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在遗传教学中,遗传几率的计算是这部分教学的重点、难点,因为其涉及的概念多,内在规律性强,学生很难把握好。本人通过几年的教学实践,摸索出一条行之有效的方法,利用一题多问、多解,不但突破难点掌握重点,而且也培养学生发散思维能力。下面通过事例来说明。 [例]人类中,多指是受显性基因A控制的,先天性聋哑是受隐性基因b控制的,这两对性状独立遗传。现有一对夫妇,男方多指,女方正常,第一胎生了一个先天性聋哑的儿子。如果还能生育的话,请分析回答:(1)生下的子女中,单患先天性聋哑的几率是多少?(2)生下的子女中,单患多指的几率是多少?(3)生下的子女中,表现正常的几率是
In hereditary teaching, the calculation of heritability is the key and difficult part of this part of the teaching. Because it involves many concepts and inherent regularity, it is difficult for students to grasp. Through several years of teaching practice, I have explored an effective method. Using one question to ask more questions and more explanations, I will not only break through difficulties and master key points, but also develop students’ divergent thinking skills. The following examples illustrate. [Examples] In humans, multiple fingers are controlled by the dominant gene A. Congenital deafness is controlled by the recessive gene b. These two pairs of traits are inherited independently. A couple is present. The man has more fingers and the woman is normal. The first child has a congenital deaf-mute son. If you can still have children, please analyze and answer: (1) What are the odds of having a child with congenital deaf-muteness among children born? (2) What is the odds of having multiple-fingered children among the children born?(3) Among the children born, the odds of a normal performance are