[Campbell Biology P.253] Based on the text, how would rising atmospheric CO2 concentrations ... | Practice Question

Based on the text, how would rising atmospheric CO2 concentrations and increasing global temperatures likely affect the relative abundance of C3 and C4 plants in a given plant community?

  • A: Both C3 and C4 plants would equally benefit, leading to no change in relative abundance.
  • B: C3 plants would decrease due to increased photorespiration, while C4 plants would increase.
  • C: C3 plants would be favored by rising CO2 due to reduced photorespiration, but rising temperatures would negatively affect them; C4 plants would be largely unaffected. This suggests a complex and variable change in balance depending on the specific combination of CO2 and temperature.
  • D: C4 plants would be outcompeted by C3 plants under all new conditions.

Explanation

The text explains that rising CO2 benefits C3 plants by reducing photorespiration, while rising temperatures increase photorespiration for C3. C4 plants, however, are largely unaffected by these changes. This complex interplay means the balance between C3 and C4 plants in communities will vary depending on the specific combination of CO2 concentration and temperature.