Why Might Rubisco Have Evolved with an Inability to Distinguish

Multiple Choice

Why might Rubisco have evolved with an inability to distinguish between CO₂ and O₂?

A) Rubisco may have evolved at a time when atmospheric O₂ levels were virtually nonexistent.
B) Rubisco may have evolved at a time when atmospheric CO₂ levels were virtually nonexistent.
C) Rubisco evolved when atmospheric O₂ levels were high.
D) Rubisco possesses four subunits.
E) Rubisco denatures due to photorespiration.