Most of our nitrogen-containing waste products are a result of __________.

• A. drug use
• B. consumption of foods high in nitrates, such as green vegetables
• C. the body's attempts to maintain pH homeostasis
• D. metabolism of fatty foods
• E. protein metabolism

Answer: (E)

Verified step by step guidance

1. Understand that nitrogen-containing waste products in the body primarily come from the breakdown of proteins. Proteins are made up of amino acids, which contain nitrogen.
2. Recognize that when proteins are metabolized, the amino acids are deaminated, meaning the amino group (which contains nitrogen) is removed.
3. The removed amino group is converted into ammonia, a toxic compound, which is then converted into urea in the liver. Urea is less toxic and is excreted by the kidneys.
4. Consider the other options: drug use, consumption of foods high in nitrates, and pH homeostasis. These processes do not primarily produce nitrogen-containing waste products.
5. Conclude that the metabolism of proteins is the main source of nitrogenous waste, specifically in the form of urea, which is excreted in urine.