问题 实验题

开始使用杀虫剂时,对某种害虫效果显著,但随着杀虫剂的继续使用,该种害虫表现出越来越强的抗药性。实验证明害虫种群中原来就存在具有抗药性的个体。按照达尔文的自然选择学说解释:

(1)害虫种群中存在个体抗药性的         ,体现了生物的变异一般是           的。

(2)杀虫剂的使用对害虫起了           作用。

(3)害虫抗药性的增强,是通过害虫与杀虫剂之间的             来实现的。杀虫剂选择了害虫中具有             (即具有抗药性)的个体生存(即适者生存),而具有          (具有不抗药性)的个体死亡。这就是            。由此可见,生物的           为生物进化提供了原始的选择材料,生物的遗传使有利变异在后代里得到积累和加强。所以说,           的自然选择决定着生物的进化方向。

答案

(1)变异     遗传     (2)选择    (3)生存竞争    有利变异   不利变异 自然选择   遗传变异    定向

题目分析:(1)首先害虫存在两种变异品种:抗药能力强的害虫与抗药能力差的害虫.农药使害虫中抗药能力差的害虫死亡,而抗药能力强的害虫活了下来.害虫种群中存在着差异,体现了生物的变异一般是不定向的。

(2)生物界普遍存在变异,每一代都存在变异,没有两个生物个体是完全相同的,变异是随机产生的,这些变异都是由遗传物质决定的,是可遗传的变异,这样控制抗药能力强的基因得到积累与加强,使用时间越长,效果越差,说明杀虫剂对害虫起了选择作用,而这种作用是定向的。

(3)达尔文认为,在生存斗争中,具有有利变异的个体,容易在生存斗争中获胜而生存下去,反之,具有不利变异的个体,则容易在生存斗争中失败而死亡,害虫的有些变异具有抗药性,在生存斗争中获胜而被保留下来,从而产生了抗药性的害虫;在这个过程中害虫抗药性增强,是通过害虫与杀虫剂之间的生存斗争来实现的,环境的定向选择作用决定着生物进化的方向。

判断题
单项选择题

The Southdale shopping centre in Minnesota has an atrium, a food court, fountains and acres of parking. Its shops include a Dairy Queen, a Victoria’s Secret and a purveyor of comic T-shirts. It may not seem like a landmark, as important to architectural history as the Louvre or New York’s Woolworth Building. But it is. "oh, my god!" chimes a group of teenage girls, on learning that they are standing in the world’s first true shopping mall. "That is the coolest thing anybody has said to us all day. "

In the past half century Southdale and its many imitators have transformed shopping habits, urban economies and teenage speech. America now has some 1,100 enclosed shopping malls, according to the International Council of Shopping Centres. Clones have appeared from Chennai to Martinique. Yet the mall’s story is far from triumphal. Invented by a European socialist who hated cars and came to deride his own creation, it has a murky future. While malls continue to multiply outside America, they are gradually dying in the country that pioneered them.

Southdale’s creator arrived in America as a refugee from Nazi-occupied Vienna. Victor Gruen was a Jewish bohemian who began to design shops for fellow immigrants in New York after failing in cabaret theatre. His work was admired partly for its uncluttered, modernist look, which seemed revolutionary in 1930s America. But Gruen’s secret was the way he used arcades and eye-level display cases to lure customers into stores almost against their will. As a critic complained, his shops were like mousetraps. A few years later the same would be said of his shopping malls.

By the 1940s department stores were already moving to the suburbs. Some had begun to build adjacent strips of shops, which they filled with boutiques in an attempt to re-create urban shopping districts. In 1947 a shopping centre opened in Los Angeles featuring two department stores, a cluster of small shops and a large car park. It was, in effect, an outdoor shopping mall. Fine for balmy southern California, perhaps, but not for Minnesota’s harsh climate. Commissioned to build a shopping centre at Southdale in 1956, Gruen threw a roof over the structure and installed an air-conditioning system to keep the temperature at 75°F (24℃)—which a contemporary press release called "Eternal Spring". The mall was born.

Gruen got an extraordinary number of things right first time. He built a sloping road around the perimeter of the mall, so that half of the shoppers entered on the ground floor and half on the first floor-something that became a standard feature of malls. Southdale’s balconies were low, so that shoppers could see the shops on the floor above or below them. The car park had animal signs to help shoppers remember the way back to their vehicles. It was as though Orville and Wilbur Wright had not just discovered powered flight but had built a plane with tray tables and a duty-free service.

Which of the following is not the extraordinary thing Gruen got for the first time()

A. Sloping road around the perimeter of the mall

B. Free shipping services

C.Low balconies of the shops

D. Animal signs in car park