Anyway viruses are not by the current definition of life alive. However they have many, not all, but many charateristics of life. they 'evolve' that is why you have a different form of influenza every year, they feed, once they are in a cell, the virus will use the food the cell makes to replicate. i give you a example of where this occurs in the animal kingdom. paracites follow this exact same proccess, however they are made up of cells and most can break down very simple forms of food. they still require there host to provide all these things though. they are like larger living examples viruses. you are incorrect in saying that viruses cannot survive without a cell. this is true from some viruses like HIV however it is not true for others which will remain intacte for long peroids of time outside of a cell and you stated that a cell can survive without the virus, once a cell has been infected it cant survive without the virus. the only reason viruses are not defined as life is because by definition the fundimental form of life is the cell, and since viruses are not made up of cells the cant be called life even if they fills all of the other requirements, that is why viruses are not defined as living. IF this definition were changed which can happen very easily then viruses could be called life. there is a push in the world of science now to change this definition, these scientists propose that nucleic acids should be defined as the fundimental form of life. however, that is beside the point when i said that viruses could have been involved in evolution the theory spans from the fact that viruses can substantially change the DNA make up of a cell, it could be possible that at some point in the past there was a virus which would fuse itself with the cells DNA rather then take full control of the DNA it would would become a part of the cell and change it, in this way when the cell reproduced it would create a much different form of life. so even thou viruses are not currently defined as life they still could have affected evolution in the method decribed above.
Anyway viruses are not by the current definition of life alive. However they have many, not all, but many charateristics of life. they 'evolve' that is why you have a different form of influenza every year, they feed, once they are in a cell, the virus will use the food the cell makes to replicate. i give you a example of where this occurs in the animal kingdom. paracites follow this exact same proccess, however they are made up of cells and most can break down very simple forms of food. they still require there host to provide all these things though. they are like larger living examples viruses. you are incorrect in saying that viruses cannot survive without a cell. this is true from some viruses like HIV however it is not true for others which will remain intacte for long peroids of time outside of a cell and you stated that a cell can survive without the virus, once a cell has been infected it cant survive without the virus. the only reason viruses are not defined as life is because by definition the fundimental form of life is the cell, and since viruses are not made up of cells the cant be called life even if they fills all of the other requirements, that is why viruses are not defined as living. IF this definition were changed which can happen very easily then viruses could be called life. there is a push in the world of science now to change this definition, these scientists propose that nucleic acids should be defined as the fundimental form of life. however, that is beside the point when i said that viruses could have been involved in evolution the theory spans from the fact that viruses can substantially change the DNA make up of a cell, it could be possible that at some point in the past there was a virus which would fuse itself with the cells DNA rather then take full control of the DNA it would would become a part of the cell and change it, in this way when the cell reproduced it would create a much different form of life. so even thou viruses are not currently defined as life they still could have affected evolution in the method decribed above.