阅读材料,回答题。
High Blood Pressure
There is evidence that the usual variety of high blood pressure is,in part,a familial disease.Since families have similar genes as well as similar environment,familial diseases could be due to shared genetic influences,to shared environmental factors,or to both.For some years,the role of one environmental factor commonly shared by families,namely dietary salt,has been studied at Brook—haven National Laboratory.These studies suggest that chronic excess salt ingestion(摄取)can lead to high blood pressure in man and animals.Some individuals,however,and some rats consume large amounts of salt without developing high blood pressure.No matter how strictly all environmental factors were controlled in these experiments,some salt-fed animals never develop hypertension(高血压)whereas a few rapidly developed very severe hypertensions followed by early death.These marked variations were interpreted to result from differences in genetic constitution.
By mating in successive generations only those animals that failed to develop hypertension from salt ingestion,a resistant strain(the R strain)has been evolved in which consumPtion of large quantities of salt fails to influence the blood pressure significantly.In contrast,by mating only animals that quickly develop hypertension from salt,a sensitive strain(the S strain)has also been developed.
The availability of these two strains permits investigations not therefore possible.They provide a plausible laboratory model on which to investigate some clinical aspects of the human developing methods by which genetic susceptibility(敏感性)of human beings to high blood pressure can be defined without waiting for its appearance.
The main idea of this passage is__________. 查看材料
A.Genetic constitution,or hereditary factor is all important factor that may underlie hypertension
B.Excessive use of salt may cause high blood pressure
C.Shared environmental factors may lead to familial disease
D.There are two different kinds of strains in animals which cause their different reactions to excess salt ingestion
第1题
A.Shared environmental factors can cause hypertension
B.Dietary salt can lead to high blood pressure in man and animals
C.Some rats not some individuals do not develop high blood pressure by consuming large amounts of salt
D.High blood pressure can be developed as a result of too much consumption of dietary salt
第2题
A.quantities of salt consumed
B.choice of mating partner
C.blood pressure
D.reaction to salt
第3题
A.Scientists engaged in the experiments
B.Investigations made by people
C.The resistant strain and the sensitive strain
D.The availability of the two strains
第4题
A.The experiments show that salt ingestion does not necessarily cause animals to develop hypertension bypretension with the environmental factors being equal.
B.Dietary salt is harmful to human being"s health.
C.Human beings" high blood pressure will never be easily put under control.
D.In order not to develop hypertension, man should consume chemically pure salt.
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