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
All mammals feed their young. Beluga whale mothers, for example, nurse their calves for some twenty months, until they are about
All mammals feed their young. Beluga whale mothers, for example, nurse their calves for some twenty months, until they are about
admin
2012-08-25
49
问题
All mammals feed their young. Beluga whale mothers, for example, nurse their calves for some twenty months, until they are about to give birth again and their young are able to find their own food. The behavior of feeding of the young is built into the reproductive system. It is a nonelective part of parental care and the defining feature of a mammal, the most important thing that mammals-- whether marsupials, platypuses, spiny anteaters, or placental mammals -- have in common.
But not all animal parents, even those that tend their offspring to the point of hatching or birth, feed their young. Most egg-guarding fish do not, for the simple reason that their young are so much smaller than the parents and eat food that is also much smaller than the food eaten by adults. In reptiles, the crocodile mother protects her young after they have hatched and takes them down to the water, where they will find food, but she does not actually feed them. Few insects feed their young after hatching, but some make other arrangement, provisioning their cells and nests with caterpillars and spiders that they have paralyzed with their venom and stored in a state of suspended animation so that their larvae might have a supply of fresh food when they hatch.
For animals other than mammals, then, feeding is not intrinsic to parental care. Animals add it to their reproductive strategies to give them an edge in their lifelong quest for descendants. The most vulnerable moment in any animal’s life is when it first finds itself completely on its own, when it must forage and fend for itself. Feeding postpones that moment until a young animal has grown to such a size that it is better able to cope. Young that are fed by their parents become nutritionally independent at a much greater fraction of their full adult size. And in the meantime those young are shielded against the vagaries of fluctuating of difficult-to-find supplies. Once a species does take the step of feeding its young, the young become totally dependent on the extra effort. If both parents are removed, the young generally do no survive.
The author lists various animals in line 5 to
选项
A、contrast the feeding habits of different types of mammals
B、describe the process by which mammals came to be defined
C、emphasize the point that every type of mammal feeds its own young
D、explain why a particular feature of mammals is nonelective
答案
C
解析
转载请注明原文地址:https://kaotiyun.com/show/LryO777K
0
托福(TOEFL)
相关试题推荐
Choosethecorrectletter,A,B,CorD.Writethecorrectletterinboxesonyouranswersheet.Accordingtothepassage,iti
Completethesummarybelow.ChooseNOMORETHANTHREEWORDSfromthepassageforeachanswer.Writeyouranswersinboxe
Answerthequestionsbelow.ChooseNOMORETHANTHREEWORDSAND/ORANUMBERfromthepassageforeachanswer.Writeyouranswers
DothefollowingstatementsagreewiththeinformationgiveninReadingPassage?Inboxes11-13onyouranswersheet,writeTRU
Answerthequestionsbelow.ChooseNOMORETHANTWOWORDSAND/ORANUMBERfromthepassageforeachanswer.Writeyouranswersi
Answerthequestionsbelow.ChooseNOMORETHANTWOWORDSAND/ORANUMBERfromthepassageforeachanswer.Writeyouranswersi
WhichmetalweretheCeltsusingatthebeginningofthefirstmillenniumB.C.?
Completetheformbelow.WriteNOMORETHANTHREEWORDSAND/ORANUMBERforeachanswer.ProductIncidentReportExampleAnswer
Completetheformbelow.WriteNOMORETHANTHREEWORDSAND/ORANUMBERforeachanswer.ProductIncidentReportExampleAnswer
随机试题
白术与苍术并用的方剂是()
TheDefinitionof"Price"Pricesdeterminehowresourcesaretobeused.Theyarealsothemeansbywhichproductsandservi
患者,女性,50岁。因右下肺脓肿抗生素治疗1个月余,疗效欠佳,确定病原菌最好做的检查是
患者,女,35岁。因左下后牙对冷热刺激敏感1周前来就诊。检查发现左下第一磨牙面深龋洞,探诊洞底感酸痛,冷测反应一过性敏感,叩痛(-)。牙龈无异常。该患牙的诊断是
女孩,2岁。发热伴咳嗽、咳痰4天。查体:T38.8℃,P132次/分,R42次/分,轻度鼻翼扇动,双肺闻及中细湿啰音,腹稍胀,肝肋下2cm。胸部X线片见双下肺片状模糊影。实验室检查,血WBC13.5×109/L,N0.72,L0.28。治疗
A.乙胺嘧啶B.青霉素C.特布他林D.红霉素E.甲硝唑选择性β2受体激动药是
内部收益率的计算有两种特别的形式:按货币加权的收益率和按时间加权的收益率,按照时间加权的收益率的计算过程中需要( )。
A、 B、 C、 D、 D本题考核的是图形的叠加规律。第一套图中图形的规律为:第三个图形是由第一个图形旋转180度之后与第二个图形叠加而成。第二套图也遵循这个规律,因此本题只有D项相符合。
某高校拟全面进行无线校园建设,要求实现室内外无线网络全覆盖,可以通过无线网访问所有校内资源,非本校师生不允许自由接入。在室外无线网络建设过程中,宜采用的供电方式是(56)________。本校师生接入无线网络的设备IP分配方式宜采用(57)________
A、Thebusinesssectorprovidesinvestmentthroughpricing.B、Theprivatesectorisincentivizedtoinvestineconomicinfrastruc
最新回复
(
0
)