问题 单项选择题

有人曾对日本的胃癌进行过移民流行病学调查研究,发现胃癌在日本高发,在美国低发。在美国出生的第二代日本移民胃癌的死亡率高于美国人,但低于日本国内的日本人,说明()

A.环境因素对胃癌的发生有较大关系

B.遗传因素对胃癌的发生有较大关系

C.遗传和环境交互作用

D.很难判断

E.以上均不正确

答案

参考答案:A

解析:此题是理解判断题,考查考生对移民流行病学的理解。移民流行病学是对移民人群的疾病分布进行研究,以探讨病因。它是通过观察疾病在移民、移民移入国当地居民及原居住地人群间的发病率、死亡率的差异,从其差异中探讨病因线索,区分遗传因素或环境因素作用的大小。若环境因素是引起发病率、死亡率差别的主要原因,则移民中该病的发病率及死亡率与原居地人群的发病率或死亡率不同,而与移居地当地居民人群的发病率及死亡率相近。若遗传因素主要是对发病率及死亡率起作用,则移民的发病率及死亡率不同于移居地,而与原居地人群的频率相同。

单项选择题
阅读理解

第三部分 阅读理解(共20小题;每小题2分,满分40分)

Will it matter if you don't have your breakfast ? A short time ago , a test was given in the United States. People of different ages, from 12 to 83, were asked to have a test . During the test , these people were given all kinds of breakfasts , and sometimes they got no breakfast at all. Scientists wanted to see how well their bodies worked when they had different kinds of breakfasts.

The rules show that if a person eats a right breakfast , he or she will work better than if he or she has no breakfast. If a student has fruit , eggs, bread and milk before going to school ,he or she will learn more quickly and listen more carefully in class.

The result is opposite to what some people think . Having no breakfast will not help them lose weight . This is because they are so hungry at noon that eat too much for lunch . They will gain weight instead of losing it . You will lose weight if you reduce your other meals.

56. During the test , the people were given _________.

A. no breakfast at all          B. different breakfast or sometimes none

C. very rich breakfast         D. little food for breakfast

57. Scientists wanted to know whether __________.

A. breakfast had any effect on work and studies.   B. people were interested in breakfast

C. breakfast did harm to people 's health   D. people would work better without breakfast

58. According to the passage , some people think without breakfast they will ____

A. lose weight      B. get a good result in their work

C. gain weight      D. not be hungry at all.

59. Which of the following sciences is not right?

A. It is bad for your health to have no breakfast.

B. No breakfast and more lunch may make you fatter.

C. The more breakfast you have, the more quickly you will learn in class.

D. If you don't eat much for lunch and supper , you may lose weight.