- [材料题]
请阅读 Passage 2 ,完成第 26 ~ 30小题。
Passage 2
Most growing plants contain much more water than all other materials combined. C. R. Barnes hassuggested that it is as proper to term the plant a water structure as to call a house composed mainly of brick 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 rooL. They are carried Lo all parts of the growing plant and are built into essential plant materials while in a dissolved state. The carbon dioxide( C02 ) 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 t0 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 one time,however,is only a very small part of what passes through it during its development. The processes photosynthesis,by which carhon dioxide and water are combined-in the presence of chlorophyll and with energy derived from light-to form sugars,require thaL 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 minuLe openings,through which the carbon dioxide enters. The same structure that permits the one gas to enter the leaf,however,permits another gas-water vapm-to be lost from it. Since carbon dioxide is present in the air only in trace quantities(3 to4 parts in 10000 parts of air) and water vapor is near saturation in the air spaces within the leaf(at 80degree F,saturated air would contain about 186 parts of water vapor in 10000 parts of air) ,the total amount of water vapor lost is many times the carbon dioxide intake. Actually,because of wind and otherfactors,the loss of water in proportion to carbon dioxide intake may be even greater than the relativeconcentrations of the two gases. Also,not all of the carbon dioxide that enters the leaf is synthesizedinto carbohydrates.
- 多项选择题1.A growing plant needs water for all of the following expect .
A、 forming sugars
B、 sustaining woody stems
C、 keeping green
D、 producing carbon dioxidle
关注下方微信公众号,搜题查看答案
- 多项选择题2.The essential function of' photosynthesis in terms of plant needs is .
A、 to form sugars
B、 to derive energy from light
C、 to preserve water
D、 to combine carbon dioxide with water
关注下方微信公众号,搜题查看答案
- 多项选择题3.The second paragraph uses facts to develop the essential idea that .
A、 a plant efficiently utilizes most of che water it absorbs
B、 carbon dioxide is the essential substance needed for plant development
C、 a plant needs more water than is found in its composition
D、 the syronger Lhe wind,che more the water vapor loss
关注下方微信公众号,搜题查看答案
- 多项选择题4.According to the passage,which of the following statements is TRUE?
A、 The mineral elements will not be absorbed by the plant unless they are dissolved in its root,
B、 The woody stems contain more water than the leaves.
C、 Air existing around the leaf is found to be saturated.
D、 Only part of the carbon dioxide in the plant is synthesized.
关注下方微信公众号,搜题查看答案
- 多项选择题5.This passage is mairily about_____
A、 che functions of carbon dioxide and water
B、 the role of water in a growing plant
C、 the process of simple sugar formation
D、 the synthesis of water with carbon dioxide
关注下方微信公众号,搜题查看答案
- 造成牙釉质发育不全的病因不包括:A、婴幼
- 什么是急性瘙痒?
- 超声诊断左位上腔静脉的主要方法是A、二维
- 超声波在人体组织传播过程的声衰减与下列哪
- 茯苓四逆汤的药物组成A、茯苓、人参、附子
- 关于人绒毛膜促性腺激素的说法正确的是A、
- 医师注册后有下列情形之一的,应当注销注册
- 伤寒病人最严重的并发症是A、肠出血B、肠
- 简述我国重症肺炎病人的诊断标准。
- 滴虫性阴道炎患者阴道分泌物典型的特点是A
- 下列属于丙类传染病的是A、病毒性肝炎、痢
- 关于冠状动脉循环,叙述正确的有A、起源于
- 四岁患儿,发烧、头痛、皮疹12小时, 频
- 不表示第三人称的是( )A、"渠亦不自省
- 套细胞淋巴瘤的病理特点是什么?
- 针刺睛明穴时,下列操作中不可应用的是(
- X线诊断时应与临床相结合,故应考虑到患者
- 眩晕伴听力障碍常见于 ( 难度:4)
- 质量手册封面通常不包括的内容是( )。
- 据《灵枢·本神》所论,"因思而远慕谓之"