The overall mechanism of cellular respiration<span> involves four subdivisions: glycolysis, in which glucose molecules are broken down to form pyruvic acid molecules; the Krebs cycle, in which pyruvic acid is further broken down and the energy in its molecule is used to form high-energy compounds such as NADH.
Source: </span><span>Cellular Respiration - Cliffs Notes</span>
Answer is D.
you can learn A,B, and C from examining fossils
The ensemble of formations and folds in a single linear chain of amino acids sometimes called a polypeptide constitutes the tertiary structure of a protein. Finally, the quaternary structure of a protein refers to those macromolecules with multiple polypeptide chains or subunits.
