What are tropic movements? Explain phototropism and geotropism with examples, and describe how auxin makes a shoot bend towards light.

1. 1 · Define in one line. A tropic movement is the directional growth of a plant part towards or away from a stimulus.
2. 2 · Phototropism. Shoots bend towards light (positive); roots grow away from it (negative).
3. 3 · Geotropism. Roots grow down with gravity (positive); shoots grow up (negative).
4. 4 · Other tropisms. Hydrotropism: roots grow towards water. Chemotropism: the pollen tube grows towards the ovule.
5. 5 · Role of auxin. Made at the shoot tip, it moves to the shady side and makes those cells grow longer, so the shoot bends towards light.
6. 6 · Draw the set-up. [Diagram: flask with germinating seeds on a mesh in a box open on one side; shoots bending to light, roots away]
7. 7 · Link to daily life. A money plant near a window leans towards the light.
8. 8 · Close in one line. Thus plants coordinate their growth with hormones instead of nerves.

Scoring tip: Write positive or negative with each tropism, and name auxin when you explain the bending.