Question

Review A plant uses solar energy to make ATP and NADPH, which then drive the synthesis of carbohydrates in the leaves. At least one carbohydrate, sucrose, is translocated to nonphotosynthetic parts of the plant (stems, roots, flowers, and fruits) for use as a source of energy. Thus, ATP is used to make sucrose, and the sucrose is then used to make ATP. It would seem simpler for the plant just to make ATP and translocate the ATP itself directly to other parts of the plant, thereby completely eliminating the need for a Calvin cycle, a glycolytic pathway, and a TCA cycle.

Answer 1

ATP is highly polar and would be difficult to move across the membrane.

Generation of ATP stops as soon as the sun sets , and there is no practical way to store enough of it to meet the ongoing energy needs of the organism at night.

ATP would be a very easy way to move energy about, because it has a molecular weight of about 500 Daltons and contains 2 high energy phosphate bonds. Sucrose, in contrast, has a molecular weight of about 340 Daltons and can give 72 molecules of ATP elsewhere in the plant.