Growth and Movement in Plants

Directional Growth (Tropisms)

Plants may not walk, but they move by growing. This growth is directional, responding to stimuli like light (Phototropism) and gravity (Geotropism).

Activity 10.3: Roots and Shoots

An experiment with seedlings placed in different orientations (upright vs. inverted) helps us understand this.

Observations

1. Upright Plant: Roots grow down, shoot grows up.
2. Inverted Plant:
   • The Root bends and turns downwards (towards gravity).
   • The Shoot bends and turns upwards (away from gravity/towards light).
3. Side Lighting: If light comes from only one side, the shoot bends towards the light.

Visualizing Plant Response

Key Findings

• Roots are positively geotropic (grow down) and negatively phototropic (grow away from light).
• Shoots are negatively geotropic (grow up) and positively phototropic (grow towards light).
• This ensures roots find water/soil and leaves find sunlight.