[Campbell Biology P.259] In C3 plants, what primary condition leads to photorespiration, and... | Practice Question

In C3 plants, what primary condition leads to photorespiration, and what is Rubisco's role in this process?

  • A: Abundant CO2 causes Rubisco to bind O2, leading to photorespiration.
  • B: Hot, dry conditions cause stomata to close, increasing O2 and decreasing CO2, prompting Rubisco to bind O2 instead of CO2.
  • C: High light intensity causes Rubisco to switch its substrate from CO2 to O2.
  • D: Low temperatures enhance Rubisco's affinity for O2 over CO2.

Explanation

As described in Concept 10.5, on dry, hot days, C3 plants close their stomata to conserve water. This closure leads to a decrease in internal CO2 concentration and an increase in O2 concentration. Under these conditions, Rubisco, the enzyme normally responsible for fixing CO2, binds O2 instead, leading to photorespiration.