Question

1. scientific claims should be questioned if

a) peer review was used to examine the claims made by scientists
b) the experimental results cannot be repeated by other scientists
c) conclusions follow logically from the evidence
d) the data are based on samples that are very large

1. base your answer to the following question on the information below and your knowledge of biology.

ulcers: mystery solved
stomach ulcers are painful sores that develop in the stomach. doctors once thought that ulcers were caused by stress. in the 1980s, a pair of physicians, barry j. marshall and j. robin warren, questioned the cause of ulcers. they found the bacterium helicobacter pylori in the ulcer tissue of their patients. even though they repeatedly presented their findings to colleagues, they were ignored until marshall performed an astonishing experiment: he drank broth containing the bacteria and made himself sick with an ulcer! he then cured himself by taking an antibiotic.
the results were published in 1985, but it took another 10 years for doctors to regularly use antibiotics to treat ulcers. marshall and warren received a nobel prize in 2005 for this discovery.
the work of marshall and warren shows that
a) hypotheses made by physicians are always correct
b) scientific explanations are revised based on new evidence
c) peer review always leads to the immediate acceptance of results
d) conclusions must always be consistent with those made by other scientists

1. base your answer to the following question on the information below and on your knowledge of biology.

a student designed an experiment to determine if air temperature had an effect on the rate of photosynthesis in corn plants.
the independent variable in this experiment is the
a) air temperature at which the corn plants were grown
b) amount of carbon dioxide used by the corn plants
c) volume of oxygen produced by the corn plants
d) number of corn plants used

1. the development of an experimental research plan should not include a

a) list of safety precautions for the experiment
b) list of equipment needed for conducting the experiment
c) procedure for the use of technologies needed for the experiment
d) conclusion based on data expected to be collected in the experiment

1. researchers performing a well-designed experiment should base their conclusions on

a) the hypothesis of the experiment
b) data from repeated trials of the experiment
c) a small sample size to insure a reliable outcome of the experiment
d) results predicted before performing the experiment

Explanation:

Question 1

To determine when scientific claims should be questioned, we analyze each option:

• Option A: Peer review is a standard way to validate scientific claims, so this is not a reason to question them.
• Option B: If experimental results cannot be repeated by other scientists, the claim's validity is questionable as reproducibility is key in science.
• Option C: If conclusions follow logically from evidence, the claim is well - supported, not a reason to question.
• Option D: Large sample sizes generally make data more reliable, not a reason to question.

We analyze the story of Marshall and Warren's work on ulcers:

• Option A: The fact that their initial findings were ignored shows hypotheses aren't always correct.
• Option B: Doctors originally thought ulcers were from stress, but new evidence (Marshall and Warren's work) led to a revised explanation (ulcers from bacteria, treated with antibiotics), so scientific explanations are revised based on new evidence.
• Option C: Their results were published in 1985 but took 10 years to be accepted, so peer review doesn't always lead to immediate acceptance.
• Option D: Their conclusions were not consistent with previous ones at first, so conclusions don't have to always match others.

In an experiment, the independent variable is the one that is manipulated. The experiment is to determine the effect of air temperature on photosynthesis in corn plants.

• Option A: Air temperature is what the student would manipulate to see its effect on photosynthesis, so it's the independent variable.
• Option B: The amount of carbon dioxide used is a dependent variable (depends on photosynthesis rate, which is affected by temperature).
• Option C: The volume of oxygen produced is also a dependent variable (depends on photosynthesis rate).
• Option D: The number of corn plants is likely a controlled variable, not the independent variable.

Answer:

B. the experimental results cannot be repeated by other scientists

Question 2