Class 10 Zoology simulations · Control and Coordination

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

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See all Class 10 Zoology simulations or every Physica simulation.