Final answer:
Auxin can inhibit cell elongation in plants, affecting growth and development. It causes the bending of stems towards light sources during phototropism.
Step-by-step explanation:
Auxins are plant hormones that have various effects on plant growth and development. One response that occurs due to auxin is inhibition of cell elongation. This means that auxin can prevent cells from growing longer, which can affect the overall size and shape of the plant. For example, auxin can inhibit the elongation of stem cells, leading to shorter stems.
Example: When a plant is growing towards light (phototropism), the side of the stem that is receiving more light produces more auxin. This auxin inhibits the elongation of cells on that side, causing the stem to bend towards the light source.