首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
You will listen to part of a lecture and answer a question about it. After you hear t question, you will have 20 seconds to prep
You will listen to part of a lecture and answer a question about it. After you hear t question, you will have 20 seconds to prep
admin
2022-05-28
2
问题
You will listen to part of a lecture and answer a question about it. After you hear t question, you will have 20 seconds to prepare a response and 60 seconds to record the response.
Now listen to part of a lecture in a biology class.
Using points and examples from the lecture, describe two functions of aerial roots.
Now listen to part of a lecture in a biology class.
Roots are not always underground. When they arise from the stem and either pass for some distance through the air before reaching the soil or remain hanging in the air, they are called aerial roots. Simply put, aerial roots are roots that grow on the aboveground parts of a plant. Aerial roots serve several functions for a plant. But today, we will first look at two examples to better understand this phenomenon.
One function of aerial roots is support. A good example of this is the maize plant, also commonly known as corn. The maize root system is fibrous and shallow, meaning that the roots are weak and do not go deep into the ground. The underground root system cannot adequately support the tall plant. The maize plant compensates for this inadequacy by growing aerial roots from the lower stem segment to prop up the plant. These aerial roots go down in the soil and further branch out, giving the plant the additional support it requires. The supportive aerial roots protect the maize plant from high winds so that it doesn’t not get blown away.
A second function of aerial roots is to absorb moisture and nutrients, just like underground roots. Plants that live in marshes and bogs have underground roots, but these roots can’t absorb gases from the air because they are constantly underwater or submerged during high tide. An example of this is mangrove trees, which use aerial roots for aeration and not water absorption. Mangrove trees are found in swamps and bogs, which are wet environments affected by tidal patterns. Mangrove trees produce aboveground roots to help them with air exchange, absorbing, converting, and storing nutrients crucial to the development and survival of the trees.
选项
答案
Aerial roots are aboveground roots arising from the stem. They can either extend for some distance through the air before reaching the soil or remain hanging in the air. Two major functions of aerial roots are to support and to absorb essential moisture and nutrients. One example of its support function is corn. The root system of corn is too shallow underground to support the tall plant. So aerial roots grow from the lower stem and sustain the plant. The second function can be showed by mangrove trees. Like other swamp plants, the roots of mangrove trees are always underwater during high tide. The trees, therefore, produce aboveground roots to take in air and help with air exchange. In this way, they can absorb, convert and store nutrients necessary for its growth.
解析
转载请注明原文地址:https://kaotiyun.com/show/IOfO777K
0
托福(TOEFL)
相关试题推荐
Whatadvantagedoesthespeakermentionforeachofthefollowingphysicalactivities?ChooseSIXanswersfromtheboxandwrite
Whatadvantagedoesthespeakermentionforeachofthefollowingphysicalactivities?ChooseSIXanswersfromtheboxandwrite
Completethenotesbelow.WriteONEWORDONLYforeachanswer.EffectsofurbanenvironmentsonanimalsIntroductionRecenturba
Labelthemapbelow.Writethecorrectletter,A-l,nexttoQuestions14-20.Widenedpavement______
WhatinformationdoesAnniegiveaboutskiingoneachofthefollowingmountaintrails?ChooseFOURanswersfromtheboxandwri
WhatcommentsdothespeakersmakeabouteachofthefollowingaspectsofRuss’spreviouspresentation?ChooseFIVEanswersfrom
Labelthemapbelow.WritethecorrectletterA-H,nexttoQuestions11-15.NorthPoint
ChooseFOURletters,A-G.WhichFOURofthefollowingarerequiredofstudentteachers?AweeklyjournalBsamplelessonplansC
ChooseFOURletters,A-G.WhichFOURofthefollowingarerequiredofstudentteachers?AweeklyjournalBsamplelessonplansC
随机试题
关于书刊的左翻本形态,说法正确的是()。
某女丁某,6岁8个月。主诉下前牙长出"双层牙",求治。
在票据签发前,出票人与付款人之间必须先有资金关系的票据是指()。
我国古代荀子曾说过:“法不能独立,类不能自行,得其人则存,失其人则亡。”说明了下列哪个道理?
关于法律规则、法律条文与语言的表述,下列哪些选项是正确的?(2010年卷一51题)
场景某施工单位中标,承担了某段公路的路面工程,决定全面采用水泥混凝土对路面进行铺设整修。考虑到有些地段的道路岩石较多、湿度较大,抗压力较弱等因素,于是施工负责人又进行了路面基层、面层、垫层等的设置工作。根据场景,回答下列问题。在温度和湿度状况不良的
小李在某设区精神疾病康复日托中心开展社会工作服务,通过探讨和观察,小李发现精神疾病患者的家属对患者理解不够,无法提供有效照顾。为此,家属对患者的病情反复感到无能为力,备感压力。为此,小李计划为患者家属提供专业服务,其服务内容应包括()。
学校的出现是教育相对独立形态开始的标志。()
教育行动研究是一个螺旋式加深的过程,其最后一个环节是()
民警小王、小李驾车巡逻时,接到110指挥中心指令前往长江路某店面火警现场进行处置,在赶赴现场途中,两位民警必须要做的工作是:
最新回复
(
0
)