Two studies were done to examine how the proportion of vermicompost (feces from earthworms) in a particular potting soil affects the yield of each of 2 plant species: Solanum lycopersicum (a tomato plant) and Capsicum annuum (a pepper plant). The yield of a plant species is the mass of fruit produced per plant of the species.
Six different mixtures (Mixtures 1-6) were prepared according to the percents listed in Table 1
Equal amounts of Mixtures 1-6 were distributed among thirty-six 2 L pots in the following manner: 1.5 kg of Mixture 1 was put into each of 6 pots, 1.5 kg of Mixture 2 was put into each of 6 other pots, 1.5 kg of Mixture 3 was put into each of 6 other pots, and so on. Then, 3 S. lycopersicum seeds were added to each pot. For the next 158 days, all the pots received equal amounts of water and light. On Day 28 of the 158 days, all the seedlings that had emerged were removed from the pots with the exception of a single seedling in each pot. On Day 158, the yield of the remaining plant in each pot was measured. The average yield of the plants grown in each mixture was then calculated. The results are shown in Figure 1.
The procedures of Study 1 were repeated, except that 5 C. annuum seeds instead of 3 S. lycopersicum seeds were added to each pot, the pots received water and light for
149 days instead of 158 days, seedling removal occurred on Day 42 of the 149 days, and plant yield was measured on Day 149. The results are shown in Figure 2.
1. In both studies, as the percent by volume of vermicompost increased from 0% through 100%, the average yield:
2. In Study 1, which of the following mixtures was most likely intended to serve as a control for the effect of vermicompost on plant yield?
3. Suppose that in Study 1, average yield had been calculated in kilograms per plant (kg/plant) instead of g/plant. The average yield for Mixture 5 would have been:
4. Which of the factors listed below were the same in Study 2 as they were in Study 1 ?
5. Is the statement "Tomato plants require a lower proportion of vermicompost in the potting soil to achieve maximum yield than do pepper plants" consistent with the results of Studies 1 and 2 ?
6. In a 2 L pot, the presence of more than one plant can negatively affect the growth of all the plants in the pot, due to competition among the plants. What action was taken in the studies to prevent competition among the plants?
7. S. lycopersicum and C. annuum required water and light for the process represented by which of the following expressions?
1. The correct answer is D.
According to Figure 1, as the percent vermicompost increased, the average yield for S. lycopersicum increased and then decreased. Figure 2 shows that as the percent vermicompost increased, the average yield for C. annuum also increased and then decreased.
2. The correct answer is A.
According to Table 1, Mixture 1 had 0% compost. This mixture would serve as a control so that the scientists could determine the effect that vermicompost had on the yield.
3. The correct answer is B.
In order to answer this item, you must know how to convert units. According to Figure 1, in Study 1, the average yield for Mixture 5 was 3,500 g/plant. This is equal to 3,500 g/plant × 1,1 k 000g g = 3.5 kg/plant.
4. The correct answer is B.
According to the passage, both studies used thirty-six 2 L pots. The type and number of seeds used in each study was different, and the amounts of time that the plants were allowed to grow were different. The number of pots used per mixture and the volume of each pot were the same in both studies.
5. The correct answer is A.
According to Figure 1, S. lycopersicum, a tomato plant, had its greatest average yield in Mixture 2, which was 20% vermicompost. According to Figure 2, C. annuum, a pepper plant, had its greatest average yield in Mixture 3, which was 40% vermicompost. The statement is consistent with the results of the studies.
6. The correct answer is D.
According to the passage, in Study 1, after 28 days all the seedlings except 1 were removed from each pot. In Study 2, the seedlings were removed after 42 days.
7. The correct answer is D.
In order to answer this item, the examinee must know the overall chemical reaction for photosynthesis. Carbon dioxide, water, and sunlight are used to produce oxygen and glucose.