Summary
Auxin moves to the shaded side of a shoot, causing cells there to elongate so it bends toward light.
In depth
Light causes lateral auxin transport (PIN proteins) to the shaded side; auxin acidifies cell walls (acid growth hypothesis) so cells elongate. Darwin and Went did early experiments with coleoptiles.
Auxin is made in shoot tips and moves by polar transport. Acid growth hypothesis: auxin activates proton pumps that loosen cell walls. Phototropin photoreceptors sense blue light.
Example: Darwin's experiments with covered coleoptile tips showed the tip senses light.
Frequently asked questions
What is Auxin and Phototropism?
Auxin moves to the shaded side of a shoot, causing cells there to elongate so it bends toward light.
Which area of biology covers Auxin and Phototropism, and how advanced is it?
Auxin and Phototropism is one of the 56 topics in Plant Biology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Gravitropism, Xylem, Stomata.
Can you give an example of Auxin and Phototropism?
Potted plants on a windowsill bend toward the light.
What should I learn before Auxin and Phototropism?
Work through the Beginner topics in Plant Biology first, such as Plant Kingdom, Photosynthesis, Chlorophyll, then return to Auxin and Phototropism. Intermediate topics assume the Beginner vocabulary.
What topics are related to Auxin and Phototropism?
The closest topics to Auxin and Phototropism are Gravitropism, Xylem, Stomata, Phytochrome Signalling. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Auxin and Phototropism?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Auxin and Phototropism. To practise the whole of Plant Biology, use the Plant Biology quiz.
How is Auxin and Phototropism different from Gravitropism?
Auxin and Phototropism: Auxin moves to the shaded side of a shoot, causing cells there to elongate so it bends toward light. Gravitropism: Directional growth in response to gravity, with roots growing down and shoots growing up. Read both side by side and note what each one explains.
How should I study Auxin and Phototropism step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Gravitropism and explain the difference aloud. Finally, take the Plant Biology quiz and come back to this page for any question you miss.