But hang on! How do we know that something is alive? Computers have different bits that work together, but are they alive? Living things vary from the simplest single-celled plants and animals up to giant trees and whales. But no matter how simple or complicated, all living things show 7 characteristics of life. All plants and animals are alive. What are these magnificent 7? Mrs Gren will help you to remember them. The 7 letters of her name are their initial letters. /**/