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遗传习题的解答,是学习中学《生物》的重点和难点之一。掌握正确的思维方法,有助于提高解题的速度和准确度。现就一些遗传题型的解题思维过程介绍如下: 一、紧扣题设条件,缩短思维时间 例1,基因型为AaBb的一个精原细胞,经减数分裂后,可能形成的精子类型和实际形成的精子类型分别是（） A、3种和4种 B、3种和1种C、4种2种D、4种和1种 [解析]该题题设有三个条件:精原细胞个数是“1”;“可能类型”和“实际类型”,三者缺一不可。抓住这三个关键点,可迅速找出正确答案C。 二、进行信息转换,另辟思维捷径 例2,某DNA分子中,腺嘌呤A数量为200,占碱基总数的20％,该DNA分子连续复
The answer to genetic exercises is one of the key points and difficulties in learning “biology” in secondary schools. Grasping the correct way of thinking helps increase the speed and accuracy of problem solving. The following is a brief explanation of the problem-solving thinking process of some genetic questions: 1. Closely set the conditions and shorten the thinking time. Example 1. A spermatogonia with a genotype of AaBb. After meiosis, the possible types of spermatozoa may be The actual sperm types formed are () A, 3 and 4 B, 3 and 1 C, 4 2 and 2 D, 4 and 1 [Analysis] This question has three conditions: spermatogonia The number is “1”; “possible type” and “actual type”, all three are indispensable. Grab these three key points and quickly find out the correct answer C. Second, to carry out information conversion, another way to create a shortcut to thinking Example 2, a DNA molecule, the number of adenine A is 200, accounting for 20% of the total number of bases, the DNA molecule continuous recovery