What is the way followed by the energy absorbed by plants to be used in photosynthesis?         

Ans) The energy source of photosynthesis is the sun, the single and central star of our planetary system. In photosynthesis the solar energy is transmitted into chemical energy, the energy of the chemical bonds of the produced glucose molecules (and of the released molecular oxygen). The energy of glucose then is kept as starch (a glucose polymer) or it is used in the cellular respiration process and transfered to ATP molecules. ATP is consumed in metabolic processes that spend energy (for example, in active transport across membranes).