Question

In leaves, the chloroplasts align themselves along the walls of the mesophyll cells

• A. to prevent sunlight from falling on the chloroplast
• B. to provide optimum sunlight for photosynthesis
• C. to facilitate the dark reaction
• D. none of the above

Answer 1

The correct option is B to provide optimum sunlight for photosynthesis

The specialized cells present in the leaves that are capable of performing photosynthesis are called mesophyll cells.

The chloroplast is a type of plastid that contains chlorophyll pigment and is present in the mesophyll cells.
Chlorophyll pigment is responsible for trapping light energy for photosynthesis. Based on the availability of light, the chloroplasts arrange themselves in the mesophyll cells.

The region of mesophyll which is exposed to the light is called the wall of the mesophyll. To get optimum light required for photosynthesis when the intensity of light is low, chloroplasts align themselves parallel to the walls of mesophyll cells, this condition is called epistrophe. They get aligned perpendicular to the mesophyll cells when the intensity of light is very high to prevent the photooxidation of chlorophyll a and the condition is called parastrophe.

Dark reaction is a light-independent reaction. It occurs in the stroma and does not involve thylakoids.