Students in a science class investigated the conditions under which corn seeds would germinate most successfully. They set up an experiment in which 10 corn seeds were placed on moist paper towels in each of four identical glass dishes. Two dishes were left uncovered; the other two were covered with a transparent plastic wrap in which a number of holes had been poked (Figure 1, below). Figure 1. Uncovered and Covered Dishes Open Top Corn Seeds Moist Paper Towel Plastic Wrap with Holes Corn Seeds Moist Paper Towel Two of the dishes, one covered and one uncovered, were placed in a dark room. The other two dishes were placed in a well-lighted room. Both rooms were kept at 25°C. The students observed the seeds each day and recorded the number that had germinated. Results are shown in Figure 2. Number Germinated Figure 2. Seed Germination under Four Experimental Conditions 101. Dark, Covered 8 II. Light, Covered III. Dark, Uncovered -IV. Light, Uncovered 34 Based on the results, which of these factors appears most important for successful corn seed germination? High temperature K High humidity L High amount of light M High level of oxygen 35 A student was concerned that the results might have been altered because the seeds were disturbed by the daily observations. If true, which dishes would probably have been most affected? A Dishes I and II (both covered dishes) B Dishes III and IV (both uncovered dishes) C Dishes I and III (both dishes in dark) D Dishes II and IV (both dishes in light) 36 The students wanted to obtain additional information about the effects of light on corn seed germination. They prepared four covered dishes like the one shown in Figure 1. Which of these placements of the dishes would provide the most useful information about the effects of light? J Place all four dishes in a well-lighted room. K Place two dishes in a dark room and two dishes in a well-lighted room. L Place one dish in a dark room and three dishes in a well-lighted room. M Place one dish in a dark room and three dishes in differently lighted, separate rooms. 37 Based on the results, which of these statements best describes the effect that light appeared to have on successful corn seed germination? A A positive effect; light triggered the start of germination. B A positive effect; light sped up the metabolism of the germinating seed. C A negative effect; light made the moisture in the dishes evaporate more quickly. D A negative effect; light caused the seeds to heat up too much. 38 on Day 4, the following outcome was observed by the students. Mold appeared on the paper towels in Dishes I and II, but not on the paper towels in Dishes III and IV. If no holes had been poked in the plastic wrap on the covered dishes (I and II), would this outcome have been affected? JYes; mold would have appeared before Day 4. K Yes; mold would have appeared after Day 4. L Yes; mold would not have appeared at all. M No. 0 2 4 5 Day of Experiment - IV