Because all organisms are made up of cells and there are different types of cells which carry different functions.
A. stream erosion Just think about how the Grand Canyon was maid
Answer:Generally, the longer ago the last common ancestor lived, the less the organisms have in common. Turtles and tortoises share a common ancestor, but began evolving separately a long time ago. ... Scientists can compare the DNA of two organisms; the more similar the DNA, the more closely related the organisms.