Question

1. maggie read that some plants grow better if the soil is acidic. she puts potting soil in two planting containers and transplants two of her geraniums that seem about the same size into the pots. she puts the pots in the same location so that they both get the same amount of sunlight each day and are at the same temperature. she also makes sure they get the same amount of water. however, maggie puts a tablespoon of vinegar, a household acid, in the water she gives to one of the plants. she measures the growth of the plants every week for five weeks and records the results in a data table. which of the following is the independent/manipulated variable in the experiment?

the length of time for the experiment
the growth of the plants
the acidity of the water
the sunlight

Explanation:

To determine the independent variable, we analyze the experiment: Maggie is testing if acidic soil affects plant growth. She manipulates the acidity of the water (by adding vinegar to one plant's water) while keeping other factors (sunlight, time, water amount) constant. The independent variable is the factor changed to observe its effect on the dependent variable (plant growth).

• The length of time for the experiment is a controlled duration, not manipulated to test its effect.
• The growth of the plants is the dependent variable (what's being measured).
• The sunlight is kept constant, so it's a controlled variable.
• The acidity of the water is what Maggie changes (adds vinegar to one, not the other) to see its impact on plant growth, so it's the independent variable.

Answer:

the acidity of the water