2013年高考理科综合生物试题广东卷和山东卷中都出现了一对同源染色体的一条染色体缺失的遗传几率分析.考生解答此类试题的最大困惑在于缺乏解题方法,不知如何下手.下面通过例析,让考生从中感悟,形成解题方法,达到举一反三.例1(2013年高考广东卷第25题)果蝇红眼对白眼为显性,控制这对性状的基因位于X染色体.果蝇缺失1条Ⅳ号染色体仍能正常生存和繁殖,缺失2条则致死.一对都缺失1条Ⅳ号染色体的红眼果蝇杂交 2013 college entrance examination science comprehensive biological test Guangdong and Shandong volumes have a pair of homologous chromosomes a chromosomal loss of genetic probability analysis of the candidates to answer such questions the biggest confusion lies in the lack of problem-solving methods, I do not know how to start. Example 1, so that candidates from the sentiment, the formation of problem-solving methods, to reach one-off .Example 1 (2013 college entrance examination Guangdong Volume 25) Drosophila red eye dominant eyes, the genes controlling the trait are located on chromosome X. Drosophila deletion A chromosome IV still survive and reproduce normally, and the two are dead, while a pair of red-eye fruit flies that lack a chromosome IV