题干

在下列甲、乙、丙、丁四组相同培养基上分别接种正常R型菌、正常S型菌、加热杀死的S型菌、加热杀死的S型菌和正常R型菌,培养一段时间,观察菌落的生长情况如下图。下列有关叙述正确的是(  )

A:本实验设计思路是把DNA和蛋白质分开,单独地直接地观察它们的作用

B:实验可以说明DNA是遗传物质

C:S型细菌能利用小鼠的核糖体合成它的蛋白质

D:S型细菌中某物质使R型细菌转化成S型细菌

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D

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    Colorado officials will stick to a plan to kill some mountain lions and bears to support the state's dropping mule deer (长耳鹿) population.

    Wednesday's vote permits organizations to kill up to 25 black bears and 15 mountain lions per year in the central and western parts of the state. The project will run for three years, to be followed by a six-year study of how deer populations respond to fewer predators(捕食者).

    The population of Colorado's mule deer has suffered a puzzling, years-long drop to about 450,000, which state officials said was about 110,000 fewer than there should be. A 2014 state study tied it to seven causes, including predators, whose number has greatly increased in recent years.

    Some experts, however, said the state should focus first on the human-led destruction(破坏) of mule deer habitat(栖息地). “The drop of the mule deer population is obviously not a simple problem with simple causes,” Brian Kurzel, director of the National Wildlife Federation, said. “By far, the greatest problem—the one that I think deserves the most attention in any science-based study—is habitat quantity and quality.”

    Kurzel pointed out that the U.S Bureau of Land Management recently agreed to create 15,000 new oil and gas wells somewhere in western Cororado, which was often called “the mule-deer factory”. There, the number of mule deer has fallen to about 30,000 from more than 100,000 in the early 1980s. Though state officials have known oil and gas development affects the population of mule deer, they didn't go against the plan.

    Other causes like building highways, population growth and human activities are also curbing the mule deer population, according to the study.

    State Parks and Wildlife officials don't necessarily disagree. They started a $4.5 million program as a way to gather research for later decisions.