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
专升本
Tundra ecosystems are treeless regions found in the Arctic and on the tops of mountains, where the climate is cold and windy and
Tundra ecosystems are treeless regions found in the Arctic and on the tops of mountains, where the climate is cold and windy and
admin
2022-06-23
53
问题
Tundra ecosystems are treeless regions found in the Arctic and on the tops of mountains, where the climate is cold and windy and rainfall is low. Tundra lands are snow-covered for most of the year, until summer brings a burst of wild flowers.
The Arctic tundra, where the average temperature is rather low, supports a variety of animal species, including Arctic foxes, polar bears, Arctic wolves, caribou, snow geese and musk oxen. The summer growing season is just 50 to 60 days, when the sun shines 24 hours a day.
The few plants and animals that live in the harsh conditions of the tundra are essentially clinging to life. They are highly vulnerable to environmental stresses like reduced snow cover and warmer temperatures brought on by global warming.
The Arctic tundra is changing dramatically due to global warming. Already, more southern animals like the red fox have moved onto the tundra. The red fox is now competing with the Arctic fox for food and territory.
Another major concern is that the melting of the permafrost (永冻土层) is contributing to global warming. Estimates suggest that about 14 percent of the Earth’s carbon is tied up in the permafrost. Until recently, the tundra acted as a carbon sink and captured huge amounts of carbon dioxide from the atmosphere as part of photosynthesis(光合作用). This process helped keep the amount of this greenhouse gas from accumulating in the atmosphere. Today, however, as the permafrost melts and dead plant material rots(腐烂) and releases CO
2
, the tundra has changed from a carbon sink to a carbon contributor.
The tundra used to be a carbon sink because ________.
选项
A、it supported a variety of animal species
B、it captured huge amounts of carbon dioxide from the atmosphere
C、the temperature was extremely low there
D、the tundra ecosystems were treeless regions
答案
B
解析
根据最后一段第三句“…the tundra acted as a carbon sink and captured huge amounts of carbon dioxide from the atmosphere…”可知,苔原在过去充当着碳汇的作用,从大气中捕获大量的二氧化碳。故选B。
转载请注明原文地址:https://kaotiyun.com/show/TtQD777K
本试题收录于:
英语题库普高专升本分类
0
英语
普高专升本
相关试题推荐
Manyayoungpersontellsmehewantstobeawriter,Ialwaysencouragesuchpeople,butIalsoexplainthatthere’sabigdiff
Thisarticle________moreattentiontotheproblemofculturalinterferenceinforeignlanguageteachingandlearning
Thereissomuchmoremeaningtoamessagethanwhatexistsinthespokenorwrittenwords.Forexample,ifapersonsays,"you
Toourgreatsurprise,Mr.Bakerhasquicklyrecoveredfromhis________illness.
Howcanwegetridofgarbage?Dowehaveenoughenergysourcestomeetourfutureenergyneeds?Thesearetwoimportantquestio
TundraecosystemsaretreelessregionsfoundintheArcticandonthetopsofmountains,wheretheclimateiscoldandwindyand
Whatisyourfavoritecolor?Doyoulikeyellow,orange,orred?Ifyoudo,youmustbeanoptimist(乐观主义者),aleader,anactive
Pleasewaitamoment!I_______thefishfordinnernow,andIwillhelpyouafterthat.
________happenedintheArcticregionsoundslikeafairytale,butittrulyexists.
Itisnaturalthatatreewouldgrowbestinaclimatewithplentyofsunlightandrainfall.
随机试题
现阶段预防心绞痛发作常用的药物是
脑卒中患者偏瘫侧上肢多表现为
腰椎间盘突出症最容易发生的部位是
高中生钱某于1980年9月2日出生。1998年6月1日钱某在校将同学李某打伤,致其花去医药费2000元。钱某毕业后进入一家炼钢厂工作。1999年2月,李某起诉要求钱某赔偿医药费。该民事责任应由谁承担?
下列情形中,可以享受免征土地增值税税收优惠政策的是()。
公安机关的刑事执法权的内容包括()。
理想的行政组织建立在下述哪种权威基础上?
根据刑法规定,盗窃信用卡并使用的,构成()。
Whichofthefollowingisnotawordwithaprefix?
Whichcompanyorganizedthemeeting?
最新回复
(
0
)