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
37
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] According to the passage, which of the following statements is TRUE?
选项
A、The mineral elements will not be absorbed by the plant unless they are dissolved in its root.
B、The stems contain more water than the leaves.
C、Air around the leaf is found to be saturated.
D、Part of the carbon dioxide in the plants is synthesized.
答案
D
解析
仔细阅读第三段中作者所提供的数据和第二段中"Also, not all of the carbon dioxide that enters the leaf is synthesized into carbohydrates (碳水化合物) "的内容。
转载请注明原文地址:https://tihaiku.com/zcyy/2982226.html
相关试题推荐
Mostgrowingplantscontainmuchmorewaterthanallothermaterialscombine
Mostgrowingplantscontainmuchmorewaterthanallothermaterialscombine
Mostgrowingplantscontainmuchmorewaterthanallothermaterialscombine
[originaltext]Aftertwodecadesofgrowingstudentenrollmentsandeconomic
Nowadays,wehearalotaboutthegrowingthreatofglobalisation,accompani
Nowadays,wehearalotaboutthegrowingthreatofglobalisation,accompani
Nowadays,wehearalotaboutthegrowingthreatofglobalisation,accompani
Nowadays,wehearalotaboutthegrowingthreatofglobalisation,accompani
Nowadays,wehearalotaboutthegrowingthreatofglobalisation,accompani
[originaltext]W:I’vejustpreparedrelevantpresentationmaterialsoftheWint
随机试题
下面你将听到的是一段有关旅游的讲话。旅游是一项集观光、娱乐、健身为一体的愉快而美好的活动。旅游业随着时代进步而不断进步。从20世纪中期起,现代旅游业在
PartyTimeAmericansplanparties【T1】______.Asinothercultures,many
Wethinkit,possible__________thelocalgovernmentwillbeabletosolvetheho
TheAbortionClinicShootings:Why?A)Asthenationheardwith
TheCoolestClubAround EverySunda
2012年1-4月,该市平均每天观看电影的观众超过10万人次的月份有几个?
A. B. C. D.
很久以前,在法国土豆被称为“鬼苹果”,农民们都不愿意引种。一位农学家想出一个方法
期货从业人员在向投资者提供服务前,应当()地告知投资者期货投资的特点以及在期货
选磨方法中,错误的有A.一般先磨改正中验的早接触区,不轻易磨改功能牙尖 B.侧
最新回复
(
0
)