Which statement correctly describes a step in the process of urea production in the human liver?
Amino acids are converted directly into urea during the process of transamination.
Ammonia, produced by the deamination of excess amino acids, combines with carbon dioxide in the ornithine cycle to form urea.
The ornithine cycle occurs in the kidneys to convert ammonia into urea.
Urea is significantly more toxic than ammonia and is produced to prevent cellular damage.