What is the advantage in this??

Dear Student,

Auxin promotes cell elongation , causing the plant to grow more on the shady side and bend in the direction of light source. Also entire process of making food can only be done in the presence of sunlight. The leaves, therefore, lean towards the light for photosynthesis. Without sunlight green plants cannot survive. As long as one part of the plant gets sunlight, it can make food and the whole plant survives.

Regards.