问题 单项选择题

Drug use is rising dramatically among the nation’ s youth after a decade of decline. From 1993 to 1994, marijuana use among young people (1) from 12 to 17 jumped 50 percent. One in five high school seniors (2) marijuana daily. Monitoring the Future, which (3) student drug use annually, reports that negative attitudes about drugs have declined for the fourth year in a row. (4) young people see great risk in using drugs. Mood-altering pharmaceutical drugs are (5) new popularity among young people. Ritalin, (6) as a diet pill in the 1970s and now used to (7) hyperactive children, has become a (8) drug on college campuses. A central nervous system (9) , Ritalin can cause strokes, hypertension, and seizures. Rohypnol, produced in Europe as a (10) tranquilizer, lowers inhibitions and suppresses short-term memory, which has led to some women being raped by men they are going out with. (11) taken with alcohol, its effects are greatly (12) . Rock singer Kurt Cobain collapsed from an (13) of Rohypnol and champagne a month before he committed (14) in 1994. In Florida and Texas, Rohypnol has become widely abused among teens, who see the drug as a less expensive (15) for marijuana and LSD. Alcohol and tobacco use is increasing among teenagers, (16) younger adolescents. Each year, more than one million teens become regular smokers, (17) they cannot legally purchase tobacco. By 12th grade, one in three students smokes. In 1995, one in five 14-year-olds reported smoking regularly, a 33 percent jump (18) 1991. Drinking among 14-year-olds climbed 50 percent from 1992 to 1994,and all teens reported substantial increases in (19) drinking. In 1995, one in five 10th graders reported having been drunk in the past 30 days. Two-thirds of high school seniors say they know a (20) with a drinking problem.

6()

A.described

B.prescribed

C.inscribed

D.instructed

答案

参考答案:B

解析:

[解题思路] 动词辨析。described意为“描述”;prescribed意为“开处方”;inscribed意为“在某物上写或题字”;instructed意为“指导”。此处Ritalin作为一种处方药,因此选prescribed。

读图填空题

刺毛兔(2N=28)背上有硬棘毛,体黑色或白色,章教授在一封闭饲养的刺毛兔繁殖群中,偶然发现一只无刺雄兔(黑色),全身无棘毛,并终身保留无刺状态。章教授为了研究无刺小兔的遗传特性,让这只无刺雄兔与雌性刺毛兔交配,结果F1全是刺毛兔;再让F1刺毛兔雌雄交配,生产出8只无刺小兔和25只刺毛兔,其中无刺小兔全为雄性。

(1)章教授初步判断:

①.该雄兔无刺的原因是种群中基因突变造成的,而不是营养不良或其他环境因素造成的。

②.控制无刺性状的基因位于性染色体上。写出章教授做出上述两项判断的理由:

判断①的理由____________________________________。

判断②的理由____________________________________。

(2)若该黑色无刺雄兔的某精原细胞经减数分裂产生了一个DddXa的精子,则同时产生的另外三个精子的基因型分别为_______、Y、Y,这四个精子中染色体数目依次为_________,这些精子与卵细胞结合后,会引起后代发生变异,这种变异属于_________。

(3)在刺毛兔中,毛色黑色与白色是一种相对性状。黑色为显性(D),白色为隐性(d)。下图表示两组交配实验,亲代刺毛兔A、B、P、Q均为纯合子,子代刺毛兔在不同环境下成长,其毛色如图所示,请据图分析回答:

①.刺毛兔C与刺毛兔D的表现型不同,其原因是_________________,说明_____________________。

②.刺毛兔C与刺毛兔R交配得到子代:若子代在-15℃中成长,表现型最可能的比例是_______;若子代在30℃中成长,表现型最可能是_______________________。

填空题