问题 单项选择题

下列关于生物群落的叙述中,不正确的是()

A.生物群落是由不同的种群形成的

B.区别不同群落的重要特征是群落中各生物之间的关系

C.生物群落具有垂直结构和水平结构

D.生物群落是生活在一定的自然区域内,相互之间具有直接或间接关系的各种生物的总和

答案

参考答案:B

解析:生物群落是指生活在一定自然区域中的具有直接或间接关系的所有生物,由多个不同的种群组成;区别不同群落的重要特征是群落的丰富度;生物群落具有垂直结构和水平结构。考点:考查生物群落的知识。点评:难度较小,理解群落的概念和特点。

问答题 简答题
单项选择题

When Dr. John W. Gofman, professor of medical physics at the University of California and a leading nuclear critic, speaks of "ecocide" in his adversary view of nuclear technology, he means the following. A large nuclear plant like that in Kalkar, the Netherlands, would produce about 200 pounds of plutonium each year. One pound, released into the atmosphere, could cause 9 billion cases of lung cancer. This waste product must be stored for 500,000 years before it is of no further danger to man. In the anticipated reactor economy, it is estimated that there will be 10,000 tons of this material in Western Europe, of which one table-spoonful of plutonium-239 represents the official maximum permissible body burden for 200,000 people. Rather than being biodegradable, plutonium destroys biological properties.

In 1972 the .U.S. Occupational Safety and Health Administration ruled that the asbestos level in the work place should be lowered to 2 fibers per cubic centimeter of air, but the effective date of the ruling has been delayed until now. The International Federation of Chemical and General Workers’ Unions report that the 2-fiber standard was based primarily on one study of 290 men at a British asbestos factory. But when the workers at the British factory had been reexamined by another physician, 40--70 percent had X-ray evidence of lung abnormalities. According to present medical information at the factory in question, out of a total of 29 deaths thus far, seven were caused by lung cancer. An average European or American worker comes into contact with six million fibers a day. "We are now, in fact, finding cancer deaths within the family of the asbestos worker," states Dr. Irving Selikoff, of the Mount Sinai Medical School in New York.

It is now also clear that vinyl chloride, a gas from which the most widely used plastics are made, causes a fatal cancer of the blood-vessel cells of the liver. However, the history of the research on vinyl chloride is, in some ways, more disturbing than the "Watergate cover- up. " "There has been evidence of potentially serious disease among polyvinyl chloride workers for 25 years that has been incompletely appreciated and inadequately approached by medical scientists and by regulatory authorities," summed up Dr. Selikoff in the New Scientist. At least 17 workers have been killed by vinyl chloride because research over the past 25 years was not followed up. And for over 10 years, workers have been exposed to concentrations of vinyl chloride 10 times the "safe limit" imposed by Dow Chemical Company.

According to the text, the author mentions plutonium in paragraph 1 to()

A. estimate the amount of nuclear material in Europe

B. exemplify one of the possible causes of lung cancer

C. highlight the measures needed to prevent lung cancer

D. show the destructive properties of industrial waste materials