Question

which substances are actively transported from the blood into the filtrate through tubular secretion?
sodium ions and chloride ions
hydrogen ions, potassium ions, and certain drugs.
calcium ions and magnesium ions
glucose and amino acids
carbon dioxide and oxygen molecules

Explanation:

Tubular secretion is an active process. Hydrogen ions (\(H^+\)) help in regulating the pH of the body fluids. Potassium ions (\(K^+\)) balance is maintained through tubular secretion. Certain drugs like penicillin are also actively secreted into the filtrate. Sodium ions (\(Na^+\)) and chloride ions (\(Cl^-\)) are mainly reabsorbed. Calcium (\(Ca^{2+}\)) and magnesium (\(Mg^{2+}\)) ions are reabsorbed in the nephron. Glucose and amino acids are almost completely reabsorbed. Carbon dioxide (\(CO_2\)) and oxygen (\(O_2\)) are not part of tubular secretion in the context of nephron function related to filtrate formation in this way.

Answer:

Hydrogen ions, potassium ions, and certain drugs.