AZSCI Planning Investigations 2

Question 1

A student plans to investigate the effect of different types of soil on the growth rate of a specific bean plant. To ensure the experiment is a 'fair test,' they use identical pots, the same amount of water, and equal exposure to sunlight for all plants. However, they unknowingly source their 'sandy soil' from a location with high pesticide runoff. Which scientific concept does this oversight primarily introduce into the investigation?

Accepted Answer

A confounding variable

Answer

A confounding variable is an unmeasured third variable that influences the relationship between the independent (soil type) and dependent (growth rate) variables. In this case, the pesticide in the sandy soil, not just its texture, could affect plant growth, making it impossible to determine the true effect of the soil type alone. This confounds the results. The other options are less relevant; it's not a measurement error, a larger sample size wouldn't fix the hidden variable, and it's not an ethical issue in this context.

Question 2

A research team wants to study the long-term effects of a new, potentially life-saving but high-risk medication on a rare genetic disorder. Which of the following investigation plans is most appropriate and ethically sound, given the circumstances?

Accepted Answer

A retrospective observational study analyzing the health records of patients who have already been treated with the medication for other reasons.

Answer

Given the high-risk nature of the medication and the rarity of the disorder, a randomized controlled trial that involves giving a placebo or no treatment to a control group could be unethical if it withholds a potentially life-saving drug. Intentionally exposing healthy individuals is also unethical. A retrospective observational study is the most ethical starting point, as it uses pre-existing data and does not involve manipulating patient treatment or exposing them to unnecessary risk.

Question 3

A student conducts a preliminary, small-scale investigation (a pilot study) to test the feasibility of their experimental design for a larger project. The pilot study yields unexpected, inconclusive results. What is the most scientifically productive next step?

Accepted Answer

Refine the procedure, variables, or data collection methods based on the pilot study's outcome before starting the main investigation.

Answer

The primary purpose of a pilot or preliminary study is to test and refine the methodology of an investigation. Inconclusive or unexpected results are valuable because they highlight potential problems with the experimental design, such as issues with measurements, uncontrolled variables, or feasibility. The most productive step is to use this information to improve the plan for the main experiment, ensuring that the time and resources for the larger study are used effectively.

Question 4

Which of the following scenarios describes a situation where an observational study is more appropriate than a controlled experiment?

Accepted Answer

Investigating the correlation between daily sun exposure and the incidence of skin cancer in a human population over 20 years.

Answer

It would be unethical and impractical to conduct a controlled experiment where a group of people is intentionally exposed to high levels of sun for 20 years to see if they develop cancer. An observational study, such as a longitudinal cohort study, allows researchers to gather data on naturally occurring behaviors and outcomes without assigning a harmful intervention. The other scenarios can all be ethically and practically investigated using controlled experiments.

Question 5

A student is planning an investigation into the insulating properties of different materials. They plan to wrap beakers of hot water with wool, cotton, and aluminum foil and measure the temperature change over 30 minutes. Which of the following represents the most critical refinement to this initial plan?

Accepted Answer

Including a fourth beaker with no wrapping to serve as a control group.

Answer

While all the other options are good scientific practices, the most critical omission in the initial plan is a control group. A beaker with no insulation serves as the baseline to which the other materials can be compared. Without it, the student can see which material insulates best relative to the others, but they cannot determine how effective any of them are compared to having no insulation at all. The control is fundamental to interpreting the effect of the independent variable (the insulating material).

(AZSCI) Arizona Science Test Practice Test

(AZSCI) Arizona Science Test Practice Test

AZSCI Planning Investigations 2