Question

8. Jake conducted an experiment with four bean plants.

They were placed next to one another on a sunny
windowsill. He gave each plant equal amounts of a
different type of water. The plants were given tap water.
distilled water, flavored water, or carbonated water. He
made the following observations after three weeks.

Based on his results. Jake concluded that tap water is not
good for plants. How can Jake change his experimental
design to improve the validity of his results?
A. carry out multiple trials, and increase the number of
plants that are given each type of water
B. establish a control group that includes different types of
plants
C. establish another dependent variable to generate more
data
D. carry out multiple trials that include fewer plants, and
increase the types of water given to the plants

Answer 1

To improve the validity of Jake's experimental results on the effects of tap water on plants, he should carry out multiple trials and increase the number of plants for each type of water. Adding a control group and controlling for other variables is also crucial to isolate the effect of the water type and ensure a reliable conclusion. Therefore, the correct way to improve the experimental design is option A: carry out multiple trials, and increase the number of plants that are given each type of water.

Step-by-step explanation:

To improve the validity of the results in Jake's experiment where he concluded that tap water is not good for plants, he can take the following steps:

• Carry out multiple trials, which would provide a more reliable set of data by reducing the likelihood that results are due to chance.
• Increase the number of plants that are given each type of water to reduce the individual plant variation effect and obtain a more accurate average response for each treatment.
• Have a control group that receives no treatment or a standard treatment for comparison. This would help determine if the tap water is indeed having a negative effect compared to a baseline.
• Control for other variables such as soil, container size, amount of sunlight, and temperature—all of which can influence plant growth—to isolate the effect of the type of water used.

It should be noted that establishing another dependent variable (option C) might provide more insight but would not necessarily improve the validity concerning the type of water used. Moreover, increasing the types of water and reducing the number of plants (option D) could introduce more variables and further complicate the analysis. Option B, while helpful for a broader study, does not directly address the validity of the conclusions about tap water's effects.