If light shines on a plant stem from one side auxin ...?

If light shines on a plant stem from one side, auxin is produced and concentrated on the shaded side of the stem. This hormone promotes cell elongation, causing the cells on the shaded side to grow longer than those on the illuminated side. As a result, the stem bends towards the light source, a phenomenon known as phototropism. This adaptation helps the plant maximize its light absorption for photosynthesis.