篇一：大自然中的语文
大自然中的语文
我没想到我竟如此鲁莽，和妈妈吵了一架独自瞪上自行车一气之下不知走了多远。停下来双脚着地，大喘了半天。耳边不时还想起跑出门时，妈妈说的那番话：“兰兰啊！还是选择英语吧！中考能加分呢！语文，就当是一项爱好行吗？”
越想我越是心烦，索性不要想了。顷刻间，一抬头，啊！好美的景色。我看呆了。
于是，把车子停在一边，坐在草坪上，望着湖中的水。湖水是绿色的，因为没有一丝风，湖显得十分平静，宛如一面镜子。湖上的游船激起地一圈圈涟漪慢慢地向四周扩散开来，好美丽！
在湖的不远处有一片树林。我漫步在树林里，婉转的鸟鸣仿佛天籁之音一般在心中激起一圈圈涟漪。也许是盛夏的缘故吧！花儿都显得十分有精神地站在那献媚，伴着青草绿树的搭配，花儿显得更加娇艳了。
走了不知多久，又回到了原点，累的躺在了绿油油的草地上。草很软，很软。仿佛是世界上最软的棉花做的，使我感到十分惬意。
躺在草地上，过了很久才睁开眼睛，天是那么蓝，好像被洗过一般，纯纯的，毫无肮脏之处。云白白的，好像前几天吃的棉花糖一般。轻轻的，薄薄的好像一阵风就能把它们吹跑掉。鸟儿们不时在天空飞过，来展示它们的英姿。此时，惬意的躺在草地上，心情已经恢复过来了，才明白大自然如同一名老师在教导着我们语文。此时，灵感特好，把所看见的都写在了脑子里。蹬上自行车，飞快地骑着。夕阳拉长了我的影子。
谁能说大自然中没有语文呢？
篇二：大自然中的生物
(j)
A cell cycle checkpoint has been identified in this phase.
2. 同一个体不同组织的细胞中, 核仁的大小和数目都有很大的变化, 这种变化和细胞中蛋白质合成的旺盛程度有关。( )
3. 将同步生长的M期细胞与同步生长的S期细胞融合,除了见到正常的染色体外,还可见到细线状的染色体。( )
4. 在有丝分裂后期，通过对周期蛋白的遍在蛋白多聚化，介导周期蛋白被蛋白酶体降解，从而退出M期。( )
5. 核纤层是由核纤层蛋白A、核纤层蛋白B和核纤层蛋白C构成的，其中只有核纤层蛋白
A与内核膜相连，核纤层蛋白B和C则与染色质相连。( )
6. 在细胞周期中，如果纺锤体装配不正常，则被阻止G2期。
7. 结合有核糖体的内质网被称为粗面内质网，脱去核糖体的内质网则称为光面内 质网。( )
8. 同源异型框是一类同源异型基因表达产物中60个氨基酸的保守序列, 它的突变 可以改变发育的方向。( )
9. 叶绿体的核酮糖二磷酸羧化酶是由16个亚基组成的聚合体, 其中8个大亚基是核基因编码的。( )
10. 有丝分裂器中有三种类型的纺锤体微管，其中星微管的可能作用是给核分裂传 递信号。（ ）
11. 在减数分裂过程中,染色体间发生的分子重组是随机发生的。( )
三、选择题(请将正确答案的代号填入括号，每题1分，共15分)
1. Ethyl alcohol is detoxified in the liver. You would expect alcohol to have which of the following effects on liver cells? （ ）
a. Nuclear degeneration
b. Growth of the smooth ER
c. Increased lysosomes
d. Growth of rough ER
e. None of the above
2. Which of the following proteins would not be found in the smooth
endoplasmic reticulum?（ ）
a. Ca2+-pumping enzymes
b. cytochrome P450
c. glucose 6-phosphatase
d. signal peptidase
3. Which of the following explains why microsomes can't be seen in cells viewed with the electron microscope?（ ）
a. They are far too small.
b. They are artifacts of homogenization and centrifugation.
c. They are transparent to electrons.
d. They actually can be seen in electron micrographs of cells.
