Passage IV
Photosynthesis is the process by which green plants convert light energy into chemical energy. The process is shown in the generalized reaction below.
To study photosynthesis in the plant Elodea, a scientist conducted three experiments using the apparatus shown in Figure 1 below. In each experiment, the cut end of a 5-inch length of Elodea was inserted into the opening of an inverted graduated cylinder in Beaker A. All tests were conducted using a 60-watt floodlamp in a room at constant temperature. The amount of oxygen (O2) produced in the graduated cylinder, in milliliters (mL), was used as an estimate of the photosynthetic activity. The results from all three experiments are reported in Table 1.
Experiment 1
In this experiment, the effect of light intensity was studied. The distance between the floodlamp and Beaker A was varied. In each test, the amount of O2 produced after 10 minutes was recorded.
Experiment 2
In this experiment, the effect of light duration was studied. The amount of O2 produced in the graduated cylinder after various durations of light exposure was recorded.
Experiment 3
In this experiment, the effect of light color was studied. Filters of different colors were placed between Beaker A and Beaker B. Only wavelengths of light the same color as each filter could pass through the filters.
18. Based on the results of all three experiments, one can generalize that photosynthesis is influenced by which of the factors listed below?
I. Light intensity
II. Light duration
III. Light color
Your Answer is
Correct Answer is J
Explanation
The variables were controlled for all three experiments, and only one variable was changed. As a result, the oxygen produced, that is, the light and intensity, all changed. So all three factors are related