What are tropisms?

A tropism is a growth in a plant in response to a stimulus. The stimulus could be a change in the direction of light or a water source. To recap, a stimulus is a change in the environment of an organism that could cause a response. There are different types of tropisms. Phototropism is a growth in response to the direction of light, and geotropism is a growth in response to gravity. Tropisms can also be negative or positive, where negative tropism is growth away from the stimulus, and positive tropism is a growth towards the stimulus. The direction of growth is controlled by a plant hormone called 'auxin'. Auxins are produced in the tips of shoots or roots and change the rate of elongation in plant cells. During phototropism for example, if a plant is only receiving light on one side, auxins gather on the shaded side of the tip of the shoot. This causes the shaded side to grow longer, and so the shoot bends towards the light.

HP
Answered by Holly P. Biology tutor

13343 Views

See similar Biology GCSE tutors

Related Biology GCSE answers

All answers ▸

How does temperature affect the rate of diffusion?


The destruction of habitat can lead to the extinction of animals. Name 3 other disadvantages of deforestation.


What are the differences between eukaryotes and prokaryotes


What are indicator species and what are they used for?


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences