将甲、乙、丙三块等体积并去皮的萝卜条分别放入0.3%、11%和25%的蔗糖溶液中。甲变得硬挺，乙基本无变化，丙变小变软。这说明萝卜细胞液的浓度为[]A．低于0.3%B．约为0.3%C．-七年级生物

更多内容推荐

• 下列关于植物细胞结构和功能的叙述中，错误的是[]A．植物细胞是植物体结构和功能的基本单位B．植物细胞具有细胞壁、细胞膜、细胞质和细胞核等结构C．成熟的植物叶肉细胞具有叶绿-七年级生物
• 市场上买菜的人常常给蔬菜喷水，这样做的道理是使蔬菜[]A．细胞吸水，保持硬挺B．细胞失水，保持硬挺C．细胞吸水，保持柔软D．细胞失水，保持柔软-七年级生物
• 将细胞的结构与其功能连接起来。细胞壁储存遗传物质细胞膜光合作用细胞核支持作用叶绿体进行物质交换-七年级生物
• 切西瓜时流出的液汁来自细胞的什么结构：[]A．细胞核B．细胞膜C．叶绿体D．液泡-七年级生物
• 阅读理解。 Today there are 6 billion people on the earth. By the year 2050 there may be 12.5 billion. Thi
• 阅读理解。 Many students ask for advice about improving their English. There are three basic questions.Th
• 阅读理解。 In the summer of 1978 an English man named Steven was driving his tractor through a field of w
• 阅读理解。 Scientist Without Laboratories When you hear the word "scitentist", what do you thin
• 植物细胞细胞质中，与植物制造有机物有关的结构、与呼吸作用有关的结构依次是[]A．线粒体叶绿体B．叶绿体线粒体B．核糖体内质网D．内质网核糖体-七年级生物
• 人们在切西瓜时，流出的汁液来自细胞的[]A．细胞膜B．细胞质C．液泡D．细胞核-七年级生物
• 阅读理解。 Most people have a cellphone (手机). When you are walking on a busy street, you will see many pe
• 叶绿体和线粒体共同具有的特点是[]A．存在于动植物细胞中B．只存在于动物细胞中C．能进行光合作用D．与细胞的能量转换有关-八年级生物
• 在植物细胞中能够把光能转变为有机物的能量，并称为能量转换器的结构是[]A．细胞壁B．细胞核C．叶绿体D．细胞质-七年级生物
• 高倍镜视野内观察到的细胞具有细胞壁、细胞核和大液泡，这种细胞最可能：[]A．动物细胞B．植物细胞C．细菌D．病毒-七年级生物
• 樱桃素有“开春第一果”之称，吃起来酸甜可口。这些酸甜物质主要存在于樱桃细胞的_____中[]A．细胞壁B．细胞膜C．细胞质D．细胞核-七年级生物
• 植物细胞周围水溶液浓度大于植物细胞液的浓度时[]A．水由细胞外的水溶液向细胞内渗透B．水由细胞内向细胞外渗透C．细胞吸水D．细胞液中的水分增加-七年级生物
• 阅读短文，选择正确答案。 Water is all around us. Water is in the ocean. Water is in the lakes and rivers. Water
• 阅读理解。 At the moment, it may be difficult to imagine, but many people believe that, by the year 2100,
• 阅读简答：阅读下面短文，简要回答文后问题。 History is the story of us, human beings. Everyone who has lived and everythin
• 阅读下面的短文，按要求完成所给任务。 Reading is a very good hobby for all the students. You can know much about the wo
• 阅读理解。Sitting on exercise balls brings more than a smile to students and teachers.Some fourth-graders
• 阅读理解。 In the United States, parents usually encourage their children to develop their potential (潜能)
• 在短文的空格内填入适当的词，使其内容通顺，每空格限填一词，词首字母已给。 Teenagers are always stressed out now. They are often too busy
• 阅读理解。 E-book is short for electronic (电子的) book. It is usually read on personal computers. Some mobi
• 绿色的菠菜用清水怎么洗，清水中仍不见绿色物质；若放入沸水中一烫，水立刻变成绿色。这个现象说明[]A．沸水杀死细胞，使细胞膜失去选择透过性B．在清水中没有物质进出细胞C．沸-七年级生物
• 阅读理解。 Now satellites are helping to forecast (预报) the weather. They are in space, and they can reach
• 阅读理解。 If someone asked you to draw a picture of a robot, how would it look? Like a person? That'
• 阅读短文，选词填空。(jobs map look useful took how part)What do you know about a robot? Robots are machines th
• 要把制成的洋葱表皮细胞临时装片进行染色，最准确的方法是[]A．在盖玻片的一侧滴加稀碘液B．直接将碘液滴在洋葱叶表皮上C．在盖玻片的一侧滴加稀碘液，用吸水纸在同一侧吸引D．在-七年级生物
• 阅读短文，完成各小题。 Some countries have large numbers of earthquakes. Japan is one of them. One of the most
• 烟草含有一种对人体有害的物质，叫做尼古丁，它主要存在于烟草细胞的[]A．细胞壁B．细胞质C．细胞液D．细胞核-七年级生物
• 根据短文内容，判断句子正误。正确的用“A”表示，不正确的用“B”表示 。 Is an earthquake dangerous? Yes. of course. But this doesn
• Cloze test. Many Chinese students don't pay much attention to spoken English at school. They th
• Reading comprehension. Teachers say buying homework answers online is not many in schools, but an in
• 完形填空。 Have you ever complained (抱怨) why life is so tiring? Does the sky sometimes1 dark to you? Are
• 在短文的空格内填入适当的词，使其内容通顺。 At one time, making a film was an expensive activity only for a small group of
• 阅读短文，然后在下面的表格中完成内容提要，每空不超过3个单词。New Energy in the Twenty-first CenturyEnergy from the windWind is a k
• 细胞内能将光能转变成化学能的结构是[]A．细胞膜B．细胞核C．叶绿体D．线粒体-七年级生物
• Reading comprehension. Fruit and vegetables should be a part of what we eat every day. Educating you
• 阅读理解。 When you cough or sneeze, please turn your head away from others and cover your mouth with the
• 阅读理解。 If you want to become a better reader, what should you know about speed of reading? Some peopl
• 阅读下面短文，在表格内的空白处填入合适的答案(每格限填一词)。 The way in which we communicate with others can be greatly improved
• 阅读上面短文，完成表格内容。 Do you believe there are aliens (外星人)? Well, make a phone call and you will know. A
• 阅读材料，然后从各小题所给的四个选项中选出最佳选项。 Leaves are nature's food factories. Plants take water from the groun
• 下面是植物细胞的平面结构模式图，请据图回答问题：（1）切西瓜时，流出的红汁水是__________，这些汁水主要来自图中的结构[]__________。（2）图中结构可以缓缓流动的部分是[]__-七年
• 阅读理解。 Children are children after all, and most of them speak their mind. When they are just toddler
• 阅读理解。 Strong earthquakes hit the east of Japan in the afternoon of March 11, causing several meter-h
• 阅读短文，根据回答问题。 November 24, 1859 was a special day in London. On that day, many Londoners rushed to a
• 阅读理解。 My summer hols wr CWOT. B4, we used 2 go 2 NY 2C my bro, his CF & thr 3:-@ kids FTF ILNY,i
• 阅读理解。 Rivers are one of our most important natural resources (自然资源). Many of the world's great