Pearson Edexcel · GCSE · Biology
Course version: 1BI0 · Version from Sept 2016
7.22B State that urea is produced from the breakdown of excess amino acids…
Full specification wording
Topic 7 – Animal coordination, control and homeostasis: 7.22B State that urea is produced from the breakdown of excess amino acids in the liver
When a person eats more protein than the body needs, the surplus amino acids cannot be stored, so they are broken down in the liver.
Checked against the Pearson Edexcel 1BI0 specification (opens in a new tab) on .
- Point 19 of 19
Study notes
From the checked teaching notes for this specification point.
The idea
When a person eats more protein than the body needs, the surplus amino acids cannot be stored, so they are broken down in the liver. This process, deamination, removes the nitrogen-containing part of the amino acid and converts it into urea, while the remaining part can be used for energy. Urea is a waste product that must be removed from the body, which the kidneys do by filtering it out of the blood so it can be excreted in urine. The key facts to state are the location (the liver) and the source (breakdown of excess amino acids), giving urea as the product.
What earns the marks
- Urea is produced in the liver.
- Urea is formed from the breakdown of excess amino acids.
- The breakdown of excess amino acids is needed because surplus amino acids cannot be stored by the body.
- Urea is a waste product that must be removed from the body, for example by the kidneys in urine.
Common mistakes and how to put them right
Saying urea is made in the kidneys.
Put it right: Urea is produced in the liver, and the kidneys remove it from the blood.
Saying urea comes from the breakdown of proteins directly.
Put it right: It comes from the breakdown of excess amino acids.
Confusing urea with faeces or with carbon dioxide.
Put it right: Urea is a nitrogen-containing waste product excreted in urine.
Exam tips
- Name the organ (liver) and the starting material (excess amino acids) in the same answer.
- Use the term deamination to show understanding of the breakdown process.
- Link urea production to its removal by the kidneys to show the whole pathway.
Try the lesson
The start of the Topic 7 – Animal coordination, control and homeostasis: 7.22B State that urea is produced from the breakdown of excess amino acids in the liver lesson, made from checked teaching notes for this specification point.
Have a go first
In which organ of the human body is urea produced from the breakdown of excess amino acids?
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