Here's why:

* Chromosomes contain DNA: DNA is the genetic material that carries the instructions for building and maintaining an organism.

* All living organisms need DNA: Both animals and plants are living organisms and therefore need DNA to function.

* DNA is organized into chromosomes: To fit inside the nucleus of a cell, DNA is tightly packaged and organized into structures called chromosomes.

So, whether it's a complex animal or a simple plant, you'll find chromosomes inside the cells!