Final answer:
Fertilizer is a material that provides essential nutrients to plants, commonly containing macronutrients like nitrogen, phosphorus, and potassium, which are crucial for plant growth. In an experiment with plants, the varying amounts of fertilizer used can serve as the independent variable to study its effect on plant growth.
Step-by-step explanation:
In the context of the student's question, fertilizer is a substance that is added to soil to supply one or more essential nutrients to the growth of plants. Fertilizers can be of natural or synthetic origin and include key macronutrients like nitrogen, phosphorus, and potassium, which are crucial for plant health. In an experimental setup where plants are given equal amounts of water and sunlight, but varying amounts of fertilizer, the fertilizer serves as the independent variable, which is the factor that the scientist changes to observe the effects on plant growth.
Essential Nutrients for Plants
Plants require a variety of essential nutrients to thrive, including macronutrients like carbon, nitrogen, hydrogen, oxygen, phosphorus, potassium, calcium, magnesium, and sulfur. These nutrients are commonly found in fertilizers and are vital for various plant processes, including growth, photosynthesis, and reproduction.
Fertilizers also can improve soil's physical properties, such as water retention and aeration, thereby enhancing the soil's overall ability to support plant life.