sentence2_structure: Urea<>is made<>in the liver$$$Urea<>excreted<>in urine
sentence1: Metabolic excretory product Excretory organ Excreted as Carbon dioxide Urea Excess water Bile pigments Lungs Gas in expired air Kidneys Constituent in urine Kidneys Constituent in urine Liver Constituent in faeces
sentence2: Urea is made in the liver and excreted in urine.
question: What is made in the liver and excreted in urine?