Explain two tropic movements with suitable examples

Tropic movements are directional growth responses of plants to environmental stimuli. They can be classified into two main types: phototropism and gravitropism.

Phototropism

Phototropism is the growth of a plant towards light. This movement occurs because plants contain a hormone called auxin, which promotes cell elongation. When light shines on one side of a plant, auxin accumulates on the shaded side, causing that side to grow faster and bend towards the light.

• Example: A sunflower is a classic example, as it turns its head to follow the sun throughout the day.

Gravitropism

Gravitropism, also known as geotropism, is the growth response of a plant to gravity. Roots typically exhibit positive gravitropism, growing downward, while stems show negative gravitropism, growing upward. This ensures that roots anchor the plant and access water and nutrients from the soil.

• Example: When a seed germinates, the root grows downward into the soil, while the shoot grows upward towards the surface.