The Citric Acid Cycle is the single most effective way for plants to metabolize the \"nutrients\" that they receive. Unlike animals, plants find nutrition in the form of Carbon Dioxide (CO2) and sunlight. There are many variations of the Citric Acid Cycle which help account for differences in sunlight (too much/too little) and Carbon Dioxide (too much/too little). Solution The Citric Acid Cycle is the single most effective way for plants to metabolize the \"nutrients\" that they receive. Unlike animals, plants find nutrition in the form of Carbon Dioxide (CO2) and sunlight. There are many variations of the Citric Acid Cycle which help account for differences in sunlight (too much/too little) and Carbon Dioxide (too much/too little)..