Question

If there will we no sunlight for one month then how plant do photosysthesis

Answer 1

without sunlight plants cannot do photosynthesis .by the defination photosynthesis is the process in which green plants uses sun energy to transform water , carbon dioxide and mineral into oxygen and also organic compounds. 
if there is no sunlight the plants will not do photosynthesis. to survive without sunlight , they use oxygen in replace of carbon dioxide but this process is not called photosynthesis....