Class 11 Botany simulations · Plant Growth and Development

Phototropism and auxin

Shine light from one side on a coleoptile. Auxin moves to the shaded side, cells there elongate more, and the shoot bends.

Open the simulation

What to notice

Covering or removing the tip stops bending — the tip senses light (Darwin’s experiment).

Key relation

More auxin (IAA) on the shaded side → faster elongation → bending towards light

Try this

Cover the tip, then remove the cover. Compare the response.

What you can change

• Light direction: -90 to 90 °
• Coleoptile tip: choose Intact tip, Tip covered (opaque cap), Tip removed
• Hours in light: 0 to 12 h

More in Plant Growth and Development

• Arithmetic, geometric and sigmoid growth
• Photoperiodism and flowering

See all Class 11 Botany simulations or every Physica simulation.