Question 1

A scientist wants to test whether a new drug reduces the duration of cold symptoms. She randomly assigns 100 volunteers with colds to two groups: one receives the drug, and the other receives a placebo. What is the independent variable in this experiment?

Accepted Answer

Whether the volunteer receives the drug or placebo

Question 2

Which of the following best describes a scientific hypothesis?

Accepted Answer

A testable explanation for a question or problem

Question 3

A researcher is studying the effect of stress on susceptibility to colds. She finds a strong correlation between high stress levels and increased frequency of colds. What does this result mean?

Accepted Answer

People with high stress are more likely to get colds, but causation is not proven

Question 4

Which of the following is an example of a double-blind experiment?

Accepted Answer

Neither the subjects nor the researchers know which group receives the treatment

Question 5

A botanist grows 50 plants under different amounts of artificial light for 60 days, keeping all other conditions constant. At the end, she measures the size of each leaf. What is the dependent variable?

Accepted Answer

Size of each leaf

Question 6

Why do scientists use large sample sizes in experiments?

Accepted Answer

To reduce the impact of random variation and increase statistical significance

Question 7

Which of the following is a testable hypothesis?

Accepted Answer

Drinking green tea daily reduces the risk of catching a cold

Question 8

A clinical trial tests a new medication for high blood pressure. The results show a p-value of $0.03$. What does this mean in terms of statistical significance?

Accepted Answer

There is a 3% chance the results are due to random variation

Question 9

Which of the following best describes a cohort study?

Accepted Answer

Comparing lifetime exposure to a risk factor in a group and following them over time for disease incidence

Question 10

A scientist claims that eating more fruits and vegetables reduces the risk of heart disease. Which type of study would best test this claim?

Accepted Answer

A randomized controlled trial

Question 11

Which of the following is a reason why a result may be statistically significant but not practically significant?

Accepted Answer

The effect size is very small and unlikely to have real-world impact

Question 12

A researcher wants to minimize bias in assigning subjects to experimental and control groups. Which method should she use?

Accepted Answer

Random assignment

Question 13

Which of the following is a limitation of correlational studies?

Accepted Answer

They cannot establish causation between variables

Question 14

A study finds a p-value of $0.08$ when comparing two treatments. What should the researcher conclude?

Accepted Answer

The difference is not statistically significant at the $0.05$ level

Question 15

Which of the following is the best example of a control group in an experiment testing a new fertilizer's effect on plant growth?

Accepted Answer

Plants grown without the new fertilizer

Question 16

Why is peer review important in scientific research?

Accepted Answer

It helps ensure the validity and reliability of scientific findings before publication

Question 17

A newspaper reports that a new study found a strong correlation between eating chocolate and intelligence. What is a critical limitation of this report?

Accepted Answer

Correlation does not imply causation

Question 18

Which of the following is a characteristic of a good scientific theory?

Accepted Answer

It is supported by a large amount of experimental evidence

Question 19

A scientist is testing the hypothesis that a certain gene increases the risk of diabetes. Which of the following would be the best experimental design?

Accepted Answer

Compare diabetes rates in individuals with and without the gene, controlling for other risk factors

Question 20

Which of the following best defines a sample in statistics?

Accepted Answer

A small subgroup of a population to be studied

The Scientific Method and Experimental Design in Biology

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