Which process is essential for providing energy to plants?

Photosynthesis is the key process that provides energy to plants by converting light energy, usually from the sun, into chemical energy stored in glucose. During this process, plants take in carbon dioxide from the atmosphere and water from the soil, utilizing sunlight to drive the chemical reactions that produce glucose and oxygen. This glucose serves as a primary energy source for the plant's growth and metabolism.

While fermentation, nitrogen fixation, and glycolysis are important biological processes, they do not serve as the primary mechanism for energy production in plants. Fermentation is primarily a means of energy production under anaerobic conditions, which is more relevant for certain microorganisms and some plant tissues under specific conditions. Nitrogen fixation is essential for converting atmospheric nitrogen into a usable form for plants, but it does not provide energy. Glycolysis is a metabolic pathway that breaks down glucose to produce energy, but it occurs after glucose has been produced via photosynthesis. Therefore, among the options provided, photosynthesis is the fundamental process that fuels the energy needs of plants.