view the night skies. Stargazers usually camp in the desert to have an uninterrupted view of the stars, planets, and the Milky Way.1. Which park serves as a heritage site for astronomy?A. Sark.B. Pic du Midi de Bigorre.C. Warrumbungle National Park.D. Ramon Crater/Makhtesh Ramon.2. What do we know about Sark from the passage?A. Not a single car runs there.B. It was an island belonging to Normandy.C. The Milky Way can only be seen there.D. Visitors like to stay on the island in groups.3. What makes it difficult for humans to live in Ramon Crater?A. High altitude.B. The large area.C. Geographical conditions.D. Cultural features.参考答案Passage 11. A细节理解题。
《瓦尔登湖》阅读笔记2By Skye 在上一次的阅读笔记中,我写了对于《瓦尔登湖》的经济篇中梭罗提出的看法的观点。
我认为当时我写的看法是比较浅层次的,因为或许所有看过《瓦尔登湖》的人都会产生这样的看法。
而我今天想写的也是一个在文中比较简单的观点,但是在人们阅读《瓦尔登湖》时大多会为了体会梭罗在文中所想要表达的深层含义而忽略这个简单的点point,那就是生态保护,回归自然。
当时的美国正处于由农业时代向工业时代转型的初始阶段,人们疯狂贪婪霸占有限的自然资源,而梭罗的作品引起了人们的生态关怀,(这也是梭罗声名鹊起的原因之一)。
在冬天的禽兽Winter Animals这一章中,梭罗用了几乎一半的篇幅来描述各种各样的生物在瓦尔登湖林中自由快乐的生活场景,而另一半则用来写了猎户这样依靠贩卖动物为生的一类人。
在最后一段,他运用了反问“What is a country without rabbits and partridges?”来表达自己对当时现象的讽刺。
“The latter raises the moss and bark gently with his knife in search of insects”这句话在这一章The Pond in Winter中是一句毫不起眼,藏在角落里的话,但是却引起了我的思考。
因为在我看来最开始科学家先要研究昆虫的原因大概是受古时候人们所想象出来《诺亚方舟》等故事的影响,想要在灾难来临之际能够保证一些物种活下去来保证新的开始。
但是现在科学家的研究方式似乎与这个初衷相违背。
他们的研究不仅没有使物种得以延续,反倒加速了它们的灭亡。
“The perch swallows the grub-worm, the pickerel swallows the perch, and the fisher-man swallows the pickerel; and so all the chinks in the scale of being are filled。
小学上册英语第四单元期中试卷英语试题一、综合题(本题有100小题,每小题1分,共100分.每小题不选、错误,均不给分)1. A fish lives in _________ (水).2.The chemical formula for zinc oxide is _____.3.The island of Greenland is mostly ________ (冰盖).4.I have a favorite __________ (玩具类型) that is __________ (形容词).5.The state of matter that has a definite volume but not a definite shape is _____.6.The _____ (desk/table) is made of wood.7. A chemical reaction can be classified based on the changes it causes in ______.8.I want to ___ a musician. (become)9.The ________ (河流) Thames flows through London.10.The parakeet can learn to mimic human ________________ (语言).11.The ______ writes poems and songs.12.The __________ (沙滩) is a popular vacation spot.13.The __________ is a famous city known for its wine production. (波尔多)14.The cake is very ___. (rich)15.The ________ was a key event in the development of democracy.16.The _____ (fennel) plant has a distinct flavor.17.Certain plants can ______ (为动物提供) food and shelter.18. A __________ solution has less solute than it can dissolve.19.My sister is learning to play the ____ (trumpet).20.The monkey is ________ in the zoo.21.She has a ________ (passion) for art.22.The ancient Egyptians used _______ for mummification.23.What do we call a person who performs magic tricks?A. IllusionistB. MagicianC. EntertainerD. All of the above24.What is the term for the energy produced by nuclear fusion in stars?A. Stellar EnergyB. Radiant EnergyC. Cosmic EnergyD. Gravitational Energy25.I like to draw _______ (我喜欢画_______).26.The _______ (The Space Race) was marked by significant technological advancements.27.The ______ (植物的医用特性) are explored in research.28.What do you call a story that is made up?A. BiographyB. FictionC. Non-fictionD. History答案:B29.The river is _____ (wide/narrow).30.I love to _______ (做运动) every day.31.My friend loves __________ (科学实验).32.I saw a _______ (小鲸鱼) swimming in the ocean.33.The teacher is _____ us a new game. (showing)34. A substance that absorbs moisture from the air is called a(n) _______.35.I call my father's sister __________. (姑姑)36.Which animal can fly?A. ElephantB. DogC. SparrowD. Fish答案:C37.What do we call the time when the sun sets?A. DawnB. DuskC. NoonD. Midnight38. A __________ has a long neck and legs, often found in Africa.39.What is the name of the famous American singer known for "Jolene"?A. Reba McEntireB. Dolly PartonC. Carrie UnderwoodD. Miranda Lambert答案:B40. A __________ is a popular site for cultural exchange.41.I enjoy learning about ______ in science class.42.What do we call the process of moving from one place to another?A. MigrationB. JourneyC. TravelD. Voyage答案:A Migration43.The __________ is a famous archaeological site in Mexico. (特奥蒂瓦坎)44.I like to ride my ______ (摩托车) along the beach on sunny days.45.My favorite ice cream flavor is ______.46. A ______ has a very keen eyesight.47.What do we call the study of numbers?A. BiologyB. MathematicsC. ChemistryD. Physics48.My cousin is a talented ____ (pianist).49. A chemical bond forms between ______.50.Telescope lenses can be made of _______ glass.51.The lemur is native to _________ (马达加斯加).52. A ________ (花坛) is often found in parks.53.The pizza is _____ (hot/cold) and cheesy.54.The chemical symbol for sulfur is _____.55.What is the primary ingredient in sauerkraut?A. CabbageB. CarrotC. OnionD. Beet56.What do we call the natural process by which rainwater is absorbed into the ground?A. InfiltrationB. EvaporationC. PrecipitationD. Transpiration57.What is the name of the structure that protects your foot?A. ShoeB. SockC. SandalD. Boot答案:A58.The country known for its historical significance is ________ (以历史重要性闻名的国家是________).59.What is the term for a baby sheep?A. CalfB. KidC. LambD. Pup答案:C60.What is the term for a group of words that expresses a complete thought?A. SentenceB. PhraseC. ClauseD. Paragraph答案:A61.What do you call a place where you can watch plays?A. TheaterB. CinemaC. MuseumD. Concert hall答案:A62.I can ride my ___. (bicycle)63.What do we call a large-scale farming operation?A. PlantationB. RanchC. OrchardD. Garden答案:A64.The musician plays various _____ (乐器) skillfully.65.What is the name of the famous character known for his red and white striped hat?A. The Cat in the HatB. WaldoC. The GrinchD. Dr. Seuss66.I like to listen to _____ (music/radio) while studying.67.Which instrument has black and white keys?A. GuitarB. DrumsC. PianoD. Violin答案:C68.My dad likes to _______ (动词) on weekends. 他觉得这个活动很 _______ (形容词).69.What do you call a person who repairs cars?A. MechanicB. ElectricianC. PlumberD. Painter70.She is _______ (cooking) dinner for her family.71.What is the main language spoken in the USA?A. SpanishB. FrenchC. EnglishD. Chinese答案:C72.I have a ___ (dream).73.What do you call a shape with four equal sides?A. RectangleB. SquareC. TriangleD. Circle答案:B74.How many months are in a year?A. TenB. TwelveC. ElevenD. Thirteen答案:B75. A _____ (植物探索活动) can spark interest in botany.76.I can ___ (swim) in the pool.77.What is the capital city of Kazakhstan?A. AlmatyB. Nur-SultanC. ShymkentD. Aktobe78.The __________ (印加帝国) was located in South America.79.I feel excited when I go to ________.80.The cake is ________ and sweet.81.Ducks like to _______ (游泳) in ponds.82.The __________ (历史书籍) provide insight into different eras.83.The owl is active at ______.84.The cow gives us fresh _________. (牛奶)85.I like to learn new games that I can play with my ________ (玩具名).86.The koala sleeps for up to _______ (20小时) a day.87.What do we call the art of folding paper into decorative shapes?A. OrigamiB. CalligraphyC. PotteryD. Weaving答案:A88.The stars are shining ________.89.What do we call the process of water turning into steam?A. FreezingB. BoilingC. MeltingD. Evaporating90.The _______ (Lousiana Purchase) doubled the size of the United States in 1803.91.