Answer:
The matrix of mitochondria in animals, and stroma of Chloroplasts in plants.
Step-by-step explanation:
The process of Chemiosmosis, is the name of the sequence of reaction of movements of hydrogen ions across membranes which leads to the ATP synthesis, ATPs is synthesized by enzyme ATPase synthase in the stroma and matrix of chloroplasts and mitochondria respectively.
The energy for the synthesis is obtained by the Proton Motive Force, which continuously pump protons, and therefore set up its electrochemical gradients between the thylakoid membrane or intramembranes of matrix/stroma respectively.
It is the energy generated from the influx of protons into the matrix/stroma that ATPase synthase used to catalysed ADP with Pi (inorganic phosphate)to give ATP in these media.
ADP + Pi → ATP.
Therefore, the site of production of ATP are matrix of mitochondria and stroma of chlorplasts