What is phototropism and how does it occur?

Phototropism is the growth movement of plants in response to light direction, primarily driven by the hormone auxin.

Phototropism is a fascinating biological phenomenon that allows plants to maximise their exposure to sunlight, which is crucial for photosynthesis. This process is primarily regulated by a plant hormone called auxin. The term 'phototropism' is derived from the Greek words 'photo-', meaning light, and '-tropism', meaning to turn or change direction.

The process of phototropism begins when light hits the plant. If the light source is unilateral, meaning it comes from one direction, the plant will respond by bending towards the light. This is achieved through differential growth, where one side of the plant grows faster than the other. The side of the plant that is away from the light grows faster, causing the plant to bend towards the light source.

The hormone auxin plays a pivotal role in this differential growth. When light hits the plant, auxin is produced at the tip of the plant and then transported down the shady side. This hormone promotes cell elongation, causing the cells on the shady side to grow faster and thus the plant bends towards the light.

This process is crucial for the survival and growth of the plant. By bending towards the light, the plant can maximise its exposure to sunlight and therefore optimise its photosynthesis process. Photosynthesis is the process by which plants convert light energy, usually from the Sun, into chemical energy that can be later released to fuel the plant's activities.

In summary, phototropism is a complex process regulated by the hormone auxin, which allows plants to respond and adapt to their light environment, ensuring they can effectively carry out photosynthesis.