Terrestrial vertebrates use the urea cycle to convert the ammonium ion to urea, which can then be excreted. In the production of urea, only one of the nitrogens in the product comes from an ammonium ion. What is the source of the other nitrogen in urea?

aspartate

Explanation:

Aspartic acid, is an α-amino acid that is used in the biosynthesis of proteins. Similar to all other amino acids, it contains an amino group and a carboxylic acid.

cock topography

the study of the surface of a large voluptuous cock.

look at that sorostitute right she's a cock topographer!

what classes are you taking this

cock topography!

la respuesta es si te gusta hacer lo que siempre haces cuando nunca ves a alguien en el espejo porque sabes que no siempre están ahí.