Phototropism & Gravitropism Lab
Rotate the pot and move the light, predict which way the shoot and root will grow, then run the simulation and check your prediction.
About the Phototropism & Gravitropism Lab
Free phototropism & gravitropism lab. Rotate the pot and move the light, predict which way the shoot and root will grow, then run the simulation and check your prediction. Drag, change the sliders and see the result live. No sign-up, works on phone and computer. Built for botany, the phototropism & gravitropism lab runs instantly in your browser: change a setting or drag an object and the result updates at once, so you learn by trying things out rather than only reading about them.
Rotate the pot and move the light, predict which way the shoot and root will grow, then run the simulation and check your prediction. Use it to explore botany ideas at your own pace, then check what you found against the key ideas further down this page.
How to use the Phototropism & Gravitropism Lab
- Use the controls to change Pot rotation, Light direction. The simulation reacts instantly.
- Press "Run simulation", "Reset to defaults", "📄 Lab Report" to start, reset or change what is happening.
- Where you see a glowing handle, object, weight or atom, drag it with your mouse or finger. Everything responds in real time.
- Watch the readouts and graphs update as you experiment, and compare what you see with the key ideas below.
Things to try
- Set the light straight up and predict the shoot direction before running.
- Rotate the pot 90 degrees and predict again - did your answer change?
- Move the light to a hard side angle and see how far off gravity alone the shoot ends up.
- Try to predict correctly three times in a row.
Key ideas you can learn
- Shoots show negative gravitropism (grow away from gravity) combined with positive phototropism (grow toward light).
- Roots show strong positive gravitropism and are largely insensitive to light.
- Dense statoliths inside root and shoot cells settle toward the lowest side under gravity, triggering the auxin redistribution that curves the organ.
- Rotating a plant makes the statoliths resettle, so the plant actively re-aims its growth at the new 'down'.
Where this is used in the real world
Farmers count on gravitropism when planting seeds any-side-up, and space agencies studied plant tropisms on the International Space Station to see how growth changes with weaker or absent gravity.
Who is this simulation for?
Students, teachers and curious learners of all ages.
For teachers: project it on the board, let students predict what will happen, then run it together. For students: change one thing at a time and write down what changes.
Frequently asked questions
Why do shoots grow up and roots grow down?
Shoots combine negative gravitropism with phototropism to reach for light, while roots use strong positive gravitropism to anchor and find water and nutrients in the soil.
What happens if you rotate a growing seedling on its side?
Statoliths resettle to the new lowest side of the cells, and within hours the shoot curves back upward and the root curves back downward.
Is the Phototropism & Gravitropism Lab free to use?
Yes. It is completely free, with no signup, no download and no ads inside the simulation. It runs in your web browser.
Does the Phototropism & Gravitropism Lab work on a phone or tablet?
Yes. It uses touch as well as the mouse, so you can drag objects with your finger. A larger screen makes the controls easier to see.