Final answer:
An experiment can be conducted to test the effect of day length on plant growth. By comparing the growth of plants under different day lengths and measuring the size of the stem and weight, the hypothesis can be tested. The experimental group exposed to longer day length and the control group exposed to regular day length will help determine the effect of day length on plant growth.
Step-by-step explanation:
To test the hypothesis that plants grow more when the day is longer, an experiment can be conducted by comparing plant growth under different day lengths. The independent variable is the day length, with two levels: longer and shorter days. The dependent variable is the amount of plant growth, which can be measured by the size of the stem and weight. The experimental group will be exposed to permanent artificial LED daylight, while the control group will be exposed to regular daylight. The plant growth of both groups will be compared to determine the effect of day length on plant growth.
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