In plant biology, what is phototropism?

Phototropism refers specifically to the directional growth of a plant in response to light. When a plant senses light, it typically grows towards the source in order to maximize the amount of sunlight it receives, which is crucial for efficient photosynthesis. This growth response is often mediated by the plant hormone auxin, which redistributes itself to the shaded side of the plant, causing those cells to elongate and resulting in a curvature towards the light. This adaptation allows plants to optimize their exposure to sunlight, which is essential for their survival and growth.

The other options describe different plant processes or responses but do not accurately capture the concept of phototropism. For example, maintaining water balance is more indicative of a plant's adaptation to its environment, while photosynthesis is the process through which plants convert light into energy, not a growth response. In contrast, the idea of growing away from light contradicts the basic principle of phototropism, as plants typically seek out light to thrive.