Hakeem is testing the effects of sunlight on samples of soil

Subject : Biology

Question: Hakeem is testing the effects of sunlight on samples of soil. Which of these actions would introduce confounding variables into Hakeem’s experiment?

A) He tests a theory that’s already been established.

B) He tests multiple hypotheses at a time.

C) He uses identical specimens when completing multiple trials.

D) He adjusts the independent variable and records the effects.

E) He uses different types of soil in each of his samples.

Expert Verified Solution:

The correct answer is:

E) He uses different types of soil in each of his samples.

Explanation:

Confounding variables are variables that the experimenter has not controlled for and that could affect the results of an experiment, leading to misleading or invalid conclusions. For Hakeem’s experiment, which aims to test the effects of sunlight on soil, the independent variable is the amount of sunlight the soil receives.

E) He uses different types of soil in each of his samples.

This action introduces confounding variables because different types of soil can have varying properties (such as moisture retention, nutrient content, and composition) that could affect the results. If the soil types are not consistent across all samples, any observed effects could be due to differences in soil type rather than the amount of sunlight, thus confounding the results.

A), B), C), and D) are not correct because:

A) Testing an established theory doesn’t introduce confounding variables; it just relates to the study’s originality.

B) Testing multiple hypotheses at a time might complicate the analysis but does not directly introduce confounding variables.

C) Using identical specimens actually helps to control variables, ensuring consistency across trials.

D) Adjusting the independent variable (sunlight) and recording effects is the correct method to assess the relationship between the independent and dependent variables.

Therefore, using different types of soil would introduce confounding variables into Hakeem’s experiment.