Question

Chloroplasts do not align themselves with their flat surfaces parallel to the the walls ? What does this flat surface mean?

Answer 1

Chloroplasts will be aligned with their flat surfaces parallel to the walls under low light intensities so that they can get maximum quality of the incident light.
They would align themselves perpendicular to the incident light in extremely higher light intensities to avoid photooxidation.
Flat surface

Flat surface of the chloroplast.