Final answer:
An appropriate hypothesis for Fiona's question is that plants given chemical fertilizer will grow more due to the higher nutrient content. The reason for having the same container size and water amount in Gary's experiment is to control variables and focus on the effects of sunshine or fertilizer on plant growth.
Step-by-step explanation:
An appropriate hypothesis for Fiona's question regarding whether plants grow more when given chemical or natural fertilizer would be, "If plants are given chemical fertilizer, then they will grow more because this kind of fertilizer has more nutrients that the plants need." This hypothesis directly addresses the research question by suggesting a measurable outcome (growth) and identifies a reason for the expected difference (nutrient content in the fertilizer).
Regarding Gary's hypothesis, choice b is a reasonable statement as it suggests a testable relationship between sunlight and plant growth. Gary might insist on the same container size for all plants, as in choice b, to minimize the effects of container size on plant growth and focus on other variables like sunshine or fertilizer. Similarly, by ensuring all plants receive the same amount of water every day, as stated in choice a, Gary can isolate the effect of sunlight on plant growth, eliminating water as a confounding variable.
Synthetic fertilizers often contain high amounts of nitrogen and phosphorus because they are essential for plant growth. However, an excess of these nutrients can cause ecological disturbances like eutrophication. In contrast, organic agricultural methods that improve soil quality can enhance biodiversity and contribute to beneficial biogeochemical cycles.