Question

The site of light reaction is

• A. Granum
• B. Stroma
• C. Unit membrane
• D. Stroma lamellae

Answer 1

The correct option is A Granum

The light-dependent reactions take place on the thylakoid membranes. The inside of the thylakoid membrane is called the lumen, and outside the thylakoid membrane is the stroma, where the light-independent reactions take place. Thylakoids are arranged in stacks called grana.
The chloroplast matrix is called the stroma and contains enzymes that catalyze the light-independent reactions of photosynthesis. But stroma is not the site for light reactions.
Stromal lamellae connect two or more grana to each other. In this way, the lamellae act as a skeleton of the chloroplast, maintaining efficient distances between the grana, thereby maximizing the overall efficiency of the chloroplast.
Each chloroplast is enclosed by (surrounded) a chloroplast envelope or unit membrane consisting of three layers. Overall the chloroplast envelope is semi-permeable. It is permeable to glucose molecules and certain ions including Fe${}^{2+}$and Mg${}^{2+}$, and oxygen and carbon dioxide.

So, the correct answer is option A.