Question

From where does PQ get its protons?

• A. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Lumen of thylakoid
• B. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Membrane of thylakoid
• C. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Stroma of chloroplast
• D. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Within the photosystem

Answer 1

The correct option is C <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Stroma of chloroplast

Plastoquinone (PQ) is a unique protein as it is not just an electron carrier but also a proton carrier. It is a lipid soluble protein. It carries 2 electrons from pheophytin and 2 protons from the stroma of the chloroplast. It transfers the electrons to cytochrome $b_{6}f$ and the protons to the lumen of thylakoid.