The cell needs to replicate its DNA before mitosis for a very simple but crucial reason: to ensure that each daughter cell receives a complete and identical copy of the genetic material.

Here's why:

* Mitosis creates two identical daughter cells. These cells need to be identical to the parent cell in order to maintain the organism's tissues and functions.

* DNA contains the blueprint for life. This includes the instructions for building and maintaining the entire organism.

* If DNA wasn't replicated, each daughter cell would only receive half the genetic information. This would lead to incomplete cells that couldn't function properly, resulting in problems for the organism.

Think of it like this: Imagine you have a recipe for baking a cake. If you want to bake two cakes, you need two copies of the recipe. Similarly, before a cell divides, it needs to duplicate its DNA (the recipe) to ensure both daughter cells have a full set of instructions.

So, DNA replication is essential for mitosis to ensure that each new cell has a complete set of genetic instructions to function correctly.