小猴子) likes to climb trees. The ___92.The Earth's atmosphere contains gases that are essential for ______.93.We like to sing ________ songs.94.What is the main source of light during the day?A. MoonB. StarsC. SunD. Lamp95.The river is ______ with fish. (full)96.What is the capital city of Chile?A. Buenos AiresB. SantiagoC. LimaD. Bogotá答案:B97. A ____ is a tiny creature that can build intricate webs.98.What is the name of the area around a planet where its magnetic field interacts with solar winds?A. MagnetosphereB. AtmosphereC. ExosphereD. Thermosphere99.The Great Red Spot is a giant storm on the planet ______.100.The chemical symbol for hafnium is ______.。
如何激发学生对数学的感兴趣英语作文Igniting the Spark: Making Math Come AliveThe classroom buzzes, a symphony of whispers and rustling papers. A wave of dread washes over me – math class. Numbers are cold, distant, a series of rules to memorize, not a language to speak. Yet, somewhere, deep within the rigid equations, a glimmer of something different beckons.Imagine a world where numbers become vibrant colors, equations dance, and problems transform into puzzles begging to be solved. This isn't a fantasy; it's the potential for the captivating world of mathematics.The key? Embracing the wonder that exists within the subject itself. Forget rote memorization; let's explore the beauty of patterns, the thrill of discovering connections, the satisfaction of solving a mind-bending problem.A simple graph, when brought to life, can tell a captivating story.A geometric proof, when animated, unveils the elegance of logic. Real-world applications, from the design of a roller coaster to the intricate workings of a computer program, reveal the power of math beyond the textbooks.Teachers, imagine yourselves as storytellers, painting a canvas of mathematical concepts with passion and enthusiasm. Students, let curiosity lead the way, allowing the joy of discovery to overcome initial apprehension.Math isn't about memorizing formulas, but about unleashing the creative potential within each of us. It’s about daring to explore, to question, to ask "Why?" and to delve into the fascinating world of patterns, relationships, and logic.Let's leave the cold, sterile environment behind and enter a world where mathematics becomes a source of excitement, where the numbers speak, and the world becomes a breathtaking mathematical masterpiece waiting to be explored.。
2025年人教版英语中考仿真试题及解答参考一、听力部分(本大题有20小题,每小题1分,共20分)1、Listen to the following conversation and choose the best answer.A. The man is asking for help with his homework.B. The woman is offering to help the man with his math problems.C. The man is explaining how to solve a math equation.D. The woman is correcting the man’s math answers.Answer: BExplanation: The man is struggling with his math and the woman offers to help him, indicating that she is willing to assist him with his math problems. The conversation revolves around the topic of solving math equations, making option B the correct answer.2、Listen to the following dialogue and complete the sentence with the missing information.W: Hi, John. How was your science project?M: Oh, it was quite challenging. I had to conduct an experiment on plant growth.W: That sounds interesting. What was the result?M: Well, the plants grew faster when they were exposed to more sunlight.W:___________Answer: 1. It’s great that you found a conn ection between sunlight and plant growth.Explanation: The listener is expected to infer that the woman is expressing interest in the findings of the science project. The provided answer is a natural continuation of the dialogue, showing curiosity and appreciation for the results of the experiment.3.You will hear a conversation between two friends discussing their weekend plans. Listen carefully and answer the following question.Question: What does the girl plan to do on Saturday afternoon?A. Visit her grandparents.B. Go shopping with her friends.C. Study for her exams.Answer: BExplanation: In the conversation, the girl mentions that she is planning to go shopping with her friends on Saturday afternoon. Therefore, option B is the correct answer.4.Listen to a short dialogue about the weather forecast. Answer the question that follows.Question: What is the weather expected to be like tomorrow?A. SunnyB. RainyC. WindyAnswer: AExplanation: The dialogue mentions that the weather forecast for tomorrow is sunny. Therefore, option A is the correct answer.5.You will hear a short conversation between two students discussing their weekend plans. Listen carefully and choose the best answer to the question.Question: What is the first activity that the students plan to do this weekend?A. Go to the movies.B. Visit a museum.C. Attend a sports game.D. Have a picnic.Answer: A. Go to the movies.Explanation: In the conversation, the students mention that they plan to watch a new movie together this weekend, which indicates that going to the movies is the first activity on their list.6.You will hear a short monologue about the importance of reading. Listen carefully and answer the following question.Question: What is the main reason the speaker gives for encouraging people to read more?A. Reading improves vocabulary.B. Reading makes you smarter.C. Reading is a good way to relax.D. Reading helps you learn about different cultures.Answer: D. Reading helps you learn about different cultures.Explanation: In the monologue, the speaker emphasizes that reading exposes individuals to different cultures and perspectives, which broadens their understanding of the world. While the other options are also benefits of reading, the main focus of the speaker’s argument is on cultural exposure.7.You are going to listen to a short conversation between two friends about their weekend plans. Listen carefully and choose the best answer to the following question.What are they going to do this weekend?A. Go shopping.B. Watch a movie.C. Go to the beach.Answer: BExplanation: In the conversation, one friend suggests, “Why don’t we go see that new movie this weekend?” which indicates that they are planning to watcha movie.8.Listen to a short dialogue between a teacher and a student about the student’s homework. Answer the following question.How does the teacher respond to the student’s excuse?Question: Why was the student late with the homework?A. The student