Plastoquinone (pq), an electron carrier of small molecular weight, is found in the electron transport chain associated with photosystem ii. if pq is not directly anchored to other membrane or cytoplasmic structures, it is probably

Mobile

Explanation:

Plastoquinone has a similar structure and role to Ubiquinone, found in other electron transport chains.  It's a mobile electron transport carrier through the thylakoid membrane (thylakoids are present in chloroplasts), and is present in the photosystem II in plants and other photosynthetic organisms.  PSII produces the chemical energy as  ATP.

PQ is reduced when it accepts electrons from PSII, and then it delivers them to plastocyanin, that is a water-soluble electron carrier in the cytochrome b6f complex.