What is the function of auxin in plants?

Auxin is a key plant hormone primarily involved in regulating growth and development processes. One of its most notable functions is the stimulation of cell elongation. Auxin influences growth by promoting the elongation of cells on the side of the plant that is facing away from light (a process called phototropism), allowing the plant to bend toward the light source. It achieves this by loosening the cell wall, which allows for increased water uptake and subsequently, cell expansion.

Other options may represent different functions of various hormones. For example, while flowering can be influenced by many factors, including other hormones like gibberellins, it is not the primary role of auxin. Similarly, auxin does not inhibit root growth; in fact, it usually stimulates root elongation in specific contexts. Furthermore, fruit ripening is mainly regulated by hormones like ethylene, rather than auxin. Therefore, auxin's role in stimulating cell elongation is essential for plant growth and adapting to environmental stimuli.