Question

using light - filtering cloths, scientists exposed sage plants to four different light intensities. half of the sage plants were exposed to light for 60 days, while the other half were exposed to light for 75 days. the rate of photosynthesis in each plant was then determined (figure 1). which of the following statements best describes the data? a at 100% light intensity, the rate of photosynthesis was higher in plants that were treated for 60 days than in plants that were treated for 75 days. b at 75% light intensity, the rate of photosynthesis was unaffected by an increase in treatment time. c at 50% light intensity, the rate of photosynthesis was the same as the rate of photosynthesis at 75% light intensity, regardless of the length of treatment time. d at 25% light intensity, the rate of photosynthesis was higher in plants treated for 75 days than it was in plants treated for 60 days.

Explanation:

For option A: The bar graph shows that at 100% light intensity, the 60-day treatment bar (dark) is taller than the 75-day bar (white), so the photosynthesis rate is higher for 60 days. For option B: At 75% light intensity, the 60-day bar is taller than the 75-day bar, so treatment time affects the rate. For option C: At 50% light intensity, the bars are shorter than at 75% for both treatment times, so rates are not the same. For option D: At 25% light intensity, the 60-day bar is slightly taller than the 75-day bar, so the rate is not higher for 75 days. Thus, option A is correct.

Answer:

A. At 100% light intensity, the rate of photosynthesis was higher in plants that were treated for 60 days than in plants that were treated for 75 days.