首页
登录
职称英语
About fifty years ago, plant physiologists set out to grow roots by themselv
About fifty years ago, plant physiologists set out to grow roots by themselv
游客
2024-01-02
40
管理
问题
About fifty years ago, plant physiologists set out to grow roots by themselves in solutions in laboratory flasks. The scientists found that the nutrition of isolated roots was quite simple. They required sugar and the usual minerals and vitamins. However, they did not require organic nitrogen compounds. These roots got along fine on mineral inorganic nitrogen. Roots are capable of making their own proteins and other organic compounds. These activities by roots require energy, of course: The process of respiration uses sugar to make the high energy compound ATP, which drives the biochemical reactions. Respiration also requires oxygen. Highly active roots require a good deal of oxygen.
The study of isolated roots has provided an understanding of the relationship between shoots and roots in intact plants. The leaves of the shoots provide the roots with sugar and vitamins, and the roots provide the shoots with water and minerals. In addition, roots can provide the shoots with organic nitrogen compounds. This comes in handy for the growth of buds in the early spring when leaves are not yet functioning. Once leaves begin photosynthesizing, they produce protein, but only mature leaves can "export" protein to the rest of the plant in the form of amino acids. [br] The use of the phrase "comes in handy" underlined in Paragraph 2 indicates that the process is ______
选项
A、unavoidable
B、predictable
C、necessary
D、successful
答案
C
解析
见第二段第四句:This comes in handy for the growth of buds in the early spring when leaves are not yet functioning.这对于芽(蓓蕾)在早春的生长很是必要,因为叶在那时还没有起作用。所以comes in handy应表“必要”,所以选项 C为答案。
转载请注明原文地址:https://www.tihaiku.com/zcyy/3325999.html
相关试题推荐
Astronautsreceive(extensive)trainingtoprepare(themselves)(both)physicall
Fromcolonialtimes,UnitedStatespropertyownersagreedtotaxthemselvesont
Somepeoplethinkthattheycanlearnbetterbythemselvesthanwithateach
Somepeopleprefertoworkforthemselvesorownabusiness.Othersprefertowo
Sincetheexecutiveteamsofbothfirmshavecommittedthemselvestothedeal,t
Aboutfiftyyearsago,plantphysiologistssetouttogrowrootsbythemselv
Aboutfiftyyearsago,plantphysiologistssetouttogrowrootsbythemselv
Aboutfiftyyearsago,plantphysiologistssetouttogrowrootsbythemselv
Aboutfiftyyearsago,plantphysiologistssetouttogrowrootsbythemselv
Aboutfiftyyearsago,plantphysiologistssetouttogrowrootsbythemselv
随机试题
Theyoungmangetssopopularwithhiscolleaguesthatevenhisinanitiesareco
[originaltext]M:Goodmorning!HowcanIhelpyou?W:Goodmorning.[1]I’dlike
Theartististhecreatorofbeautifulthings.Torevealartand【C1】____
Followingrepeateddelays,onNovember19ththeIMFfinallyapproveda$2.1
CampusCrimeWeoftenthinkofagricultureaspl
小学体育《双摇跳》 一、考题回顾 二、考题解析 【教学过程】
内服具有去祛痰平喘,截虐之功的药物是A.炉甘石 B.升药 C.硼砂 D.砒
据对一批企业的调查显示,这些企业总经理的平均年龄是57岁,而在20年前,同样的这
(2017年真题)关于交易所上市基金的特征,下列说法不正确的是()。A.它
以下( )属于期货交易所履行职责引起的商事案件。A.期货交易所会员及其相关人员、
最新回复
(
0
)