问题 单项选择题

遗传是指生物按照亲代所经历的同一发育途径和方式,摄取环境中的物质建造自身,产生与亲代相似的复本的一种自身繁殖过程。 下列属于遗传的是( )。

A.老张是经商老手,他的儿子小张经商也很在行

B.王某眉梢有一颗红色的豆状痣,他的儿子三岁时也在同一部位长出一颗痣

C.赵某有精神病,他父亲生前也有这种精神病

D.刘某很擅长打乒乓球,他女儿也很喜欢打乒乓球

答案

参考答案:C

解析:根据遗传的定义,A、D分别指的是人的长项和兴趣爱好而不是一种发育途径和方式,因此排除A、D:而B明显不是按照亲代所经历的同一发育途径和方式,产生与亲代相似的复本的一种自身繁殖过程,也应排除。只有C完全符合遗传的定义,故选C。

单项选择题

This week marks the 10th anniversary of the Alar apple scare, in which many American consumers were driven into a panic following the release of a report by an environmental organization claiming that apples containing the chemical Alar posed a serious health threat to preschoolers. The report was disseminated through a PR (Problem Report) campaign and bypassed any legitimate form of scientific peer review. Introduced to the American public by CBS "60 Minutes", the unsubstantiated claims in the report led some school districts to remove apples from their school lunch programs and unduly frightened conscientious parents trying to develop good eating habits for their children.

Last month, Consumers Union released a report warning consumers of the perils of consuming many fruits and vegetables that frequently contained "unsafe" levels of pesticide residues. This was especially true for children, they claimed. Like its predecessor 10 years earlier, the Consumers Union report received no legitimate scientific peer review and the public’s first exposure to it was through news coverage.

Not only does such reporting potentially drive children for consuming healthful fruits and vegetables, the conclusions were based on a misleading interpretation of what constitutes a "safe" level of exposure. Briefly, the authors used values known as the "chronic reference doses", set by the U. S. environmental Protection Agency, as their barometers of safely. Used appropriately, these levels represent the maximum amount of pesticide that could be consumed daily for life without concern. For a 70-year lifetime, for example, consumers would have to ingest this average amount of pesticide every day for more than 25,000 days. It is clear, as the report points out, that there are days on which kids may be exposed to more; it is also clear that there are many more days when exposure is zero. Had the authors more appropriately calculated the cumulative exposures for which the safety standards are meant to apply, there would have been no risks and no warnings.

Parents should feel proud, rather than guilty, of providing fruits and vegetables for their children. It is well established that a diet rich in such foods decreases the risk of heart disease and cancer. Such benefits dramatically overwhelm the theoretical risks of tiny amounts of pesticides in food. So keep serving up the peaches, apples, squash, grapes and pears.

With regard to the pesticides in food, this passage seems to argue that ().

A. parents should keeps their children from the food with pesticides

B. they should be applied to fruits and vegetables wit caution

C. more research needs to be done on their harmfulness to health

D. they are not as threatening as said to children most of the time

判断题