Q43 - CAM Photosynthesis and Carbon Limitation in an Aquatic Plant
Crassula helmsii is a succesfull aquatic plant with CAM photosynthesis. In a cross-factorial study, including 2 light levels: LL and HL; and 2 CO₂ levels: LC and HC, the CAM activity of C. helmsii was measured (Fig.).
CAM activity measured as dry matter production in plants. LL and HL = low and high light, resp. LC and HC = low and high CO2, resp. (from Klavsen & Maberley 2010).
Figure 1.
Using the information and data, determine which of the statements are true or which are false.
A. CAM seems to be an adaptation to survive in waters rich in carbon
B. The circadian stomatal opening rhythm of CAM plants enables them to take up CO₂ at nighttime
C. CAM increases nighttime photorespiration
D. At LL, there is less dry matter production, because CAM plants also require light for photosynthesis
Question reproduced from IBO 2015, Theoretical Exam B, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)