Q48 - CO2 and Temperature Effects on C3 versus C4 Photosynthesis
Plants have different photosynthetic systems. Most plants have the C3 system, but others, especially grasses, have a C4 system. The two systems show different photosynthetic rate, when CO2 and ambient temperature vary (Fig.). Photosynthetic rate (A) and expected dominance (B) of C3 and C4 plants as a function of ambient CO2 level and temperature.
Figure 1.
Using the information and data, determine which of the statements are true or which are false.
A. The proportion of C4-plant species increases towards the poles
B. At current atmospheric CO2 levels, CO2 is limiting the growth of both C3- and C4-plants
C. The predicted CO2-increase can be more advantageous to C4- than C3-plants
D. In dry and warm regions during the last glacial period, C4-plants were probably more widespread
Question reproduced from IBO 2015, Theoretical Exam A, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)