Define with examples-phototrophism,geotropism,hydrotropism,chemotropism & thigmotropism

Asked by akshaymaan | 10th Oct, 2008, 09:14: AM

Expert Answer:

Phototropism is the direction of growth of a plant in response to the direction of the light. Eg - Movement of shoot of plant upwards towards light.

The movement of a plant in response to gravity is called geotropism. Eg - Root growing downward.

The movement of a plant (or other organism) either towards or away from water is called hydrotropism. An example is that of plant roots growing in humid air bending toward a higher relative humidity level.

The movement of plant towards or away from chemicals is called chemotropism. Eg - Growth of pollen tubes towards ovules.

Thigmotropism is a movement in which an organism moves or grows in response to touch or contact stimuli. Eg. Climbing plants, such as vines, contain tendrils that coil around supporting objects. Also the leaves of Mimosa pudica close up when touched, they fold up and droop.

Answered by  | 10th Oct, 2008, 12:16: PM

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