下列有关细胞的基因组成中，最可能不是体细胞的一项是（ ）
A．TT
B．Tt
C．T
D．tt
基因是染色体上具有控制生物性状的DNA片段，染色体存在于细胞核里；在人的体细胞中，染色体是成对存在的，基因也是成对存在的，分别位于成对的染色体上；在形成生殖细胞的过程中，成对的染色体分开，每对染色体中的一条进入精子或卵细胞中，基因也随着染色体的分离而进入不同的生殖细胞中．因此控制某一性状的基因在生殖细胞中是不成对的．
故选：C．
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| A boy was walking home from school when he saw a large, tempting (诱人的) apple on one of the branches of an apple tree hanging out over a tall fence.The boy wasn't much of a fruiteater,__1__ a bar of chocolate if given the choice,__2__, as they say, the forbidden fruit can be tempting.Seeing the apple, the boy wanted it.The more he looked at it, the__3__ he felt and the more he wanted that apple. He stood on tiptoe (脚尖) , __4__ as high as he could, but even at his tallest __5__ he was unable to touch it.He began to __6__up and down, as high as he could, at the __7__ of each jump stretching his arms to get the apple.Still it remained out of __8__. Not giving up, he thought, if only he had something to __9__ on.His school bag wouldn't give enough height and he didn't want to __10__ the things inside, like his lunch box, pencil case, and Gameboy. Looking __11__, he hoped he might find an old box, a rock, or, __12__ luck,even a ladder, but it was a tidy neighbourhood and there was nothing he could use. He had tried everything he could think to do.__13__ seeing any other choices, he gave up and started to walk __14__.At first he felt angry and disappointed thinking about how hungry he had become from his __15__,and how he really wanted that apple.The more he __16__ like this, the more unhappy he became. __17__, the boy of our story was a pretty smart guy, even if he couldn't always get what he wanted.He started to say to himself, "This isn't __18__.I don't have the apple and I'm feeling miserable as well.There's __19__ more I can do to get the apple-that is unchangeable-but we are supposed to be able to __20__ our feelings.If that's the case, what can I do to feel better?" | |||
| ( )1．A.preferring ( )2．A.so ( )3．A.sadder ( )4．A.expanding ( )5．A.strength ( )6．A.jump ( )7．A.tip ( )8．A.hope ( )9．A.put ( )10．A.break ( )11．A.up ( )12．A.for ( )13．A.After ( )14．A.back ( )15．A.wishes ( )16．A.thought ( )17．A.Therefore ( )18．A.skilful ( )19．A.something ( )20．A.change | B．offering B．then B．angrier B．stretching B．length B．look B．stage B．hand B．stand B．shake B．forward B．with B．Through B．away B．beliefs B．imagined B．However B．cheerful B．anything B．express | C．receiving C．but C．hungrier C．swinging C．range C．walk C．top C．sight C．get C．take C．down C．on C．Without C．up C．efforts C．tried C．Moreover C．harmful C．everything C．forget | D．allowing D．or D．tastier D．pulling D．height D．glance D．level D．reach D．hold D．strike D．around D．of D．Upon D．down D．goals D．claimed D．Otherwise D．helpful D．nothing D．describe |