Photosynthesis Question 2
2. In a chloroplast the highest number of protons are found in
[2016]
(a) stroma
(b) lumen of thylakoids
(c) inter membrane space
(d) antennae complex
Show Answer
Answer : b
Hints & Solution
(b) Proton concentration is higher in the lumen of thylakoid due to photolysis of water, $H^{+}$pumping and NADP reductase activity in stroma. During the light-dependent reaction, protons are pumped across the thylakoid membrane into the lumen making it acidic down to $pH 4$. The light - included electron transfer in photosynthesis drives protons into the thylakoid lumen. The excess protons flow out of the lumen through ATP synthase to generate. ATP in the stroma.
