The Living World 8th Edition by George Johnson

Exercise 5

Classification systems summarize much information about organisms, although often a key trait allows us to immediately distinguish between two different ones. Most of us are very familiar with dogs and cats, which are common pets. What key traits can you think of that would always distinguish a dog from a cat?
Your friend wants to know what the big deal is-everyone knows that a rose is a rose, so why bother with the fancy Latin name Rosa odorata ? What do you tell him?