Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.

[Q]: Question: What is a layer of saturated porous rock? Answer: an aquifer
[A]: An aquifer is a layer of saturated porous rock. It lies below the water table. An impermeable layer, such as clay, is below the aquifer.

[Q]: Question: Both endocytosis and ______ are active transport processes. Answer: exocytosis
[A]: Both endocytosis and exocytosis are active transport processes.

[Q]: Question: Hydrogen peroxide is commonly sold as a 3% by volume solution for use as a what? Answer: disinfectant
[A]:
Hydrogen peroxide is commonly sold as a 3% by volume solution for use as a disinfectant.