I think its Uracil replaces thymine on rna
Hope this helps
Answer:
In the bloodstream
Explanation:
The metabolic breakdown of amino acids creates ammonia, which is especially toxic to the brain. The liver converts ammonia to urea, and it is then released into the bloodstream, where it travels to the kidneys and is excreted in the urine.
Separate kingdoms but fossil evidence shows they have evolved from a common ancestor