Control and coordination in plants — practice question

An experiment was done to find out how different blue-light intensities affect the percentage germination of barley seeds. The barley seeds were exposed to blue light for seven days. All other variables were kept the same. The findings are given in Table 9.1. The influence of blue light on the concentration of abscisic acid (ABA) was also examined. ABA concentration was recorded at intervals across seven days in barley seeds exposed to blue light with an intensity of 57 arbitrary units. The findings are given in Table 9.2. For comparison, in the dark the concentration of ABA in barley seeds decreased from $100\ \text{au}$ at the start (day 0) to $45\ \text{au}$ on day 1 and then stayed unchanged from day 1 to day 7.