Any process that results in 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 cyclopentenone stimulus. Cyclopentenones are oxylipins derived from polyunsaturated fatty acids. They are structurally similar to jasmonic acid, but contain a reactive unsaturated carbonyl structure in the cyclo-ring. Cyclopentenones include phytoprostanes and 12-oxo-phytodienoic acid.