Final answer:
The energy-rich organic compound needed by organisms is glucose, a simple carbohydrate that cells convert to energy through cellular respiration.
Step-by-step explanation:
An energy-rich organic compound needed by organisms is glucose. Glucose is a simple carbohydrate with the chemical formula C6H12O6, which stores chemical energy that cells can utilize through cellular respiration. In this process, cells extract energy from glucose, converting it into ATP (adenosine triphosphate), the energy currency of the cell. Organic compounds such as glucose are vital because they are made of carbon atoms covalently bonded to other atoms like hydrogen and usually oxygen; these compounds are essential for the structure and function of living organisms, comprising other important groups like lipids, proteins, and nucleic acids as well.