ACT Extra Credit

Name: Martin Silva-Torres Passage Amphiprion percula, a species of clownfish, are kept in many home aquariums. Two experiments were conducted to determine how diet and stocking density (number of fish per liter of seawater, fish/L) affect the specific growth rate (SGR; percent increase in length per day, percent/day) in A. percula. Experiment 1 Each of 12 identical 15 L tanks received 10 L of seawater having a salinity of 33 parts per thousand (ppt), a temperature of 27°C, and a pH of 8.2. Salinity, temperature, and pH were kept constant over the course of the experiment. A. percula of similar lengths were selected, and their lengths were measured, in cm, with a ruler. Then they were equally distributed among the tanks at a stocking density of 1 fish/L. The tanks were then divided equally into 4 groups. For 4 months, each group was fed a different diet (Diets Q–T). Each group was fed the same mass of food 3 times daily. At the end of 4 months, the length of each fish was measured, in cm, with a ruler, and the SGR of each fish was calculated. The average SGR was then determined for each group (see Table 1). Table 1 Average SGR Diet (percent/day) Q 0.30 R 0.40 S 0.50 T 0.35 Experiment 2 The procedures for Experiment 1 were repeated except that each group was kept at a different stocking density, 0.5 fish/L, 1 fish/L, 2 fish/L, or 3 fish/L, and all fish were fed Diet T. At the end of 4 months, the average SGR was determined for each group (see Table 2). Table 2 Stocking density Average SGR (fish/L) (percent/day) 0.5 0.50 1 0.35 2 0.25 3 0.20 Tables adapted from João Chambel et al., “Effect of Stocking Density and Different Diets on Growth of Percula Clownfish, Amphiprion percula (Lacepede, 1802).” ©2015 by Springer. Question 1 of 6 (highlight correct answers) Which of the following statements about the relationship between the number of A. percula per tank and the average SGR is consistent with the results of Experiment 2? On average, as the number of A. percula per tank increased, the average SGR: A)​ increased only. B)​ decreased only. C)​ remained the same. D)​varied with no general trend. Question 2 of 6 The following table gives the percent protein in each of the 4 diets. Percent Diet protein Q 52.5 R 48.0 S 41.1 T 38.1 Which of the following statements about the percent protein in each diet and the average SGR is consistent with the data shown in the table and the results of Experiment 1? The diet that resulted in the: A)​ highest average SGR also had the highest percent protein. B)​ highest average SGR had the lowest percent protein. C)​ lowest average SGR had the highest percent protein. D)​lowest average SGR also had the lowest percent protein. Question 3 of 6 Based on the results of Experiment 1, if Experiment 2 were repeated except that all the A. percula were fed Diet R, would the average SGRs more likely have been lower or higher for each group? A)​ Lower; on average, A. percula fed Diet R had an SGR 0.05 percent/day less than those fed Diet T. B)​ Lower; on average, A. percula fed Diet R had an SGR 0.10 percent/day less than those fed Diet T. C)​ Higher; on average, A. percula fed Diet R had an SGR 0.05 percent/day greater than those fed Diet T. D)​Higher; on average, A. percula fed Diet R had an SGR 0.10 percent/day greater than those fed Diet T. Question 4 of 6 Suppose that, in the experiments, 1 g of food were added to each tank at each feeding. A total of how many grams of food would have been placed into an individual tank each day? A)​ 1 g B)​ 3 g C)​ 12 g D)​36 g Question 5 of 6 How many A. percula were placed in each of the tanks in Experiment 1? A)​ 1 B)​ 4 C)​ 10 D)​16 Question 6 of 6 Which of the following was a dependent variable in Experiment 1? A)​ Volume of seawater in each tank B)​ Specific growth rate C)​ Diet fed to the A. percula D)​Stocking density of the A. percula