AP BIOLOGY

Detailed explanation-1: -The Correct Answer is Nitrogen. Proteins are made up of molecules called amino acids and are found in all living organisms.

Detailed explanation-2: -Because of that Carbon and hydrogen is the most abundant elements, respectively, in proteins.

Detailed explanation-3: -Therefore, Nitrogen is the most essential element in proteins.

Detailed explanation-4: -Nitrogen is a naturally occurring element that is essential for growth and reproduction in both plants and animals. It is found in amino acids that make up proteins, in nucleic acids, that comprise the hereditary material and life’s blueprint for all cells, and in many other organic and inorganic compounds.

Detailed explanation-5: -Proteins are one of the primary constituents of living matter. They consist of long chains of amino acids, which are bonded together by peptide linkages and thus called polypeptides. There are about 20 amino acids, and the atoms most prevalent in these are carbon, hydrogen, oxygen, nitrogen, and sulfur.