Final answer:
Carbohydrates are the main source of energy for living things, providing immediate energy needs and breaking down into glucose for ATP production.
Step-by-step explanation:
The main source of energy for living things is carbohydrates. Although other organic compounds like lipids, proteins, and nucleic acids also provide energy in different forms, carbohydrates are primarily responsible for supplying immediate energy needs, especially in the form of glucose. When digested, carbohydrates break down into simple sugars such as glucose which is then utilized by cells to produce ATP (adenosine triphosphate), the energy currency of the cell.
Lipids, including fats and oils, can also be an energy source and serve as energy reserves. Proteins primarily supply amino acids for building and repairing tissues rather than serving as a primary energy source. Meanwhile, nucleic acids, like DNA and RNA, carry genetic information and are not considered a main energy source.