首页
登录
职称英语
It has been known since ancient times that certain plants regularly open the
It has been known since ancient times that certain plants regularly open the
游客
2024-06-05
8
管理
问题
It has been known since ancient times that certain plants regularly open their leaves in daytime and close them at night. It was assumed this periodic change was triggered by the alternating sunlight and darkness. It was then discovered that such leaves stick to their daily routine even when kept in constant darkness.
What is a circadian rhythm? Many biological processes follow a 24-hour schedule. These cycles are called circadian rhythms. These innate rhythms are governed by sophisticated chemical mechanisms which can be described as biological clocks. Such rhythms are important for humans too! We sleep through most of the hours of darkness and awake through most of the hours of daylight. Pulse rate and blood pressure rise sharply on awakening. Body temperature increases during the day and decreases during the night. The secretion (分泌) of various hormones (激素) that control life’s processes rises and falls to a circadian rhythm.
How does this relate to health? Circadian rhythms are important for optimal functioning of the many processes vital to health. This is most effectively illustrated when the normal circadian rhythms are disrupted by lack of sleep or by crossing time zones. It may take days or even weeks for the circadian rhythms to readjust appropriately. The turmoil that results from the readjustment process when time zones are crossed is experienced as the phenomenon of jet lag. That is also experienced by people who do shift work.
Understanding circadian rhythms may be relevant to the understanding and treatment of disease. Therapy can be more effective and toxic effects reduced when drugs are administered at carefully selected times of the day—chronotherapy. A simple example of chronotherapy is the use of antihistamines (抗阻胺剂) and decongestants (解充血药) for the treatment of allergic symptoms. Cardiovascular disease (心血管疾病) is the single biggest killer of adults and is also influenced by circadian rhythms. The immediate cause of a heart problem is inadequate blood flow to the heart muscle. They may result in no symptoms, or it may cause angina (心绞痛), or, most severely, a heart attack may occur. It has been shown that heart attacks are much more common in the morning than at other times of the day. [br] According to the passage, what may cause the periodic change of certain plants?
选项
A、It is caused by intensity of sunlight.
B、It is decided by humans’ daily activities.
C、It is the result of chemical reactions by scientist.
D、It is up to the regular recycling of time.
答案
D
解析
细节题。根据文章第一和第二句,植物白天张开叶子,晚上闭合叶子。
转载请注明原文地址:https://tihaiku.com/zcyy/3620922.html
相关试题推荐
[originaltext]Ifyou’vebeenoncampusforverylong,I’mcertainthatyou’
[originaltext]Ifyou’vebeenoncampusforverylong,I’mcertainthatyou’
[audioFiles]audio_eusm_0113(20106)[/audioFiles]A、Movehisplantsawayfromthe
Mostgrowingplantscontainmuchmorewaterthanallothermaterialscombine
Mostgrowingplantscontainmuchmorewaterthanallothermaterialscombine
Mostgrowingplantscontainmuchmorewaterthanallothermaterialscombine
____________________(通过考试来竞争,其好处的点让人怀疑),butcompetitioninthecertainknowled
Certainspeciesdisappearedorbecameextinct___________________(是由于产生了新物种形式,它们可
Mostplantscanmaketheirownfoodfromsunlight,【C1】______somehavedisco
Mostplantscanmaketheirownfoodfromsunlight,【C1】______somehavedisco
随机试题
Accordingtothespeaker,"LoveThyNeighbor"shouldoriginallybe[br][origin
Duringsleep,thefatigueofthebodydisappearsandrecuperation(恢复)begin
A. B. C. D.
指数按其所反映的现象的性质不同,可分为( )。 A、总指数、个体指数 B
对基金信息披露质量的最低要求是()。 A.通俗性B.真实性C.时效性D
某商业银行的财务指标如下表所示(单位:亿元) 根据以上资料,回答下列问题:
按上下顺序排列的资产负债表格式是()。A.账户式 B.单步式 C.报告式
施工企业发放给职工的夏季防暑降温费的应从()列支。A.人工费用 B.材料费用
张力性气胸造成呼吸、循环障碍的机理是 A.胸壁软化,反常呼吸 B.肺组织挫伤
根据《建筑安装工程费用项目组成》(建标[2013]44号),按造价形成划分,属于
最新回复
(
0
)