Which plant group is most common and lacks carbon concentrating mechanisms to reduce photorespiration?

Which plant group is most common and lacks carbon concentrating mechanisms to reduce photorespiration?

• A. C4 plants.
• B. CAM plants.
• C. C3 photosynthesis.
• D. C3 plants.

Answer: (D)

Photorespiration happens when RuBisCO fixes oxygen instead of carbon dioxide, wasting energy and carbon. Plants counter this with carbon-concentrating mechanisms that raise CO2 levels at the site of RuBisCO. C4 plants separate initial CO2 fixation in mesophyll cells and the Calvin cycle in bundle-sheath cells, concentrating CO2 there to keep RuBisCO from grabbing O2. CAM plants open stomata at night to fix CO2 into organic acids and release it during the day for fixation, achieving a similar CO2 boost. The plant group that is most widespread and does not have these adaptations fixes CO2 directly through the Calvin cycle without any CO2 concentration strategy. That group is C3 plants.

Photorespiration happens when RuBisCO fixes oxygen instead of carbon dioxide, wasting energy and carbon. Plants counter this with carbon-concentrating mechanisms that raise CO2 levels at the site of RuBisCO. C4 plants separate initial CO2 fixation in mesophyll cells and the Calvin cycle in bundle-sheath cells, concentrating CO2 there to keep RuBisCO from grabbing O2. CAM plants open stomata at night to fix CO2 into organic acids and release it during the day for fixation, achieving a similar CO2 boost. The plant group that is most widespread and does not have these adaptations fixes CO2 directly through the Calvin cycle without any CO2 concentration strategy. That group is C3 plants.