【島根大（医）】次の文は，The Process of Science というタイトルで書かれた文章の一部です．よく読んで以下の設問に答えなさい．

Science helps human beings understand the natural world.

Science aims to beobjective rather than subjective, even though it is very difficult to make objective
observations and to come to objective conclusions because we are often influenced by ourown particular prejudices. Still, scientists strive for objective observations and conclusions.
We also keep in mind that scientific conclusions are subject to change whenever new findings
dictate so.

Quite often in science, new studies, which might utilize new techniques andequipment, tell us when previous conclusions need to be modified or changed entirely.

The Scientific Method Has (1)Steps
Scientists, including biologists, employ an approach to gathering information
known as the scientific method.

The approach of individual scientists to their work is asvaried as they themselves; still, for the sake of discussion,
it is possible to speak of the scientific method as
consisting of certain steps.

AAfter making initialobservations, a scientist will most likely study any

Bprevious data, which are facts pertinent to the matter athand.

Imagination and creative thinking also help ascientist formulate a hypothesis that becomes the basis
for more observations and/or experimentation.

Thenew data help a scientist come to a conclusion that either
supports or does not support the hypothesis.

-1-Because

CD

Figure 1: A Controlled
Laboratory Studyhypotheses are always subject to modification, they can never be proven true; however, they
can be proven untrue.

When the hypothesis is not supported by the data, it must berejected; therefore, some think of the body of science as what is left after alternative
hypotheses have been rejected.
When scientists are doing a study, they often perform experiments in the laboratory
where conditions can be kept constant.

In (2)the experiment discussed next, physiologists

are trying to determine if sweetener S is a safe food addictive.
On the basis of available information, the physiologists formulate a hypothesis thatsweetener S is a safe food addictive even when 50% of the diet is sweetener S.

If so, mice

whose diet contains 50% sweetener S should suffer no ill effects.

HYPOTHESIS: Sweetener S is a safe food addictive.
PREDICTION: If mice are fed a diet that contains 50% sweetener S,
there will be no effect on health.

In this study, the scientists decide on the following experimental design.

They use

a control group, which goes through all the steps of an experiment but lacks the factor being
tested, in order to ensure that their results are due to this factor.

Test group: 50% of diet is sweetener S.
Control group: Diet contains no sweetener S.

To help ensure that conditions for the two groups are identical, the researchers placea certain number of randomly chosen genetically similar mice into the various groups, say,
100 mice per group. If any of the mice are different from the others, it is hoped that random
selection has distributed them evenly among the groups.

The researchers also make surethat all conditions, such as availability of water, cage set-up, and temperature of the-2-

surroundings, are constant for both groups.
except for (3).

The food for each group is exactly the same

After several weeks, both groups of mice are examined for bladdercancer. Let’s suppose that one-third of the mice in the test group are found to have bladdercancer, while none in the control group have bladder cancer.

The results of this experiment

do not support the hypothesis that sweetener S is a safe food addictive when 50% of the dietis sweetener S.

CONCLUSION: The hypothesis is not supported.
Sweetener S is not a safe food addictive
when the diet is 50% sweetener S.

These results cause the scientists to believe that sweetener S may be less harmful if
the diet contains less amount. So, they decide to do (4)another experiment.

（Mader 著”Human Biology”より．
）

設問 1．Figure 1 は下線(1)の内容を示します．A～D に当てはまる語句を文中から選んで書き入れなさい．

設問 2．設問 1 の答にそって，下線(2)の内容を説明しなさい．（200 字以内）
設問 3．文中の（ 3 ）に入る英語の語句を記しなさい．
設問 4．Control group が必要な理由を述べなさい．（200 字以内）
設問 5．下線(4)の内容を考えなさい．（50 字以内）
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