问题 解答题

利用学过的生物学知识分析解答下列问题:

(1)电视上宣传达克宁产品的广告词:“杀菌治脚气,请用XXX”.那么,脚气和脚气病是一回事吗?请尝试说出它们发病的主要原因.

(2)黄宏、宋丹丹表演的经典小品《超生游击队》有一句台词:“生男生女老爷们是关键”.如何正确理解这句话?

答案

(1)一般说的脚气,其实是“脚湿气”,也叫“香港脚”是由真菌引起的,症状为脚部发痒、糜烂、蜕皮…;

而脚气病即维生素B1缺乏病,多见于以米食为主的地区,如菲律宾、越南、泰国、缅甸等.主要累及神经系统、心血管系统和水肿及浆液渗出.

(2)男性的精子有带x、y染色体两种,女性的卵子只有带x的,因受精时,卵细胞与x、y精子的结合是随机的,当含x的精子与卵细胞结合时形成的受精卵发育为女性,含y染色体的精子与卵细胞结合时形成的受精卵发育成男性.

故答案为:1.不是一回事,脚气是由真菌寄生引起的传染性皮肤病;脚气病是由于维生素B1缺乏的.

2.因受精时,卵细胞与x、y精子的结合是随机的,当含x的精子与卵细胞结合时形成的受精卵发育为女性,含y染色体的精子与卵细胞结合时形成的受精卵发育成男性

单项选择题 案例分析题

Questions 21 to 25 are based on the following passage.

Lead deposits, which accumulated in soil and snow during the 1960’s and 70’s, were primarily the result of leaded gasoline emissions originating in the United States. In the twenty years that the Clean Air Act has mandated unleaded gas use in the United States, the lead accumulation worldwide has decreased significantly.

A study published recently in the journal Nature shows that air-borne leaded gas emissions from the United States were the leading contributor to the high concentration of lead in the snow in Greenland. The new study is a result of the continued research led by Dr. Charles Boutron, an expert on the impact of heavy metals on the environment at the National Center for Scientific Research in France. A study by Dr. Boutron published in 1991 showed that lead levels in arctic (北极的) snow were declining.

In his new study, Dr. Boutron found the ratios of the different forms of lead in the leaded gasoline used in the United States were different from the ratios of European, Asian and Canadian gasolines and thus enabled scientists to differentiate (区分) the lead sources. The dominant lead ratio found in Greenland snow matched that found in gasoline from the United States.

In a study published in the journal Ambio, scientists found that lead levels in soil in the Northeastern United States had decreased markedly since the introduction of unleaded gasoline.

Many scientists had believed that the lead would stay in soil and snow for a longer period.

The authors of the Ambio study examined samples of the upper layers of soil taken from the same sites of 30 forest floors in New England, New York and Pennsylvania in 1980 and in 1990. The forest environment processed and redistributed the lead faster than the scientists had expected.

Scientists say both studies demonstrate that certain parts of the ecosystem (生态系统) respond rapidly to reductions in atmospheric pollution, but that these findings should not be used as a license to pollute.

Lead accumulation worldwide decreased significantly after the use of unleaded gas in the US ()

A.was discouraged

B.was enforced by law

C.was prohibited by law

D.was introduced

单项选择题