Biology · 14.5 Tropic responses · Paper 5/6 practical
Tropisms. Watch them bend.
Plant shoots grow towards light (positive phototropism) and away from gravity; roots grow towards gravity (positive gravitropism). Change the light direction or the orientation — and use a clinostat to cancel gravity — and watch the seedlings respond.
0610 Topic 14.5 — Tropic responses
phototropism · gravitropism
Paper 5/6 — Practical
Day 0
Conditions
Observation
What happens
grow to see…
📋 Method & ideas
⚠ Controls & precautions
- Use a clinostat (slowly rotating) to cancel a one-sided stimulus as a control — the seedling then grows straight.
- Keep seedlings the same age and species; water equally; change only the stimulus direction.
- Tropisms are growth responses caused by auxin redistributing to the shaded/lower side.
🎯 Syllabus reference (0610)
- 14.5 Tropic responses — investigate gravitropism and phototropism in shoots and roots; explain in terms of auxin and unequal growth.