When will chloroplasts be aligned with their flat surfaces parallel to the walls in mesophyll cells? When will they be perpendicular to the incident light?
Chloroplasts will be aligned with their flat surfaces parallel to the walls under low/optimum light intensities so that they can get maximum quantity of the incident light.
They would align themselves perpendicular to the incident light in extremely higher light intensities to avoid photooxidation (causes destruction of chlorophyll).
They would align themselves perpendicular to the incident light in extremely higher light intensities to avoid photooxidation (causes destruction of chlorophyll).