Why do all "normal" cells in the human body have the same number of chromosomes?

Which identifies the main purpose of biological taxonomy?

Why is the theory of evolution important? it disproves all other theories about how life began. it provides a topic for debate. it is a unifying concept in biology. it explains how life began. i know for sure, it is not "it is a unifying concept in biology."

What pattern of migration do whales follow?