Select the correct answer to the questions from the given options. (Do not copy the questions, write the correct answer only.)
The site of light reaction in the cells of a green leaf is:
Topic: Site of the light reaction
Try it
Pick an option and check your answer. The full worked answer is below either way.
Answer
(b) Grana of chloroplast.
The LIGHT reaction occurs in the GRANA — the stacks of thylakoid membranes inside the chloroplast, where the CHLOROPHYLL is held.
The DARK reaction occurs in the STROMA, the fluid matrix surrounding the grana, which contains the enzymes that fix carbon dioxide into glucose.
THE LOGIC that lets you reason it out: the light reaction needs CHLOROPHYLL to trap light, and chlorophyll sits in the membranes of the grana. Wherever the pigment is, that is where light is absorbed.
Option (d) is the trap, because both grana and stroma are inside the chloroplast and both are correct for one stage. Read which stage is being asked about.
So the two stages of photosynthesis happen in two different parts of the SAME organelle — which is why a labelled chloroplast diagram, as asked in 2024, is worth being able to draw.
Grana of chloroplast.