The energy for life processes primarily comes from the conversion of nutrients, particularly through cellular respiration. In the case of most living beings, this involves breaking down organic molecules, such as glucose, through metabolic pathways within cells. During cellular respiration, energy is released and captured in the form of adenosine triphosphate (ATP), which serves as a universal energy currency for various biological activities. Photosynthetic organisms, like plants, harness energy from sunlight to convert carbon dioxide and water into glucose, providing a foundational energy source. Ultimately, the intricate processes of metabolism enable living organisms to extract and utilize energy for their vital functions.