题干

DNA溶解温度(Tm)是使DNA双螺旋结构解开一半时所需要的温度吗,不同种类DNA的Tm值不同.如图表示DNA分子中G+C含量(占全部碱基的比例)与Tm的关系.下列有关叙述,不正确的是(    )

A:一般地说,DNA分子的Tm值与G+C含量呈正相关

B:Tm值相同的DNA分子中G+C的数量有可能不同

C:生物体内解旋酶也能使DNA双螺旋结构的氢键断裂而解开螺旋

D:DNA分子中G与C之间的氢键总数比A与T之间多

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D

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