时间:2018-12-24 作者:英语课 分类:Scientific American(一)月


英语课

This is Scientific American’s 60-Second Science. I’m Karen Hopkin. This will just take a minute.


Every expecting mother gets asked the question: boy or girl? For mammals like us, it’s an easy call. Two X chromosomes 1 you get pink booties. X and a Y you get blue. But for some reptiles 2, the answer depends on the weather. Well, on the temperature to be precise. For many lizards 4 and turtles and gators, the sex of the hatchlings depends on the temperature in the nest where the eggs incubate. But why would animals bother with such a seemingly slapdash system for assigning sex? And the only logical answer is, there must be some benefit. Each sex must fare better at the temperature that tends to produce that sex. A fine theory, but no one has been able to test it until now. In the January 20 online issue of Nature, scientists at Iowa State University describe how they used hormones 5 to produce lizards with the wrong sex:animals that came out male even though they were incubated at the female temperature, and vice 6 versa. They found that females born and raised at the female temperature made more babies than females hatched at the wrong, male temperature, Ditto for the males. Call it the Goldilocks principle: you are born at a temperature that’s just right, at least if you are a lizard 3.


Thanks for the minute for a Scientific Americans' 60-Second Science. I’m Karen Hopkin.

 



1 chromosomes
n.染色体( chromosome的名词复数 )
  • Chromosomes also determine the sex of animals. 染色体也决定动物的性别。 来自《简明英汉词典》
  • Each of four chromosomes divide longitudinally. 四种染色体的每一种都沿着纵向分裂。 来自《现代汉英综合大词典》
2 reptiles
n.爬行动物,爬虫( reptile的名词复数 )
  • Snakes and crocodiles are both reptiles. 蛇和鳄鱼都是爬行动物。 来自《简明英汉词典》
  • Birds, reptiles and insects come from eggs. 鸟类、爬虫及昆虫是卵生的。 来自《现代汉英综合大词典》
3 lizard
n.蜥蜴,壁虎
  • A chameleon is a kind of lizard.变色龙是一种蜥蜴。
  • The lizard darted out its tongue at the insect.蜥蜴伸出舌头去吃小昆虫。
4 lizards
n.蜥蜴( lizard的名词复数 )
  • Nothing lives in Pompeii except crickets and beetles and lizards. 在庞培城里除了蟋蟀、甲壳虫和蜥蜴外,没有别的生物。 来自辞典例句
  • Can lizards reproduce their tails? 蜥蜴的尾巴断了以后能再生吗? 来自辞典例句
5 hormones
n.坏事;恶习;[pl.]台钳,老虎钳;adj.副的
  • He guarded himself against vice.他避免染上坏习惯。
  • They are sunk in the depth of vice.他们堕入了罪恶的深渊。
标签: SSS lizard
学英语单词
adjusted quantity
allenylic
aquula
arbitration expense
Autogenous Mills
Bacillus enteritidis
benthic trawling gear
Berëzovskiy
Biharamulo
blackly
bombastic
bowel cancers
boxercise
Bumbuli
cajuputole
carbon process
centrifugal pump with vertical axis
clairin
connector socket
contestant
crono
customer departmentalization
cylinder in line engine
Cystacanthus paniculatus
Data.
diffusion icterus
diiamb
dohyaline
efficiency of retrieval system
ethren
exchange rate arrangement
findfields
form-family
Fortel
fractional driving
genus listerias
gnomonic ruler
heading marker alignment
hit and miss governor
holmstroms
hypothermal ore deposit
inactive optics
increasing section
inherently ambiguous contextfree language
intraabdominal
intrados
iridarsenite
kesso oil
kid oneself
lexemic alternation pattern
livestock number
lymphoblasts
made broad our phylacteries
Mateszalka
minimicrosphere
mountain-man
mouthlike
neutral fats
ochthebius formosanus
oil drain-cock
opisthenar alopecia
owner-controlled
Parada Guayabos
pit molding
play football
price growth per cent
radioactive colloid
read text program
rectal swab holder
Regent's Park
restrictive mutation
ruddleman
run-out of shaft
scale modeling
schirryve
school technology
self-energized
sidney
software simulator
source distance
space charge tetrode
spaic
sporotrichin
storm eddy
strophalloside
stutterers
tactosol
testing-program time
Theo-X
thermindicator
thomas carews
thrashin'
three operating crane
tide and half tide
toot one's own horn
tussars
undersalt
universal default
velvia
vertebral nerve
xeroxes
yzma