Question

When rubisco binds to oxygen, the net result is a reversal of the light reactions, leading to:

a) Increased carbon fixation
b) Increased glucose synthesis
c) Photorespiration
d) Enhanced ATP production
e) Accelerated electron transport

Answer 1

c) Photorespiration. When rubisco binds to oxygen instead of carbon dioxide, it results in photorespiration, a wasteful pathway that conserves water but reduces carbon fixation and overall photosynthetic efficiency.

Step-by-step explanation:

When rubisco binds to oxygen, the net result is photorespiration. Photorespiration is a process that takes place when the CO₂ concentration is low inside the leaf, leading the enzyme rubisco to add O₂ to RuBP instead of CO₂. This results in the production of 3-phosphoglycerate (3-PGA) and phosphoglycolate, effectively consuming oxygen and releasing CO₂, thus reversing parts of the photosynthesis process.

When rubisco binds to oxygen, it does not enhance photosynthesis but instead leads to a reduction in carbon fixation as the process uses ATP and NADPH without producing sugar, thereby wasting energy that could have been used for photosynthesis.