Which of the following results from the incomplete breakdown of glucose that occurs under anaerobic conditions?

A. The kidneys do not play a role in the chemical breakdown of protein. Their primary function is filtration and regulation of blood composition.

B. The mouth is where mechanical digestion (chewing) occurs, but chemical digestion of proteins does not begin there. Enzymes like amylase break down carbohydrates, not proteins.

C. The stomach is where protein digestion begins. The enzyme pepsin, activated by stomach acid (HCl), starts breaking down proteins into smaller peptides. This is the correct answer.

D. The small intestine continues the digestion of proteins, but the initial breakdown occurs in the stomach. The pancreas also releases digestive enzymes, including trypsin, to further digest proteins in the small intestine.

A. Pernicious anemia is caused by vitamin B12 deficiency due to impaired absorption, not excessive destruction of erythrocytes.

B. Aplastic anemia results from the bone marrow's inability to produce enough blood cells, leading to a deficiency of all blood cell types, rather than the destruction of erythrocytes.

C. Immunohemolytic anemia is characterized by the immune system mistakenly attacking and destroying the body's own erythrocytes, leading to excessive destruction of red blood cells.

D. Iron-deficiency anemia is caused by insufficient iron to produce hemoglobin, resulting in low red blood cell production, but not excessive destruction of erythrocytes.