Question

Discuss the various types of tropic movements.

Answer 1

Tropic movements:

1. Tropic movement is the directional movement of plants in response to various directional environmental stimuli.
2. Tropic movements can occur either in the direction of the stimuli or opposite the direction of the stimuli.
3. Phototropism, geotropism, hydrotropism, chemotropism, and thigmotropism are the common tropic movements exhibited by plants.

Phototropism:

1. The movement of the part of a plant in response to the directional stimulus light is called phototropism.
2. Sunflowers exhibited phototropism.
3. Shoots bend toward the light source and exhibit positive phototropism, whereas roots bend away from the light and exhibit negative phototropism.

Geotropism:

1. Geotropism refers to the growth movement of curvature in plants that occurs in response to the gravitational pull.
2. Since roots grow deep in the soil, they are positively geotropic and shoot negatively phototropic.

Chemotropism:

1. The movement of the parts of a plant in response to a directional chemical stimulus is called chemotropism.
2. A typical example of chemotropism is seen during the fertilization process in plants, where the pollen tube moves towards the ovary.

Hydrotropism:

1. The movement of roots towards an area of a higher water concentration in the soil is called hydrotropism.
2. Roots of a plant are hence, positively hydrotropic.

Thigmotropism:

1. Thigmotropism is the movement of the parts of the plant in response to a touch stimulus.
2. The growing tendril of a plant starts coiling around an object after coming in touch with the object.