Question

1. proper soil composition is important for plants. some elements, like nitrogen, are known to increase plant growth. a researcher wants to develop a soil with added minerals and nutrients to determine the best composition to promote healthy plant growth. what are good positive and negative controls?

Explanation:

To determine positive and negative controls for the soil composition experiment:

• Positive Control: Use a soil known to promote healthy plant growth (e.g., a commercial potting mix with proven nutrients). This shows the experiment can detect growth if the new soil works.
• Negative Control: Use a soil lacking essential nutrients (e.g., sterile sand with no added minerals/nutrients). This shows no growth (or minimal growth) without proper nutrients, validating the experiment’s sensitivity to nutrient effects.

Answer:

• Positive Control: Soil with known effective nutrient composition (e.g., commercial potting mix).
• Negative Control: Soil with no added minerals/nutrients (e.g., sterile sand).