Here's how it works:

* Dehydration synthesis removes a water molecule (H2O) to join two smaller molecules, forming a larger one. This is how polymers (large molecules) are built from monomers (smaller units).

* Hydrolysis adds a water molecule to break a larger molecule into two smaller molecules. This is how polymers are broken down into their constituent monomers.

Think of it like this:

* Dehydration synthesis: Building a chain by removing a link (water molecule) between two pieces.

* Hydrolysis: Breaking a chain by adding a link (water molecule) between two pieces.

Examples:

* Building a protein: Dehydration synthesis joins amino acids together, removing water molecules to form a polypeptide chain (protein).

* Breaking down a protein: Hydrolysis adds water molecules to break the polypeptide chain into individual amino acids.

In summary:

* Dehydration synthesis = building molecules by removing water

* Hydrolysis = breaking down molecules by adding water

These two processes are essential for life, enabling the creation and breakdown of complex molecules for all biological functions.