Question

Warburg effect refers to

• A. Decreased photosynthetic rate at very high $O_2$ concentration
• B. Increased photosynthetic rate at very high $O_2$ concentration
• C. Decreased photosynthetic rate at very low $O_2$ concentration
• D. Increased photosynthetic rate at very low $O_2$ concentration
  

Answer 1

The correct option is A Decreased photosynthetic rate at very high $O_2$ concentration

• In plant physiology, the Warburg effect is the decrease in the rate of photosynthesis due to high oxygen concentrations.
• Oxygen is a competitive inhibitor of carbon dioxide fixation by RuBisCO which initiates photosynthesis. Furthermore, oxygen stimulates photorespiration which reduces photosynthetic output.
• Hence Warburg effect refers to the decreased photosynthetic rate at very high $O_2$ concentration.
• So, the correct answer is 'Decreased photosynthetic rate at very high $O_2$ concentration.