Final answer:
The dependent variable in the experiment to determine the best level of light intensity for photosynthesis in an aquatic plant is the amount of gas produced by the plant. If too intense light is used, it can lead to photoinhibition, reducing photosynthesis. Factors not controlled in Gary's experiment include plant variation and environmental conditions.
Step-by-step explanation:
The dependent variable in the scientist's experiment to determine the best level of light intensity for photosynthesis in an aquatic plant is C) The amount of gas produced by the plant. Dependent variables are the outcomes or results of an experiment that are expected to change in response to the independent variable, which in this case is the level of light intensity. Since the experiment is concerned with the rate of photosynthesis, the amount of gas (commonly oxygen in the case of photosynthesis) produced is a direct measure of the photosynthetic activity and therefore serves as the dependent variable. Evaluate the claim that the experiment is based on the assumption that there is an upper limit on the intensity of light used to support growth of algae. If too great an intensity of light is used, it could lead to photoinhibition, where the photosynthetic apparatus is damaged, ultimately reducing the efficiency of photosynthesis and potentially limiting algal growth.
The variable being tested in Gary's experiment was b. the amount of water on plant growth. Factors that were not controlled in the experiment and could have had an effect on the outcome include individual plant variation, soil temperature due to different colors of containers, water loss due to evaporation from the soil, and the effect of insects which may attack one set of plants but not the other.