Leaving Certificate Photosynthesis Practice Test

Where is NADPH formed during the light-dependent reactions?

NADPH is formed when NADP+ accepts electrons at the end of the electron transport chain at PSI NADPH is formed in the thylakoid lumen by water splitting NADPH is formed in the stroma near the chloroplast by the reduction at PSI NADPH is formed in the mitochondria

Correct Answer:

NADPH is formed in the stroma near the chloroplast by the reduction at PSI

Explanation:

In the light-dependent reactions, NADPH is formed in the stroma of the chloroplast. After Photosystem I absorbs light, electrons are transferred to ferredoxin and then to the enzyme ferredoxin–NADP+ reductase (FNR) on the stromal side of the thylakoid membrane. FNR uses those electrons to reduce NADP+ to NADPH, so the molecule is produced in the stroma. Water splitting at the oxygen-evolving complex happens on the lumen side and supplies electrons, but NADPH formation itself occurs in the stroma, not in the lumen or mitochondria. This NADPH (along with ATP) powers carbon fixation in the Calvin cycle within the stroma.

Access more questions from this quiz

Continue to Leaving Certificate Photosynthesis Practice Test for more practice questions and the full quiz experience.

Access More Questions