问题 选择题

小麦的抗病(T)对不抗病(t)是显性.两株抗病小麦杂交后代中有一株不抗病,其余未知.这个杂交组合的可能的基因型是(  )

A.TT x TT

B.TT x Tt

C.Tt x Tt

D.Tt x tt

答案

亲代个体都为抗病小麦,而在后代个体中出现了不抗病单冠,说明不抗病是隐性性状,抗病是显性性状,不抗病由隐性基因t控制,控制亲代抗病的基因组成不是纯合的,由一个显性基因T和一个隐性基因t组成,即Tt;子代中抗病的基因组成有两种情况:TT或Tt;如图所示:

故选C

选择题
完形填空
I went to a group activity,“Sensitivity Sunday”,which was to make us more ____the problems faced by disabled people.We were asked to “____ a disability”for several hours one Sunday.Some members,___,chose to use wheelchairs.Others wore sound-blocking earplugs(耳塞) or blindfolds(眼罩).
Just sitting in the wheelchair was a____experience.I had never considered before how___it would be to use one.As soon as I sat down,my ____made the chair begin to roll.Its wheels were not____.Then I wondered where to put my____.It took me quite a while to get the metal footrest into____.I took my first uneasy look at what was to be my only means of____for several hours.For disabled people,“adopting a wheelchair” is not a temporary(临时的)____.
I tried to find a____position and thought it might be restful,____kind of nice,to be___around for a while.Looking around,I____I would have to handle the thing myself!My hands started to ache as I____the heavy metal wheels.I came to know that controlling the____of the wheelchair was not going to be a(n)____task.
My wheelchair experiment was soon____.It made a deep impression on me.A few hours of “disability” gave me only a taste of the____,both physical and mental,that disabled people must overcome.
小题1:
A.curious aboutB.interested in
C.aware ofD.careful with
小题2:
A.cureB.preventC.adoptD.analyze
小题3:
A.insteadB.strangelyC.as usualD.like me
小题4:
A.learningB.workingC.satisfyingD.relaxing
小题5:
A.convenientB.awkwardC.boringD.exciting
小题6:
A.heightB.forceC.skillD.weight
小题7:
A.lockedB.repairedC.poweredD.grasped
小题8:
A.handsB.feetC.keysD.handles
小题9:
A.placeB.actionC.playD.effect
小题10:
A.operationB.communication
C.transportationD.production
小题11:
A.explorationB.education
C.experimentD.entertainment
小题12:
A.flexibleB.safeC.startingD.comfortable
小题13:
A.yetB.justC.stillD.even
小题14:
A.shownB.pushedC.drivenD.guided
小题15:
A.realizedB.suggestedC.agreedD.admitted
小题16:
A.liftedB.turnedC.pressedD.seized
小题17:
A.pathB.positionC.directionD.way
小题18:
A.easyB.heavyC.majorD.extra
小题19:
A.forgottenB.repeatedC.conductedD.finished
小题20:
A.weaknessesB.challenges
C.anxietiesD.illnesses