forgot about it.B. The student’s computer broke.C. The student was sick.Answer: BExplanation: The student explains, “My computer broke, so I couldn’t finish the homework,” and the teacher responds by saying, “Okay, as long as you get it done by next class.” This shows that the teacher acknowledges the student’s computer problem as an excuse for being late with the homework.9.Listen to the dialogue and answer the question.W: Excuse me, where is the nearest bank around here?M: It’s about a 10-minute walk from here. You can take the first left after the post office and then you’ll see it on your right.Question: How far is the nearest bank from the post office?A) 5 minutes’ walkB) 10 minutes’ walkC) 15 minutes’ walkD) 20 minutes’ walkAnswer: B) 10 minutes’ walkExplanation: The man tells the woman that the nearest bank is about a 10-minute walk from the post office. Therefore, the correct answer is B) 10 minutes’ walk.10.Listen to the passage and answer the question.In the past, people used to write letters by hand and send them through thepost office. Now, with the development of technology, email has become the most popular way of communication. It is fast, convenient, and environmentally friendly. However, some people still prefer to send physical letters because they believe it is more personal and has a special touch.Question: Why do some people still prefer to send physical letters?A) Because it is more environmentally friendly.B) Because it is faster.C) Because it is more personal and has a special touch.D) Because it is cheaper.Answer: C) Because it is more personal and has a special touch.Explanation: The passage mentions that some people still prefer to send physical letters because they believe it is more personal and has a special touch. Therefore, the correct answer is C) Because it is more personal and has a special touch.11.You hear a conversation between two friends. The first speaker is asking abou t the second speaker’s weekend plans. Listen and answer the question.Question: What does the second speaker plan to do on Saturday?A. Go shopping.B. Visit a friend.C. Stay at home and read.Answer: BExplanation: The second speaker mentions that they are planning to visit a friendon Saturday, so the correct answer is B. Visit a friend.12.Listen to a short dialogue between a student and a teacher. The studentis asking for advice on a project.Question: What does the teacher suggest the student do to complete the project?A. Use more resources.B. Consult with a classmate.C. Start working on it as soon as possible.Answer: CExplanation: The teacher advises the student to “start working on it as soon as possible,” which indicates that the correct answe r is C. Start working on it as soon as possible.13.Listen to the following dialogue and answer the question.A: How do you like the new movie that just came out?B: I think it’s amazing! The special effects are fantastic, and the story is really interesting.Question: What does the man think of the new movie?Answer: He thinks it’s amazing.Explanation: In the dialogue, the man uses the phrase “I think it’s amazing” to express his opinion about the new movie. The word “amazing” indicates that he has a positive view of the movie.14.Listen to the following question and answer and complete the sentence.Question: What does the woman want to do?Answer: She wants to go to the library.Complete the sentence: The woman said she was going to the library because she needed to finish her research for her paper.Explanation: In the dialogue, the woman states her reason for going to the library, which is to finish her research for her paper. The sentence in the question asks for the woman’s intention, and the answer is provided by the dialogue.15.You are listening to a conversation between two friends, Alice and Bob. They are discussing their weekend plans.Alice: Hey Bob, do you have any plans for this weekend?Bob: Well, I was thinking of going hiking. How about you?Alice: That sounds great! I’ve never been hiking before, but I’m up for a challenge.Bob: Good! I’ll show you the best spots in the mountains. You won’t regret it.Question: What activity does Bob plan to do this weekend?A. Go hikingB. Go swimmingC. Go shoppingD. Go campingAnswer: A. Go hikingExplanation: In the conversation, Bob mentions that he was thinking of going hiking, which indicates that his plan for the weekend is to go hiking.16.Listen to a short dialogue between a teacher and a student.Teacher: Hi Sarah, how was your science project?Sarah: It was really fun, Mr. Johnson! I learned a lot about the solar system.Teacher: That’s great to hear. What did you find most interesting?Sarah: Well, I was fascinated by the fact that Mars has two moons.Question: What subject is the teacher discussing with Sarah?A. MathematicsB. EnglishC. ScienceD. HistoryAnswer: C. ScienceExplanation: The dialogue revolves around Sarah’s science project, and she mentions learning about the solar system and Mars, which clearly indicates that the subject being discussed is science.17.Listen to the conversation between two students discussing their weekend plans.Student A: Hi, do you have any plans for this weekend?Student B: Yes, I’m planning to visit my grandparents in the countryside. How about you?Student A: I’m going to go hiking with my friends. We’re planning to go to the mountains.Question: What is Student B’s plan for this weekend?A) Go hikingB) Visit grandparentsC) Go to the beachD) Stay at homeAnswer: B) Visit grandparentsExplanation: In the conversation, Student B mentions that they are planning to visit their grandparents in the countryside, so the correct answer is B.18.Listen to the short dialogue between a teacher and a student about a school project.Teacher: Hey, Sa rah, how’s your science project coming along?Sarah: It’s going pretty well, actually. I’ve already finished the research part. Now I’m working on the experiment.Teacher: That’s great! What did you find out during your research?Sarah: Well, I learned that renewable energy sources are becoming more popular. I’m planning to focus on solar energy in my project.Question: What is Sarah’s project about?A) Renewable energyB) Science fairC) BiologyD) ChemistryAnswer: A) Renewable energyExplanation: In the dialogue, Sarah mentions that she is working on a project about renewable energy and that she learned about solar energy during her research. Therefore, the correct answer is A.19.You will hear a conversation between two friends. Listen carefully and answer the following question.What is the main topic of the conversation?A. How to study effectively.B. The importance of physical exercise.C. The best way to choose a major.D. The latest news about technology.Answer: BExplanation: The conversation focuses on the importance of physical exercise and how it affects their daily lives.20.You will hear a short lecture about the history of the Internet. Listen carefully and answer the following question.Which of the following statements about the Internet is NOT true?A. The Internet was created in the 1960s.B. It started as a project for the U.S. military.C. The first email was sent in 1971.D. The World Wide Web was invented in 1991.Answer: DExplanation: The World Wide Web was not invented in 1991; it was actually created in 1989 by Tim Berners-Lee.