表型 植物数 有色淀粉 1774 白色蜡质 420 有色蜡质 263 白色淀粉 279 这两对基因的重组百分比是多少？

37、兔子的花斑等位基因对本色是显性，短毛对长毛（安哥拉）是显性。一个英国的花斑短毛兔与长毛安哥拉本色兔杂交，F1与安哥拉本色品系回交。假使回交产生26只花斑安哥拉兔，144只本安哥拉兔，157只花斑短毛和23只本色短毛这两个基因之间的重组百分比是多少？ 38、The primrose, Primula kewensis, has 36 chromosomes that are similar in appearance to the chromosomes in two related species, Primulafioribunda (2n = 18) and Primula verticillata (2n = 18). How could P kewensis arise from these species? How would you describe P kewensis in genetic terms? 39、 A couple, looking ahead to planning a family, are aware that through the past three generations on the husband's side a substantial number of stillbirths have occurred and several malformed babies were born who died early in childhood. The wife has studied genetics and urges her husband to visit a genetic counseling clinic, where a complete karyotype-banding analysis is performed. Although the tests show that he has a normal complement of 46 chromosomes, banding analysis reveals that one member of the chromosome 1 pair (in group A) contains an inversion covering 70 percent of its length. The homologue of chromosome 1 and all other chromosomes show the normal banding sequence.

(a) How would you explain the high incidence of past still-births?

(b) What can you predict about the probability of abnormality/normality of their future children ?

(c) Would you advise the woman that she will have to “wait out” each pregnancy to term to determine whether the fetus is normal? If not, what else can you suggest?

40、在接合实验中，Hfr菌株应带一个敏感位点，这样，在发生接合后可用选择性培养基消除Hfr供体。试问这个位点距离Hfr染色体的转移起点（O）应该远还是近，为什么？

41、When the interrupted mating technique is used with five different strains of Hfr bacteria, the following order of gene entry and

recombination is observed, On the basis of these data, map the bacterial chromosome. Do the data support the concept of circularity? Hfr stain order

1 T C H R O 2 H R O M B 3 M O R H C 4 M B A K T 5 C T K A B

42、If a single bacteriophage infects one E. colt' cell present on a lawn of bacteria and upon lysis yields 200 viable viruses, how many phages will exist in a single plaque if only three more lyric cycles occur?

43、在一棵荔枝树上发现有一枝条上所有的果实均比其他枝条早熟，a.提出一个假设解释这一现象，b.设计一个试验验证这一现象，c.讨论它的生产应用。

44、在某个二倍体作物的品种群体中，发现有一株的某个性状有明显变异，提出研究方案，以a.鉴定该性状的真假变异，b.鉴定变异的显隐性，c.把控制该性状的基因定位于染色体上。

已知玉米叶色受一对基因控制，基因型CC为深绿，Cc为浅绿，cc为黄色（苗期死），杂交：深绿×浅绿，并让F1随机交配，产生F2，则F2成株中，深绿：浅绿：黄色的表型比例如何？

45、玉米胚乳受一对基因Y-y控制，胚乳基因型与表现型的关系为：YYY-深黄、Yyy-黄、Yyy-浅黄、yyy-白色，现有两个玉米自交系，其胚乳颜色分别为深黄和白色，作正反交，可以预期杂交当代胚乳的基因型及颜色分别是什么？

46、在人群中。已知右癖占84％，问此人群中杂合子（Rr）占多少？右癖中杂合子占多少？（左癖对右癖为隐性）

47、在一个完全随机交配的群体中，基因型AA.Aa和aa的频率分别为0.2，0.6，0.2，问：若没有其他因素干扰，子5代的基因频率是多少？

48、已知某作物品种的感病株（rr）占９％，抗病株（RR和Rr）占91％，其中感病株的幼苗是致死的，抗病株幼苗可以正常生长，并开花授粉，问经过三代随机交配后，在育出的幼苗中，感病株所占的百分比是多少？

49、已知玉米籽粒的黄色和白色是由一对等位基因控制的，其中黄色（Y）为显性，白色（y）为隐性，若在某自然群体中各基因型频如下：（YY）D0=0.4,（Yy）H0=0.4,?(yy)R0=0.2，让其自由授粉，其F1和F2代的基因频率和基因型频率如何？若该隐性基因频率（q0）要达到qn=0.02时，需要多少个世代（n=?）？