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对于两对或两对以上相对性状的杂交遗传,可能遵循基因的自由组合规律或基因的连锁互换规律。快速判断遗传规律,是提高解题速度的关键。笔者在生物教学实践中探索出一种快速判断法则。本法则适于两对相对性状的杂交。一、判断自由组合规律和连锁互换规律当两对相对性状杂交时,若后代出现四种不同的表现型,它们之比不等于9∶3∶3∶1或不等于1∶1∶1∶1时,就需要判断是什么遗传规律,进而确定亲本的基固型。方法一如果杂交后代中双显性个体数≠双隐性个体数(双显∶双隐≠1∶1),则
For two or more pairs of relative traits of hybrid inheritance, may follow the rules of gene free association or gene exchange rules. Quickly determine the genetic law is the key to improving the speed of problem solving. The author explores a quick rule of thumb in biological teaching practice. This law applies to the cross between two pairs of relative traits. First, to determine the law of free association and the law of interchanging When two pairs of relative traits hybridized, if the offspring of four different phenotypes, their ratio does not equal 9: 3: 3: 1 or not equal to 1: 1: 1: 1, you need to determine what genetic law, and then determine the parent’s solid type. Method One If the number of dominating individuals ≠ the number of double recessive individuals (double significant: double implicit ≠ 1: 1), then