Question: Where does diffusion occur in the excretory system?
Disambiguated questions and answers: question: Where does diffusion occur in the marine invertebrate excretory system?
Where does diffusion occur in the amphibian excretory system?
Where does diffusion of oxygen and carbon dioxide occur in the human excretory system?
Where does diffusion of salt, water, and waste occur in the excretory system?
Where does diffusion of calcium occur in the excretory system?
answer: through the skin
skin
Lungs
Kidneys
Intestines
Natural Questions answer: diffusion (from the Wikipedia article "Excretory system")