(a) Chloroplasts of higher plants show phototectic movement, under strong light. Chloroplasts are aligned with the longitudinal walls of mesophyll ’ cells with their edges only towards light. This position is called parastrophe.
(b) In moderate light, chloroplasts arrange themselves perpendicular to the incident light. The arrangement is called epistrophe.
©In poor light the chloroplasts are arranged variously. This position is called apostrophe.