二、阅读理解(30分)Reading ComprehensionPassage:On a warm summer afternoon, a young boy named Tom was playing with his friends in the park. The park was filled with the sounds of laughter and children playing game s. Tom’s favorite game was tag, where he would chase his friends around the playground. As the sun began to set, the sky turned a beautiful shade of orange and pink. Tom and his friends decided it was time to stop playing and head home. However, as they were leaving, they noticed a small dog, looking lost and tired, wandering around the park.Tom, being the kind-hearted boy he was, decided to help the dog. He followed it and found a nearby house that seemed to be the dog’s home. The door was slightly ajar, so Tom gently pushed it open and called out to see if anyone was inside. To his surprise, he heard a soft voice reply. An old lady, who lived alone, opened the door and was thrilled to see Tom with her dog.The old lady explained that her dog had been her constant companion for years, but recently, he had started wandering off. She was worried sick about him. Tom told her that he had found her dog and brought him back. The old lady was sograteful that she invited Tom and his friends in for a small celebration. They all had a wonderful time, sharing stories and laughter.Questions:1.What was Tom doing when he first noticed the dog?A) He was reading a book.B) He was playing tag with his friends.C) He was having a picnic.D) He was watching a movie.2.What did the old lady do when she saw her dog back home?A) She shouted in joy.B) She cried in sadness.C) She ignored the dog.D) She called the police.3.How did Tom and his friends celebrate the return of the dog?A) They gave the old lady a gift.B) They had a small party with food and music.C) They left immediately.D) They played another game of tag.Answers:1.B) He was playing tag with his friends.2.A) She shouted in joy.3.B) They had a small party with food and music.三、完型填空(15分)Instructions:For questions 1-5, select the most appropriate word or phrase to complete the passage.Passage:There was once a shy rabbit named Benny who lived in a forest full of (1)____ animals. Benny loved to play but was afraid to make new friends because he thought they would laugh at his long ears. One day, a wise old owl told him that everyone has special qualities and it’s these differences that make us unique. Encouraged by these words, Benny decided to (2)____ his fears and introduce himself to the other animals. To his surprise, the other animals were very friendly and soon he had many new friends. Benny learned that being (3)____ isn’t about changing who you are; it’s about being brave enough to let others see the real you. From that day on, Benny hopped around the forest with a smile, no longer (4)____ about what others thought of him. His long ears became his pride because they were part of what made him (5)____.Now, let’s fill in the blanks with the correct options.Here are the options for filling in the blanks:1.There was once a shy rabbit named Benny who lived in a forest full of _____ animals.•Options: wonderful, scary, funny, beautiful•Correct Answer: wonderful2.Encouraged by these words, Benny decided to _____ his fears and introduce himself to the other animals.•Options: overcome, face, hide, ignore•Correct Answer: overcome3.Benny learned that being _____ isn’t about changing who you are; it’s about being brave enough to let others see the real you.•Options: popular, smart, strong, fast•Correct Answer: popular4.From that day on, Benny hopped around the forest with a smile, no longer _____ about what others thought of him.•Options: worried, happy, excited, confused•Correct Answer: worried5.His long ears became his pride because they were part of what made him _____.•Options: special, ordinary, quiet, brave•Correct Answer: special四、语法填空题(本大题有10小题,每小题1分,共10分)1、My mother often tells me that I should be more punctual, but I always find it 1 difficult to get up early.A. veryB. soC. tooD. enough答案:A解析:本题考查副词的用法。
Solving the puzzles of cutin and suberin polymer biosynthesis Fred Beisson1,Yonghua Li-Beisson1and Mike Pollard2Cutin and suberin are insoluble lipid polymers that provide critical barrier functions to the cell wall of certain plant tissues, including the epidermis,endodermis and periderm.Genes that are specific to the biosynthesis of cutins and/or aliphatic suberins have been identified,mainly in Arabidopsis thaliana. They notably encode acyltransferases,oxidases and transporters,which may have either well-defined or more debatable biochemical functions.However,despite these advances,important aspects of cutin and suberin synthesis remain obscure.Central questions include whether fatty acyl monomers or oligomers are exported,and the extent of extracellular assembly and attachment to the cell wall.These issues are reviewed.Greater emphasis on chemistry and biochemistry will be required to solve these unknowns and link structure with function.Addresses1Department of Environmental Plant Biology and Microbiology,CEA/ CNRS/Aix-Marseille University,IBEB/UMR7265/LB3M,13108 Cadarache,France2Department of Plant Biology,Michigan State University,East Lansing, MI48824,USACorresponding author:Beisson,Fred(frederic.beisson@cea.fr)Current Opinion in Plant Biology2012,15:329–337This review comes from a themed issue onPhysiology and metabolismEdited by Julian M Hibberd and Andreas PM WeberAvailable online30th March20121369-5266/$–see front matter#2012Elsevier Ltd.All rights reserved.DOI10.1016/j.pbi.2012.03.003IntroductionThe epidermis of fruits,leaves,primary stems andflowers are sealed by an extracellular lipid layer termed cuticle [1].This hydrophobic layer consists of wax crystals, beneath which waxes are embedded in cutin,an insoluble lipid polyester specific to plants[2].Cutin covers the outer face of the epidermal wall(Figure1)and extends into the polysaccharide region by an ill-defined depth. The cutin-wax barrier plays a central role in the inter-action and adaptation of plants to the terrestrial environ-ment,particularly by imparting resistance to desiccation and providing thefirst barrier to many pathogens. Suberin is the other major lipid polyester[2].The best-known form is cork.In contrast to cutin,suberin is mostly deposited on the inner face of primary cell walls,either constitutively during plant development(e.g.periderm of