An ecology student investigated the rate of decomposition of fallen oak leaf litter by measuring the percentage of dry mass remaining over a period of 60 days.
The student used the following method:
Table 1 shows the measurements obtained at 12∘C12^\circ\text{C}12∘C:
Time (days)0102030405060Dry mass remaining (%)100989280655245\begin{array}{|c|c|c|c|c|c|c|c|} \hline \text{Time (days)} & 0 & 10 & 20 & 30 & 40 & 50 & 60 \\ \hline \text{Dry mass remaining (\%)} & 100 & 98 & 92 & 80 & 65 & 52 & 45 \\ \hline \end{array}Time (days)Dry mass remaining (%)0100109820923080406550526045
Answer the following questions:
Suggest how the student could maintain the soil at a constant temperature of 12∘C12^\circ\text{C}12∘C for the 60-day period.
State one variable, other than temperature, that the student should control to ensure a valid comparison between the two trials.
If these results are plotted on a graph with the percentage of dry mass remaining on the y-axis and Time (days) on the x-axis, describe how the curve representing the leaf litter kept at 20∘C20^\circ\text{C}20∘C would compare to the curve for 12∘C12^\circ\text{C}12∘C.