<prompt> Chitin containsAlpha 1-4 bondb-1-6 bondAlfa 1-6 bondb-1-4 bond  <response>: It is present in exoskeletons of crustacea and insects. It is composed of units of N-acetyl-glucosamine with beta -1,4-glycosidic linkage.Ref: DM Vasudevan, page no: 79 