How many additional ATP molecules are required by a C₄ plant compared to a C₃ plant for the synthesis of one molecule of glucose?

Step-by-step solution

In C₃ plants, the fixation of one CO ₂ molecule via the Calvin cycle requires 3 ATP molecules. To synthesize one molecule of glucose (which requires 6 CO ₂ molecules), a C₃ plant consumes 6 3 = 18 ATP molecules. In C₄ plants, the initial fixation of one CO ₂ molecule in the mesophyll cells requires 2 extra ATP molecules (to regenerate PEP), bringing the total to 5 ATP molecules per CO ₂ fixed. To synthesize one molecule of glucose, a C₄ plant consumes 6 5 = 30 ATP molecules. The additional number of ATP molecules r