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系谱法是进行人类单基因遗传病分析的传统方法。通常系谱图中必须给出的信息包括：性别、性状表现、______、______以及每一个体在世代中的位置。如果不考虑细胞质中和Y染色体上的基因，单基因遗传病可分成4类，原因是致病基因有______之分，还有位于______上之分。
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人类遗传病一般可以分为单基因遗传病、多基因遗传病和______遗传病。多基因遗传的发病除受遗传因素影响外，还与______有关，所以一般不表现典型的______分离比例。
在系谱图记录无误的情况下，应用系谱法对某些系谱图进行分析时，有时得不到确切结论，因为系谱法是在表现型的水平上进行分析，而且这些系谱图记录的家系中______少和______少。因此，为了确定一种单基因遗传病的遗传方式，往往需要得到______，再进行合并分析。
气候变化与生态系统的碳循环密切相关。下表为A、B两个不同时期陆地生态系统与大气环境的碳交换情况。 时期 碳吸收量(kgC·a-1) 碳释放量(kgC·a-1) A B 1.20×1014 1.20×1014 1.20×1014 1.26×1014 表中______时期的生态系统处于稳定状态，原因是______。
Passage Two We can begin our discussion of "population as global issue" with what most persons mean when they discuss "the population problem": too many people on earth and a too rapid increase in the number added each year. The facts are not in dispute; it was quite right to employ the analogy that likened demographic growth to "a long, thin powder fuse that burns steadily and haltingly until it finally reaches the charge and explodes". To understand the current situation, which is characterized by rapid increases in population, it is necessary to understand the history of population trends. Rapid growth is a comparatively recent phenomenon. Looking back at the 8,000 years of demographic history, we find that populations have been virtually stable or growing very slightly for most of human history. For most of our ancestors, life was hard, often nasty, and very short. There was high fertility in most places, but this was usually balanced by high mortality. For most of human history, it was seldom the case that one in ten persons would live past forty, while infancy and childhood Were especially risky periods. Often, societies were in clear danger of extinction because death rates could exceed their birthrates. Thus, the population problem throughout most of history was how to prevent extinction of the human race. This pattern is important to notice. Not only does it put the current problems of demographic growth into a historical perspective, but it suggests that the cause of rapid increase in population in recent years is not a sudden enthusiasm for more children, but an improvement in the conditions that traditionally have caused high mortality. Demographic history can be divided into two major periods: a time of long, slow growth which extended from about 8000 B.C. till approximately 1650 A.D. In the first period of some 9,600 years, the population increased from some 8 million to 500 million in 1650. Between 1650 and 1975, the population has increased from 500 million to more than 4 billion. And the population reached 6.2 billion throughout the world by the year 2000. One way to appreciate this dramatic difference in such abstract numbers is to reduce the time frame to something that is more manageable. Between 8000 B.C. and 1650, an average of only 50,000 parsons was being added annually to the world’s population. At present, this number is added every six hours. The increase is about 80,000,000 persons annually. The word "demographic" (Line 4, Para. 1) means ______.
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