The chemical reactions and pathways resulting in the breakdown of polysaccharides, polymers of more than 10 monosaccharide residues joined by glycosidic linkages [goid 272] [evidence IEA]; A change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of an acid stimulus [goid 1101] [pmid 11085997] [evidence TAS]; The chemical reactions and pathways involving carbohydrates, any of a group of organic compounds based of the general formula Cx(H2O)y. Includes the formation of carbohydrate derivatives by the addition of a carbohydrate residue to another molecule [goid 5975] [evidence IEA]; The chemical reactions and pathways resulting in the breakdown of chitin, a linear polysaccharide consisting of P-1,4-linked N-acetyl-D-glucosamine residues [goid 6032] [pmid 11085997] [evidence NAS]; The chemical reactions and pathways involving cell wall chitin, a linear polysaccharide consisting of P-1,4-linked N-acetyl-D-glucosamine residues, found in the walls of cells [goid 6037] [pmid 11085997] [evidence TAS]; Any immune system process that functions in the calibrated response of an organism to a potential internal or invasive threat [goid 6955] [pmid 11085997] [evidence NAS]; The whole of the physical, chemical, and biochemical processes carried out by multicellular organisms to break down ingested nutrients into components that may be easily absorbed and directed into metabolism [goid 7586] [pmid 11085997] [evidence NAS]; The chemical reactions and pathways, including anabolism and catabolism, by which living organisms transform chemical substances. Metabolic processes typically transform small molecules, but also include macromolecular processes such as DNA repair and replication, and protein synthesis and degradation [goid 8152] [evidence IEA]; A change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a stimulus from a fungus [goid 9620] [pmid 11085997] [evidence TAS]