首页
登录
职称英语
Most growing plants contain much more water than all other materials combine
Most growing plants contain much more water than all other materials combine
游客
2023-09-03
23
管理
问题
Most growing plants contain much more water than all other materials combined. C. R. Darnes has suggested that it is as proper to term the plant a water structure as to call a house composed mainly of bricks a brick building. Certain it is that all essential processes of plant growth and development occur in water. The mineral elements from the soil that are usable by the plant must be dissolved in the soil solution before they can be taken into the root. They are carried to all parts of the growing plant and are built into essential plant materials while in a dissolved state.’ The carbon dioxide from the air may enter the leaf as a gas but is dissolved in water in the leaf before it is combined with a part of the water to form simple sugars—the base material from which the plant body is mainly built. Actively growing plant parts are generally 75 to 90 percent water. Structural parts of plants, such as woody stems no longer actively growing, may have much less water than growing tissues.
The actual amount of water in the plant at any one time, however, is only a very small part of what passes through it during its development. The processes of photosynthesis, by which carbon dioxide and water are combined—in the presence of chlorophyll (叶绿素) and with energy derived from light to form sugars, require that carbon dioxide from the air enter the plant. This occurs mainly in the leaves. The leaf surface is not solid but contains great numbers of minute (细小的) openings, through which the carbon dioxide enters. The same structure that permits the one gas to enter the leaf, however, permits another gas—water vapor to be lost from it. Since carbon dioxide is present in the air only in trace quantities (3 to 4 parts in 10, 000 parts of air) and water vapor is near saturation in the air spaces within the leaf (at 80 F , saturated air would contain about 186 parts of water vapor in 10,000 parts of air), the total amount of water vapor lost is many times the carbon dioxide intake. Actually, because of wind and other factors, the loss of water in proportion to carbon dioxide intake may be even greater than the relative concentrations of the two gases. Also, not all of the carbon dioxide that enters the leaf is synthesized into carbohydrates(碳水化合物). [br] A growing plant needs water for all of the following except ______.
选项
A、forming simple sugars
B、keeping woody stems
C、keeping green
D、producing carbon dioxide
答案
D
解析
根据第一段中的相关内容"The carbon dioxide from the air may enter the leaf as a gas but is dissolved in water in the leaf before it is combined with a part of the water to form simple sugars—the base material from which the plant body is mainly built. Actively growin
转载请注明原文地址:https://tihaiku.com/zcyy/2982223.html
相关试题推荐
Whatheisreadingisaquarterlycontaining_________ofdoctoralthesesinpro
Plants,oncethrivedonbothpoles,arebecomingalmost_________fortheharsh
Schoolslookingtobancellphonesmayhaveanewexcuse:agrowingnumbero
Schoolslookingtobancellphonesmayhaveanewexcuse:agrowingnumbero
Schoolslookingtobancellphonesmayhaveanewexcuse:agrowingnumbero
Schoolslookingtobancellphonesmayhaveanewexcuse:agrowingnumbero
Schoolslookingtobancellphonesmayhaveanewexcuse:agrowingnumbero
Schoolslookingtobancellphonesmayhaveanewexcuse:agrowingnumbero
[originaltext]M:Imagininggrowingupandneverknowingthatyouhadasistera
[originaltext]M:Imagininggrowingupandneverknowingthatyouhadasistera
随机试题
Agreenandyellowparrot,whichhunginacageoutsidethedoor,keptrepea
TheTruthabouttheEnvironmentA)Formanyenvironmentalists
廉洁从教是指教师要坚持(),发扬(),自觉抵制社会不良风气的影响,绝不利用职
下列非露天的50m长的钢筋混凝土结构,宜设置伸缩缝的是( )。A.现浇框架结构
生命伦理学的基本原则有()A.尊重人 B.有益 C.不伤害 D.
设计任务:请阅读下面学生信息和语言素材,设计20分钟的英语听力教学方案。 教案
根据《婚姻登记条例》《民法典》规定,以下说法正确的是()。A.协议离婚登记
我国中央银行公布的贷款基准利率是市场利率。()
工程质量检测单位的质量责任和义务中档案管理制度中,需要按年度统一编号的有()。
与传统融资方式相比较,项目融资的特点是()。A.风险种类少 B.前期工作量较
最新回复
(
0
)