secondary roots and stems,abscission zones)or in response to stress and wounding.Suberin-based layers are also found in the cell walls of some internal tissues such as the root endodermis or the bundle sheaths of monocots.Suberized tissues have roles in resistance to pathogens,water relations and mineral nutrition.Since thefirst analyses of polyester composition in Arabi-dopsis leaves/stems[3,4],roots[5],seeds[6]andflowers[7], studies on the biosynthesis and biological functions of cutin and suberin are accelerating and an increasing number of biosynthetic enzymes and regulatory proteins have been identified based on genetic approaches,mostly in Arabi-dopsis,but also in tomato and potato.Properties and physiological functions of cutin and suberin-based barriers have been recently reviewed elsewhere[8].This update is thus focused on biosynthesis.It includes polymer structure solely from the perspective of the specifics required to understand biosynthesis.Other fatty acid-based polymeric materials such as cutan and sporopollenin are poorly charac-terized and will remain outside the scope of this review. Cutin and suberin monomers and basic linkagesCutin and suberin are polymers of fatty acid derivatives linked by ester bonds,that is,polyesters.Glycerol is also present.While cutin is mostly composed of C16and C18 v-hydroxyacid,polyhydroxyacid,epoxyacid and a,v-dicarboxylic acid(DCA)(Figure2),suberin is usually distinguished by higher levels of hydroxycinnamic acids (predominantly ferulate),fatty alcohols and saturated aliphatics with chain lengths C20.Insoluble hydro-phobic residuals highly resistant to depolymerization are also present in suberized[9]and cutinized[10]tissues. Monomers of these residues are thought to be linked by C–C and C–O–C(ether)bonds.Proportions of the various ester-linked fatty acid derivatives found in cutin or sub-erin can differ greatly between species and even between organs within the same species.For example,in Arabi-dopsis thaliana the cutin of leaves and stems is dominated by DCAs[4],while the cutin offlowers is mainly com-posed of polyhydroxyacids[7].Whether the differences in monomer composition observed between cutins or sub-erins reflect different structural and functional properties is unknown.Ester linkages between specific monomers have been identified based on nuclear magnetic resonance(NMR) and mass spectrometry(MS)studies of dimers,trimers and up to heptamers isolated on partial chemical depolymer-ization of cutins and suberins[11,12].These linkagesAvailable online at include v -hydroxy fatty acids to each other and to glycerol,to DCA and to ferulate.Covalent linkages between some cutin hydroxyacids and cell wall sugars have also been provisionally identified [12].Other structural details of the polymers remain to be determined.As discussed pre-viously,polyester domains could be arranged as dendrimer or cross-linked structures [13].Besides,it is not known if the insolubility of cutin and suberin results from covalent anchoring to the cell wall,to cross-linking within the polyester domain,or to very high molecular weight.Hydroxylation and epoxidation of fatty acyls by cytochrome P450sBiochemical studies conducted in the 1970s using Vicia faba epidermis or suberized potato discs first showed the likely involvement of cytochrome P450monooxygenases in the hydroxylations and epoxidations of fatty acyl chains destined to polyester synthesis (reviewed in [2]).Several of these proteins are now identified (Figure 2,Table 1).Addition of a hydroxyl group at the terminal position of the acyl chain (v -hydroxylation)is catalyzed in vitro by mem-bers of the P450family CYP86(reviewed in [14]).Evi-dence of involvement of CYP86A members in polyester synthesis was suggested by cuticular defects in the lacerata mutant (CYP86A8)[15]and directly demonstrated bypolyester analysis in loss-of-function mutants for several other members of the family [3,16,17 ,18–20,21 ,22].Sur-prisingly,unsubstituted fatty acids (which cannot form polyester linkages)dominate the seed suberin composition in cyp86b1knockouts,thus challenging the idea that sub-erin comprises an extended polyaliphatic domain [21 ].CYP86A1[19]and CYP86B1[20]have been predomi-nantly localized to the ER.Interestingly,the pleiotropic effects observed in the lacerata mutant [15]and the sec-ondary localization of CYP86B1in the chloroplast [20]suggest that v -hydroxyacids generated by CYP86As may have other roles in addition to polyester monomers.Besides CYP86s,the only other P450able to catalyze the v -hydroxylation of C16–C18fatty acids and identified as important for cutin formation is CYP704B2from rice anthers [23 ].How v -hydroxyacids are further v -oxidized to v -oxoacids and then DCAs is still unclear.In Arabidop-sis,candidates are the putative oxidoreductase HOT-HEAD [24]and the cytochrome P450CYP86A2[16]for which the loss-of-function mutants show reduced DCAs and unaltered or increased v -hydroxyacid contents.Introduction of a hydroxyl group at a mid-chain position is required for the synthesis of 10,16-dihydroxypalmitate,a major monomer of the C16family (Figure 2).The mid-chain hydroxylase has now been identified in Arabidopsis330Physiology and metabolismFigure1Overview of subcellular locations and major biosynthetic steps of cutin and suberin.Acyl activation,oxidation and esterification to glycerol arecommon to both cutin and suberin biosynthesis,while acyl chain elongation,acyl reduction and feruloylation are suberization-specific and are offset to the right.The ordering of reactions shown does not imply the in vivo biosynthetic sequence for the intracellular synthesis of acylglycerol precursors.Depending on the site(s)of polymerization of the polyester precursors,acylglycerols,oligomers or polymers might be transported through the plasma membrane and the cell wall.as CYP77A6,a member of an orphan P450family [17 ].Biochemical activity of the recombinant protein and cutin monomer profiles of Arabidopsis knockouts demonstrate that CYP77A6hydroxylates 16-hydroxypalmitate at a mid-chain position to form 10,16-dihydroxypalmitate,the most abundant cutin monomer in Arabidopsis flowers.In cutins or suberins rich in C18v -hydroxyacid mono-mers,mid-chain epoxy and vicinal dihydroxy monomers are often present in substantial amounts.Epoxides might be generated by cytochrome P450s and partly converted to their dihydroxy derivatives by epoxide hydrolases [2],or further cross-linked by apoplastic enzymes to produce ethers as part of the cutan formation process [10].Although it has been shown that Arabidopsis CYP77A4P450can catalyze in vitro the conversion of linoleic acid to predominantly its 12S,13R-epoxy derivative [25 ],evi-dence that this P450is required for polyester synthesis isstill lacking.Another possible route of synthesis of epoxy cutin monomers