IGCSE Biology glossary
Urea
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Definition
A nitrogen-containing waste substance produced in the liver by the deamination of excess amino acids. Urea is transported in the blood plasma to the kidneys, where it is filtered out and excreted in urine.
What to include in an exam answer
Urea is made in the LIVER by deamination, not in the kidneys. The kidneys only remove urea from the blood. State the pathway: excess amino acids are deaminated in the liver, producing urea, which is transported to the kidneys.
Example in context
Describe how urea is produced and removed from the body (3 marks): Excess amino acids are deaminated in the liver, producing urea. Urea is transported in the blood plasma to the kidneys. In the kidneys, urea is filtered out of the blood at the glomerulus and excreted in urine.
Related syllabus topic
Excretion in humans