Which of the following are considered to be alive and why? Proteins: Bacteria: Yeast: Viruses: Prions: DNA: Candles: Chemical reactions: Water: Solution Biologists have defined some characteristics to categorize an entitiy as alive. These are - organization, metabolism, homeostasis, growth, reproduction, response and evolution. However, some of the entities may possess a few of these qualities, the ones which show all the afore- mentioned characteristics are classified as alive. Bacteria and yeast are alive in the mentioned list as they possess all the qualities of being alive. One might think of viruses as living things but they are not as they cannot reproduce/divide on their own, they need the host cellular machinaries, therefore they are dependent on other living cells for their own replication..