Question

what names are given to the reactions by which large carbohydrate molecules are built up and broken down?

Answer 1

Large carbohydrate molecules are built up in the reactions called condensations, in which monomeric carbohydrates are linked together in the larger units, while water is formed as other product.
On the other hand, large carbohydrate molecules are broken down in the reaction called hydrolysis, in which large units are separated into smaller one by addition of water.