4. If you compared the proteins in a cis Golgi compartment with those in a trans Golgi compartment, you would find:（ ）
a. the proteins in the two compartments are identical.
b. the proteins in the cis compartment are glycosylated and contain
modified amino acids, whereas those in the trans compartment are not modified.
c. the proteins in the cis compartment are glycosylated, whereas those in the trans compartment are glycosylated and contain modified amino acids.
d. the proteins of the cis compartment are shorter than those of the trans compartment.
5. Which type of vesicle of the trans Golgi network would be most likely to carry hormones destined for regulated secretion?（ ）
a. lysosomal vesicles
b. clathrin-coated vesicles
c. non-clathrin-coated vesicles
d. all of the above
6. If you treated cells with a drug that interferes with microtubules, such as colchicine, which of the following would result?（ ）
a. Cell shape would be disrupted.
b. Mitosis and meiosis would not occur.
c. The intracellular location of organelles would be disrupted.
d. All of the above would result.
7. First you dissolve the membrane from an intact flagellum, using the detergent Triton X-100. Next you soak the axoneme in a solution containing EDTA, which removes the Mg2+. What remains of the axoneme after these treatments?（ ）
peripheral tubules only
b. peripheral tubules and central tubules, but no side arms or ATPase activity
c. peripheral tubules, central tubules, side arms, and ATPase activity
d. peripheral tubules, central tubules, side arms, ATPase activity, and a Membrane
8. The sarcoplasmic reticulum must have integral membrane proteins that can:
a. release and pump Ca2+.（ ）
b. bind to tropomyosin and troponin.
c. undergo action potentials.
d. contract.
When chromatin is treated with nonspecific nucleases, what is the length of the
reulting pieces of DNA?
a. random numbers of base pairs
b. about 60 base pairs
c. about 8 base pairs
d. about 200 base pairs
10. What do telomeres do?（ ）
a. They protect the chromsomes from degradation by nucleases.
b. They prevent the ends of chromosomes from fusing with one another.
c. They are required for complete chromosomal replication.
d. all of the above
11. Cyclin concentrations are highest during which periods of the cell cycle?（ ）
a. late G1 and early S
b. late G2 and early M
c. late G1 and late G2
d. late M and late S
ARF是一种单体G蛋白, 它有一个GTP/GDP结合位点, 当结合有GDP时, 没
有活性。若ARF-GDP同( )结合, 可引起GDP和GTP的交换。
a.GTPase; b.GTP酶激活蛋白;
c.Ca2+-ATPase d.鸟嘌呤核苷释放蛋白。
13. 用剧烈方法分离到的叶绿体是Ⅱ型叶绿体，不能( ) 。
a. 产生O2 b.不能合成ATP
c. 不能产生NADPH d.不能固定CO2
14. 细胞的生长和分化在本质上是不同的, 生长是细胞数量的增加、干重
的增加；而细胞分化则是: ( )
a. 形态结构发生变化; b. 生理功能发生变化;
c. 生化特征发生变化; d. 以上都是正确的。
15. 真核生物的基因表达调控发生在四个水平上。通过对DNA的甲基化来关闭基因的调控则是属于( )。
a. 染色质活性水平的调控；b. 转录水平调控；
c. 转录后加工水平的调控；d. 翻译水平的调控。
四、简答题(选做4题，每题5分，20分)
1. How does regulated secretion differ from constitutive secretion?
2. Dynamic instability causes microtubules either to grow or to shrink rapidly. Consider an individual micro-tubule that is in its shrinking phase. What would happen if the solution contained an analogue of GTP that cannot be hydrolyzed?
3. State the conclusion that can be drawn from the following finding:
When an animal cell is treated with colchicine, its microtubules depolymerize and virtually disappear. If the colchicine is then washed away, the MTs appear again, beginning at the centrosome and elongating outward at about the rate (1 gm/min) at which tubulin polymerizes in vitro.
4. 什么是蛋白质N-连接糖基化和O-连接糖基化？发生在何种部位？
5. 过氧化物酶体是怎样进行氧浓度调节的?有什么意义?
五、计算与推理(第1题必做，2、3选一题，每题5分，共10分)
1. In an electron micrograph of a human chromosome spread, you observe a thick fiber with a length of about 900 nm and an apparent diameter of 30 nm, which is expected
for the solenoid structure of condensed chromatin.
