请将下列结构名称与其相应功能用线条连接起来： ①细胞膜A利用_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题解答题

请将下列结构名称与其相应功能用线条连接起来：

①细胞膜 A利用无机物合成有机物

②叶绿体 B控制细胞内外物质的进出

③染色体 C与呼吸作用有关

④线粒体 D保护作用

⑤叶的表皮 E细胞核中含有DNA的结构．

答案

植物细胞的结构包括细胞壁、细胞膜、细胞质、细胞核、液泡、叶绿体、线粒体．不同的结构具有不同的功能．其中细胞壁的功能是保护和支持细胞的作用，维持细胞的正常形态；细胞膜的功能是控制物质的进出，使有用的物质不能轻易地渗出细胞，有害的物质不能轻易地进入细胞；细胞质能不断的流动，它的流动加速了细胞与外界之间的物质交换；细胞核内含有遗传物质DNA，染色体由DNA和蛋白质组成，能传递遗传信息；细胞中的能量转换器有叶绿体和线粒体．叶绿体是植物细胞进行光合作用的场所，利用无机物合成有机物．线粒体是广泛存在于动物细胞和植物细胞中的细胞器，是细胞呼吸产生能量的主要场所，被称为能量转换器和细胞内能量供应的“动力工厂”，是细胞进行呼吸作用的场所．叶的表皮，无色透明具有保护作用．

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单项选择题

甲、乙公司于2001年11月1日签订了一份买卖合同，合同约定一旦乙收回其应收账款，立即给甲的银行账户汇款，并约定如果1个月内不能履行，则合同失效。2001年11月14日；乙的银行账户上收到了10万元的应收账款，乙于当日即向甲汇款，履行了合同。根据《合同法》的规定；甲、乙公司的买卖合同的生效日期为（）。

A．11月1日

B．11月14日

C．12月1日

D．12月14日

填空题

[A] Possible ways to keep free from Alzheimer’s
[B] Deficiency of data-collecting in the study
[C] The new findings of ineffectiveness of past cures
[D] Weak evidence of the research
[E] How the new analysis coming from
[F] Future direction of the research concerned
[G] Traditional beliefs in preventive measures

Lifestyle May Not Prevent Alzheimer’s

A comprehensive analysis by an independent government panel has found that there is not enough scientific evidence to date to support the advice doctors currently give—such as exercising, doing crossword puzzles or eating a Mediterranean-style diet—for preventing or controlling symptoms of Alzheimer’s disease and dementia.
(41)______
As rates of age-related dementia and Alzheimer’s disease have continued to rise in the U.S.—largely because Americans are living longer and the over-65 population has swelled to record highs—researchers have worked relentlessly to understand the causes of these mind- robbing diseases and to help prevent or slow their progression. To clarify the state of the current evidence and offer physicians clearer treatment guidelines, the National Institutes of Health (NIH) in early 2009 commissioned a detailed analysis of existing studies, covering 165 papers published between 1984 and 2009.
(42)______
For years, the prevailing hypothesis has been "Use it or lose it" when it comes to avoiding gradual age-related mental decline. Data has associated behaviors such as keeping the mind actively engaged throughout life, staying physically active, eating certain foods and supplementing the diet with specific vitamins and nutrients with lower rates of dementia in old age. These lifestyle factors appeared to limit cognitive decline of various kinds, from occasional "senior moments" to the more serious episodes of cognitive impairment that can be a prelude to Alzheimer’s disease.
(43)______
Now researchers at Duke University report in the current issue of the Annals of Internal Medicine that the data on the preventive effects of lifestyle factors is not as p as they had thought. Led by Brenda Plassman, a professor of psychiatry and behavioral sciences, the study authors analyzed decades’ worth of research, including observational studies in which scientists looked retrospectively at a group of participants to tease out associations between certain behaviors (like exercise) and selected effects (like scores on tests of memory and cognitive skills), as well as the more definitive clinical trials that randomly assign volunteers to intervention or control groups and then assess how the intervention affects cognitive ability.
(44)______
Overall, the researchers say they were dismayed with the paucity and weakness of the existing evidence. "When we applied rigorous but consistent standards to review all the studies, we found that there was not sufficient evidence to recommend any single activity or factor that was protective of cognitive decline later in life, " says Plassman.
(45)______
However weakly, though, the review did support what doctors know about risk factors for cognitive decline: smoking, diabetes, depression, metabolic syndrome and specific gene variants were all linked with increased risk of developing Alzheimer’s disease. In addition, preventive behaviors such as eating a Mediterranean diet, exercising, maintaining cognitive engagement (doing puzzles, learning new things) and fostering extensive social relationships were linked to a lower risk.
The problem is that none of these relationships were particularly robust, the authors say. And none were p enough to justify recommending the behaviors to people who want to prevent or slow down the onset of dementia. The findings led the NIH to issue Monday’s state-of-the-science statement, in which the agency notes, "Currently, firm conclusions cannot be drawn about the association of any modifiable risk factor with cognitive decline or Alzheimer’s disease." Although the statement does not constitute an official policy or government recommendation, it serves as a guideline for doctors advising patients about the best evidence on the role of lifestyle factors in Alzheimer’s prevention.