[Campbell Biology P.252] Based on the provided text, why is photorespiration considered an '... | Practice Question

Based on the provided text, why is photorespiration considered an 'apparently wasteful process' for plants, particularly C3 plants, in hot, dry conditions?

  • A: It consumes ATP, produces no sugar, decreases photosynthetic output, and releases CO2 that was previously fixed.
  • B: It leads to excessive water loss from the plant, causing dehydration.
  • C: It converts CO2 into a toxic compound, harming the plant's metabolic processes.
  • D: It primarily occurs in the dark, wasting the energy collected during the light reactions.

Explanation

The text describes photorespiration as 'energetically costly, much like a hamster running on its wheel' because it consumes ATP, unlike normal cellular respiration, it produces no sugar, and it decreases photosynthetic output by siphoning organic material from the Calvin cycle and releasing CO2 that would otherwise be fixed. These factors collectively make it a wasteful process.