What living organism doesn use energy?
That sounds a bit like a trick question. All living things NEED to use energy. This is based on the laws of thermodynamics. Life is the creation of order (enthalpy) by harnessing the universe’s continual increase of disorder (entropy). Entropic reactions are exothermic (meaning they give off heat). By taking advantage of the energy given off by an entropic reaction, living organisms are able to create greater organization in themselves. For example the sun, which is slowly becoming more entropic as it burns, releases energy in the form of light. Plants absorb this energy via chlorophylls, allowing the plant to produce sugar, an organized structure. Your teacher is not asking for you to name a living organism that uses no energy, by the way. She is asking you to identify a structure that is capable of reproduction without creating any energy of it’s own. You should learn this on your own, so I’ll just give you a hint: read the microbiology section of the wikipedia page on viruses. It sh
There is no living organism which doesn’t use energy–one of the defining characteristics of ‘life’ is the use of energy. I think your teacher might be hinting towards viruses. Almost all viruses consist of a self-assembling crystalline protein coat/capsid (some also have an external lipid bilayer) containing a strand of nucleic acid (DNA or RNA, depending on the virus type). The nucleic acid strand codes for both the virus coat proteins and replication enzymes which allow a virus to hijack its host cell’s reproductive machinery. There is some debate regarding the status of viruses as ‘life-forms’. The debate centres on whether our current definition of life is too narrow, since viruses display multiple characteristics of ‘life’ (reproduction, evolution, protein/nucleic acid-based, etc.), but–crucially–cannot reproduce independantly of a host cell nor carry out any of the ‘normal’ metabolic processes of ‘life’ as currently defined (e.g. respiration, excretion).
