问题 单项选择题

用纯合子果蝇作为亲本研究两对相对性状的遗传实验,结果如表所示。下列说法不正确的是()

A. 果蝇的灰身、红眼是显性性状

B.由组合②可判断控制眼色的基因位于X染色体上

C.若组合①的F1随机交配,则F2雌蝇中组合的灰身红眼占1/16

D.若组合②的F1随机交配,则F2雄蝇中黑身白眼占1/8

答案

参考答案:C

解析:

第一组亲代有黑身白眼,后代全为灰身红眼,说明灰身是显性,红眼是显性;第二组,后代雌性全为红眼,雄性全为白眼,说明控制眼色的基因位于X染色体上,A、B正确;第一组的亲代是AAXBXB(灰身红眼)和aaXbY(黑身白眼),所以第一组的子代是AaXBXb(灰身红眼)、AaXBY(灰身红眼),若组合①的F1随机交配,则F2雄蝇中灰身白眼的概率为3/16,C错误;第二组的亲代是aaXbXb(黑身白眼)和AAXBY(灰身红眼),所以第二组的子代是AaXBXb(灰身红眼)、AaXbY(灰身白眼),若组合②的F1随机交配,则F2雄蝇中黑身白眼占1/8。 考点:本题考查遗传定律与伴性遗传的知识。意在考查能理解所学知识的要点,把握知识间的内在联系的能力。

单项选择题 共用题干题
单项选择题

"WHAT’S the difference between God and Larry Ellison" asks an old software industry joke. Answer: God doesn’t think he’s Larry Ellison. The boss of Oracle is hardly alone among corporate chiefs in having a reputation for being rather keen on himself. Indeed, until the bubble burst and the public turned nasty at the start of the decade, the cult of the celebrity chief executive seemed to demand bossly narcissism, as evidence that a firm was being led by an all-conquering hero.

Narcissus met a nasty end, of course. And in recent years, boss-worship has come to be seen as bad for business. In his management bestseller, "Good to Great", Jim Collins argued that the truly successful bosses were not the serf-proclaimed stars who adorn the covers of Forbes and Fortune, but instead self-effacing, thoughtful, monkish sorts who lead by inspiring example.

A statistical answer may be at hand. For the first time, a new study, "It’s All About Me", to be presented next week at the annual gathering of the American Academy of Management, offers a systematic, empirical analysis of what effect narcissistic bosses have on the firms they run. The authors, Arijit Chatterjee and Donald Hambrick, of Pennsylvania State University, examined narcissism in the upper levels of 105 firms in the computer and software industries.

To do this, they had to solve a practical problem: studies of narcissism have hitherto relied on surveying individuals personally, something for which few chief executives are likely to have time or inclination. So the authors devised an index of narcissism using six publicly available indicators obtainable without the co-operation of the boss. These are: the prominence of the boss’s photo in the annual report; his prominence in company press releases; the length of his "Who’s Who" entry; the frequency of his use of the first person singular in interviews; and the ratios of his cash and non-cash compensation to those of the firm’s second-highest paid executive.

Narcissism naturally drives people to seek positions of power and influence, and because great self-esteem helps your professional advance, say the authors, chief executives will tend on average to be more narcissistic than the general population. How does that affect a firm Messrs Chatterjee and Hambrick found that highly narcissistic bosses tended to make bigger changes in the use of important resources, such as research and development, or in spending and leverage; they carried out more and bigger mergers and acquisitions ; and their results were both more extreme (more big wins or big losses) and more transient than those of firms run by their humbler peers. For shareholders, that could be good or bad.

Although (oddly) the authors are keeping their narcissism ranking secret, they have revealed that Mr Ellison did not come top. Alas for him, that may be because the study limited itself to people who became the boss after 1991--well after he took the helm. In every respect Mr Ellison seems to be the classic narcissistic boss, claims Mr Chatterjee. There is life in the old joke yet.

We can infer from the passage that()

A. the results of the new study has already been publicized

B. the researchers think Mr. Ellison is more classic than narcissistic

C. the joke about Mr. Ellison is actually adapted from real life

D. the ranking might be different if the survey focused on an earlier period