How does light reach the photoreceptors in plants? Does it need to travel through the plant or are the photoreceptors on the surface of the plant ?
The photoreceptors relevant to photosynthesis are the light-harvesting complexes. These are found embedded in the thylakoid membranes found within chloroplasts. To reach the thylakoid membranes, light from outside the plant must pass through the cell wall, cell membrane, cytoplasm, both membranes of the chloroplast, and some amount of chloroplast stroma. If the photosynthetic cell is not on the surface of the plant, the light would also need to pass through some number of intervening cells.