题干

如图1是人工设计的生态系统图,图2是人们绘制的在蚯蚓养殖池中加入一定量食用菌杂屑后蚯蚓种群数量随时间变化的示意图.下列叙述不符合生态学观点的是(   )

A:该生态系统能量经过了多级利用,提高了系统总能量利用效率

B:合理使用农家肥可以提高流经该生态系统的总能量

C:食用菌和蚯蚓属于分解者,它们促进了生态系统中物质循环和能量流动的进行

D:蚯蚓种群数量达到 K2 值时,种内斗争最激烈

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答案(点此获取答案解析)

D

同类题3

阅读下列短文,从每题所给的四个选项(A、B、C和D)中,选出最佳选项。

       Each new school year brings fresh reminders of what educators call the summer learning gap. Some call it the summer learning setback. Simply speaking, it means the longer kids are out of school, the more they forget. The only thing they might gain is weight.

       Most American schools follow a traditional nine-month calendar. Students get winter and spring breaks and about ten weeks of summer vacation. Some schools follow a year-round calendar. They hold classes for about e ight weeks at a time, with a few weeks off in between. The National Association for Year-Round Education says there were fewer than three thousand such schools at last count. They were spread among forty-six of the fifty states.

       But many experts point out that the number of class days in a year-round school is generally the same as in a traditional school. Lead researcher Paul von Hippel said, “Year-round schools don't really solve the problem of the summer learning setback. They simply spread it out across the year.”

Across the country, research shows that students from poor families fall farther behind over the summer than other students. Experts say this can be prevented. They note that many schools and local governments offer programs that can help.

       But calling them “summer school” could be a problem. The director of the summer learning center at Johns Hopkins, Ron Fairchild, said research with groups of different parents in Chicago and Baltimore found that almost all strongly disliked the term “summer school”. In American culture, the idea of summer vacation is connected to beliefs about freedom and the joys of childhood. The parents welcomed other terms like “summer camp”, “enrichment”, “extra time” and “hands-on learning”.