is through peroxidases [26].GPATs,a set of acyltransferases linking fatty acyl to glycerolEnzymes responsible for the linkage of cutin and suberin fatty acyl precursors to glycerol have been identified in a family of eight Arabidopsis acyltransferases (glycerol-3-phosphate:acyl-CoA acyltransferase (GPAT))previously known to catalyze in vitro the transfer of acyls from acyl-CoAs to glycerol-3-phosphate [27].Using a knockout approach,GPAT5has been shown to be involved in suberin synthesis in roots and seeds [7],GPAT4and GPAT8to be essential for cutin formation in leaves [18],and GPAT6required for cutin synthesis in flowers [17 ].None of these GPATs seem to be required for the synthesis of membrane or storage lipids.While GPAT1isSolving the puzzles of cutin and suberin polymer biosynthesis Beisson,Li-Beisson and Pollard 331Figure2Biosynthesis of the C16and C18families of polyester fatty acyl monomers.Substrates in vivo may be acyl-CoAs (R =CoA),free fatty acids (R =H)or glycerolipids.DH:dehydrogenase.Synthesis of the suberin monomers with chain lengths C20requires elongation steps involving ketoacyl-CoA synthases.present in ER and mitochondria[27],GPAT8is ER-localized[28].Further evidence of the specific role of GPATs in the synthesis of surface polyesters is provided by overexpres-sion studies in planta.When GPAT5is overexpressed ectopically in Arabidopsis,monoacylglycerols(MAGs)with C22-28saturated acyl chains accumulate at the plant surface(predominantly the sn-2MAG isomer)[29]. These results demonstrate in vivo that a GPAT can catalyze the transfer of acyl chains to a glycerol-based acceptor and that the products can be exported to the cuticle.Furthermore,co-overexpression of GPAT5and either the v-hydroxylases CYP86A1or CYP86B1required332Physiology and metabolismTable1Proteins identified in the plant polyester biosynthetic pathways.Protein function and species Protein name Gene ID Polyesteraffected In vitroactivityIn plantaover-expressionReferencesFatty acyl v-hydroxylaseArabidopsis CYP86A1/HORST At5g58860Suberin**[18,19] Arabidopsis CYP86A2At4g00360Cutin*[3,16] Arabidopsis CYP86A4At1g01600Cutin*[17 ] Arabidopsis CYP86A8/LCR At2g45970Cutin*[15] Arabidopsis CYP86B1/RALPH At5g23190Suberin*[20,21 ] Rice CYP704B2Cutin*[23 ] Potato CYP86A33EU293405Suberin[22]Fatty acyl in-chain hydroxylaseArabidopsis CYP77A6At3g10570Cutin*[17 ]Long-chain acyl-CoA synthetaseArabidopsis LACS1/CER8At2g47240Cutin*[40] Arabidopsis LACS2At1g49430Cutin*[38,39] Ketoacyl-CoA synthaseArabidopsis KCS2/DAISY At1g04220Suberin*[43 ,44] Arabidopsis KCS20At5g43760Suberin*[43 ,44] Potato StKCS6ACF17125Suberin[45]sn-2glycerol-3-phosphate acyltransferaseArabidopsis GPAT4At1g01610Cutin**[18,31 ] Arabidopsis GPAT5At3g11430Suberin**[7,18,31 ] Arabidopsis GPAT6At2g38110Cutin**[17 ,31 ] Arabidopsis GPAT8At4g00400Cutin[18] Feruroyl transferaseArabidopsis ASFT At5g41040Suberin*[21 ,32] Potato FHT FJ825138Suberin*[33 ] Arabidopsis DCF At3g48720Cutin*[34]Other acyltransferaseArabidopsis PEL3/DCR At5g23940Cutin*[35,36 ,37] Fatty acyl-CoA reductaseArabidopsis FAR1At5g22500Suberin*[42 ] Arabidopsis FAR4At3g44540Suberin*[42 ] Arabidopsis FAR5At3g44550Suberin*[42 ]Other putative enzymeArabidopsis HTD At1g72970Cutin[24] Arabidopsis BDG At1g64670Cutin[46]ABC transporterArabidopsis ABCG11/WBC11/DSO/COF1At1g17840Cutin,suberin[53–55] Arabidopsis ABCG13At1g51460Cutin[57] Arabidopsis ABCG32/PEC1At2g26910Cutin[58 ]Wild barley HvABCG31AB534898Cutin[59 ]Rice OsABCG31AB534899Cutin[59 ] Regulatory proteinArabidopsis WIN1/SHN1At1g15360Cutin*[60,61] Arabidopsis SHN2At5g11190Cutin[61] Arabidopsis SHN3At5g25390Cutin[61] Arabidopsis ESB1At2g28670Suberin[65] Arabidopsis CFL1At2g33510Cutin[64] Tomato CD2100316889Cutin[63 ] Cutin/suberin refers to the polyesters shown to be impaired in loss-of-function mutants.Stars denote that evidence for function is not only based on monomer composition of the mutants but is also demonstrated by in vitro measurement of protein activity and/or characterization of the products obtained following in planta overexpression.Housekeeping enzymes of lipid metabolism and proteins likely to affect polyesters indirectly are not included.for suberin synthesis result in formation of long and very long chain v -hydroxyacids and DCAs in the cutin layer,whereas overexpression of either P450alone does not yield any detectable product in the cuticle [18,21 ].It is thus clear that GPAT5acts in synergy with fatty acid v -hydro-xylases and provide acyl-or perhaps polyacyl-glycerol building blocks for suberin synthesis.GPATs appear to be co-limiting enzymes in the pathway because their over-expression increases cutin loads [18,30].A detailed enzymology study with recombinant Arabi-dopsis GPATs expressed in yeast has yielded further insights into the important role of these enzymes in the pathway.GPAT4,GPAT5and GPAT6were all shown to be sn -2acyl transferases with glycerol-3-phos-phate as the acyl acceptor [31 ].Good activity levels were observed with coenzyme A (CoA)esters of hydro-xyacids and DCA as acyl donors.In addition,GPAT4and GPAT6have retained phosphatase activity such that the main in vitro product was not a 2-acyl-lysophosphatidic acid but 2-MAG.Clearly,the sn -2specificity (and phos-phatase activity for some GPATs)allows separation of fatty acyl chains destined to lipid polymers from those used for membrane and storage lipids (Figure 3).Other families of acyltransferases acting on glycerol probably exist because it is unlikely that the glycerol present in polyesters is acylated at the sn -2position only.The BAHD superfamily of acyltransferasesRecent studies have identified members of the B EAT,A HCT,H CBT1,D AT (BAHD)acyltransferase super-family that are important for polyester formation.A suberin feruloyltransferase was discovered indepen-dently by three groups based on loss-of-function mutants in Arabidopsis [21 ,32]and potato [33 ].Heterologous expression of the proteins confirmed that Arabidopsis ASFT (aliphatic suberin feruloyl transferase)and the potato homolog FHT (fatty omega-hydroxyacid/fatty alcohol hydroxycinnamoyltransferase)catalyze the transfer of ferulate from feruloyl-CoA to v -hydroxyfatty acids and fatty alcohols.In Arabidopsis asft mutants the ester linkage between ferulate and v -hydroxyalipha-tics had to be inferred based on approximately stoichio-metric reductions of ferulate and v -hydroxyaliphatics and on enzymology.By contrast,potato periderm contains alkyl ferulates which were observed to be greatly reduced in the fht mutant.The surprising aspects of the Arabidopsis and potato feruloyltransferase mutants were that the lamellar structure of suberin remained intact and that the aliphatic suberin remained insoluble.This appeared contrary to many models of the suberin where ferulate was suggested as a crucial com-ponent of both lamellae