What do organisms store energy in?
ATP is what cells use to perform most cellular work. Energy ready to be spent exists in this form. Saccharides (sugars) are used to create ATP in the process in the process of cellular respiration. Lipids(fats) are the back up energy source for when sugar molecules are running low.
All living organisms need energy to survive. This energy comes from the foods that they eat. However, in order to meet the demands of energy required throughout the day the body of the organism must store its energy for use later on. Lipids and carbohydrates are the compounds used in these organisms to store energy.
An ecosystem is a system comprised of living organisms and nonliving material working together through nutrient cycles and energy flows. The basic requirements of an ecosystem include a source of energy, the ability to store energy in chemical bonds, and a means by which to recycle essential substances between organisms and the environment.
Unlike organisms, viruses are not cellular, nor do they have ribosomes or any other organelles for protein production, energy generation, etc. They cannot capture or store free energy but can only use energy derived from their host. Also, viruses can only reproduce via the host and not on their own.