Photosynthesis as an energy transfer process — practice question

Scientists are looking for new methods to lower the concentration of carbon dioxide ($\text{CO}_2$) in the global atmosphere. There is concern that a rising atmospheric $\text{CO}_2$ concentration could cause changes that reduce biodiversity. Algae are aquatic photosynthetic protoctists. Some researchers genetically altered the unicellular alga, $\textit{Chlorella vulgaris}$, in an attempt to raise the rate of the light independent stage of photosynthesis. $\textit{C. vulgaris}$ was changed so that the gene coding for aldolase was expressed more strongly. Aldolase is an enzyme that increases the concentration of rubisco. Two cultures of $\textit{C. vulgaris}$, one genetically unmodified (unmodified) and one genetically modified, were grown under controlled conditions for 14 days. At regular intervals during the 14 days, samples were removed from the cultures to measure dry mass. The results are shown in Fig. 2.1.