formation and aliphatic suberin cross-linking.Clearly,these models will need to be revisited.Solving the puzzles of cutin and suberin polymer biosynthesis Beisson,Li-Beisson and Pollard 333Figure3The specificity of glycerol-3-phosphate acyltransferases results in distinct pools of acylglycerol precursors for cutin,suberin or membrane/storage lipids in Arabidopsis.Glycerol-3-phosphate acyltransferases (GPATs)involved in lipid polyester synthesis consist of a C-terminal plsC acyltransferase domain and an N-terminal domain that is homologous to conserved motifs of the HAD-like hydrolase superfamily which includes phosphatases.They esterify glycerol-3-phosphate at the sn -2position while the classical GPATs providing membrane and storage lipids are sn -1glycerol-3-phosphate acyltransferases.Phosphatase activity of GPAT4has been confirmed by site-directed mutagenesis of residues predicted to be essential for activity [31 ].Consistent with the absence of such residues in GPAT5,no phosphatase activity could be measured on this isoform.Appearance of MAGs following GPAT5overexpression in Arabidopsis [29]probably results from an endogenous epidermal phosphatase.There are several options for the omega functional group R.In the case of GPAT5we know it can be -CH3in vivo [29].If MAGs are the exported monomers (synthons)for extracellular polymerization or the propagator for further intracellular oligomerization,R =–OH or –COOH.However,if glycerol esterification is an intracellular oligomerization terminator R may be esterified –OH or –COOH,namely –OCOR or –COOR.A second member of BAHD acyltransferase superfamily, closely related to ASFT and FHT,has recently been shown in Arabidopsis to be essential for the incorporation of ferulate,a minor component of cutins.The dcf(defective in cutin ferulate)knockout has no ferulate left in leaves [34].DCF is localized to the cytosol of epidermal cells and can catalyze in vitro the transfer of ferulate and sinapate from their CoA esters to v-hydroxyfatty acids.A third,more distantly related BAHD gene had been previously shown to be important for cuticular per-meability based on the isolation of the mutant pel3 (permeable leaves3)[35].Isolation and analysis of another mutant allele termed dcr(defective in cuticular ridges) demonstrated a strongly reduced cutin content[36 ] and an absence of nanoridges onflower surfaces,a phe-notype similar to that seen in knockouts for CYP77A6and GPAT6[17 ].DCR/PEL3was found to be mostly loca-lized in the cytosol[36 ]and biochemical data show that it is able to acylate diacylglycerol in vitro[37].Further work on DCR activity will be needed to rule out a regulatory function and determine its role in the pathway.Other enzymes identifiedLong chain acyl-CoA synthetases(LACS)are required to activate free fatty acids to the acyl-CoAs used by acyl-CoA-dependent acyltransferases.In Arabidopsis,LACS2is clearly important for cutin biosynthesis[38,39]and LACS1 (CER8)has an established role in cuticular wax biosyn-thesis[40,41]and an additional function in stem cutin deposition[40].The LACS enzymes involved in suberin biosynthesis have yet to be identified but three acyl-CoA reductases producing C18–C22saturated fatty alcohols [42 ],the Arabidopsis b-ketoacyl-CoA synthases(KCS, elongases)KCS2/DAISY and KCS20[43 ,44],as well as a potato periderm KCS[45],have demonstrated roles in suberin biosynthesis.KCS and LACS catalyze reactions required for many lipids(e.g.waxes or sphingolipids)and it is thus not certain that isoforms impacting cutin or suberin are specific to polyester metabolism,which hampers the interpretation of physiological phenotypes of mutants. Other putative enzymes known to be important for proper organization of the cutin layer include two putative hydro-lases:Arabidopsis BODYGUARD(BDG),a cell wall-located alpha/beta hydrolase fold protein[46],and rice WILTED DWARF AND LETHAL1(WDL1),a mem-ber of the GDSL hydrolase superfamily localized to the ER [47].Further biochemical characterization of these proteins will be needed to demonstrate a role in polyester synthesis or anchorage to cell wall and discard an indirect effect on polyester layers,as probably occurs in the polysaccharide mutant ces9[48],the membrane lipid mutant ugt80b1[49] and the fatty acyl carrier protein reductase mutant dpw[50]. Sequential order of reactionsAlthough major uncertainties remain regarding the order of the steps of acyl activation,oxidation and transfer to glycerol,some progress has been made since we last reviewed the topic[13].Best established is perhaps the sequential action of an v-hydroxylase and a mid-chain hydroxylase to form the cutin monomer10,16-dihydrox-ypalmitate,which is supported by both genetic and bio-chemical evidence[17 ].But what is the in vivo substrate of P450v-hydroxylases?Clearly,free fatty acids are sub-strates of v-hydroxylases in in vitro assays.The2-fold preference of recombinant LACS2for v-hydroxypalmitate over palmitate[38]also supports the idea that P450s may act before LACS.However,an in vitro study on Petunia CYP86A22shows that acyl-CoAs might also be substrates of P450s[51].Other possible in vivo substrates of P450s include membrane lipids and GPAT-generated acylgly-cerols.However,GPAT6acyltransferase can accept v-oxidized C16acyl-CoA substrates[31 ],which provides an argument that hydroxylation precedes acylation to glycerol.The same conclusion comes from our studies on seed suberin,where the monomer1,22-docosane-diol requires CYP86B1[21 ]for its synthesis,but not GPAT5 [7,16].As its synthesis presumably proceeds via the action of an acyl-CoA reductase on22-hydroxy-docosanoyl-CoA, the inference is that glycerol acylation is not required for v-hydroxylation.When viewing the putative biochemical pathways to suberin precursors,the presence of elongation and feruloyl transfer reactions complicates the matrix of possibilities.Further substrate specificity studies will be required to establish a definitive map of the pathway leading to polyester precursors.A major puzzle:intracellular or extracellular polymerization of the precursors?The site of polymerization of the precursors(catenation reactions)is a major unknown in polyester biosynthesis (Figure1).It is not necessarily intracellular.Polymeriz-ation using lipases in organic media(at moderate tem-peratures)does not require rigorous water-stripping to drive esterification to produce polymers with high mol-ecular weights[52].Thus,although the apoplast is an aqueous domain,it seems plausible that monomers/oli-gomers delivered to the aqueous–aliphatic interface of the cuticular layer,would be efficiently incorporated into polyesters by extracellular lipolytic enzymes.Candidate enzymes for extracellular polymerization include the cell-wall located lipase-like proteins of the BDG family[46] and the apoplastic