Plants move very slowly due to growth.
A tropism is a growth in response of a stimulus. The tropism is positive if the plants grow towards the simulus and negative if it grows away.
They grow towards water and sun which is what they need to survive. They also need it for photosynthesis.
Auxin ( made at the tip of stems and roots) is a hormone produced in the stem tips and roots which controls the direction of growth. Plant hormones are used in weedkillers and rooting powder.m If the tips of the stem is cut off no auxin is produced so no growth. If the tips are covered the auxin cant break…