Which of the following organisms have the greatest problem with photorespiration?

Correct answer: C. C3 plants

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

Explanation

C3 plants have the disadvantage that in hot dry conditions their photosynthetic efficiency suffers because of a process called photorespiration. When the CO2 concentration in the chloroplasts drops below about 50 ppm, the catalyst rubisco that helps to fix carbon begins to fix oxygen instead. Thus the rate of photosynthesis begins to decrease, posing a problemC4 plants-including maize, sugarcane, and sorghum-avoid photorespiration by using another enzyme called PEP during the first step of carbon fixation. This step takes place in the mesophyll cells that are located close to the stomata where carbon dioxide and oxygen enter the plant.

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Cellular respiration explains how cells release energy from glucose through glycolysis, the link reaction, Krebs cycle and electron transport chain. It includes ATP production, substrate-level and oxidative phosphorylation, aerobic versus anaerobic respiration, and the roles of mitochondria, oxygen and fermentation in energy transfer.

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