GDSL-motif hydrolases.A role of these two groups of enzymes in attachment of polyesters to the cell wall or in polysaccharide metabolism should not be ruled out however.Transport issuesAnother intriguing issue of polyester biosynthesis is the way hydrophobic components(monomers,oligomers or polymers)are transported through hydrophilic environ-ments and membranes,namely ER,cytosol,plasma membrane(PM)and eventually,for cutin,cell wall. Possible mechanisms are intertwined with those of the334Physiology and metabolismsite(s)of polymerization and have been reviewed pre-viously[13].Proteins identified so far as involved in cutin/suberin trans-port processes are all PM-localized ATP-binding cassette (ABC)transporters.Null mutations in a gene encoding the half-transporter ABCG11cause dwarfism,postgenital organ fusions,altered epidermal cell differentiation, reduced cutin and wax content[53,54]and altered suberin composition[55].Studies using bimolecularfluorescence complementation and protein traffic assays in vivo demon-strate ABCG11forms homodimers andflexible dimer partnerships with other half transporters like ABCG12/ CER5[56 ].Other transporters identified as important for cutin deposition include Arabidopsis ABCG13[57]and the full-transporters Arabidopsis ABCG32[58 ],wild bar-ley ABCG31and its rice ortholog[59 ].Interestingly,in several mutants for these transporters,cytosolic lipid-like inclusions have been observed within epidermal cells. Identification of the molecules actually bound by these transporters will be needed to confirm their direct involve-ment in the polyester pathway and help discriminate between the cytosolic and apoplastic polymerization hy-potheses.How cutin components are further transported across the cell wall to the outer epidermal surface is unknown.Lipid transfer proteins might be involved[13]. ConclusionThe development of routine quantitative methods to analyze cutin and suberin in Arabidopsis[4,5]combined with genetic approaches in this model plant have proven very powerful in dissecting the biosynthesis of polyesters. Genes identified in the pathway have increased from3in 2004to37to date.Determination of the targets of the regulatory proteins identified[60–62,63 ,64,65,66 ]and characterization of gene candidates coming from tran-scriptomic studies[67]are important tasks which will aid in the identification of new players.Another major chal-lenge will be the biochemical characterization of meta-bolic intermediates and putative enzymes identified to put together correct and detailed pathways. AcknowledgementThis work was supported by National Science Foundation grant MCB-0615563,and in part by a FP7Marie-Curie International Reintegration Grant#224941to F.B.References and recommended readingPapers of particular interest,published within the period of review, have been highlighted as:of special interestof outstanding interest1.Samuels L,Kunst L,Jetter R:Sealing plant surfaces:cuticularwax formation by epidermal cells.Annu Rev Plant Biol2008,59:683-707.2.Kolattukudy PE:Polyesters in higher plants.In Advances inBiochemical Engineering/Biotechnology.Vol71.Biopolyesters Babel W,Steinbuschel ABerlin:Springer;2001:1-49.3.Xiao FM,Goodwin SM,Xiao YM,Sun ZY,Baker D,Tang XY,Jenks MA,Zhou JM:Arabidopsis CYP86A2repressesPseudomonas syringae type III genes and is required forcuticle development.EMBO J2004,23:2903-2913.4.Bonaventure G,Beisson F,Ohlrogge J,Pollard M:Analysis of thealiphatic monomer composition of polyesters associated with Arabidopsis epidermis:occurrence of octadeca-cis-6,cis-9-diene-1,18-dioate as the major component.Plant J2004,40:920-930.5.Franke R,Briesen I,Wojciechowski T,Faust A,Yephremov A,Nawrath C,Schreiber L:Apoplastic polyesters in Arabidopsissurface tissues—a typical suberin and a particular cutin.Phytochemistry2005,66:2643-2658.6.Molina I,Bonaventure G,Ohlrogge J,Pollard M:The lipidpolyester composition of Arabidopsis thaliana and Brassicanapus seeds.Phytochemistry2006,67:2597-2610.7.Beisson F,Li YH,Bonaventure G,Pollard M,Ohlrogge JB:Theacyltransferase GPAT5is required for the synthesis of suberin in seed coat and root of Arabidopsis.Plant Cell2007,19:351-368.8.Schreiber L:Transport barriers made of cutin,suberin andassociated waxes.Trends Plant Sci2010,15:546-553.9.Bernards MA,Lopez ML,Zajicek J,Lewis NG:Hydroxycinnamicacid-derived polymers constitute the polyaromatic domain of suberin.J Biol Chem1995,270:7382-7386.10.Villena JF,Dominguez E,Stewart D,Heredia A:Characterizationand biosynthesis of non-degradable polymers in plantcuticles.Planta1999,208:181-187.11.Graca J,Santos S:Glycerol-derived ester oligomers from corksuberin.Chem Phys Lipids2006,144:96-107.12.Tian SY,Fang XH,Wang WM,Yu BW,Cheng XF,Qiu F,Mort AJ,Stark RE:Isolation and identification of oligomers from partial degradation of lime fruit cutin.J Agric Food Chem2008,56:10318-10325.13.Pollard M,Beisson F,Li YH,Ohlrogge JB:Building lipid barriers:biosynthesis of cutin and suberin.Trends Plant Sci2008,13:236-246.14.Pinot F,Beisson F:Cytochrome P450metabolizing fatty acidsin plants:characterization and physiological roles.FEBS J2011,278:195-205.15.Wellesen K,Durst F,Pinot F,Benveniste I,Nettesheim K,Wisman E,Steiner-Lange S,Saedler H,Yephremov A:Functional analysis of the LACERATA gene of Arabidopsis providesevidence for different robes of fatty acid omega-hydroxylation in development.Proc Natl Acad Sci U S A2001,98:9694-9699.16.Molina I,Ohlrogge JB,Pollard M:Deposition and localization oflipid polyester in developing seeds of Brassica napus andArabidopsis thaliana.Plant J2008,55:437-449.17.Li-Beisson Y,Pollard M,Sauveplane V,Pinot F,Ohlrogge J,Beisson F:Nanoridges that characterize the surfacemorphology offlowers require the synthesis of cutinpolyester.Proc Natl Acad Sci U S A2009,106:22008-22013. The in-chain fatty acid hydroxylase of the C16cutin monomer synthesis pathway is identified as the orphan P450CYP77A6based on a gene coexpression approach followed by genetic and biochemical character-ization.Direct evidence that cutin is essential for the formation offlower nanoridges is also provided by electron microscopy analysis of Arabi-dopsis mutants.18.Li YH,Beisson F,Koo AJK,Molina I,Pollard M,Ohlrogge J:Identification of acyltransferases required for cutinbiosynthesis and production of cutin with suberin-likemonomers.Proc Natl Acad Sci U S A2007,104:18339-18344. 19.Hofer R,Briesen I,Beck M,Pinot F,Schreiber L,Franke R:TheArabidopsis cytochrome P450CYP86A1encodes a fatty acid omega-hydroxylase involved in suberin monomerbiosynthesis.J Exp Bot2008,59:2347-2360.pagnon V,Diehl P,Benveniste I,Meyer D,Schaller H,Schreiber L,Franke R,Pinot F:CYP86B1Is required for very long chain omega-hydroxyacid and alpha,omega-dicarboxylic acidSolving the puzzles of cutin and suberin polymer biosynthesis Beisson,Li-Beisson and Pollard335。