题干

某二倍体动物有K对染色体,经减数分裂形成遗传信息不同的配子,其种类为

A:2K

B:(1/2)K

C:K2

D:K+

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A

同类题1

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同类题4

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团雾——高速公路上的杀手

       ①2013年6月4日6时许,在京港澳高速公路驻马店833-841千米路段,东西两侧车道突发16起交通事故,共造成56车相撞,致14人死亡。

       ②有关人员在分析上述事故的发生原因时发现,造成这些严重交通事故的杀手就是团雾。

       ③从气象学意义上讲,团雾的本质也是雾。受局部地区微气候环境的影响,在大雾中数十米到上百米的局部范围内,那些雾气更“浓”、能见度更低的雾,就是团雾,秋冬季昼夜温差较大、无风的夜间或是清晨6-8时,较容易出现团雾。团雾的形成,与局部小气候环境关系密切,其易出现的地域一般为地势低洼、空气湿度大的地区。另外,雨后山区的高速公路地段也较易出现团雾。

       ④与普通的雾相比,团雾具备以下几个特点:第一,与大雾弥漫有所不同,团雾的势力范围比较小,就像一朵落在地上的云彩,团雾似的,四顾朦胧,团雾以外,视线良好;第二,团雾内能见度很低,一般只有10-20米;第三,团雾覆盖范固呈分段形态,有的地方雾很少,有的地方雾很浓;第四,团雾的覆盖面积大小不一,大的团雾覆盖区域长约5000米,小的团雾覆盖区域长度仅有1000米。

       ⑤团雾因其飘浮不定和能见度低的特点,而被称为“高速公路杀手”。高速公路上的团雾,往往与重特大交通事故相伴发生,严重威胁着人们的生命财产安全。

       ⑥团雾的危害之所以这样大,究其原因,主要有以下几点:

       ⑦首先,团雾的特性造成了其在高速公路上多发。团雾不仅能在大雾天气中现身,就是在天气状况良好的情况下,也有可能在局部区域内出现。

       ⑧其次,驾驶员视觉的明暗适应特性不佳,是团雾路段内交通事故多发的原因之一。明适应指的是,人们从暗处走到明处,视觉感受性逐步提高的过程。正常情况下,人眼需要1分钟能完成明暗适应性的转换。暗适应就是由明到暗,人的视觉感受性逐步提高的过程,这个过程要比明适应慢得多。一般情况下,人眼需要15分钟才能恢复一半的视觉感受性,大概40分钟才能完全恢复。因此驾驶人由明朗路段一下子进入团雾路段时,周围环境的能见度大幅降低,人眼不能迅速适应,视力无法得到及时恢复,由此造成反应滞后,导致交通事故多发。

       ⑨再次,人类的知觉会因参照物的不同而产生错觉,使得团雾路段内交通事故多发。当车辆在高速公路上由明朗路段驶入团雾路段时,虽然驾驶员会本能地采取制动措施以降低车速,但往往会因为知觉错觉,低估进入团雾路段的车速。这就非常容易使前后车发生追尾。

       ⑩最后,人类的反应特性也是团雾路段内交通事故多发的原因之一。在车辆行驶过程中,驾驶员接收到各种各样的交通刺激信号,并对其中影响交通安全的信号做出反应。选择反应时间的长短,与刺激信号的辨别难度有关,辨别难度越大,反应时间越长。当车辆驶入团雾区后,四周白茫茫一片,降低了车辆给驾驶人的刺激强度,增大了驾驶员的辨别难度,使得他们很难从周围的环境中把车辆辨别出来,也就是使驾驶人的反应时间变长,从而延长了车辆的制动非安全区,导致道路交通事故发生的可能性大增。

       ⑪此外,还要考虑驾驶人超速行驶、疲劳驾驶等交通违法行为,与团雾区能见度低的负面效果相互叠加,这也是造成团雾路段内交通事故多发的原因之一。

       ⑫那么,面对团雾,我们该怎么办?

       ⑬公安部交管局的专家提醒大家,驾车出行前要充分考虑天气情况,注意沿途天气预报。一般来讲,当低层水汽条件比较好的时候,团雾更容易出现,尤其是雨后一两天,如果天气晴好,就比较容易在清晨出现团雾。

       ⑭同时,驾驶员行经团雾多发路段需加倍注意,如遇突发团雾,应保持镇定,不要慌乱,减速行驶。

                                                                                                                                                           (选自《百科知识》2015年第1期,有改动)