Here's a breakdown:

* Dehydration: This refers to the removal of water.

* Synthesis: This means building or putting together.

* Large molecule: This is a complex molecule, like a protein or carbohydrate.

* Small ones: These are the smaller building blocks, like amino acids (for proteins) or simple sugars (for carbohydrates).

Essentially, dehydration synthesis involves taking two smaller molecules, removing a water molecule from them, and joining them together to create a larger molecule. This is a common process in biological systems, essential for building complex molecules like:

* Proteins: Amino acids are linked together by peptide bonds through dehydration synthesis.

* Carbohydrates: Monosaccharides (simple sugars) are joined to form disaccharides and polysaccharides by dehydration synthesis.

* Nucleic acids: Nucleotides are linked together to form DNA and RNA through dehydration synthesis.

Let me know if you'd like more details on any of these processes!