What is the length in base pairs of the double-helical DNA present in this fiber? Assume, for simplicity, that there is one helical turn of the solenoid per 30 nm along the fiber.
2. One of the functions of the mitotic Cdk (the MPF protein kinase) is to cause a precipitous drop in cyclin concentration halfway through M phase. Describe the consequences of this sudden
decrease and suggest possible mechanisms by which it might occur.
3. A protein that inhibits certain proteolytic enzymes (proteases) is normally secreted into the bloodstream by liver cells. This inhibitor protein, antitrypsin, is absent from the bloodstream of patients who carry a mutation that results in a single amino acid change in the protein. Antitrypsin deficiency lung tissue, because of the uncontrolled activity of proteases. Surprisingly, when the mutant antitrypsin is synthesized in the laboratory, it is as active as the normal antitrypsin at inhibiting proteases. Why then does the mutation cause the disease? Think of more than one possibility and suggest ways in which you could distinguish between them.
六、比较题（每题5分，共10分）
1. Compare and contrast the following:
cytoplasmic dynein vs. kinesin
2. 后期A与后期B
七、综合问答题(任选一题，20分)
1. 细胞内蛋白质有那些分选途径？各自的机理如何？
2. 比较裂殖酵母、芽殖酵母和哺乳动物细胞周期调控的异同。
八、附加题（每题5分，共15分）
1. State the conclusion that can be drawn from the following finding:
Extracts from nondividing frog eggs in the G2 phase of the cell cycle
were found to contain structures that could induce the polymerization
of tubulin into microtubules in vitro. When examined by immunostaining,
these structures were shown to contain pericentrin（中心粒旁侧蛋白）.
2. The signal recognition particle (SKP)) is involved in regulating the elongation of nascent secretory proteins and targeting them to the endoplasmic reticulum. Describe an experiment in which these functions of SRP have been demonstrated.
3. Dephosphorylation is an important event that affects cellular structures during mitosis. Describe two of these events.
试题四参考答案
篇三：我是大自然中的一员
我是大自然中的一员
学校：嘎囡完小 班级：六（1）班 作者：玉金旺 指导教师：余永林
我是大自然中的一员，我就是草原上不起眼的一颗蒲公英，但我很自由，也很快乐快。
春天，我还躺在草原妈妈的怀里做着美梦，突然，一阵“沙沙沙”的声音把我吵醒了。我睁开曚昽的睡眼，隐隐约约听见了一群小孩子正在谈话，其中一个穿着花裙子的小女孩说：“看啊！这里真美啊！”我想：“她那样庞大，会不会踩到我？”这时草原妈妈好像看出了我的心思，说：“孩子，你不用担心，我相信他们不会伤害你的。”我对这句话半信半疑，那一个小女孩突然出现在我的眼前，说到：“是蒲公英，好漂亮！”我很紧张。但我发现他们好像没有恶意。她那笑容，像彩虹一样灿烂。
她用她那温暖的手捧起我，轻轻一吹，我乘着妈妈给我准备的降落伞，慢慢地，慢慢地，我飞向了天空。我真的飞起来了，想去哪里就去哪里。在我飞行的途中，我看到了许多我从不没看到的好风景。 我俯身凝望着大地，大地上盛开着漂亮的花儿，风中传来美妙的乐曲，空气中弥漫着芬芳清香的气味。
我乘着降落伞，自由地飞翔，心中满是快乐。我不断的前行，一路看，一路听，一路享受。
如果没有那位小姑娘，就没有我现在的自由、快乐和幸福。原来，人与自然和谐相处，是如此的妙不可言。
教师点评：
小作者在习作中能把自己当成大自然中的一员——蒲公英，与大自然进行对话，并在恰当的地方展合理的开联想与想像，并融入自己的感受，用比喻、拟人等多种修辞手法表达出自己的独特感受，结尾与前文相照应，是真篇文章浑然一体。
《
大自然中的好妈妈》
由：
建材加盟网互联网用户整理提供,链接地址：
http://m.yuan0.cn/a/21547.html
转载请保留,谢谢!