Which of the following organic molecules is primarily responsible for energy storage?

Lipids are primarily responsible for energy storage in living organisms due to their high energy content and efficient storage capabilities. They are hydrophobic molecules, which allows them to store more energy in a compact form compared to other macromolecules. The structure of lipids, particularly triglycerides, consists of three fatty acids attached to a glycerol backbone. This structure enables them to store a significant amount of chemical energy, which can be released during metabolic processes when needed by the organism.

In addition to their role in energy storage, lipids also serve other important functions, such as providing insulation and protection for organs, forming cell membranes, and serving as signaling molecules. The energy stored in lipids is primarily used during prolonged periods of energy demand, such as during fasting or extended physical activity, where the body taps into lipid reserves to meet its energy needs.

Carbohydrates also store energy, but they are generally utilized for short-term energy needs and are less energy-dense than lipids. Proteins and nucleic acids have different roles in the organism, focusing more on catalysis, structure, and genetic information rather than energy storage.