题干

为了研究根的向地生长与生长素和乙烯二者的关系,实验如下:将某种开花植物的根尖放在含不同浓度生长素的培养液中,并加入少跫蔗糖作为能源.发现在这些培养液中出现了乙烯,且生长素浓度越高,培养液中乙烯的浓度也越高,根尖生长所受的抑制也越强.下列叙述最严谨的是(  )

A:为使实验更严谨,还需将另一个根尖放在不含生长素和等星蔗糖的培养液中,作为对照组

B:据此实验结果,可推知水平放罝的植物根向重力生长的原因是近地侧生长素浓度高,促进乙烯的合成,从而抑制根的生长

C:生长素与乙烯对根的生长表现为拮抗作用

D:植物激素对生长发育的调节作用,在根本上是基因组在一定时间上程序性表达的结果

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B

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